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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).
Stability analysis of complex double-sided slope
PAN Chi, LI Sa
Accepted Manuscript  doi: 10.12170/20190730001
[Abstract](10) [FullText HTML](10) [PDF 1811KB](0)
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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 about 3%. However, for concave slopes, the safety factor is higher than that of the flat slope, and the curved surface slope with 1:2 gradient under rough-rough boundary condition is the largest, which is higher than that of the flat slope 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.
Optimization of water exchange based on RBF surrogate model and particle swarm optimization
QI Lan, ZHENG Shihao, ZHANG Conglin
 doi: 10.12170/20190724002
[Abstract](11) [FullText HTML](9) [PDF 885KB](0)
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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 is not conducive for finding the optimal water exchange scheme. To solve this problem, this paper establishes the optimization model of water exchange based on the radial basis function (RBF) surrogate model and uses 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.
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](11) [FullText HTML](8) [PDF 1063KB](0)
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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.
Estimation of non-point source pollution load in core area of Zhangjiakou Winter Olympic Games
ZHANG Ran, XIA Jianxin, REN Huatang
 doi: 10.12170/20190822001
[Abstract](10) [FullText HTML](7) [PDF 1102KB](0)
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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 1154.25~17,540.39 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 Taizicheng River was relatively high.
Deformation simulation and stability analysis of frame seawall
ZHENG Anxing, MAO Qian, ZANG Zhentao, ZHOU Jianfeng
 doi: 10.12170/20190806002
[Abstract](11) [FullText HTML](5) [PDF 834KB](0)
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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.
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
Accepted Manuscript  doi: 10.12170/20190626001
[Abstract](125) [FullText HTML](77) [PDF 975KB](7)
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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 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.
Analysis of tipping time characteristics of Tipping Bucket Rain Gauge
LIAO Minhan, LIU Jiufu, LIAO Aimin, HUANG Yixin, CAI Zhao, MIN Xing, LI Xuegang
Accepted Manuscript  doi: 10.12170/20190610001
[Abstract](46) [FullText HTML](26) [PDF 798KB](1)
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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 proposed 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 times of the JDZ02 and CQS·JD02 buckets decreased with increasing rain intensity, and showed a good linear relationship, with R2 of 0.99 and 0.86, respectively. The linear relationship between JDZ05 and CQS·JD05 was not obvious, and the R2 was 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.
Strain characteristics of polymer anti-seepage wall under traffic load
GUO Chengchao, YANG Jianchao, SHI Mingsheng, CAI Binghua, LI Zhongchao
 doi: 10.12170/20190520001
[Abstract](70) [FullText HTML](35) [PDF 1278KB](2)
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The polymer anti-seepage wall is a new anti-seepage technology specially for anti-seepage and reinforcement of earth dams. It has many advantages such as quick and convenient construction, excellent anti-seepage performance, green environmental protection. In order to analyze the strain characteristics of 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 load (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 strain of the polymer anti-seepage wall and its depth under different loadings applied at the same position and 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 stage 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.
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
Accepted Manuscript  doi: 10.12170/20190603002
[Abstract](75) [FullText HTML](46) [PDF 1165KB](2)
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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 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 periodictiy of 2~7 a, 10.4 a, 19 a, 22 a and 25 a, of which 10.4 a and 22a 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.
Analytical calculation of cnoidal wave diffracted force on a V-shaped breakwater
CAI Hantao, HUANG Hua, ZHAN Jiemin
 doi: 10.12170/20190608001
[Abstract](132) [FullText HTML](90) [PDF 1131KB](4)
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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 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.
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](129) [FullText HTML](76) [PDF 764KB](3)
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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.
Layout principles of hydraulic project in the branch mouth of a tidal river
LI Shouqian, ZHU Mingcheng, ZHU Hao, HANG Dan, LU Yongjun
[Abstract](140) [FullText HTML](129) [PDF 761KB](1)
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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, this paper obtains the overall flow condition, reveals the formation mechanism of bad flow pattern, and puts forward the overall layout principles of the junction. The results showed that 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 lock approach channel. While the boundary the inner river is fixed, and the sluice is located in the middle of the inner river, which leads 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, the upper cascade is at blunt angles, to coordinate the drainage function; the sluice is arranged in 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.
