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Meiyu identification of Yangtze-Huaihe region in Anhui Province based on Meiyu monitoring indices
ZHOU Ping, ZHOU Yuliang, JIN Juliang, NING Shaowei, CUI Yi, WU Chengguo
 doi: 10.12170/20200823003
[Abstract](2) [FullText HTML](0) [PDF 474KB](0)
Abstract:
According to the definition of the onset and the ending of Meiyu period in China’s National Standard “Meiyu monitoring indices” (GB/T 33671—2017), Meiyu processes and their signatures in Yangtze-Huaihe region of Anhui province during 1957-2020 were identified. The identified signatures of the Meiyu process were compared with that identified by methods proposed before the release of the National Standard to investigate the impact of the Meiyu identification method on its signatures. The results show an overall consistency between the Meiyu processes identified based on the National Standard and other methods. The identified Meiyu processes based on rain day (which is defined as the days with the precipitation greater than half of the average daily precipitation during June-July) have generally more years with no Meiyu and later onset of Meiyu than those identified based on National Standard. A total of 13 empty Meiyu seasons are identified during 1957-2020, which results in an empty Meiyu frequency of about 20%. For the years with Meiyu, their average onset and ending dates are 19 June and 13 July respectively, which results in an average length of Meiyu season of 23.7 days. The average amount of precipitation-concentration period and the whole period of Meiyu season are 270.7 and 263.0 mm respectively, accounting for about 1/4 of annual precipitation and 3/4 of precipitation during June-July. When the study area is small, instead of the day after the last rainy day, the ending date of a Meiyu season should be determined based on the conditions of atmospheric circulation and regional rain days. It is also shown that there are severe droughts in the Yangtze-Huaihe region of Anhui province are more likely to appear during empty or dry Meiyu season, especially when there are consecutive empty or dry Meiyu seasons. Conversely, in the same region, severe floods are more likely to appear in years with heavy and concentrated precipitation during the Meiyu season, especially for those with precipitation larger than 400 mm in Meiyu season, e.g. the year 2020.
Turbulence characteristics in open channel with glass-sphere quincunx arrays
ZHONG Liang, GE Chenxi, SUN Jianyun
 doi: 10.12170/20191026002
[Abstract](65) [FullText HTML](38) [PDF 12142KB](1)
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.
3D simulation of stress wave propagation in jointed rock mass with filling joint
DING Yingxun, WANG Zhiliang, HUANG Youpeng
Accepted Manuscript  doi: 10.12170/20190529001
[Abstract](9) [FullText HTML](6) [PDF 1422KB](1)
Abstract:
In order to study the propagation characteristics of stress wave in rock mass with filling joints, the three 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 when the azimuth Angle of joint inclination is 0°~60°, the transmission coefficient decreases with the increase of beta, but increases with the increase of beta when the azimuth Angle is 60°~90°. 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 transmission (reflection) coefficient is larger (smaller) than the corresponding value on the critical transmission (reflection) curve.
Rock strength and deformation characteristics under different unloading rates
QIAN Yajun, WU Yingli, PEI Weiwei, ZHU Yueyan
Accepted Manuscript  doi: 10.12170/20200428001
[Abstract](70) [FullText HTML](49) [PDF 968KB](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.
