Display Method:
Articles in press have been peer-reviewed and accepted, which are not yet assigned to volumes /issues, but are citable by Digital Object Identifier (DOI).
Influence of marine organisms adhesion on durability of concrete structures
HE Xiaoyu, LI Tian, SHEN Jian, ZHANG Yajun, XIA Jin, JIN Weiliang
 doi: 10.12170/20190906003
[Abstract](49) [FullText HTML](44) [PDF 791KB](0)
Abstract:
To investigate the influence mechanism of marine organisms on concrete structures, marine organisms were introduced in three categories: marine animals, plants and microorganisms. The corrosion and enhancement mechanisms of marine organisms on concrete structures were analyzed in three categories. Also, the ways of prevention and utilization of the marine organisms were discussed in detail. Through the long term field exposure test of the wharf piles, the distributions of the chloride concentration, concrete resistivity and steel potential in concrete were obtained. The results show that the chloride ion contents at the concrete surface in the splash zone are lower than those of the tidal zone. However, the chloride ion diffusion coefficients of the concrete are fairly close in both of the splash zone and tidal zone. The accumulation of shellfish has both positive and negative effects on the chloride resistance of concrete. On one hand, the chloride ion contents at the surface of concrete covered with shellfish are lower than those without the coverage of shellfish, which indicates that the presence of shellfish might help to reduce the concentration of chloride ions on concrete surface. Shellfish exhibits a physical protection mechanism for the concrete surface, which is beneficial for the prevention of chloride ion ingression into concrete to some extent. On the other hand, the chloride diffusion coefficients of concrete covered by the shellfish are larger than those with the smooth concrete surface. Theoretically speaking, the presence of shellfish may lead to the chemical change of concrete, weaken the chloride resistance of concrete, and eventually accelerate the chloride ion transport in concrete. Additionally, the concrete covered by the shellfish presents the lowest surface resistance, and the reinforcing steel bars embedded in it indicates a relatively negative corrosion potential. Finally, the results demonstrate that the steel reinforcement in the concrete covered by shellfish shows the highest corrosion risk. The existence of shellfish may adversely affect the durability of concrete structures.
Analysis of lateral bearing capacity of wing-monopile with symmetrical wing plates
HE Jianxin, LI Zhi, MENG Xingyu, SU Xiaodong, CHEN Canming
 doi: 10.12170/20191222001
[Abstract](44) [FullText HTML](33) [PDF 858KB](0)
Abstract:
There are many factors that affect the lateral bearing capacity of wing-monopile, among which the number of wing plates, the angle between load direction and wing plates are the main influencing factors. The ABAQUS finite element calculation software was used to calculate the horizontal displacement of the pile at mud surface, tilt rate, internal force, stress and ultimate bearing capacity of 5 m diameter wing-monopile in the soft clay foundation with two, three and four symmetrical wing plates under different load directions. By comparing with the bearing characteristics of monopile under the same conditions, the extent of improvement of the lateral bearing capacity of the wing-monopile was analyzed, the mechanism for the wing plates to improve the lateral load-bearing performance by simultaneously or alternately bearing the end force, side frictional resistance, lateral earth pressure, and increasing the bending stiffness of the pile was clarified, the calculation formula of the lateral ultimate bearing capacity of wing-monopile with two, three and four symmetrical wing plates under load was proposed, and the control conditions of the ultimate bearing capacity of the wing-monopile were compared and analyzed.
Damage analysis of foundation pile of bridge pier under collision of drifting ship after dragging anchor
XU Jingwen, LI Zhi, SU Xiaodong, HE Jianxin, CHEN Canming
 doi: 10.12170/20190905003
[Abstract](11) [FullText HTML](7) [PDF 1495KB](0)
Abstract:
A dredging ship was drifted by flood after dragging the anchor and collided with the bridge pier of the non-navigation hole of the Xunjiang Grand Bridge. According to the investigation of the hydrometeorological conditions, the drifting ship state, the damage status of the accident and the exterior appearance of the damaged bridge pier, the ultrasonic opposite measurement method and the reflected wave method were used to detect the internal damage of the impact area of the concrete bridge pier and the integrity of the pile foundation, and ABAQUS was used to calculate the stress, displacement and damage distribution of the bridge pier under the action of the impact of the drifting ship after dragging anchor to analyze and judge the damage status of the bridge pier in the accident, which provides a technical basis for the subsequent processing. The results show that there was no cracking and obvious damage at the collision of the pier, the connection between the pier and the cover beam was intact, and the upper structure was normally shelved on the pier. There was no obvious damage inside the concrete in the collision area, and the structure of the pile body was intact without obvious defects. High-risk damage existed at the upper left and lower right joints of the beam at the variable diameter area. There was a huge difference between the impact of ship anchoring and ship drifting on the pier, and it can be concluded that the collision did not cause damage to the structure of the pier.
Numerical simulation of crack propagation in gravity dam heel under in-crack water pressure and earthquake action
HU Liangming, LI Shuyu, JIA Xin, YANG Xu
 doi: 10.12170/20190907001
[Abstract](11) [FullText HTML](7) [PDF 799KB](0)
Abstract:
Aiming to study the influence from the collective effect of the pressure between earthquake and water in the construction joint to the gravity under various working conditions, we took advantages of extended finite element method (XFEM) and interaction integral theory to build a mathematical model of dam crack fracture under the collective effect of water pressure in the construction joint and earthquake, with Koyna gravity dam as an example. During the process, the effects of different dam foundation and dam elastic modulus ratios, length of initial crack and joint surface water pressure distribution on dam crack propagation were studied as well. It is proved by the calculation results that the expanded length of crack gets weakened with the increase of the dam base to dam body elastic modulus ratio on the condition that the crack water pressure distributes evenly and initial length of crack is fixed; when the elastic modulus ratio of dam and dam base is certain and the crack water pressure distributes evenly, the crack propagation route gradually increases with the increase of the initial length of crack and gradually approaches the dam base surface; when the elastic modulus ratio of the dam foundation and the dam body as well as the initial crack length are fixed, as the water pressure of the construction joint coefficient increases, the crack expanding length gradually decreases, and the crack gradually expands to the rock foundation.
Deformation forecasting model and its modeling method of super high arch dams during initial operation periods
HU Jiang
 doi: 10.12170/20190908001
[Abstract](53) [FullText HTML](48) [PDF 1018KB](4)
Abstract:
The dam temperature field has not been stabilized, and the time dependent effect does not increase non-monotonously for super high arch dams during initial operation period. Therefore a special deformation monitoring and forecasting model was developed, and its modeling method was proposed in the study. The key temperature measurement points were chosen by the hierarchical clustering on principal component method, and the corresponding time series were inputted as thermal predictors. The combined time dependent effect, including creep and its restoration, was introduced as time dependent deformation. This time dependent effect was employed to validate its characterization for the valley contraction deformation. Considering the predictor variables such as reservoir water level, adopted measured temperatures, estimated time dependent effect, the simple boosted regression tree (BRT) based dam deformation prediction model was constructed. Through the backward elimination method, a simplified BRT (SBRT) model only including major predictors was obtained. The marginal effects of variables on deformation were analyzed, and the relative influences can be quantitatively analyzed. With the help of partial dependence plot, the correlations among variables and the influences of variables on deformation can be explored, and the deformation mechanism can be revealed. The model was applied to a super high arch dam, and the case study verified the feasibility of the model. The results were compared with those by the support vector machine model and the traditional multiple regression models, which shows the superiority of the developed model.
Effect of internal crack defects on fracture properties of concrete
WANG Siyao, HU Shaowei
 doi: 10.12170/20190923001
[Abstract](54) [FullText HTML](49) [PDF 1133KB](1)
Abstract:
Concrete beams with different types of horizontal crack defect were designed and tested through the three-point bending test to investigate the influence of internal crack defect on the fracture behavior of concrete. The effects of different lengths, locations, and numbers of horizontal crack defects on the fracture performance of concrete were analyzed. The fracture parameters and fracture energy of the concrete within different crack defects were calculated and compared on the basis of P-Dm and related test data. Results show that the initial cracking load and initiation fracture toughness of the concrete beams were slightly affected by the internal horizontal crack defects, whereas unstable load and fracture toughness were seriously affected by the additional horizontal crack defects. A large horizontal crack length and a small distance between the horizontal crack and the bottom of the beam corresponded to a small carrying capacity of the beam and a small unstable fracture toughness and fracture energy. The more the horizontal cracks in the concrete beams were, the smaller the unstable load and the unstable fracture toughness were and the smaller the fracture energy was. This phenomenon shows that the larger the material loss caused by crack defects in the concrete beams, the smaller the energy consumed by complete fracture and the smaller the fracture parameters measured.