Security evaluation of water-energy-food nexus system in China
LIU Jing, LIU Cuishan, LI Xiao, WANG Guoqing, BAO Zhenxin
 doi: 10.12170/20190603009
[Abstract](223) [FullText HTML](109) [PDF 951KB](7)
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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. The 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.
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
Accepted Manuscript  doi: 10.12170/20190603003
[Abstract](170) [FullText HTML](96) [PDF 740KB](6)
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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 the seven hydropower stations. The results show that 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 resource 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.
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2020, (3): 1-128.  
[Abstract](0) [PDF 9663KB](0)
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contents

2020, (3): 1-2.  
[Abstract](8) [FullText HTML](19) [PDF 386KB](5)
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Indoor simulation test of ice temperature expansion force and analysis of related factors
WANG Enliang, LENG Yupeng, HAN Hongwei, XIAO Yao, FU Xiang
2020, (3): 1-10.   doi: 10.12170/20191009001
[Abstract](235) [FullText HTML](139) [PDF 1441KB](9)
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The winter climate in Northeast China is cold. The ice cap of hydraulic structures such as rivers, canals and reservoirs in winter will produce static ice load acting on hydraulic structures. With the increase of temperature, ice cover plate produces ice temperature expansion force, which will cause damage to hydraulic structures in the field. Due to the long period of field observation and various conditions limiting field observation, in order to study the ice temperature expansion force and influencing factors of ice sheet, the indoor simulation test of ice temperature expansion force was carried out in the low-temperature simulation experiment pool, and the relevant influencing factors such as ice temperature and ice thickness were analyzed. The results show that the expansion force of ice temperature is produced at the stage of temperature rise, and with the increase of temperature, the expansion force of ice temperature tends to increase. When the expansion force of ice temperature reaches its peak, the ice temperature is −1.9 ℃ and the ambient temperature is close to 0 ℃, which is consistent with the field observation results. The maximum expansion force of ice temperature in laboratory test was 118.7 kPa, and the peak value of ice temperature expansion force appeared at 3.5 cm of ice sheet. The maximum ice thickness of the test was 10.65 cm, indicating that the operation point of ice temperature expansion force was at 1/3 of the maximum ice thickness, and the distribution of ice temperature expansion force first increased and then decreased along the distribution of ice thickness.
Discrete element analysis of ice loads on polar ships under pilotage of icebreaker
LIU Lu, HU Bing, JI Shunying
2020, (3): 11-18.   doi: 10.12170/20200305001
[Abstract](192) [FullText HTML](156) [PDF 1096KB](1)
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The pilotage of icebreaker can effectively guarantee the navigation safety of merchant ships in polar ice regions. The dilated polyhedron based on the Minkowski sum theory is used to generate the sea ice element with irregular shapes. The bond-failure model of the dilated polyhedron element is developed to simulate the breaking process of sea ice. Accordingly a dilated polyhedron based discrete element method (DPDEM) is established. The interaction between ship hull and sea ice is simulated with the DPDEM, while the ice load on the ship hull is analyzed. The ice load on ship hull which is based on the hull model of icebreaker Xuelong is simulated using the DPDEM. The result is validated with the result of the Lindqvist formula and the Riska formula which are most commonly used for the ice load analysis on ship hull. The validation illustrates that the results by the DPDEM and the empirical formula are close. It is convincing that the DPDEM can be used for the ice load analysis on ship hull. Moreover, the ice loads on ships under the pilotage of icebreaker is simulated using the DPDEM. The ice resistance under different ship speed and ratio of ship width is analyzed. The DPDEM can effectively be used for the analysis of ice load on the ship hull. The results by the DPDEM can provide important references for the ice ship design and navigation safety.