Assessment of typhoons in ERA-Interim and ERA-5 reanalysis datasets
LI Jiangxia, HU Yuzhi
 doi: 10.12170/20200222001
[Abstract](1) [FullText HTML](1) [PDF 988KB](1)
Abstract:
Based on two of the most commonly used parameters in ocean hydrodynamic simulation, i.e. 10 m wind speed and sea level pressure, we obtained the typhoon centres, maximum wind speeds and central air pressures from the ECMWF ERA-Interim (ERA-I) reanalysis dataset and the most recently released ERA-5 reanalysis dataset and used them to evaluate their representation of typhoons in the northwest Pacific region from 2013 to 2015. The results indicate that there are differences in the locations of the typhoon centres provided by the ECMWF reanalysis wind data and the measurement data. When the typhoon intensity decreases, the bias in the location of the typhoon centre in the ECMWF data increases. The maximum wind speed of typhoons in the reanalysis data is lower than that in the measurement data, whereas the central air pressure is higher. Although the precision of ERA-5 wind data is greatly improved for the simulation of typhoons from that of the ERA-I data, it is still not sufficiently accurate in the description of typhoon intensity in the northwest Pacific Ocean, which is underestimated. When the typhoon intensity increases, this underestimation is more obvious. In this study, we established an empirical correlation between the maximum wind speed of typhoons in ERA-5 and Best-track data. On this basis, the ERA-5 data can be improved using a direct modification method without the requirement for observed typhoon track data. After validation based on the measured wind speed, the modified ERA-5 reanalysis data during the typhoon period was confirmed to have greatly improved accuracy compared to the original data.
Research on the coupling coordinative degree among urban water-energy-food system
WANG Lichuan, HOU Baodeng, ZHOU Yuyan, CHEN Xiaoqing, WANG Xin, HUANG Ya
 doi: 10.12170/20200217001
[Abstract](0) [FullText HTML](1) [PDF 701KB](0)
Abstract:
Water, energy and food are important resources in China. These resources are interdependent and play an important role in the process of urban development. In addition, they are important basic resources for sustainable urban development. Taking Shanghai as an example, a comprehensive evaluation index system of the Shanghai Water-Energy-Food (W-E-F) system is constructed. The entropy and coefficient of variation methods are used to weight the index. Then, a coupling coordination model is established to analyse the coordinated development level of the Shanghai W-E-F system and its subsystems. Next, the grey GM (1, 1) model is applied to predict the coupling coordination development trend of the Shanghai W-E-F system during the period from 2018 to 2025. The results show that the development of the W-E-F system in Shanghai is divided into two stages. The first stage occurs from 2003-2013, during which the W-E-F system shows a downward trend; the second stage occurs from 2013 to 2017, during which the W-E-F system shows a stable upward trend. The coupling coordination degree shows a stable upward trend during the future period of 2018-2025 and a transition to a good coordinated development level by 2025. However, the results do not show a transition to a high-quality coordinated development level. Therefore, Shanghai should continue to develop its resource utilization efficiency and improve the coordinated development space of the city.
Three-dimensional numerical simulation analysis of landslide surge in reservoir area
DENG Chengjin, DANG Faning, CHEN Xinzhou, YUAN Qiushuang, CHEN Lili
 doi: 10.12170/20191125002
[Abstract](66) [FullText HTML](65) [PDF 934KB](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.
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
 doi: 10.12170/20191225002
[Abstract](13) [FullText HTML](11) [PDF 8158KB](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.
Analysis on sliding displacement of slope with muddy intercalation considering blasting cumulative damage effect
YAN Changbin, ZHANG Yanchang, CHEN Yanguo, XU Xiao
 doi: 10.12170/20200127001
[Abstract](2) [FullText HTML](1) [PDF 822KB](0)
Abstract:
Repeated blasting vibrations are one of important triggers of landslides, especially those developed on complex rock slopes with muddy intercalation. To reveal the failure mechanism of complex rock slope with muddy intercalation under repeated blasting vibrations, a novel method was proposed to evaluate cumulative sliding displacement and critical blasting times for this type of slopes based on the law of conservation of energy and Newmark sliding block method. In this method, the cumulative damage effects of repeated blast vibrations were characterized through multiple strength reduction factors of muddy intercalation parameters, e.g. shear modulus, dip angle and continuity. The importance of those parameters on slope cumulative sliding displacement was also addressed using sensitivity analysis. The proposed method generally shows more reasonable results regarding estimation of cumulative sliding displacement and critical blasting vibration times. The parameters of muddy intercalation show significant controls on the cumulative sliding displacement of slope under many times of blasting vibration. With the shear modulus increased, the cumulative displacement declines as the slope resistance gets enhanced. Steeper dip angle of muddy intercalation increases the slope displacement of creep section while has no obvious influence on the displacement of shear section. Higher the continuity of muddy intercalation induces larger cumulative sliding displacement as expected. The sensitivity analysis results show that the cumulative sliding displacement under repeated blasting vibrations is influenced by shear modulus, followed by dip angle and continuity of muddy intercalation.