Study on the superposition effect of hydraulic fluctuation in the lower approach channel of the Three Gorges Project
CHENG Long, LI Yun, AN Jianfeng
 doi: 10.12170/20190811001
[Abstract](162) [FullText HTML](108) [PDF 1155KB](1)
Abstract:
Hydraulic fluctuation generated by the operation of the project would superpose in the lower approach channel of the Three Gorges Project. To explore the superposition law, we established a mathematical model of the lower approach channel of the Three Gorges Project and the river course between the Three Gorges Dam and the Gezhouba Dam using Preissmann four-point implicit difference scheme, based on the basic equations of unsteady flow in open channel. In this study, the superposition law of water level fluctuation in approach channel was studied, and the influence of channel base flow and initial water level on fluctuation characteristics was analyzed. Under the conditions of constant flow rate or discharging openly of the Gezhouba Project, the regression analysis of water level fluctuations at the lower approach channel entrance of the Three Gorges Project and the lower head of the ship lift was carried out. The results indicated that the water level fluctuation at the lower approach channel entrance resulted from the superposition of the average water rise caused by the net flow between the two dams and the oscillating process around the average water rise. The water level fluctuation at the lower head of the ship lift resulted from the superposition of the water level fluctuation at the lower approach channel entrance and the reciprocating flow wave in the lower approach channel. The attenuation degree of the relative fluctuation amplitude decreased exponentially with time. The expression obtained from the regression analysis could effectively obtain the fluctuation process of water level in the approach channel. The model had high precision.
Deformation simulation and stability analysis of frame seawall
ZHENG Anxing, MAO Qian, ZANG Zhentao, ZHOU Jianfen, JIANG Ning
 doi: 10.12170/20190806002
[Abstract](145) [FullText HTML](103) [PDF 829KB](2)
Abstract:
Taking Wenzhou frame seawall as the background, the finite element strength reduction method is used to analyze the influence of the structural parameters of dense row piles and the erosion around the pile foundation on the deformation and stability of the frame seawall. The results show that with the increase of the length of dense row piles, the horizontal displacement of dense row piles decreases; the influence of the diameter of dense row piles on the horizontal displacement of piles is small; the spacing of dense row piles has little effect on the horizontal displacement of piles; and the horizontal displacement of dense row piles increases with the increase of erosion depth around piles. The maximum locations occur at the top of the pile. With the increase of the length of dense row piles, the overall stability safety factor of frame seawall increases; with the increase of the diameter of dense row piles, the overall stability safety factor of frame seawall increases; when the spacing of dense row piles is 2.1 m, the overall stability safety factor of frame seawall is the smallest.
Optimization of water exchange based on RBF surrogate model and particle swarm optimization
QI Lan, ZHENG Shihao, ZHANG Conglin
 doi: 10.12170/20190724002
[Abstract](212) [FullText HTML](119) [PDF 865KB](3)
Abstract:
Good water exchange is very essential, not only for improving the water environment, but also for enhancing the landscape effect around the water. The diversion replacement method is significant for promoting water exchange. However, the numerical simulation method used to carry out water exchange research operates at a high time cost with low calculation efficiency. Moreover, artificially changing parameters have numerous limitations and are not conducive for finding the optimal water exchange scheme. To solve this problem, we established the optimization model of water exchange based on the radial basis function (RBF) surrogate model and used the particle swarm optimization to find the optimal solution for the surrogate model. To verify the feasibility and superiority of the method, we established an RBF surrogate model based on the initial plan of the harbor pool of an artificial island yacht villa and solved it. This example showed that: (1) The water exchange optimization model based on the RBF surrogate model had high precision. (2) The order of time required by the water exchange optimization model based on the RBF surrogate model was in seconds, while the order of time required by the traditional numerical simulation was in hours. (3) The particle swarm optimization, used to solve the established water exchange optimization model based on the RBF surrogate model, obtained the optimal water exchange scheme for the study area. The results were compared with the optimal scheme results obtained through the surrogate model where the difference between the two is negligible.
Effect of complicated river boundaries on the cycle of landslide surge
WANG Meili, ZU Fuxing, XU Jiqing, WANG Pingyi, HAN Linfeng
 doi: 10.12170/20190731002
[Abstract](9) [FullText HTML](6) [PDF 938KB](0)
Abstract:
Landslide surge can cause huge damage to the area of surge generation and propagation. The effect of the river boundary on the landslide surge in a river-type reservoir will result in wave superposition. In order to study the effect of river boundary on the surge period of landslide, a 3-d numerical model of landslide surge is established based on the FLOW-3D computational fluid dynamics software, using a physical model which is identical to the prototype of a river section in Wanzhou in Three Gorges Reservoir area. The methods of numerical solution, mesh generation and boundary condition setting are given, and the consistency of the three-dimensional mathematical model is verified by physical model test results. According to the three working conditions that the water entry point of the landslide body is located in the straight section of the river channel, at the crest of the convex bank and at the crest of the concave bank of the curved channel, the relation graphs of spectrum intensity and frequency are drawn. The influence law of the complicated river boundary on the surge period of the landslide is analyzed, and the effects of different bank slopes, curvature of curved concave bank, arc angle of concave bank and arc angle of convex bank on swell period are obtained.
Stability analysis of complex double-sided slope
PAN Chi, LI Sa
 doi: 10.12170/20190730001
[Abstract](550) [FullText HTML](119) [PDF 1788KB](3)
Abstract:
In practice, slopes often have complex geometries. Therefore, the 3D finite element analysis with strength reduction method was used to study the safety factors and failure characteristics of double-sided slopes which have concave or convex structures with different gradient combinations under three boundary conditions, and the results are compared with those of flat slopes. It is shown that comparing with the flat slope, the safety factor of the convex vertical side slope is less than that of the flat slope. For other convex slopes, the safety factor under rough-rough boundary is increased by about 3%. However, for concave slopes, the safety factor is higher than that of the flat slope, and the safety factor of the curved surface slope with 1∶2 gradient under rough-rough boundary condition is the largest, and is higher than that of the flat slope by nearly 10%, and about twice as much as that of other structure of concave slopes with the same gradient. When the gradients of two sides are different, the slope will slip along the side with the large slope angle. When the gradients of two sides are equal, the slope failure area is affected by the boundary condition type. Under smooth-rough conditions, the sliding failure occurs on the constrained side, while under the other two boundary conditions, the failure area is symmetrical.
Preliminary study on evolutions of Yangtze River and Dongting Lake water and sediment fluxes exchanges based on MLP method
JIA Yalan, SHI Yong
 doi: 10.12170/20190627001
[Abstract](6) [FullText HTML](2) [PDF 845KB](0)
Abstract:
This study establishes the regression relationship among key nodes of water and sediment exchange in the Yangtze River and Dongting Lake on the basis of MLP (Multi-layers Perceptrons) method and calculates and analyzes the linkage changes of nodes between the Yangtze River and Dongting Lake. This study draws the following conclusions: (1) Analysis of changes of water and sediment flux in the three outlets and the main stream after Jingjiang artificial cut off shows that the riverbed erosion and water regime change in the Chenghan River section is one of the most important links in the water and sediment flux evolution of the Yangtze River and Dongting Lake. The serious sedimentation of the Chenghan River section leads to the discharge of water and sediment in Jingjiang blocked. (2) After the application of the TGP (Three Gorges Project), the flow and sediment relations between the upper and lower reaches, the mainstream and tributaries of the Jingjiang are weakened in a relatively prominent degree. (3) When the water level of Hankou is higher than 26 m, the flow increase of Luoshan is basically stable when the water level of Hankou has a rise of 1 m. The stable value is 4,400 m3/s, 4,300 m3/s, 4,500~4,700 m3/s and 4,000 m3/s respectively before and after the sluice construction of Tiaoxian outlet, after the Jingjiang cut off, after the interception of Gezhouba and the operation of the TGP. (4) The response of water and sediment discharge capacities of the three outlets of Jingjiang to Yichang's inflow is weakened gradually. During time intervals before the application of TGP, the response of water and sediment discharge capacities of the three outlets to Yichang's inflow is the strongest when the water discharge of Yichang is 35,000 m3/s in the flood season. After TGP is applied, the response is the strongest when the water discharge of Yichang is 25,000 m3/s before and after the flood season.