Research on ice regime evolution of the Fengman Reservoir based on satellite remote sensing images
LI Nan, CAO Rui, TUO Youcai, DENG Yun
2020, (3): 19-28.   doi: 10.12170/20200227004
[Abstract](80) [FullText HTML](51) [PDF 3104KB](5)
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Based on the ENVI 5.1 software platform and by using the Landsat-7 and Landsat-8 satellite remote sensing images, ice regime interpretation and surface temperature retrieval were performed for the Fengman Reservoir, which is located in Jilin City. Afterwards, the patterns of the overall ice regime evolutions and their relations with thermal variations of the Fengman Reservoir were investigated. The results indicated that: during the whole ice season, the ice regime was significantly influenced by the water thermodynamics of the Fengman Reservoir due to the steady inflow conditions; in the freeze-up period, the reservoir surface water temperatures showed a pattern, with the temperature lower in the middle area of the reservoir, higher in the area in front of the dam and the end area of the reservoir, the freeze-up started from the middle area of the reservoir and expanded to the area in front of the dam and the end area of the reservoir, and the area in front of the dam froze up at last; in the steady freeze-up period, vertical water temperature of the reservoir was inversely distributed underlying the ice cove, ice thickness was unevenly distributed along the reservoir, and an open water flow of 10 km to 30 km existed in the end area of the reservoir; in the break-up period, the surface water temperatures declined from the area in front of the dam to the end area of the reservoir, and the thawing started from the end area of the reservoir to the area in front of the dam in the form of over-mature break-up.
Prediction of Heilong River ice break-up mode and date based on water level change
LU Jinzhi, WANG Tao, GUO Xinlei, ZOU Dehao
2020, (3): 29-36.   doi: 10.12170/20200318003
[Abstract](9) [FullText HTML](6) [PDF 929KB](0)
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When violent break-up occurs in a natural river course, it is easy to produce ice jam and ice dam to cause the flood disaster. Based on the analysis of the ice-breaking water level and the measured daily water level, it is an important non-engineering measure to forecast the river opening mode and opening date in advance and adopt the corresponding prevention technology in time. In this study, based on the theory of ice sheet deflection damage, the water level change is used to judge the river opening pattern, the degree-day method of the one-dimensional ice thickness model is optimized, the change of ice thickness in the river channel is calculated, and the river opening mode and date of Heilong River in 2015-2018 is forecasted. The results show that except for the error of one day between the predicted value and the measured value in 2017, the predicted value and the measured value in the other years are identical for the ice break-up date, except that the insufficient hydrodynamics caused by the low water level in 2018, which affects the accuracy of the prediction, the predicted value and the measured value in the other years are identical for the ice break-up mode.
Discussion on the mechanism of pit collapse based on topographic change of the father-son’s caving pond
YING Qiang, ZHANG Xingnong, LUO Longhong, SU Changcheng, JIA Dongdong
2020, (3): 37-42.   doi: 10.12170/20190425002
[Abstract](203) [FullText HTML](110) [PDF 918KB](12)
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The pit collapse is a sloop failure that involves the interaction of water and soil. Its formation mechanism is still not fully understood because of its rapid development and difficult observation under water. A typical collapse occurring at the entrance of the left branch of Hechangzhou Island in 2012 in the lower Yangtze River, which is a reoccurring failure with a father-son’s caving pond, is chosen as a case study by comparing the topographic changes of the main channel near the mouth of the pond in the past four years before the son’s collapse. It is shown that there was siltation in the main channel with no erosion, which is inconsistent with the common situation. The topography changes of the pond upstream bend between 2011 and 2012 indicate that the pit collapse can occur when the riverbed of a shallow trough within a hydrological year is scoured. Before and after the occurrence of the son’s collapse, the bending topography of the downstream side of the father's scour pools did not change much, which indicated that the sediment generated by the pit collapse moved from the bottom to the lower level, and had little effect on the relatively high riverbed topography around it.