Study on the prediction of hydraulic concrete degradation based on gray residual GM (1,1)-Markov model
KANG Chuntao, GONG Li, WANG Zhonghui, YANG Yiqun, WANG Hong
 doi: 10.12170/20200228002
[Abstract](2) [FullText HTML](1) [PDF 588KB](0)
Abstract:
The hydraulic concrete buildings in northwest China are often affected by low temperature frost and salt erosion, so the study of concrete deterioration prediction is of great significance to the life prediction of hydraulic buildings. In order to simulate the damage of hydraulic concrete buildings, the salt freezing test of the concrete test piece was carried out by laboratory method, obtained the quality and pressure strength with increase of the salt freezing times under 4 kinds of conditions. The two of these conditions were extracted from the study as the original data. Firstly processed these data by the gray residual GM (1,1) model, and established the prediction model. Then, obtained the correction value of mass and pressure strength by the prediction model. Finally, predicted the quality and pressure resistance of 150 to 200 salt freezing tests by the gray residual GM (1,1)-Markov model. The results show that the prediction value of quality and pressure strength is less error than the original value, and in a certain range, the model can be proved to have good effect on the prediction of the deterioration of concrete and the loss of pressure strength.
Division of protection area of groundwater source area near Hutuo River based on MODFLOW mode
LENG Wenpeng, TAO Ya, SUN Ruohan, XIA Jianxin
 doi: 10.12170/20200611001
[Abstract](3) [FullText HTML](0) [PDF 713KB](0)
Abstract:
The division of underground drinking water source protection areas in scientific and reasonable ways can prevent water sources from being polluted in the most precise ways and with a lower economic cost. The MODFLOW model was utilized to develop and calculate a simulation of the groundwater flow field of the Hutuo River groundwater source area in Shijiazhuang City. By utilizing the MODPATH, the 100 days and 1 000 days reverse migration trajectories of the tracer particles when subjected to two different working conditions were calculated. The results were as follows. The average migration distances of the tracer particles at the end of 100 days under each of the two conditions were 0.54 km and 0.49 km; moreover, the average migration distance of each of the tracer particles at the end of 1000 days was 6.1 km and 5.6 km. Also, the simulation considered the change of the groundwater flow field under the condition of utilizing the infiltration field. By analyzing the calculation results of these two working conditions, the present study concluded that when the pumping wells inside of the water source area were generalized into the well groups, the specific trajectory geometry of the tracer particle reverse migration was more regular, and its migration distance was relatively short. At the same time, by considering the specific water supplement situation of the infiltration field, the whole infiltration field was included in the first-grade protection area as well.
