01 August 2022, Volume 39 Issue 8

    

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  Journal of Changjiang River Scientific Research Institute. 2022, 39(8): 0-0.

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SPECIAL CONTRIBUTION
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  Variation Characteristics of Total Phosphorus Concentration in the Yangtze River Basin in the Thirteenth Five-Year Plan Period

  JI Xiao-yan, PENG Dan

  Journal of Changjiang River Scientific Research Institute. 2022, 39(8): 1-9. https://doi.org/10.11988/ckyyb.20220083

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  The spatial-temporal variation characteristics of total phosphorus (TP) in the Thirteenth Five-Year Plan period are examined in this paper based on the TP data of 590 river sections and 116 lakes and reservoir points in the Yangtze River Basin monitored by the National Examination Network. Results revealed a decline trend of TP concentration in the Yangtze River Basin in the Thirteenth Five-Year Plan period,with the annual average concentration dropping from 0.106 mg/L in 2016 to 0.072 mg/L in 2020. TP concentration in 93.2% sections of the mainstream of Yangtze River decreased,with the annual average concentration reducing from 0.092 mg/L in 2016 to 0.059 mg/L in 2020. Minjiang River,Tuojiang River and Wujiang River witnessed apparent decrease (over 50%) of TP concentration,while the mainstream of Yangtze River experienced a rise of TP concentration due to the inflow of major tributaries including Minjiang River,Tuojiang River,Wujiang River and Hanjiang River. TP concentration at 62.9% of lake and reservoir sites decreased compared with that in 2016. Taihu lake and Chaohu Lake suffered from high TP concentration in autumn,Dongting Lake,Poyang Lake and Danjiangkou Reservoir in winter,and Dianchi Lake in summer. The research finding reflects the positive results of water pollution prevention and control in the Yangtze River Basin on the one hand,and offers reference for the in-depth control of TP pollution in the Yangtze River Basin on the other.
RIVER-LAKE PROTECTION AND REGULATION
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  Changes in Sediment Transport Rate in the Midstream of Yangtze River Before and After the Construction of Three Gorges Reservoir

  YAO Shi-ming, XING Guo-dong, CHEN Dong

  Journal of Changjiang River Scientific Research Institute. 2022, 39(8): 10-16. https://doi.org/10.11988/ckyyb.20211393

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  After the construction of the Three Gorges Reservoir (TGR),sediment-containing flow in the downstream channel of the reservoir had been in a severe sub-saturation state for a long time. The sediment transport changed from a relative equilibrium state to an unbalanced state,and the sediment transport intensity varied significantly compared with that in natural condition. Based on the cross sectional data,bed sediment and hydrological data of major hydrological stations in the midstream of the Yangtze River before and after the operation of the TGR (1992-2017),we looked into the sediment transport intensity of compound cross sections from the perspectives of sediment transport rate,bed sediment particle size,and bankfull discharge. We found that after the impoundment operation of TGR,the sediment that enters the downstream channels reduced remarkably,and the sediment transport rate of the same flow level at hydrologic stations along the midstream of Yangtze River decreased obviously. The bed sediment was coarsened in different degrees along the river. Such coarsening was most obvious in the Jingjiang reach and less obvious in the Luoshan-Wuhan reach. At hydrologic stations of Luoshan and Hankou,the sediment transport intensity in the adjacent of bankfull discharge reached the maximum under natural conditions,and the corresponding sediment carrying capacity reached peak.
WATER RESOURCES
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  Water Temperature Variation and Its Influencing Factors in the Upper Jinsha River

  SHAO Jun, DU Tao, GUO Wei, OUYANG Shuo, WANG Kun

  Journal of Changjiang River Scientific Research Institute. 2022, 39(8): 17-22. https://doi.org/10.11988/ckyyb.20210380