Dimension-reduction simulation for continuous random wave force field
LÜ Kangxuan, LIU Zhangjun
 doi: 10.12170/20190505002
[Abstract](7) [FullText HTML](6) [PDF 953KB](0)
Abstract:
According to the power spectral density (PSD) of the horizontal velocity and acceleration process for water mass point, the PSD function of random wave force is derived from the point of view of auto-correlation function for the stationary stochastic process using the linearized Morison equation. Then, based on the original spectral representation for the stationary random process, the standard orthogonal random variable set is defined as the form of orthogonal functions only containing one elementary random variable, which realizes the dimension-reduction simulation of the continuous stochastic wave force field. Meanwhile, combined with the fast Fourier transform (FFT) technology, the fast algorithm of dimension reduction simulation for the continuous stochastic wave force field is given. In the end, the random wave force acting on a small-scale straight cylindrical pile is simulated as an example. This paper provides the numerical characteristics of the method, such as mean, standard deviation, autocorrelation functions and cross-correlation functions, and the calculation results of the proposed method are compared with the Monte Carlo method. The research shows that the proposed method has a higher simulation accuracy and efficiency, which verifies the validity of the proposed method.
Analytical calculation of cnoidal wave diffracted force on a V-shaped breakwater
CAI Hantao, HUANG Hua, SU Wei
 doi: 10.12170/20190608001
[Abstract](263) [FullText HTML](174) [PDF 1129KB](4)
Abstract:
With the use of cnoidal wave theory, the theoretical solutions to shallow water wave diffraction by a V-shaped breakwater are derived, so the existing Airy small amplitude wave theory is effectively extended. By calculating the shallow water wave forces on the V-shaped breakwater, the law of cnoidal wave action on the breakwater has been revealed. The results show that the maximum dimensionless wave forces on the breakwater are obviously larger than those predicted by small amplitude wave theory under the same shallow water conditions. The reflected wave theory on the infinite long vertical thin-walled breakwater is effectively extended by using the method in the paper. The variation of incident wave angle, breakwater angle and ratio of breakwater arm length and water depth may have some related influence on wave effects and the practical maximum diffracted wave forces will increase as the shallow water wave characteristic parameter value increases.
In-situ ground motion parameters test for silty clay and back analysis of model parameters
GU Weijie, FAN Mingqiao, JI Enyue, QIAN Bin, ZHANG Xinggang
 doi: 10.12170/20190925001
[Abstract](42) [FullText HTML](37) [PDF 1271KB](2)
Abstract:
In order to solve the problem that in-situ ground motion parameters are difficult to obtain, the in-situ ground motion parameters test system, which includes a mobile system, a load servo system, a dynamic response system, and a data acquisition system and has a wide range of applications, strong controllability and high reliability, was developed to carry out the test of field nonlinear shear modulus of silty clay in Nanjing and obtain the field G-logγ curve and G/Gmax-logγ curve. It is found that when the γ exceeds 0.1%, the G decreases faster and faster, reflecting the nonlinearity and strain accumulation of soil under dynamic loading. In addition, the back analysis of model parameters by genetic algorithm was conducted based on the Martin-Davidenkov model to get the range of model parameters in the shallow soil layer of the test area.
Calculation and characteristic analyses of wind wave fields in the Yangtze Estuary
GENG Haobo, ZHANG Hongsheng, HONG Yangbin, HU Guodong
 doi: 10.12170/20200102003
[Abstract](40) [FullText HTML](45) [PDF 1101KB](0)
Abstract:
The wind wave field near the Yangtze Estuary for 20 years (from 1996 to 2015) is simulated with SWAN nested in WAVEWATCH III, based on the European Centre for Medium-Range Weather Forecasts (ECMWF) wind field data and combining the 1 Minute Gridded Global Relief Data Collection (ETOPO1) with the measured data as the calculated water depth. To simulate the wind waves precisely and improve the calculation efficiency, the sensitivity analyses of calculated significant wave heights during a typhoon and a cold wave are made so that the proper calculation domains and grid mesh types are selected. Comparing with the measured data, the variation tendency of calculated significant wave heights is in agreement with that of observed ones, and the correlation coefficient is 0.82. In order to make the calculated wave heights more correspond to the actual ones, the formula for modifying the significant wave heights at the representative point is provided. The wind and wave characteristics are analyzed statistically on the basis of the wind data and the modified significant wave heights. The results reflect the effects of both season and terrain effectively.
Stress-deformation behavior of a blast-fill dam
HUANG Zhihong, YANG Jie, CHENG Lin, SUN Xiaoning, MA Chunhui
 doi: 10.12170/20190930001
[Abstract](10) [FullText HTML](3) [PDF 1417KB](1)
Abstract:
The stress-deformation behaviour of a blast-fill dam at different stages was examined based on in-situ monitoring data and finite element analysis (FEA). The mechanical behaviour and the impervious structures of blasting rockfill were investigated. Comparative analysis showed that the maximum settlement of the blasting rock occurred at the top of the blasting rockfill. Different from the conventional dam, the maximum settlement is located at 2/3 of the dam. The compressibility of the blasting rockfills and the slope deposit were the main factor for their large settlement. The numerical simulation was used to analyse the influence of stress-deformation behaviour of impervious structures. The results showed that due to the complex composition of the dam material and the large difference in the mechanical properties of the material, some uneven settlement of the dam occurred locally. Large deformation and stress occurred at the reverse arc below the 700.00 m platform, which was a greater impact on the deformation of the asphalt concrete wall. The rise of the water level caused a great change in the stress-deformation behaviour of the asphalt concrete wall, and the stress-deformation of the impermeable body increased significantly. The above summary is a comprehensive and true reflection of the operational behaviour of the blasting rockfill body, dam body and impervious structures of the blast-fill dam. The findings of this study are of great value for the study of the safety state of high face rock-fill dam, soft rock dam, slag field, landslide and quake lake.
Different filter design criteria and their applications to reservoir design in mountainous areas of southern Ningxia
YANG Peiyao, WANG Hongyu, ZHANG Gang, HE Jinsha
 doi: 10.12170/20191227001
[Abstract](6) [FullText HTML](4) [PDF 754KB](0)
Abstract:
Seepage is one of the main causes of embankment dam failures, whereas the seepage failures in hydraulic structure can be prevented by reasonable installation of filter layers. For the purpose of evaluating the effectiveness of protective filters for the loess base soils by using different filter design criteria, and finding out an appropriate one for the hydraulic structures in the loess hilly mountainous area, this paper takes the embankment dam filter system of Qiaojiagou reservoir in the mountainous area of southern Ningxia as an example. Four different grading curves were choosing from those paralleled grading curves within the upper and lower envelope of the actual filter material grading curve, whereby the characteristic particle sizes of the these curves and base soil curves were calculated. Then seven filter design criteria were applied to these grading curves and their applicability to the project were analyzed. The results show that with respect to silty clayey loess acted as protected base soil, the current conducting Chinese filter design criteria Design Code for Rolled Earth-Rock Fill Dams (SL 274—2001) has a broad application range and an excellent performance within the upper and lower envelope of the grading curve of filter material in Qiaojiagou reservoir project, meanwhile the filtering and draining conditions satisfied well.
Numerical simulations of the group effect of large-diameter columns in regular waves
GAN Guixuan, SUN Liang, YUE Lei, HAN Songlin
Accepted Manuscript  doi: 10.12170/20191006001
[Abstract](54) [FullText HTML](51) [PDF 1106KB](1)
Abstract:
Structures with multiple columns are widely used in ocean engineering, wave loads on large-diameter columns in a group are quite different from the isolated ones. In present study, a three dimensional hydrodynamic code DIFFRACT based on potential flow theory is used to calculate wave loads on a single circular cylinder and twin circular cylinders. The accuracies of numerical results are verified by comparing with the corresponding analytical solutions. The wave loads on multiple circular columns in regular waves have been further investigated. Multiple peaks have been found in the results due to the hydrodynamic interactions between columns, which can reach 2.30 times of wave loads on isolated column. The locations of columns with maximum loads are affected by the layout of the group.
Three-dimensional numerical simulation analysis of landslide surge in reservoir area
DENG Chengjin, DANG Faning, CHEN Xinzhou, YUAN Qiushuang, CHEN Lili
Accepted Manuscript  doi: 10.12170/20191125002
[Abstract](50) [FullText HTML](56) [PDF 951KB](3)
Abstract:
Aiming at the 3 # deformable body landslide surge in a reservoir area, this paper uses three-dimensional numerical simulation to analyze the landslide surge propagation process in the reservoir area, and the effect of grid size on the accuracy of numerical analysis calculations is studied. Meanwhile, a 1:280 hydraulic physical model test is established for verification, and those results are compared with the surge height calculated by the Pan's method. The results show that the calculation accuracy of numerical analysis is related to the model grid size, the severity of the swell, and the distance of the swell. The three-dimensional numerical analysis and model tests have basically the same trend of the swell height. When the surge wave spreads to the front of the dam, the error of the surge height obtained by various methods is small, and the numerical analysis results can be used as the basis for evaluating the dam safety impact. The swell formed by 3# deformation body surpassed the dam crest by about 8.37m at the 4th peak (t=151s), only 3.3% of the maximum dam height, and the overflow was limited, which would not pose a threat to dam safety.