Effect of total dissolved gas supersaturation on fish in the reservoir between cascade hydropower stations
ZENG Chenjun, MO Kangle, GUAN Tiesheng, CHEN Qiuwen, LI Ting, ZHANG Hui
 doi: 10.12170/20200731002
[Abstract](6) [FullText HTML](1) [PDF 980KB](0)
Abstract:
The construction of reservoirs promotes the development of fishery, but discharge from high dam lead to the generation of total dissolved gas (TDG) supersaturation, which is detrimental to the fish in downstream reservoir and may cause gas bubble disease (GBD). To investigate the effect of TDG supersaturation on fish in the Xiangjiaba Reservoir on the Jinshajiang River, a laterally averaged dynamic model for TDG transport was established, and the threshold of safe depth for the control section was investigated. Then the impact of TDG supersaturation on wild freshwater fish and cage-culture fish were studied based on habits and net cage depth. The results showed that: the reservoir provide enough vertical space for wild freshwater fish to swim and acquire hydrostatic compensation to avoid GBD, the risk of fish suffered from TDG supersaturation was depend on the fish habits and the ability of utilize hydrostatic compensation. For the limit of net cage depth, cage-culture fish have no enough vertical space to swimming to safety depth. In order to avoid fish suffer from GBD, the net cage depth should be deeper than the threshold of safe depth, and the fish should be kept swimming under the threshold of safe depth during the period of TDG supersaturation. The reservoir between cascade hydropower stations was safer than the reach downstream of the last cascade hydropower station, and it is necessary to set a most strict TDG limitation standard for the last cascade hydropower station.
A comparative study of flood control standards for small and medium-sized reservoirs and recommendation
ZOU Ying
 doi: 10.12170/20200503003
[Abstract](3) [FullText HTML](0) [PDF 509KB](0)
Abstract:
Small and medium-sized reservoirs in China are numerous and widely distributed, which play a vital role in our lives. However, it should be recognized that in addition to providing economic, social, and ecological benefits, they can also be a source of risk to the downstream areas with dam failure potentially resulting in unacceptable loss of life and damage to property. This paper compares the guidelines for dam classification and selection of inflow design flood in the United States, and points out that the flood control standards for small and medium-sized reservoirs are relatively low in the relevant design specifications in China, which is not suitable for the current level of economic and social development in China. Then, the necessity and feasibility of raising the flood control standards of small and medium-sized reservoirs with high potential hazard are analyzed and demonstrated, and the suggestions to enhance the flood control ability of small and medium-sized reservoirs with high potential hazard are put forward.
Application of semipartial subtraction set pair potential method to the dynamic assessment of regional drought risk
JIN Juliang, ZHAO Xingyue, CUI Yi, ZHOU Yuliang, CHEN Menglu, NING Shaowei
 doi: 10.12170/20200901005
[Abstract](3) [FullText HTML](0) [PDF 714KB](0)
Abstract:
To gain the insights into uncertainty issues between evaluation samples and standards of dynamic drought risk assessment, we put forward a novel connection number accompanying function based on half a subtraction set pair potential, and then constructed a dynamic drought risk assessment built upon a half wide subtraction method of set pair potential (SSSPP), followed by its application to the dynamic drought risk assessment and impact factor identification study of Suzhou city in 2007-2017. The results showed that the comprehensive drought risk level of Suzhou city was above level 2 basically, in the partial danger state, while the levels in 2009, 2010 and 2011 were in a partial negative potential, (the most dangerous years), judged by the semi-partial subtraction method. Drought vulnerability indicators of Suzhou city identified were: the index of relative wetting degree, relative humidity, soil type, soil water content, rate of cultivated land per unit area, the proportion of agricultural population, reservoir storage rate and water status quo of water supply capacity per unit area, per unit area emergency ability, and water saving irrigation index evaluation. Eleven indicators mentioned above are the objects that need to be further regulated to improve the drought risk level in Suzhou.
Numerical analysis of wave run-up characteristics on dual non-submerged vertical cylinders system
CHEN Haomin, NI Yunlin
 doi: 10.12170/20191018004
[Abstract](61) [FullText HTML](30) [PDF 1150KB](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.
Study on water content and dynamic mechanical properties of fly ash concrete under water confining pressure
LIANG Jia, WANG Qianfeng, ZHANG Xiuwen, XIAO Yang
 doi: 10.12170/20191010002
[Abstract](53) [FullText HTML](44) [PDF 942KB](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.
Analysis of the influence factors on the compressive properties of cement solidified zinc contaminated soils
DAI Yuanzhi, FENG Zhonghua, FAN Chengwen
 doi: 10.12170/20191008001
[Abstract](52) [FullText HTML](45) [PDF 773KB](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.