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  As the source area of the Yangtze River,the upper Jinsha River is of special eco-environmental functions.The water temperature of the river is of great significance to the growth of aquatic organisms and the surrounding ecological environment.In this paper,the intra-annual and inter-annual changes as well as distribution along the flow direction of natural water temperature of the upper Jinsha River were examined according to measured water temperature data from hydrological stations of Gangtuo,Batang,and Shigu.Major hydrological and meteorological factors that affect the water temperature were also analyzed.Results unveiled that the monthly average water temperature at Gangtuo,Batang,and Shigu hit the highest from July to August in general,while the lowest in January.The annual water temperature at the three stations displayed a significant upward trend from 1961 to 2018,with abrupt changes in 1998,1992,and 2003,respectively.Air temperature had the largest influence on the monthly average water temperature,followed by precipitation and streamflow;relative humidity,evaporation and wind speed also had a certain impact on the change of water temperature;sunshine hour bore a weakest relationship to water temperature.From the upstream to the downstream,the coefficients of correlation between water temperature and runoff,wind speed,and water surface evaporation decreased,while those between water temperature and precipitation,temperature,and relative humidity increased.The hydrological and meteorological characteristics of the basin were closely related with water temperature changes.In addition,the main factors affecting water temperature were further verified through principal component analysis.
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  Optimal Scheduling of Reservoir Based on Long-term and Medium Long-term Nested Model

  SUN Gui-kai, SHI Rui, LIU Si-yi, WANG Guo-shuai, ZHAO Rong-na, MO Chong-xun

  Journal of Changjiang River Scientific Research Institute. 2022, 39(8): 23-28. https://doi.org/10.11988/ckyyb.20210289

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  The comprehensive benefit of reservoir is not high due to different time scales in the process of optimal scheduling.In view of this,a nested model of multi-objective optimal scheduling of reservoir is built with both flood control and operational benefit as objectives by nesting the long-term and medium-to-long-term optimal scheduling of reservoir.The multi-objective problem is transformed into a single objective problem of solving the maximum power generation after the flood control objective is transformed into a hard constraint by the constraint method.In terms of algorithm,the long-term optimal scheduling is solved by dynamic programming algorithm,and the medium-to-long-term optimal scheduling is solved by genetic algorithm.The optimization effect of the nested model is verified with Chengbihe reservoir as a case study.The results demonstrate that under the premise of meeting the flood control objectives,the nested model scheme is more effective than the long-term scheme and the actual operation scheme,which verifies the superiority of the nested model.
WATER ENVIRONMENT AND WATER ECOLOGY
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  Diagnosing Cd Pollution Source in Xiaojiang River Valley of Dongchuan in Yunnan Province Based on Element Characteristic Analysis

  LIU Yan, SU Huai, LI Wei-kang, DONG Ming

  Journal of Changjiang River Scientific Research Institute. 2022, 39(8): 29-33. https://doi.org/10.11988/ckyyb.20210487

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  Whether Cd pollution in Xiaojiang River Valley of Dongchuan,Yunnan Province originates from copper mining or agricultural pollution was still unclear,which hinders the effective prevention and control of local heavy metal pollution.In this paper,the source of Cd pollution in Xiaojiang River Valley is diagnosed by associating the main pollutants of copper mining with the content of Cd of local chemical fertilizers on the basis of investigating the spatial distribution of Cd element in the river valley.Element characteristic analysis unveils that 1) the major pollutants produced from copper mining,namely,copper ore and tailing slag,are not capable of polluting the river valley as the average content of Cd in copper ore and tailing slag is only 0.30 mg/kg,far lower than that of Cd-polluted cultivated land (4.60 mg/kg) and floodplain (2.53 mg/kg);2) phosphorus fertilizer is more likely to be the main pollution source of Cd in the watershed because the average content of Cd in local phosphorus fertilizer is 83.45 mg/kg,18 times higher than that in Cd-polluted farmland;3) the spatial distribution of Cd content in floodplain shows no trend of continuous attenuation from the mining area to the downstream,which does not support the diffusion model of Cd pollution from copper mining;4) the content of Cd in cultivated land is generally higher than that in floodplain,indicating that cultivated land is closer to pollution source,which conforms to the pollutant diffusion mode of agricultural activities;5) the correlation between Cd content in cultivated land and floodplain and available phosphorus (AP) is much higher than that between Cd content and Cu content which represents copper mining,implying that Cd pollution is more closely related to phosphorus fertilizer application than copper mining.In conclusion,the contribution of phosphorus fertilizer in agricultural activities to Cd pollution is likely to be much greater than that of copper mining.
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  Spatial Distribution and Hydraulic Driving Factors of Macrobenthic Communities in Lijiang River

  LIU Rui, LI Ruo-nan

  Journal of Changjiang River Scientific Research Institute. 2022, 39(8): 34-40. https://doi.org/10.11988/ckyyb.20210409