Analysis of spatio-temporal distribution of rainstorms in the western region of Taihu Lake Basin
TAO Yuwei, WANG Yuankun, WANG Dong, NI Lingling
2020, (3): 43-50.   doi: 10.12170/20190430002
[Abstract](113) [FullText HTML](63) [PDF 3051KB](6)
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Global warming and rapid urbanization development would affect the rainfall structure (i.e., variability in space and time) and the frequency of extreme hydrometerological events. To analyze the spatio-temporal distribution of rainstorms in the western region of Taihu Lake Basin (TLB) in the changing environment, daily rainfall data from rainfall stations from 1961 to 2015 are analysed to determine the spatial and temporal trends of 4 rainstorm indices (annual days, rainfall, intensity and percentage of rainstorms). Furthermore, the annual maximum daily rainfall for the specific return period is calculated. The results show that: (1) Annual rainfall increases from the north to the south, while annual days and rainfall of rainstorms decrease from the north and south to the center in the western region of TLB. Annual intensity of rainstorms increases firstly, and then reduces from the southwest to the northeast, while annual percentage of rainstorms in the southwest is lower than other places in the western region of TLB. (2) Annual days, rainfall and percentage of rainstorms at Yixing station have risen sharply from 1961 to 2015. (3) From 2005, there is a significant increase in all the rainstorm indices in the western region of TLB. (4) The average annual maximum daily rainfall at Jintan and Danyang stations appear higher than those at Liyang and Yixing stations. (5) The annual maximum daily precipitation for 5-year return period at the 4 representative stations (i.e., Danyang, Jintan, Liyang, Yixing stations) all exceed 100 mm to be classified as heavy rainstorms. Particularly, Jintan and Danyang stations are prone to suffer from extreme rainfall events compared with Yixing and Liyang stations.
Response of tidal asymmetry to coastline changes in radial sand ridges sea area
QIAN Pei, FENG Xi, FENG Weibing, ZHANG Wei
2020, (3): 51-60.   doi: 10.12170/20190901002
[Abstract](210) [FullText HTML](175) [PDF 4932KB](21)
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Based on Delft3D, a two-dimensional flow numerical model of the radial sand ridges sea area was established, and verified with measured tidal level and current velocity to ensure calculation accuracy. Tidal asymmetries of the radial sand ridges sea area under 1984 and 2014 coastal conditions were studied separately. Tidal wave deformations are remarkable and ebb tide duration is longer than that of flooding in most areas. Moreover, tidal wave deformation in the nearshore area has obviously weakened after changes to the coastline. At shoals and deep troughs, the relative magnitudes of current rise and fall velocities differ. Coastline changes have made the flood dominated phenomenon of the radial sand ridges sea area more prominent. Based on the analysis of the tidal asymmetry of the Lanshayang and Xiyang channels, the influence of coastal change characteristics on the two tidal systems is discussed. In the southern part of the radial sand ridges sea area, the influence of coastal change on the progressive wave is mainly reflected in the following: during spring tides, the asymmetry of rise and fall tide height varies greatly before and after coastal change; and skewness increases slightly. In the north, the influence of coastal changes on the rotating tidal wave entering the area is mainly reflected in the following: skewness clearly increases; and the main combination of tidal components that causes tidal asymmetry may change.
Experimental study on the silting and shoal protection of single row triangular cone perforated circular-hole reef dam
ZHANG Zhitao, SHI Bing, WANG Junjie
2020, (3): 61-67.   doi: 10.12170/20190416001
[Abstract](89) [FullText HTML](48) [PDF 1043KB](2)
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Based on the model test of wave flume section, the effects of single row triangular cone permeable circular-hole reef dams at different design water levels on wave attenuation, topographic evolution of sandy beaches and movement track of bottom water particles were studied. From the analysis of test data, it can be seen that artificial reef dams have great influence on wave height reduction, wave surface shape and wave climbing; artificial reef dams weaken the hydrodynamic strength of the shelter area, weaken the wave sediment carrying capacity, promote the deposition of supersaturated suspended sediment behind the reef, and prevent the offshore loss of bottom sediment by resisting the offshore velocity of horizontal movement of water particles. To a certain extent, the experimental study reveals the characteristics of wave dissipation and current blocking of artificial reef dams and the response law of sandy beach topography, which can provide a scientific basis for the application of artificial reef dams in sandy beach protection.