Improved Green-Ampt infiltration model of soil slope considering inclination
LEI Wenkai, DONG Hongyuan, CHEN Pan, Lü Haibo, MEI Guoxiong
 doi: 10.12170/20191027002
[Abstract](12) [FullText HTML](11) [PDF 1029KB](1)
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.
Experimental study on the strength behavior of EHP
DU Xuqing, WENG Jiaxing, BIE Xueqing, SONG Miaomiao, QIU Chengchun, LI Hui
 doi: 10.12170/20191213001
[Abstract](55) [FullText HTML](27) [PDF 922KB](3)
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.
Numerical simulations of the group effect of large-diameter columns in regular waves
GAN Guixuan, SUN Liang, YUE Lei, HAN Songlin
 doi: 10.12170/20191006001
[Abstract](62) [FullText HTML](60) [PDF 1110KB](4)
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.
Study on the horizontal bearing capacity of single pile foundation considering spatial variability of soil strength
HAN Jiwei, LIU Xiaoming, YANG Yuehong, LI Bing, BAO Anqi
Accepted Manuscript  doi: 10.12170/20200424001
[Abstract](4) [FullText HTML](9) [PDF 840KB](1)
Abstract:
Spatial variability is the inherent nature of soil, which needed to be considered when calculating the bearing capacity of piles. Different coefficients of variation and correlation distance will be considered. Combining with the numerical method, the existing simulation method of random field will be used to generate soil parameters, to research the effect of spatial variability of soil strength on the horizontal bearing capacity of a single pile. The results show that after considering the spatial variability of soil strength, the average value of the single pile horizontal bearing capacity is significantly less than that obtained by the deterministic analysis, and the single pile foundation designed by the standard method is still possible to fail; the correlation distance has no significant effect on the average value of the single pile horizontal bearing capacity, but the standard deviation of bearing capacity increases with the increase of the correlation distance; with the increase of the coefficient of variation, the average value of the horizontal bearing capacity of the pile foundation decreases, while the standard deviation of the bearing capacity increases. The distribution law of horizontal bearing capacity of the pile foundation considering the spatial variability can fit log-normal distribution. According to this law, the failure probability of the pile foundation under any load can be obtained.
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
Accepted Manuscript  doi: 10.12170/20200106003
[Abstract](13) [FullText HTML](6) [PDF 900KB](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.
Stability analysis of complex double-sided slope
PAN Chi, LI Sa
 doi: 10.12170/20190730001
[Abstract](584) [FullText HTML](130) [PDF 1979KB](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.
Resilience evaluation of sponge city based on the relative difference function
FENG Feng, JIN Xiaoying, LIU Cui, FENG Yuehua
 doi: 10.12170/20200318002
[Abstract](4) [FullText HTML](2) [PDF 684KB](0)
Abstract:
Aiming at the comprehensive evaluation of sponge city water system, based on the concept of engineering elasticity, this paper constructs a resilient index system with 17 factors from four dimensions: ecological, engineering, natural and social resilience. Based on the fuzzy variable evaluation model of the relative difference function, the five levels (very strong, strong, medium, weak and very weak) of the resilience thresholds corresponding to the 17 indicators are explained and defined. The paper takes Kaifeng as the research example was calculated, the result shows: in 2013, 2014, 2015 water system resilience to Ⅴ suggests that this three years of Kaifeng water system has a very weak resilience; In 2016, 2017 to Ⅳ shows city water system for medium resilience. In addition, the change trend of relative membership coverage of 17 indicators in 2013 and 2017 was compared and analyzed, compared with the construction and effect of Kaifeng sponge city, the evaluation results are highly concordant with the actual situation, and an obvious resilient enhancement process was found. Through the example verification, this paper has established a reasonable evaluation system and elastic threshold, aiming at the evaluation area of mesoscale, can determine the corresponding relative membership degree through the index information, so as to obtain accurate evaluation results, and provide reliable data support and theoretical basis for sponge city to improve the resilience of water system.