3D simulation of stress wave propagation in jointed rock mass with filling joint
DING Yingxun, WANG Zhiliang, HUANG Youpeng
 doi: 10.12170/20190529001
[Abstract](7) [FullText HTML](4) [PDF 1413KB](1)
Abstract:
In order to study the propagation characteristics of stress wave in rock mass with filling joints, the 3d Dimension Distinct Element Code was used to explore the influence of different occurrence joints on the penetration and reflection rules of P wave. First, the computational model of three-dimensional jointed rock rods is established, and the transmission boundary and Rayleigh damping are reasonably selected. Then, the calculated results are compared with the theoretical solutions of equivalent wave impedance to verify the rationality of the model. Finally, the variation characteristics of P wave transmission and reflection coefficient at different joint angles, thicknesses, spacing, Numbers and incident wave frequencies are considered. Results show that in 0~60°, the transmission coefficient decreases with the increase of the joint inclination azimuth beta, in 60°~90° with the increasing of beta. The transmission coefficient decreases with the increase of the incident wave frequency, while the reflection coefficient decreases. If the proportional relation between joint spacing and thickness is defined, the transmission coefficient increases with the increase of joint spacing, while the reflection coefficient decreases. In addition, according to the number of joints under different thickness of the joint and transmission (reflection) shot coefficient curve characteristics, define its envelope for critical transmission (reflection) curve. Then, when the number of joints is given, the total number of its reflection coefficient is large (small) on the critical reflection curve.
Current situations of thermal insulation and ice resistance technology of dam concrete in China under cold environment
ZHAO Chengxian, SUN Hongyao, PAN Xuyong, LUO Jianhua, PEI Chengyuan, LI Hongxin
 doi: 10.12170/20200106003
[Abstract](3) [FullText HTML](3) [PDF 882KB](0)
Abstract:
During the construction of dam with mass volume concrete, the higher temperature difference between the inside and outside of concrete will cause the cracking of concrete. During the operation of dams under cold environment, the freezing and thawing process of ice will cause the expansion and cracking of concrete. Therefore, temporary thermal insulation measures must be taken when pouring the concrete dam, and permanent thermal insulation measures must be taken when operating the dam. Since the thrust force, shear force and drawing force in the process of water icing will damage the thermal insulation materials at the upstream of the dam, ice resistance measures are indispensable. This paper reviews the current situations of thermal insulation and ice resistant technology of domestic concrete dams under the cold environment from the aspects of insulation materials, ice resistant technology, application cases and survey results. It is concluded that foam plastics are used as temporary thermal insulation materials, and polystyrene and polyurethane foam plastic are used as permanent insulation materials for dam. Anti-ice devices and coatings or mortar coated on the surface of insulation materials are used to resist ice damage, but the ice resistant technology is still in infancy by now. At last, this paper puts forward the existing problems and the contents to be further studied in current thermal insulation and ice resistance technology of dams.
Experimental study on the strength behavior of EHP
DU Xuqing, WENG Jiaxing, BIE Xueqing, SONG Miaomiao, QIU Chengchun, LI Hui
Accepted Manuscript  doi: 10.12170/20191213001
[Abstract](39) [FullText HTML](19) [PDF 931KB](2)
Abstract:
An improved soil-cement mixing pile construction method was developed to solve the issues such as uneven distribution of pile strength and poor pile quality appeared in the traditional mixing while drilling method. Based on the new method, an Environmental-friendly and Homogeneous Plastic (EHP) pile was formed following the procedure that cement-soil slurry mixture was blended outside the drilling hole before being mixing while drilling, which enable the operation controllable and adjustable. In this study, a series of unconfined compression tests were conducted on cement-soil samples prepared in the laboratory and field to evaluate the strength characteristics of EHP piles with various cement contents. The quantitative relationships between the unconfined compressive strength and different shapes were established. The strength reduction coefficient was employed to analyze the reduction in the unconfined compressive strength for in-situ EHP piles. Results indicate that the uniformity and strength of EHP plies are better than those constructed using the traditional construction technology. The improved construction technology can reinforce soft ground within greater depth. Compared with the samples made in laboratory and cured under standard conditions, a reduction in unconfined compressive strength of cement-soil mixing pile was found. The reduction coefficient RP of strength was introduced to evaluate the reduction in strength of EHP piles. Results showed that the value of RP decreases with the increasing cement content and RP is in the range of (0.55, 0.75). Compared with the pile constructed using traditional method, the reduction in unconfined compressive strength for EHP pile is relatively small indicating a better bearing capacity.
Rock strength and deformation characteristics under different unloading rates
QIAN Yajun, WU Yingli, PEI Weiwei, ZHU Yueyan
 doi: 10.12170/20200428001
[Abstract](49) [FullText HTML](42) [PDF 967KB](3)
Abstract:
The excavation of rock mass engineering is essentially the unloading process of rock mass, different unloading rates will significantly affect the strength and deformation characteristics of rock mass, which is of great significance for the safety and stability analysis of rock mass engineering. For modeling various unloading stress paths in the rock mass excavation, the ordinary triaxial compression test, constant axial pressure unloading confining pressure test, loading axial pressure unloading confining pressure test, and constant principal stress difference unloading confining pressure test were conducted in this paper. The effects of different unloading rates on the mechanical properties of rock mass were analyzed, the main conclusions are as follows: (1) Rock shows typical brittle failure characteristics under different unloading paths and different unloading rates, when the confining pressure decreases to a certain value, the rock sample suddenly fails, the axial pressure drops sharply, and the circumferential strain ε3 increases significantly. (2) If the confining pressure unloading rate is high, when the rock sample is near failure, the deformation modulus E decreases linearly almost at a 90° angle, and Poisson's ratio μ increases linearly almost at a 90° angle. If the unloading rate is low, the decreasing/increasing trend of E and μ is relatively slower. This shows that the brittle failure of rock sample is more obvious with the increasing unloading rate of confining pressure. (3) The stress state of rock samples under the three unloading paths are basically below the strength envelope of ordinary triaxial compression Mogi-Coulomb, which shows that the rock sample under confining pressure unloading is more easily damaged than that under normal triaxial compression.
Multi-scale analysis of precipitation in the Beijing-Tianjin-Hebei urban agglomeration in the past 55 years
CAO Yongqiang, LU Jie, LIU Mingyang, LI Linghui, NING Yue
Accepted Manuscript  doi: 10.12170/20191019001
[Abstract](49) [FullText HTML](35) [PDF 1971KB](0)
Abstract:
Based on the daily precipitation data of 25 meteorological stations in Beijing-Tianjin-Hebei urban agglomeration from 1964 to 2018, this paper uses the method of anomaly, Mann-Kendall test, linear fitting and spatial interpolation analysis to obtain precipitation from many years and precipitation during the year. And the precipitation of Beijing-Tianjin-Hebei urban agglomeration is analyzed from three aspects: average precipitation, annual precipitation distribution and extreme precipitation. The results show that: (1) The average annual precipitation in the Beijing-Tianjin-Hebei urban agglomeration fluctuated significantly, showing no significant decrease. The space is characterized by “less east, more west, less south and less north”, the precipitation variation coefficient is between 0.14-0.41. Yanshan Mountain and Haihe Plain have larger variation coefficient and higher dispersion. (2) The precipitation in the Beijing-Tianjin-Hebei urban agglomeration showed a trend of concentration during the year. The spatial performance is characterized by a gradual decrease from the northeast to the southwest. The precipitation is mainly concentrated in the late July, and the concentration period shows a trend of not significantly premature. The space shows a trend of increasing from the north to the south. (3) The extreme precipitation in the Beijing-Tianjin-Hebei urban agglomeration is 129.57-252.68 mm, accounting for 28.6%-47.9% of the total precipitation.The spatial distribution of extreme precipitation is the same as that of annual precipitation, and only 7 meteorological stations have a stable trend.
Effect of reinforcement ratio on acoustic emission characteristics during Ⅰ-Ⅱ mixed-mode fracture process of concrete
GONG Nina, HU Shaowei, FAN Xiangqian, CAI Xiaoning
Accepted Manuscript  doi: 10.12170/20191225002
[Abstract](7) [FullText HTML](4) [PDF 8167KB](0)
Abstract:
In order to study the effect of reinforcement ratio on fracture property and acoustic emission characteristics of Ⅰ-Ⅱ mixed-mode fracture in concrete, four groups of three-point bending beams with a straight offset notch in reinforced concrete were carried out for Ⅰ-Ⅱ mixed-mode fracture experiments and collection of acoustic emission signals. The test results were analyzed. The results showed that with the increase of reinforcement ratio, the unstable load increased approximately linearly, and reinforcement ratio can influence Ⅰ-Ⅱ mixed-mode fracture mode of concrete. There were several peaks in the ringing counts during the stable fracture propagation. The abrupt change of the cumulative counts could represent the critical states of Ⅰ-Ⅱ mixed-mode fracture, and the three parameters had strong correlation. The peak frequency points of acoustic emission concentrated in different frequency bands. Starting from the 85% load level, the proportion of frequency band in 140~155 kHz decreased, while proportion of frequency band in 30~45 kHz increased. When specimens approached the unstable critical state, the peak frequency distribution tended to disperse.
Improved Green-Ampt infiltration model of soil slope considering inclination
LEI Wenkai, DONG Hongyuan, CHEN Pan, Lü Haibo, MEI Guoxiong
Accepted Manuscript  doi: 10.12170/20191027002
[Abstract](7) [FullText HTML](5) [PDF 1055KB](0)
Abstract:
In view of the fact that the traditional Green-Ampt infiltration model ignores the influence of slope angle and unsaturated zone of soil on the rainfall infiltration of slope, the gradient of infiltration potential energy of soil was modified by using the slope angle, and the soil was divided into saturated layer, transition layer and non humid layer during infiltration. Then a new model based on stratified assumption considering inclination was established. The relationship between infiltration depth and rainfall duration was ascertained and the new model was compared with the traditional GA model through an infiltration example. The results show that the surface runoff initiation time and the relationship between wetting front depth and rainfall duration predicted by the new model are closer to the measured values than those by the GA model. In the stage of free infiltration, the wetting front depth of the new model is the same as that of GA model, but the infiltration rate of the new model is lower than that of GA model. In the stage of ponding infiltration, the wetting front depth and infiltration rate of the new model are higher than those of GA model, and the difference of wetting front depth increases gradually with the increase of rainfall duration, while the change of difference between infiltration rates shows the opposite trend. According to the new model, the influence of slope inclination and rainfall intensity on rainfall infiltration is analyzed. It is found that the rainfall duration required for rainwater infiltration into the same depth of slope increases with the increasing slope inclination or the decreasing rainfall intensity, which is especially obvious when the inclination is more than 60° or the rain intensity is less than 20 mm/h.
Study on water content and dynamic mechanical properties of fly ash concrete under water confining pressure
LIANG Jia, WANG Qianfeng, ZHANG Xiuwen, XIAO Yang
Accepted Manuscript  doi: 10.12170/20191010002
[Abstract](47) [FullText HTML](39) [PDF 991KB](0)
Abstract:
In order to study the effect of fly ash on the water content and dynamic mechanical properties of concrete under water confining pressure, different concrete test specimens (F00, F20, F40) with fly ash contents of 0%, 20%, and 40% were made. The dynamic compression tests under water confining pressure (1, 3 and 5 MPa) and different strain rates (10-5, 10-4, 10-3 and 10-2/s) were conducted. Dynamic compression tests of dry concrete specimens in atmospheric environment were carried out as well. The effects of water confining pressure and fly ash content on concrete moisture content are analyzed, and the relationship between fly ash content, water confining pressure and strain rate and concrete dynamic strength is further studied in combination with water content data. The research results show that: ①Under the same fly ash content, the water content of concrete shows a trend of first increase, then decrease, and then increase with the increase of water confining pressure. Under the same water confining pressure, F00 concrete has the largest water content, followed by F40 concrete. F20 concrete is the smallest, indicating that the amount of fly ash has a significant effect on the water content of concrete. ② A cubic function is used to describe the relationship between the water content of different fly ash concrete and the water confining pressure. ③ Under different water confining pressure conditions, the increase value of concrete dynamic strength corresponding to the unit volume of water content of fly ash concrete is a quadratic function relationship with strain rate, and the relationship between dynamic strength increase value of fly ash concrete and strain rate under different water confining pressure conditions is established.
Turbulence characteristics in open channel with glass-sphere quincunx arrays
ZHONG Liang, GE Chenxi, SUN Jianyun
Accepted Manuscript  doi: 10.12170/20191026002
[Abstract](47) [FullText HTML](37) [PDF 1271KB](0)
Abstract:
The quincunx array is a common structure appearing on rough bed surfaces. However, the study on the variation of flow turbulence characteristics between particles and the distribution of different quadrants is still weak. Using round glass beads of different sizes, three different quincunx arrays with arrangements of different intervals were made. From the particle-image-velocimetry (PIV) data of turbulent flow over these arrays in an open channel flume, the distributions of the dimensionless longitudinal turbulence intensity Tu, Reynolds stress R, and turbulent kinetic energy E were analyzed. They show that the area above the top of the beads features a strip-shaped change indicating the beads have little influence, whereas in the area below the tops, the beads have a greater influence. The vertical distribution of Tu, R and E is relatively complex displaying a certain periodicity and regionality that permits a classification into sphere region (SR) and inter-sphere region (ISR). The vertical distribution of Tu, R and E above the top of the particle basically coincides with each other, while the vertical distribution of Tu, R and E below the top of the particle fluctuates obviously, and the distribution curve are shaped like an “S” and an inverted “L”. The longitudinal variations of R and E of different quadrants in the ISR are smooth and close to constant, the values of R and E in the 2nd, 4th quadrant are generally greater than those of the 1st, 3rd quadrant. However, in the SR, the distribution of R and E showed a ∪-like shape and there are minimum values near the position of x+ = 0. The research results have a certain guiding significance for the design of fishway and waterway engineering.
Application of fuzzy set pair analysis method based on entropy weight in flood season staging of Xiluodu Reservoir
LIU Qiankui, WANG Wensheng, YU Siyi, WANG Ning
 doi: 10.12170/20191205001
[Abstract](42) [FullText HTML](41) [PDF 508KB](0)
Abstract:
Xiluodu Hydroproject is an important part of the Yangtze River flood-control system. It is necessary to explore the reasonable flood season staging of Xiluodu Reservoir and its flood control regulation for improving the flood control capacity and utilizable water benefit, and realizing the safe utilization of flood water resource in Jinsha River Basin. The hydrometeorological factors affecting the flood season staging of Xiluodu Reservoir are collected and determined in this paper, and then the fuzzy set pair analysis method based on entropy weight is established. The flood season of Xiluodu Reservoir is divided into secondary flood season, transitional flood season and main flood season by using the established method. Finally, compared with the results from the fuzzy set analysis method and set pair analysis method. The comparison show that the fuzzy set pair analysis method based on entropy weight is simple and practical, which can objectively reflect the impact of the characteristics of the rainstorm and flood in Jinsha River Basin on the flood season. The results of the flood season staging are basically consistent with the conclusions of the fuzzy set analysis method and the set pair analysis method, which proved that the staging is reasonable. The proposed fuzzy set pair analysis method based on entropy weight is scientific and effective in flood season staging, which provides the precondition for the establishment of dynamic limited flood water level in reservoir flood season.
Numerical analysis of wave run-up characteristics on dual non-submerged vertical cylinders system
CHEN Haomin, NI Yunlin
 doi: 10.12170/20191018004
[Abstract](53) [FullText HTML](27) [PDF 931KB](1)
Abstract:
Wave run-up is an important parameter in offshore structures and ocean platforms design. A comprehensive understanding of its characteristics benefits the structural safety and design optimization. In this paper, a numerical model is set up to solve the mild slope equation proposed by Berkhoff using the finite element method. The computational results of wave height distribution around the single non-submerged vertical cylinder match with the analytical solutions very well, verifying the validity of the numerical model. Subsequently, the effect of the spacing between two cylinders on wave run-up is investigated by observing the dual non-submerged vertical cylinders system. The numerical results show that the curve of wave height distribution around the upstream cylinder has a big fluctuation. However, the positions of maximum and minimum wave height are the same as the single cylinder case. When the spacings are odd times of 1/4 incident wavelength, the minimum wave height decreases obviously and the secondary peak appears on the shoulder of the cylinder; while when the spacings are even times of 1/4 incident wavelength, the minimum wave height obviously increases and the secondary trough appears on the shoulder of the cylinder. The curve of wave height distribution around the downstream cylinder is similar but smaller than the single cylinder case.
Analysis of the influence factors on the compressive properties of cement solidified zinc contaminated soils
DAI Yuanzhi, FAN Chengwen
 doi: 10.12170/20191008001