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  The structure and distribution of macrobenthos community are important indicators for evaluating the ecological health of rivers.Based on the surveys in wet and dry seasons of typical hydrological years,we analyzed the spatial distribution of benthic community structure,feeding groups and their responses to hydraulic factors in the middle and lower reaches of the Lijiang River Basin.The results demonstrate that:1) Gastropods are predominant in the community structure of a typical river section,and Cipangopaludina cathayensis and Semisulcospira sp.are dominant species;the density of benthic animals is 829 ind/m² in wet periods and 264 ind/m² in dry periods.2) Scrapers are dominant in the feeding groups,and their relative abundance in dry season is lower than that in wet season,while the relative abundances of collector-filterers,collector-gatherers,and predators in dry season are higher than those in wet season.The relative abundances of feeding groups in the middle reach are greater than those in the lower reach.3) The biodiversity of typical river sections is spatially heterogeneous,significantly lower in the middle reach than in the lower reach.4) Velocity,bottom shearing force and geological particle size are major factors affecting the distribution of benthic organisms in the Lijiang River during dry season;water depth and laminar layer thickness are major factors in wet season.The sorting coefficient and the thickness of laminar layer are the most important factors that affect the benthic biodiversity.
SOIL AND WATER CONSERVATION AND ECOLOGICAL RESTORATION
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  Spatial and Temporal Land Use/Cover Change Characteristics of Qinghai-Tibet Plateau

  PENG Hai-yue, REN yan, LI Qiong, WEI Jia-hua

  Journal of Changjiang River Scientific Research Institute. 2022, 39(8): 41-49. https://doi.org/10.11988/ckyyb.20210470

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  The characteristics of land use change from 1992 to 2015 in the Qinghai-Tibet Plateau are analyzed by examining the spatial-temporal distribution and change rate of land use using the 300 m high-precision land use data (abbreviated as TPDC_LUCC) of Qinghai-Tibet Plateau Research Institute on the basis of evaluating the accuracy of public land use data set. The attribution of land use change is also analyzed based on climate data and social economic data. Results reveal that:1) Among the public datasets,the TPDC_LUCC dataset has the longest sequence and the highest accuracy,especially the classification accuracy of cultivated land,urban land and water bodies;the 300 m land use data (abbreviated as ESA_LUCC) of the European Space Agency has the highest classification accuracy for grassland and the worst for cultivated land;the 30 m land use data (abbreviated as CASearth_LUCC) of the Institute of Space Information Innovation,Chinese Academy of Sciences has a relatively accurate classification of glacier and urban land,yet with a large error of unused land. 2) Grassland is the most widely distributed in Qinghai-Tibet Plateau,with a multi-year average proportion reaching 70.02%,followed by unused land such as sandy land and bare land,accounting for 15.81%. Urban land expanded rapidly,with a growth rate of 2.34% from 1992 to 2005 and 4.69% from 2005 to 2015. From 1992 to 2015,9.14% of unused land on the Qinghai-Tibet Plateau was turned into grassland,3.27% of shrub and arable land into forest land,and 5.5% of glaciers into water. 3) From 1992 to 2018,the average temperature of the Qinghai-Tibet Plateau increased by 1.17 ℃,and the increase of precipitation and temperature was the main driving factor for the increase of grassland,shrub and forest land in the eastern region. The significant increase of temperature led to the melting of glaciers in the northwest,and urbanization resulted in the increase of urban land and the decrease of cultivated land. Implementing ecological protection policies has significantly promoted the restoration of grassland and forest land on the Qinghai-Tibet Plateau.
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  Temporal and Spatial Distribution of Soil Erosion and Erosion Hotspots Analysis:A Case Study of Wangyi District,Shaanxi Province

  CHEN Si-bin, HUO Ai-di, CHEN Si-ming, ZHAO Zhi-xin, CHEN Jian

  Journal of Changjiang River Scientific Research Institute. 2022, 39(8): 50-57. https://doi.org/10.11988/ckyyb.20210394