Performance evaluation index for deepwater channel project of Yangtze River downstream of Nanjing
XIE Yiqin, KONG Zhuang, LIAO Peng, YUE Qiaohong
2020, (3): 68-74.   doi: 10.12170/20190610003
[Abstract](84) [FullText HTML](49) [PDF 685KB](4)
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To comprehensively measure the construction achievement of 12.5 m deepwater channel project of the Yangtze River downstream of Nanjing, based on the fundamental principles of value orientation and internal logic and the relationship chain of “Values-Goals-Objectives-Criteria and Standards”, we used the positive and negative deductive analysis to propose a set of performance evaluation indexes for the major state construction project that strictly follows the project objectives and closely links with the project content. According to the expert questionnaire survey, the performance evaluation index set was confirmed. The results indicate that compared with the existing performance evaluation index guidance for inland waterway engineering, the proposed index set not only focuses on the project’s construction achievements, but also pays more attention to the implementation of the strategic value for the regional and national development by revealing the relationship between the project and the national economy, social development, resources and environment comprehensively.
Model tests on effects of spudcan penetration on an adjacent pile group
YANG Xitao, WANG Jianhua, FAN Yifei
2020, (3): 75-81.   doi: 10.12170/20190316001
[Abstract](182) [FullText HTML](121) [PDF 1654KB](9)
Abstract:
A series of model tests in sand under 1g condition were conducted to investigate the influence of spudcan penetration on an adjacent pile group. Behaviors of piles with fixed pile head constraints were observed, and the pile spacing was selected as 2.5 times the pile diameter during the tests. The changing pattern of the pile shaft bending moment with spudcan penetration into the soil was analyzed by comparison of the maximum bending moment along the pile near the spudcan in the adjacent pile groups before and after spudcan penetration, and the response of a single pile with the same clearance was compared as well. The growth rate of the maximum bending moment of the pile group relative to the maximum bending moment of the single pile body was defined at the same time as the flexural strength ratio. The influence of spudcan penetration on pile group effect and the influence of clearance on the pile group effect were studied through the flexural strength ratio. Compared with the pile group effect before spudcan penetration, it is indicated that spudcan penetration weakens the pile group effect; and the influence of spudcan penetration on the pile group effect is weakened with the increase of clearance, when the clearance exceeds one time the maximum spudcan diameter. It is recommended that the influence of spudcan penetration on the adjacent pile group can be ignored. This study can provide useful guidance to investigate the influence of spudcan penetration on an adjacent pile group.
Study on microscopic deformation mechanism of sand soil shear zone in direct shear test
PAN Yuanyang, WEI Yufeng, LI Yuanzheng, YANG Hao, LEI Zhuang
2020, (3): 82-91.   doi: 10.12170/20190520002
[Abstract](55) [FullText HTML](30) [PDF 1981KB](2)
Abstract:
The formation and development of shear zone is the key factor affecting the deformation and damage of soil. We use numerical simulation test method to study the formation and evolutionary mechanism of shear zone in direct shear test for sand. In the test, the sample was marked by the strip method to observe the process of deformation and development, to record the shear stress and shear displacement, and to analyze the stress-strain characteristics of the sample. Finally, the statistical analysis is made on the average rotation, coordination number, porosity change rate and other parameters of the sample from a mesoscopic angle to reveal the mesoscopic deformation law of the sample. The research shows that the formation of sand shear zone is a gradual process, showing the characteristics of progressive failure. During the process of shearing, the particle sample will be deformed locally and form a long and narrow shear zone. The thickness of the shear zone is directly affected by the average particle size and the frictional coefficient of the particles. When the particle size is 1.25 times the average particle size and the frictional coefficient of particle is 0.5, the thickness of the shear band reaches a maximum value. In addition, the strong force chain in the shear zone region is denser, and the time of peak is most significant by analyzing the optical density and area ratio of the strong chain (the average optical density is about 1.4, and the area ratio of the strong chain is about 52%), which indicates the structural changes of the force chain network are synchronous with the formation and evolution of the shear zone. At the same time, it is found that the mesoscopic parameters such as the average rotation amount, the average coordination number and the porosity change rate of the internal and external particle systems in the shear zone are significantly different, which reflects that the shear zone is more strongly affected by external loads.