Discussion on ecological construction scheme for navigation recovery in the lower Yellow River
ZHANG Jinliang, ZHANG Yuansheng, LIAN Jijian, AN Cuihua
 doi: 10.12170/20200117001
[Abstract](7) [FullText HTML](1) [PDF 881KB](1)
Abstract:
The key issues, such as sediment accumulation, wandering river regime and the obstruction of water-related projects, are of great significance of restricting the construction of ecological waterway in the lower Yellow River. After the analysis with measured data, calculation with mathematical model and comprehensive analysis, it is believed that the minimum backfull discharge in the lower Yellow River has already reached 4, 300 m3/s, the water surface width corresponding to the minimum navigable volume has reached 120~200 m and water depth has reached 1.0~2.5 m since operation of Xiaolangdi Reservoir. Along with the completion and combined application of water-sediment regulating system in the future, a middle-water-level river channel of about 4, 000 m3/s will be maintained in a relatively long time, with a certain condition for navigations. It is proposed that with the operation of Guxian Reservoir and Dongzhuang Reservoir and construction of ecological corridor in the lower Yellow River, an ecological waterway in compliance with Class IV waterway standard (Class III at some sections) and in a length of about 800 km can be formed by virtue of ecological dredging works for middle-water-level river channel and navigable water channel, regulation in wandering river reaches and ecological reconstruction for navigation-hampering structures. It is suggested to promote and accelerate the construction of the ecological waterway in the lower Yellow River under the principles of "unified arrangement, step by step, dredging before navigation and gradual improvement".
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](14) [FullText HTML](10) [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.
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](58) [FullText HTML](40) [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.
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](50) [FullText HTML](43) [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.
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](257) [FullText HTML](140) [PDF 764KB](6)
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.
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2020, (5): 0-0.  
[Abstract](26) [FullText HTML](19) [PDF 4609KB](13)
Abstract:
contnets
2020, (5): 1-1.  
[Abstract](26) [FullText HTML](18) [PDF 322KB](4)
Abstract:
Study on the superposition effect of hydraulic fluctuation in the lower approach channel of the Three Gorges Project
CHENG Long, LI Yun, AN Jianfeng
2020, (5): 1-8.   doi: 10.12170/20190811001
[Abstract](215) [FullText HTML](114) [PDF 2365KB](22)
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.
Dimension-reduction simulation for continuous random wave force field
LÜ Kangxuan, LIU Zhangjun
2020, (5): 9-15.   doi: 10.12170/20190505002
[Abstract](23) [FullText HTML](8) [PDF 961KB](3)
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
2020, (5): 16-23.   doi: 10.12170/20190608001
[Abstract](299) [FullText HTML](188) [PDF 1116KB](6)
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.
Preliminary study on evolutions of Yangtze River and Dongting Lake water and sediment fluxes exchanges based on MLP method
JIA Yalan, SHI Yong
2020, (5): 24-32.   doi: 10.12170/20190627001
[Abstract](26) [FullText HTML](12) [PDF 888KB](5)
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.
Effect of complicated river boundaries on the cycle of landslide surge
WANG Meili, ZU Fuxing, XU Jiqing, WANG Pingyi, HAN Linfeng
2020, (5): 33-39.   doi: 10.12170/20190731002
[Abstract](22) [FullText HTML](11) [PDF 931KB](2)
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.
Optimization of water exchange based on RBF surrogate model and particle swarm optimization
QI Lan, ZHENG Shihao, ZHANG Conglin
2020, (5): 40-47.   doi: 10.12170/20190724002
[Abstract](236) [FullText HTML](127) [PDF 2079KB](9)
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.