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  The aim of this study is to evaluate the soil erosion change since the implementation of ecological measures such as gully consolidation and highland protection in Wangyi District.The vegetation coverage is estimated by Dimidiate Pixel Model,the distribution of soil erosion intensity in 2000 and 2019 is analyzed and the spatial aggregation evolution characteristics of soil erosion intensity are revealed based on GIS and exploratory spatial data analysis (ESDA-GIS).The results demonstrate that:(1) The area of forest and grassland in Wangyi District has increased markedly,and the area with high coverage (>75%) grew by 16.51 km².(2) The condition of soil erosion in Wangyi district alleviated obviously.Soil erosion area in 2000 was as high as 70.92% of the whole area,and 55.84% in 2019.The structure of soil erosion intensity has also changed.In 2000,the study area was dominated by moderate erosion,followed by strong erosion,mild erosion,and extremely strong erosion in sequence,while in 2019,mild erosion dominated,followed by moderate erosion,strong erosion,and extremely strong erosion in sequence.(3) The distribution of soil erosion intensity has obvious spatial aggregation characteristics.The Global Moran’ I index is around 0.5,and the erosion hotspots transformed from large continuous distribution to locally concentrated scattered distribution.The erosion hotspots are mainly distributed in the slope range of 15°-25°,especially in the southwest and southeast regions.The research findings provide data support for water and soil conservation planning,design and treatment in Wangyi District.
ENGINEERING SAFETY AND DISASTER PREVENTION
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  Data Mining Method for Bank Slope Monitoring Based on Association Rules

  CHEN Bo, ZHAN Ming-qiang, HUANG Zi-shen

  Journal of Changjiang River Scientific Research Institute. 2022, 39(8): 58-64. https://doi.org/10.11988/ckyyb.20210457

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  The monitoring data of slope records the whole process information of slope instability disaster.The data mining of bank slope monitoring database runs slowly.FP-Growth association rule algorithm is introduced into slope safety monitoring data mining.The causal association rule and spatial association rule in slope monitoring data are mined by FP-Growth association rule algorithm.The causality between environmental variables and affected variables of slope monitoring and the correlation among affected variables of multiple measuring points are mined respectively.Effective information reflecting slope operation characteristics is extracted from slope spatio-temporal monitoring data containing multi-measuring points and multi-items.Calculation example shows that FP-Growth association rule algorithm is simple in implementation and reliable in mining results,hence providing a good approach for monitoring data mining of similar reservoir bank slopes.
HYDRAULICS
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  Application of 2D Flow Mathematical Model to Fish Habitat Design in Braided River Channel

  YANG Yan-long, CHENG Kai-yu, SHI Jia-yue, SHENG Sheng

  Journal of Changjiang River Scientific Research Institute. 2022, 39(8): 65-70. https://doi.org/10.11988/ckyyb.20210465

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  Due to complex flow patterns,the confluence or diversion port of braided river is often encountered with estuarine beaches and deep channels.The complex and diverse hydrologic conditions provide a good habitat for fishes.In line with the complex boundary of braided river,a two-dimensional mathematical flow model based on the general curve coordinate system is established and applied to the construction of ecological river network and fish habitat design of the left bank of Angu hydropower station in Leshan reach of Dadu River.The water depth,flow velocity,flow field and diversion ratio of the river reach before and after the project are simulated and compared.By implementing ecological engineering measures in the ecological river channel on the left bank,the water flow characteristics of the spawning area still meet the requirements of fish habitat.In terms of the operation effect of Angu hydropower station,the designed ecological measures have achieved good practical effect on the improvement of fish habitat in river.
ROCK-SOIL ENGINEERING
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  Blasting Damage Characteristics of Rock Mass Near Blast Hole of Hydropower Engineering Slope

  LIANG Rui, BAO Juan, ZHOU Wen-hai

  Journal of Changjiang River Scientific Research Institute. 2022, 39(8): 71-76. https://doi.org/10.11988/ckyyb.20210269

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  Single-hole blasting damage models were established by using HJC (Holmquist-Johnson-Cook) model and RHT (Randomized Hough Transform) model respectively for comparison to study the dynamic response of rock mass blasting in the vicinity of the blast hole of hydropower engineering slope under different damage models.The blasting damage distribution,the seismic wave energy characteristics,and the threshold of damage particle peak vibration velocity (PPV) of rock mass under the two models were investigated based on the simulation result and calculation analysis.The results demonstrated that the blasting cracked area in the RHT model is approximately twice that of the HJC model under the same working condition.The smaller the damage range,the greater the proportion of explosive shock wave transformed to elastic vibration wave.The damage PPV thresholds of HJC model and RHT model were obtained by fitting the relationship between damage degree and PPV as 13.09 cm/s and 27.29 cm/s,respectively.In conclusion,the RHT model reflects more accurately the blasting damage effect of rock mass in the vicinity of actual slope.
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  Strain Accumulation Characteristics and Empirical Model of Saturated Soft Clay

  SUN Lei

  Journal of Changjiang River Scientific Research Institute. 2022, 39(8): 77-85. https://doi.org/10.11988/ckyyb.20210299