Experimental study on physical and mechanical properties of expanded composite slurry
MA Bo, LEI Jinsheng, TU Baolin, DAI Kang, CHENG Shuang
2020, (3): 92-98.   doi: 10.12170/20190227002
[Abstract](173) [FullText HTML](72) [PDF 578KB](2)
Abstract:
At present, ordinary Portland cement slurry is the common grouting reinforcement material in water conservancy engineering. In view of its poor fluidity, high drainage rate, low stone rate as well as its low strength and poor permeability performance problems, based on the preparation of different mixing ratios of cement-based expanded composite slurry, we adopted the single factor controlling variable method and the orthogonal experiment method to test the viscosity, density and mechanical performance of stone body. The experiment results reflect that adding fly ash could increase the workability and fluidity of slurry, and the bentonite could improve the stone rate of grouting and slurry stability. At the same time, bentonite also could reduce the drainage rate and slurry fluidity. The slurry mixed with bentonite and fly ash got improvement with its fluidity and stone rate, but the stone body strength was poor in the early stage. In the later stage, its strength was mainly supplemented by the hydration of fly ash. Cement slurry mixed with appropriate expansion agent had a great influence on the expansion of the stone body and could also improve the anti-permeability of the stone body. Consequently, reasonable selection and control of fly ash, bentonite and expansive agent can obviously improve the grouting effect.
Experimental study on the law of water-heat movement of remolded unsaturated loess humidified by steam
LI Renjie, WANG Xu, ZHANG Yanjie, LI Jiandong, LI Zeyuan, REN Junnan
2020, (3): 99-105.   doi: 10.12170/20190415001
[Abstract](21) [FullText HTML](8) [PDF 1041KB](0)
Abstract:
In order to study the adsorption and migration of water vapor in remolded unsaturated loess, water vapor was used to humidify unsaturated loess, and the law of water-heat movement in remolded unsaturated loess under vapor pressure gradient, temperature gradient and water content gradient was analyzed. The results show that the diffusion range of water vapor and temperature is similar to an ellipsoid in unsaturated loess. During the migration of water vapor, the water vapor pressure disappears along the radial direction, the vapor transport rate decreases, and the soil moisture content and temperature also reduce; when the vapor pressure is 0.1 MPa and the temperature is 145 ℃, the maximum humidification radius of water vapor is 80 cm, and the effective humidification radius in horizontal direction is 60 cm and that in vertical directions is 70 cm after 6.5 hours. In the ellipsoid with the point of ventilation as the center, with 40 cm in the horizontal direction and 50 cm in the longitudinal direction, the water content varies between 12% and 17%. The humidification effect is better, the moisture content close to the soil is 17.08% which is the optimum moisture content, the ventilation time is extended, and the humidification range and the humidification degree are increased; when the steam is humidifying, the migration of liquid water and the gaseous water coexist, but the migration of gaseous water is dominant within the effective humidification range. Obstructed by soil particles, the water transport rate decreases gradually along the radial direction, but the temperature conductivity is close to a fixed value in two stages; the steam humidification method is a new technology and a new method for soil humidification. The advantages have broad application prospects in the engineering practice and experiment of soil humidification.
Fatigue crack propagation model of concrete under water pressure based on energy approach
ZHANG Qiuyu, WANG Licheng
2020, (3): 106-113.   doi: 10.12170/20190303001
[Abstract](34) [FullText HTML](25) [PDF 902KB](0)
Abstract:
For the coupled action of low frequency fatigue loading and pore water pressure, the energy for fatigue crack growth of concrete is usually divided into two aspects. The theoretical approach of energy provided by low frequency fatigue loading and pore water pressure can be derived, respectively. Based on the superposition principle of energy approach, the crack propagation model under the coupled action of low frequency fatigue loading and pore water pressure was developed considering the concept of energy release rate during the fracture of concrete. Then, the theoretical results were validated using available experimental data in the literature. The comparisons indicate that the proposed model agrees reasonably well with experimental data when the pore water pressure is ignored. Moreover, it is found that under the combined action of low frequency fatigue loading and pore water pressure, the pore water pressure can provide the energy dissipated by the opening of closed crack to accelerate the crack growth. Moreover, the crack propagation rate increases with the increase of pore water pressure, which results in the reduction of the fatigue life of concrete.