[Abstract](40) [FullText HTML](37) [PDF 771KB](0)
Abstract:
Consolidation tests were carried out to investigate the effects of cement content, zinc ion concentration and curing temperature on the compression coefficient of cement solidified zinc contaminated (CSZC) soil. Regression formula was derived to correlate the compression coefficient of CSZC soil with the above-mentioned three parameters.. The results indicate that the regression formula is able to reasonably predict the compression coefficient of CSZC soil provided that the compression coefficient of CSZC soil under a given combination of cement content, zinc ion concentration and curing temperature is known or the compression coefficient of the soil without contamination is known. In addition, the compression coefficient exponentially decreases with increasing cement content for a given zinc ion concentration, and increases with increasing zinc ion concentration for a given cement content. Moreover, the compression coefficient decreases with increasing curing temperature. The ratio of compression coefficient at different temperature to that at 20 ℃ satisfies the logarithm relationship of temperature.
Study on pore water pressure in concrete under water pressure environment
SUN Bao, PENG Gang, WANG Qianfeng, LIANG Hui
Accepted Manuscript  doi: 10.12170/20190322001
[Abstract](248) [FullText HTML](136) [PDF 764KB](4)
Abstract:
In order to study the change of pore water pressure of concrete in the water pressure environment, the experiment of pore water pressure change of the concrete under different water pressure was carried out. Based on the test data, the transient inversion numerical simulation of pore water pressure variation of concrete under different water pressure is carried out by using the finite element software ANSYS, and the results are compared with the experimental results. The research results show that under the action of water pressure, the change characteristics of pore water pressure of concrete can be divided into three stages: the rapid increase stage, the slow increase stage and the stabilization stage. When the concrete is under the water pressure of 0.875 MPa, the pore water pressure of the concrete reaches the value equal to the applied water pressure for more than 9 h. The variation law of pore water pressure of concrete is in good agreement with the experimental data by using the finite element software ANSYS for numerical simulation.
Display Method:
cover
2020, (4): 0-0.  
[Abstract](11) [FullText HTML](9) [PDF 9661KB](13)
Abstract:
contents
2020, (4): 1-2.  
[Abstract](14) [FullText HTML](7) [PDF 309KB](6)
Abstract:
A parameterized general model of water, ice and snow albedo
YANG Kailin
2020, (4): 1-9.   doi: 10.12170/20200428003
[Abstract](52) [FullText HTML](40) [PDF 1051KB](2)
Abstract:
For frozen rivers and lakes with cold climate and frequent snowfall, the albedo of ice cover and snow cover has great influence on climate and ice thickness change. Using Fresnel theory, it is concluded that pure water and pure water ice can be calculated by the same albedo formula. Then, based on the existing prototype observation data, a general parameterization model of water-ice albedo is proposed. On this basis, referring to the parameterization model of CCSM3 snow-ice daily average albedo, a general parameterization model of water-ice-snow albedo is proposed, considering the latitude, the earth's rotation and the variation laws around the sun, thus making the model very universal. Calculation and analysis show that latitude and date have great influence on the daily average albedo of water, ice and snow, and the albedo varies with the date or month. The higher the latitude, the greater the albedo. Compared with the influence of ice thickness on albedo, the influence of solar altitude angle on latitude and date changes is much greater. The comparison between the calculation results of the general parameterization model of water-ice-snow albedo and the prototype observation results proves that the two are in good agreement, while the calculation results of the existing commonly used albedo model based on ice thickness are far from the observation results.
Application of projection pursuit method in assessment and prediction of water resources carrying capacity
JIN Juliang, YANG Tongzhu, LI Jianqiang, CHEN Menglu, NING Shaowei, ZHANG Haoyu
2020, (4): 10-16.   doi: 10.12170/20190609002
[Abstract](71) [FullText HTML](49) [PDF 624KB](6)
Abstract:
In order to solve the problem of high-dimensional and non-linearity of index data in the comprehensive assessment of regional water resources carrying capacity, the method of projection pursuit was adopted in this study for assessing water resources carrying capacity based on the principle of maximum information entropy, and this method was further applied to assess the spatial distribution in 16 cities of Anhui Province in 2015, and finally the dynamic assessment of Anhui Province from 2005 to 2015 was carried out. The assessment results were combined with the GM (1,1) model to predict the regional water resources carrying capacity in Anhui Province from 2018 to 2020. The results show that in terms of the overall spatial distribution of water resources carrying capacity in 2015, the water resources carrying capacity in southern Anhui was better than that in central Anhui, which was further better than that in northern Anhui. The water resources carrying capacity of the province was basically at a critical point of overload from 2005 to 2015. But the inter-annual carrying capacity was improved year by year. The forecast results show that the water resources carrying capacity of the province maintains a good development momentum from 2018 to 2020, and the overall development trend is toward the excellent capability of loading.
Evolution of drought and flood in the Haihe Rvier Basin for the last 500 years
YAN Xiaolin, ZHANG Jianyun, BAO Zhenxin, WANG Guoqing, GUAN Tiesheng
2020, (4): 17-23.   doi: 10.12170/20190603002
[Abstract](221) [FullText HTML](139) [PDF 1172KB](6)
Abstract:
The study on the evolution of drought and flood in the Haihe River Basin for the last 500 years can provide a scientific basis for regional flood control and drought relief, disaster prevention and mitigation. Based on the dryness/wetness grade data of 11 stations with complete sequence from 1470 to 2000 in the Haihe River Basin, the temporal and spatial evolution of drought and flood has been detected, using the methods of wavelet analysis, power spectrum analysis and empirical orthogonal decomposition. The results show that: (1) the Haihe River Basin has experienced obvious fluctuation of dry (1470-1644) - wet (1645-1898) - dry (1899-2000); (2) from 1470 to 2000, the occurrence of drought/flood has periodicity of 2~7 a, 10.4 a, 19 a, 22 a and 25 a, of which 10.4 a and 22 a are particularly significant; (3) the first mode of EOF analysis is characterized by drought or flood over the whole basin, and its variance contribution rate is 44%. The second mode, explaining 12% of total variance, shows the distribution characteristics of flood-drought-flood (or drought-flood-drought) from west to east.
Security evaluation of water-energy-food nexus system in China
LIU Jing, LIU Cuishan, LI Xiao, WANG Guoqing, BAO Zhenxin
2020, (4): 24-32.   doi: 10.12170/20190603009
[Abstract](484) [FullText HTML](193) [PDF 7314KB](12)
Abstract:
In order to guarantee the safety of China’s water, energy and food, the pressure state response model was applied to evaluate the safety of water-energy-food nexus system in China from 2007 to 2016. 16 representative indexes were selected to construct a collaborative safety evaluation index system of water-energy-food nexus. The analytic hierarchy process (AHP) was used to determine the index weight. Based on data during 2007-2016, the safety of water-energy-food nexus system was assessed at national and provincial levels. The results show that the collaborative security degree of water-energy-food nexus system in China has been rising in the past 10 years. The comprehensive collaborative security degree of water-energy-food nexus system in Beijing, Tianjin and Shanghai is higher than others. However, Ningxia, Xinjiang and Chongqing have low degree of collaborative cooperative security due to shortage in water resources. The level of comprehensive collaborative security in most provinces is higher during 2012-2016 than that in 2007-2011.
Long-term inflow forecast of reservoir based on Random Forest and support vector machine
LI Lingjie, WANG Yintang, HU Qingfang, LIU Dingzhong, ZHANG Anfu, BA Yaquan
2020, (4): 33-40.   doi: 10.12170/20190626001
[Abstract](332) [FullText HTML](164) [PDF 2861KB](11)
Abstract:
Long-term runoff forecasting for the reservoir is of great significance for studying the hydrological regime and guiding the regulations. In this paper, the mean inflow of annual, flood and dry seasons of the Longjiang Reservoir are selected as forecast elements. Random Forest (RF) is utilized to filter key predictors from circulation indices, sea temperature, air pressure and previous monthly runoff. Afterwards, models based on RF and support vector machine (SVM), which are calibrated using particle swarm optimization algorithm combined with cross-validation, are established to predict the inflow of the Longjiang Reservoir. Results show that climate factors in the north-central and western Pacific have generally implemented a greater influence on prediction, while the effect of the pre-monthly runoff is relatively low, however it can be comparable to some climate factors when used to predict runoff in the dry season. The average accuracy of RF and SVM is generally satisfactory, with the qualification rate of simulation and forecast exceeding 85% and the average absolute percentage error less than 15%. SVM shows stronger generalization ability compared to RF in this study case, while the ability of both models in predicting partial extreme inflow remains to be improved.
Calculation and analysis of water footprint of hydropower stations in Yalong River Basin
YU Lei, JIA Benyou, WU Shiqiang, WU Xiufeng, XU Peng, WEI Jinli
2020, (4): 41-47.   doi: 10.12170/20190603003
[Abstract](793) [FullText HTML](156) [PDF 719KB](9)
Abstract:
In order to quantify the effect of hydropower development and utilization for local water resources, this paper introduces the concept of water footprint, taking the cascade reservoirs in the Yalong River Basin as the research object, selecting the total water consumption method, using the measured data for many years, and considering three system space boundaries to calculate the water footprint of seven hydropower stations. The results show that the water footprint of the seven hydropower stations in the Yalong River Basin ranges from 0.01 to 2.91 m3/GJ and the average water footprint is 1.13 m3/GJ, which is smaller than other water footprints of global and national spatial scales. It also means that the utilization efficiency of water resources of hydropower development and utilization in the basin is higher than that of other regions and river basins. The water footprint of the hydropower station is mainly affected by the energy efficiency factor (water surface area of the reservoir area per unit installed capacity) and the topographic factor (the water surface area of the reservoir area and the average water depth ratio of the reservoir area), and the correlation indexes are 0.950 7 and 0.783 1, respectively. However, the evaporation depth and meteorological factors (rainfall and temperature) have less impact on the water footprint of hydropower stations. The water footprint of the hydropower station is related to the setting of the boundary of the space system. It is necessary to select the appropriate space system boundary according to the actual operation of the hydropower station.
Response of riverbed evolution of Yichang-Jianli reach of the Yangtze River to water and sediment conditions of Yichang Station
HU Tengfei, SHI Yong, LUAN Zhenyu, CHEN Liangang, JIN Qiu, CHEN Liming, XU Yifan
2020, (4): 48-56.   doi: 10.12170/2019062004
[Abstract](55) [FullText HTML](39) [PDF 1276KB](7)
Abstract:
Since the first impoundment of the Three Gorges Reservoir (TGR), water and sediment conditions of Yichang station have undergone a significant change, which has triggered a new round of riverbed adjustment of downstream reaches. In this study, regression analysis, mechanism analysis and other methods were used to investigate the response of the riverbed evolution of Yichang-Shashi reach (YSR) and Shashi-Jianli reach (SJR) to Yichang water and sediment conditions before and after the TGR. Results show that the correlation between scouring and silting amount (SSA) of YSR and Yichang water and sediment indexes is stronger than that of the SJR and the correlation of the former reach becomes stronger with time. On a monthly basis, the delayed response of riverbed evolution to Yichang water and sediment conditions cannot be observed for both YSR and SJR. Based on monthly average Yichang discharge, the univariate regression model for SSA can well reflect the riverbed evolution of both river reaches. According to the developed models, YSR riverbed before the TGR shows the pattern of “weak scouring under small discharge and strong silting under large discharge” and the critical Yichang discharge corresponding to the change of state is about 23,500 m3/s. After the TGR, YSR riverbed shows the characteristics of “weak scouring under small discharge and strong scouring under large discharge”. The scouring amount of YSR gradually decreases due to riverbed coarsening. SJR riverbed has the same evolution pattern with YSR riverbed before the TGR. However, its critical Yichang discharge of state change is slightly smaller (about 22,500 m3/s) and its silting amount is larger than that of YSR under the same Yichang discharge. After the TGR, SJR silting amount is slightly larger than that of YSR when Yichang discharge is small, while the former becomes much smaller than the latter when Yichang discharge is large.
Analysis on the characteristics of flow and sediment variation in Qingshuihe River basin of Ningxia
MA Jinguo, ZHENG Yanshuang, ZHANG Xiaohua, FENG Qing, PENG Hong
2020, (4): 57-63.   doi: 10.12170/20200213002
[Abstract](45) [FullText HTML](32) [PDF 853KB](2)
Abstract:
In order to achieve the variant quantity characteristics of flow and sediment in the Qingshuihe River basin in different time periods, including flood and non-flood seasons, inter annual and intra seasonal periods, the variation process of flow and sediment volume is analyzed systematic with the method of applied statistics for filed data. The long-series measured materials contain the flow and sediment data gained at three hydrological stations, namely, Guyuan, Hanfuwan and Quanyanshang sites. The change-point analysis of hydrological time series is implemented with Mann-Kendall method for obtaining the mutation year for each hydrological station. The results indicate that the mutation time of each station is asynchronous for annual runoff and sediment load. Moreover, the amount of water and sediment at each station is decreasing in recent years. Compared with the tendency in the long term, the water volume increased by 10% in 2010−2015 at Quanyanshang station and decreased at other stations. The range of water and sediment reduction is 58.8%~65.7% and 64.3%~94.4%, respectively. 58.5%~65.6% of annual water volume and 85.6%~89.4% of annual sediment volume occur in the flood seasons in the Qingshuihe River basin. The distinction of water and sediment in wet seasons and dry seasons is significant for inter-annual periods. A preliminary analysis is underway for the factors affecting discharge and sediment supply, including rainfall, slope soil-water conservation engineering, reservoir operation mode and silt arrester construction.
Research progress of spatial distribution about geomorphology-vegetation-water erosion in Pisha stone area of Yellow River
SHEN Zhenzhou, YAO Wenyi, XIAO Peiqing, RAO Liangyi, LI Mian, YANG Jishan, JIAO Peng, JING Chengran
2020, (4): 64-71.   doi: 10.12170/20191229002
[Abstract](51) [FullText HTML](40) [PDF 715KB](1)
Abstract:
The soil-covered Pisha stone area is the core source area of coarse sediment in the Yellow River and has become the focal point of ecological control of the Yellow River basin. It is thus vital to study the spatial distribution of erosion coupling between geomorphology, vegetation and water in the soil-covered Pisha stone area. In addition, the negative correlation between the spatial structure of the vegetation community and the energy dissipation impedance of erosion requires further studies. It is necessary to study the differentiation spatial structure characteristics of topography and geomorphology, the differentiation characteristics of vegetation and community, and the differentiation temporal and spatial characteristics of erosion mechanism in the Pisha sandstone area, especially through the study on the factors of the three as a coupling system. We should also study the spatial and temporal characteristics of soil erosion in different landform units, reveal the coupling mechanism between the spatial-temporal characteristics of water erosion in the slope-gully system and those of natural vegetation, and find the spatial coupling mechanism of the landform-vegetation-water erosion in the Pisha stone area. The study will directly affect the theoretical foundation of a comprehensive model for treating soil erosion in the area.
Estimation of non-point source pollution load in core area of Zhangjiakou Winter Olympic Games
ZHANG Ran, XIA Jianxin, REN Huatang
2020, (4): 72-79.   doi: 10.12170/20190822001
[Abstract](148) [FullText HTML](97) [PDF 1150KB](6)
Abstract:
Evaluating the non-point source pollution load is imperative for the water environment safety of the core area of the Zhangjiakou Winter Olympic Games. Using the export coefficient modeling approach, along with the digital elevation model, the 2015 land use remote sensing data, and the 2007–2016 statistical yearbook data, the non-point source pollution output load and spatial distribution were calculated, and the contributions of different types of pollution loads were analyzed. The results were as follows: (1) From non-land use factors pollution source, the annual output of pollution load of TN, COD, TP and NH4+-N were 1,154.25~17,540.39 kg, 2,114.76~34,552.41 kg, 51.29~842.54 kg and 34.40~514.88 kg, respectively. (2) Under different land use types, the output of pollution load of TN, COD, TP and NH4+-N were 33,372.94, 21,453.45, 512.82 and 1,129.78 kg, respectively. (3) The agricultural population life and cultivated land were the major sources of pollution for the output of non-point source pollution loads. (4) The spatial distribution of pollutant output load was uneven. In addition, the output of the upper sub-basin and the downstream sub-basin of Donggou was relatively high. Furthermore, the output load of sub-basin in the middle and lower reaches of the Taizicheng River was relatively high.
Experimental study on frost heaving characteristics of silty clay in Qiqihar region
WANG Enliang, SHANG Shuting, TIAN Yu, LI Xuhui
2020, (4): 80-87.   doi: 10.12170/20200106005
[Abstract](57) [FullText HTML](38) [PDF 1186KB](3)
Abstract:
Heilongjiang Province is affected by cold winter negative temperature, which is easy to cause channel leakage, foundation subsidence, track irregularity and other problems, which increase the difficulty of engineering construction. In order to solve the practical problems, taking the silty clay in Qiqihar region as the research object, the artificial freezing test in the closed system was carried out, and the frost heave test data were measured and analyzed, to investigate the freezing process of soil and the change of the frost heaving ratio under different moisture contents, dry densities, cold end temperatures and freezing rates. The test results show that: under the conditions of high moisture content, high dry density, low cold end temperature, and low freezing rate, the phenomenon of soil frost heaving is more significant, and the frost heaving ratio has a good correlation with the four factors. The results of frost heave orthogonal analysis show that the influence of cold end temperature on frost heaving rate is the weakest, the influence of dry density is strong, and the effect of moisture content is the most severe. Using SPSS statistical analysis software, a multiple linear regression model of frost heave rate is established under the comprehensive influence of moisture content, dry density and cold end temperature. The model has the advantages of good fitting effect, high reliability, high accuracy, meeting the actual needs, simple operation, and can be used for the correlation calculation and prediction of silty clay.