Calculation and characteristic analyses of wind wave fields in the Yangtze Estuary
GENG Haobo, ZHANG Hongsheng, HONG Yangbin, HU Guodong
2020, (5): 48-56.   doi: 10.12170/20200102003
[Abstract](61) [FullText HTML](52) [PDF 5292KB](2)
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.
Deformation simulation and stability analysis of frame seawall
ZHENG Anxing, MAO Qian, ZANG Zhentao, ZHOU Jianfen, JIANG Ning
2020, (5): 57-62.   doi: 10.12170/20190806002
[Abstract](180) [FullText HTML](107) [PDF 829KB](4)
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.
Deformation forecasting model and its modeling method of super high arch dams during initial operation periods
HU Jiang
2020, (5): 63-71.   doi: 10.12170/20190908001
[Abstract](115) [FullText HTML](59) [PDF 1986KB](21)
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.
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
2020, (5): 72-78.   doi: 10.12170/20190907001
[Abstract](36) [FullText HTML](14) [PDF 792KB](1)
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.
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
2020, (5): 79-85.   doi: 10.12170/20190905003
[Abstract](21) [FullText HTML](9) [PDF 1907KB](1)
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.
Stress-deformation behavior of a blast-fill dam
HUANG Zhihong, YANG Jie, CHENG Lin, SUN Xiaoning, MA Chunhui
2020, (5): 86-95.   doi: 10.12170/20190930001
[Abstract](26) [FullText HTML](10) [PDF 1419KB](3)
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.
Effect of internal crack defects on fracture properties of concrete
WANG Siyao, HU Shaowei
2020, (5): 96-102.   doi: 10.12170/20190923001
[Abstract](89) [FullText HTML](63) [PDF 23582KB](4)
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.
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
2020, (5): 103-108.   doi: 10.12170/20190925001
[Abstract](60) [FullText HTML](42) [PDF 2007KB](3)
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.
Analysis of lateral bearing capacity of wing-monopile with symmetrical wing plates
HE Jianxin, LI Zhi, MENG Xingyu, SU Xiaodong, CHEN Canming
2020, (5): 109-115.   doi: 10.12170/20191222001
[Abstract](64) [FullText HTML](39) [PDF 892KB](2)
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.
Influence of marine organisms adhesion on durability of concrete structures
HE Xiaoyu, LI Tian, SHEN Jian, ZHANG Yajun, XIA Jin, JIN Weiliang
2020, (5): 116-123.   doi: 10.12170/20190906003
[Abstract](76) [FullText HTML](53) [PDF 791KB](6)
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.
2020, (5): 124-124.  
[Abstract](37) [FullText HTML](21) [PDF 249KB](9)
Abstract:
Advances in studies of tailing dam break mechanism and process
ZHAO Tian-long, CHEN Sheng-shui
2015, (1): 105-111.  
[Abstract](2217) [PDF 945KB](1332)
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](1202) [PDF 1368KB](1009)
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](1175) [PDF 873KB](557)
Change law and cause analysis of water resources and water consumption in China in past 20 years
LIU Jing, BAO Zhenxin, LIU Cuishan, WANG Guoqing, LIU Yue, WANG Jie, GUAN Xiaoxiang
2019, (4): 31-41.   doi: 10.16198/j.cnki.1009-640X.2019.04.005
[Abstract](232) [FullText HTML](179) [PDF 6173KB](11)
Analysis of dam-break flood based on HEC-RAS and HEC-GeoRAS
HE Juan, WANG Xiao-song
2015, (6): 112-116.  
[Abstract](1022) [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](926) [PDF 1290KB](469)
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](1123) [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](1028) [PDF 543KB](679)
Research progress and application of floating breakwater
SHEN Yu-sheng, ZHOU Yi-ren, PAN Jun-ning, WANG Xing-gang
2016, (5): 124-132.  
[Abstract](1343) [PDF 1310KB](595)
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](951) [PDF 1360KB](383)

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)

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