Dynamic analysis of multi-compartment bucket foundation based on boundary model
WU Shiyang, CAO Yongyong
2020, (3): 114-121.   doi: 10.12170/20190523001
[Abstract](172) [FullText HTML](85) [PDF 1571KB](5)
Abstract:
As the infrastructure of offshore wind power developed in recent years, the stability of the multi-compartment cylindrical foundation impacts on the fan’s safety greatly. In order to study the stability of cylindrical foundation under extreme wind load, the AR autoregression linear filtering method was applied to simulate the fluctuating wind speed spectrum in the study, and the boundary surface elastoplastic dynamic constitutive model and the large-scale finite element analysis software ABAQUS were used to analyze the 3D dynamic value, and study the settlement development of the structure under the random wind load, dynamic response and the pore pressure change of surrounding soil. The study indicated: as the loading continued, the cylindrical horizontal displacement, rotation angle and vertical displacement all trended to increase slowly, meanwhile, the cylindrical top horizontal displacement was much larger than that in the end; affected by the subdivision plate, the pore pressure of the soil in the foundation developed slowly and was smaller than that outside the foundation; along the cylindrical diameter, the closer to the cylinder wall, the greater the pore pressure was; on the out side of the foundation, the pore pressure of the soil decreased gradually with the buried depth, and finally tended to be stable; the stress path of soil was gradually close to the critical state line, but did not reach the failure standard.
Improvement and effect evaluation of river network water environment in China International Import Expo area
CHEN Qingjiang, DING Rui, WANG Weiwei
2020, (3): 122-128.   doi: 10.12170/20200325001
[Abstract](113) [FullText HTML](93) [PDF 5215KB](4)
Abstract:
The 1st China International Import Expo (CIIE) was held in National Exhibition and Convention Center (NECC), Shanghai, in November 2018. The hydrodynamics of river network in CIIE area is weak, and the pollution discharge into river is heavy, especially the Xiaolaigang river just divorced from malodorous black in 2017. It’s quite essential to improve the water enviromment in CIIE Area. Water enviromment improvement schemes were studied based on numerical simulation and field test. Pollution intercepting, ecological restoration and hydrodynamic improvement were adopted to slove the problem of bad water quality, water turbidity and weak hydrodynamics in CIIE area. Three fabricated downflow weirs were built to form cascade water level and water circulation, promoting the ecological restoration and hydrodynamic improvement. The result of operation monitoring indicated that the transparency of the Xiaolaigang river core area was greater than 1.5 m, and the transparency of key area was greater than 1.2 m. Main water quality indicator was promoted from Ⅴ- exceed Ⅴ to Ⅱ-Ⅲ. Effect evaluation indicated that pollution intercepting played an important role in water environment improvement, about 73% proportion. The proportion of hydrodynamic improvement and ecological restoration in water environment improvement was about 15% and 12%.
Advances in studies of tailing dam break mechanism and process
ZHAO Tian-long, CHEN Sheng-shui
2015, (1): 105-111.  
[Abstract](1997) [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](1026) [PDF 872KB](556)
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](1082) [PDF 1367KB](1009)
Analysis of dam-break flood based on HEC-RAS and HEC-GeoRAS
HE Juan, WANG Xiao-song
2015, (6): 112-116.  
[Abstract](909) [PDF 679KB](1138)
Research progress and application of floating breakwater
SHEN Yu-sheng, ZHOU Yi-ren, PAN Jun-ning, WANG Xing-gang
2016, (5): 124-132.  
[Abstract](1209) [PDF 1309KB](594)
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](1009) [PDF 1877KB](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](911) [PDF 542KB](679)
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](800) [PDF 1289KB](469)
Structural design of retaining wall with ecological geo-textile bags and its changes in mechanical properties
ZHU Hai-sheng, CHEN Jian, ZHANG Gui-rong, WANG Wei, FANG Xu-shun
2015, (4): 48-55.  
[Abstract](1023) [PDF 2918KB](585)
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](841) [PDF 1359KB](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

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ISSN:1009-640X

CN:32-1613/TV

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Publication Period: Bimonthly (1979 initial issiue)

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