Experimental study on early fracture properties of steam-cured concrete
HU Shaowei, LOU Benxing, YIN Yangyang, YE Yuxiao
2020, (4): 88-95.   doi: 10.12170/20191226004
[Abstract](50) [FullText HTML](34) [PDF 1206KB](9)
Abstract:
To study the early fracture properties of steam-cured concrete, three-point bending (TPB) specimens at different curing time (4 h, 8 h, 16 h, 24 h and 48 h) were tested, and the effects of the curing time on the mechanical and fracture properties of the steam-cured concrete were analyzed. Then, the relationship between fracture parameters and maturity was developed. Based on the digital image correlation (DIC) method, the full-field displacement and strain information of crack propagation were measured, and the damage evolution process of crack propagation was studied. The results indicate that the mechanical properties of steam-cured concrete increase with the curing time in 24 hours followed by a decrease tendency when the curing time is beyond 24 h. The fracture properties of steam-cured concrete increase significantly within 4~8 h of curing time and then rise slowly after 8 h. A good correlation between the fracture toughness and the maturity was observed to provide a basis for the fracture parameters of steam-cured concrete.
Layout principles of hydraulic project in the branch mouth of a tidal river
LI Shouqian, ZHU Mingcheng, ZHU Hao, HANG Dan, LU Yongjun
2020, (4): 96-102.   doi: 10.12170/20190618001
[Abstract](626) [FullText HTML](280) [PDF 775KB](4)
Abstract:
In the inter-basin water transfer project, the hydraulic junction in the branch mouth of a tidal river is often located near the main river and keeps an open layout due to the restriction of land areas. The flow condition at the branch mouth is restrained by asymmetrical tidal current, which makes it difficult to coordinate the diversion, drainage and navigation functions. Taking Jiepai Hydraulic Junction of Xinmenghe Extension-Drainage Project as an example, by combining physical model with mathematical model test, we obtain the overall flow condition, reveal the formation mechanism of bad flow pattern, and put forward the overall layout principles of the junction. The results show that the flow condition at the branch mouth is significantly influenced by the fluctuation tide, which leads to the bank head protruding current and the oblique flow at the inlet of the pumping station, the sluice gate and the entrance of the lock approach channel. The boundary of the inner river is fixed, and the sluice is located in the middle of the inner river, which leads to a smooth flow condition. The overall layout of the project follows the principles: the branch and the main river are arranged at sharp angles, and the exact angle value depends on the duration of fluctuating tide to coordinate the diversion function; the bank head between the branch and the main river is arranged in a two-layer cascade shape, the lower cascade is at an acute angle, and the upper cascade is at blunt angles, to coordinate the drainage function; the sluice is arranged in the middle of the branch, the ship lock is arranged at the side always with smooth flow condition, and the pump station is arranged at the other side, to coordinate the navigation function. The junction should be constructed far away from the tidal river if possible, so that the pump station and approach channel are sheltered by the shoreline and bad flow pattern is reduced, to coordinate the whole functions. The junction should be constructed far away from the tidal river if possible, so that the pump station and approach channel are sheltered by the shoreline and the bad flow pattern is reduced, to coordinate the whole functions.
Strain characteristics of polymer anti-seepage wall under traffic load
GUO Chengchao, YANG Jianchao, SHI Mingsheng, GUAN Huan, CAI Binghua, LI Zhongchao
2020, (4): 103-110.   doi: 10.12170/20190520001
[Abstract](182) [FullText HTML](90) [PDF 1252KB](7)
Abstract:
The polymer anti-seepage wall is a new anti-seepage technology specially for anti-seepage and reinforcement of earth dams. It is widely used in practical engineering, but its strain characteristic under traffic load is seldom studied. In order to analyze the strain characteristics of the polymer anti-seepage wall, a three-dimensional finite element model of the dam with high-polymer anti-seepage wall is established based on the dam model test result. Then the lateral strain and vertical strain of the anti-seepage wall under various traffic loads (large load, heavy load, dynamic impact load) are obtained. Meanwhile, the rationality of the numerical simulation model is verified by the result comparison with field full-scale test. The curves between the strain of the polymer anti-seepage wall and its depth under different loadings applied at the same position and the same loadings applied at different positions are acquired respectively. It can be shown that the strain value of the polymer anti-seepage wall experienced three different stages from top to bottom: firstly increasing rapidly to the peak, then decreasing quickly, lastly keeping in steady state. In addition, the results suggest that the polymer anti-seepage wall possesses flexible characteristics, which may be beneficial to the anti-seepage ability of the anti-seepage wall.
Numerical simulation of continuous penetration of spudcan based on SPH mesh-free method
MENG Xiang, GAO Luheng, WU Hao, ATANGANA Njock Pierre Guy
2020, (4): 111-118.   doi: 10.12170/20190215002
[Abstract](13) [FullText HTML](5) [PDF 1107KB](7)
Abstract:
The penetration process of spudcan in saturated soil concomitantly involves extremely large soil deformation and complex soil-water-structure interaction, which are difficult to simulate using traditional mesh-based methods due to mesh distortion. SPH is a mesh-free method by using a set of unrelated interpolation particles, and its governing equations (PDEs) are converted to ODEs and then solved. Thus, mesh distortion is avoided. Based on the soil-water-structure coupled SPH algorithm, the entire penetration process of spudcan into medium dense sand, dense sand and clay was simulated. The penetration resistance, excess pore water pressure and the total stress of soils undergoing large deformation were investigated. Subsequently, the calculated results were compared to the aftermaths of CEL (Coupled Eulerian Lagrangian) and centrifuge tests. It was proven that by adopting soil-water-structure coupled SPH methods, the penetration resistance, the pore water pressure and the excess pore water pressure could be satisfactorily captured. It was also true for the free surface of the soil-water mixture undergoing large deformation.
Analysis of tipping time characteristics of tipping bucket rain gauge
LIAO Minhan, LIU Jiufu, LIAO Aimin, HUANG Yixin, CAI Zhao, MIN Xing, LI Xuegang
2020, (4): 119-126.   doi: 10.12170/20190610001
[Abstract](161) [FullText HTML](89) [PDF 1023KB](8)
Abstract:
During the study of the tipping bucket rain gauge (TBR), objective and sophisticated measurements of the duration of bucket rotation were difficult due to the rapid rotation speed of the bucket. In this paper, a new method of measuring the rotation time of the bucket is presented by using the inter-frame difference algorithm in image processing, combined with MATLAB software programming. The method was applied to four commonly used TBRs, and experimental research was carried out under different rain intensity scales to analyze the time characteristics of bucket rotation. The results show that: (1) The tipping time of the four TBRs used in the experiment is unstable under light rain, and the fluctuations are large; however, it is stable under heavy rain, and the fluctuations are small. (2) The tipping time of the JDZ02 and CQS·JD02 buckets decreases with increasing rain intensity, and shows a good linear relationship, with R2 of 0.99 and 0.86, respectively. The linear relationship between JDZ05 and CQS·JD05 is not obvious, and R2 is less than 0.6. (3) The introduction of the inter-frame difference algorithms during digital image processing can effectively obtain the time characteristics of bucket rotation, and deepen our understanding of the tipping bucket rain gauge.
Advances in studies of tailing dam break mechanism and process
ZHAO Tian-long, CHEN Sheng-shui
2015, (1): 105-111.  
[Abstract](2209) [PDF 945KB](1332)
Comprehensive assessment of plain reservoir health based on fuzzy and hierarchy analyses
YUE Qiang, LIU Fu-sheng, LIU Zhong-qiu
2016, (2): 62-68.  
[Abstract](1164) [PDF 873KB](557)
Analysis of three-dimensional numerical simulation methods for turbulent flow past circular cylinder
QIAO Yong-liang, GUI Hong-bin, LIU Xiang-xin
2016, (3): 119-125.  
[Abstract](1196) [PDF 1368KB](1009)
Analysis of dam-break flood based on HEC-RAS and HEC-GeoRAS
HE Juan, WANG Xiao-song
2015, (6): 112-116.  
[Abstract](1015) [PDF 679KB](1139)
Effects of granite powder fineness and addition on concrete microscopic pores
ZHAO Jing-hui, LIU Fu-sheng, WEI Mei, CHENG Ming
2016, (2): 39-45.  
[Abstract](913) [PDF 1290KB](469)
Research progress and application of floating breakwater
SHEN Yu-sheng, ZHOU Yi-ren, PAN Jun-ning, WANG Xing-gang
2016, (5): 124-132.  
[Abstract](1326) [PDF 1310KB](595)
Experimental study of distributed optical fiber temperature measurement technology for measuring leakage in embankment dam
HE Ning, DING Yong, WU Yu-long, ZHOU Yan-zhang, LI Deng-hua, HE Bin
2015, (1): 19-27.  
[Abstract](1122) [PDF 1878KB](1014)
Property analysis of concrete under coupling action of sulfate and wet-dry cycles
LIU Dao-wei, LIU Ben-yi, LI Xiang-dong, YUAN Jie
2015, (4): 69-74.  
[Abstract](1026) [PDF 543KB](679)
Analysis of runoff change trend and its attribution in Haihe River basin
ZHANG Liru, HE Yonghui, TANG Yueping, WANG Guoqing
2017, (4): 59-66.  
[Abstract](950) [PDF 1360KB](383)
2D numerical simulation of breach area and coupling simulation of dam breach flood
YANG Zhi, FENG Ming-quan
2015, (1): 7-18.  
[Abstract](1643) [PDF 2044KB](1415)

Supervisor:Ministry of Water Resources of the People's Republic of China

Sponsor:Nanjing Academy of Water Conservancy Sciences

Editor-in-Chief:Li Yun

Address:No. 34 Huluoguan, Nanjing

PostCode:210024

Tel:025-85829135

Email:jnhri@nhri.cn

ISSN:1009-640X

CN:32-1613/TV

Postal Distributing Code: 28-19

Unit-Price: 12 RMB/Issue

Total-Price: 72 RMB/Year

Publication Period: Bimonthly (1979 initial issiue)

Downloads

Links