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  Partially drained CCP (constant confining pressure) and VCP (variable confining pressure) cyclic triaxial tests were carried out on Wenzhou soft clay by using GDS (Global Digital Systems) to investigate the permanent deformation behavior of saturated soft clay in subgrade under long-term traffic load more realistically.Special attention was paid to the influences of cyclic stress ratio (CSR),stress path (α) and length (L) on the permanent axial strain of saturated soft clay.The test results unveiled that at a give cycle number (N),the permanent axial strain increased with the increase of CSR and the decrease of α,which can be described by exponential function and logarithmic function respectively.The normalized permanent axial strain undergone 10,000 cycles (ε^p_{a,10 000}/ε^p,CCP_{a,10 000}) was in a logarithmic relationship with the normalized stress path length (L/L_CCP),and a linear relationship with the normalized mean principal stress amplitude (p^ampl/p^ampl_CCP),regardless of the CSR values.Furthermore,a logarithmic empirical model considering the combined effect of CSR,α,and N was established to predict the permanent axial strain under different stress paths,and the predicted results were in good agreement with the measured deformation.
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  Influence of Rock Block Proportion on Seepage Characteristics of Soil-rock Mixture in Fault Zone

  TAN Wen-hui, DONG Feng-xin, MA Xue-wen, WANG Peng-fei

  Journal of Changjiang River Scientific Research Institute. 2022, 39(8): 86-92. https://doi.org/10.11988/ckyyb.20210392

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  Fault fracture zone is an important channel for mine water inrush. Most of the fracture zone is composed of soil-rock mixture(SRM) whose seepage characteristics have an important influence on the prediction and prevention of mine water inrush. To investigate the impact of rock content on the seepage characteristics of SRM in fault fracture zone,SRM samples were remolded in lab from the field-collected mixture of fault gouge and rubble. The permeability characteristics of samples with different rock block proportions were examined under different confining pressures and axial pressures by using GDS tri-axial test system,and the sensitivity of permeability coefficient to rock content change was analyzed. Moreover,the seepage characteristics,the crack propagation and failure of SRM samples with different rock-bearing rates were investigated by using RFPA. Results demonstrated that 1)higher rock content resulted in larger initial permeability coefficient and higher strength of SRM;2)the permeability coefficient reduced with the increase of confining pressure,and the relation between permeability coefficient and axial pressure can be described by exponential function;3)rock content of 40% and 60% had a largest influence on permeability coefficient;4)cracks during the seepage failure of SRM mainly propagated in the soil between the rocks;5)the sudden change point of permeability coefficient was consistent with the peak strength failure point of the sample and the highest point of acoustic emission frequency. The research results offer reference for preventing and controlling geological disasters such as engineering water inrush in fault areas with varied rock content.
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  Comprehensive Experimental Study of Strength and Deformation Characteristics and Mechanical Model Parameters of Sandy Pebble Soil

  WANG Ya-ping, LU Yi-wei, ZHANG Er-shuai, PENG Yuan-cheng, ZUO Yong-zhen, LI Hao-min

  Journal of Changjiang River Scientific Research Institute. 2022, 39(8): 93-98. https://doi.org/10.11988/ckyyb.20210390

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  Sandy pebble soil is a special coarse-grained soil whose strength and deformation characteristics are one of the key concerns in engineering field. The comprehensive mechanical properties of sandy pebble soil were examined via triaxial shear test,interfacial shear test and rheological test,and appropriate constitutive relationships were selected to describe the stress-strain relationships of sandy pebble soil. In addition,the corresponding model parameters were summarized. Tests results reveal that the shear strength of unsaturated sand pebble soil was remarkably larger than that of saturated samples. Under low confining pressure,unsaturated samples and saturated samples displayed shear shrinkage characteristics and dilatancy characteristics,respectively,while under high confining pressure,obvious shear shrinkage characteristics could both be observed. The shear stress and displacement on the interface between sandy pebble soil and concrete face show a good hyperbola relationship,and the shear strength and normal stress show a good linear relationship. The relationship between rheological deformation and time of sandy pebble soil is linear in logarithmic coordinates. A rheological model of sandy pebble soil with eleven parameters was proposed to better reflect the rheological properties of sandy pebble soil. The research results provide theoretical support for the research of strength and deformation characteristics and settlement prediction of sandy pebble soil foundation.
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  RVE-based Quantitative Characterization of 3D Mesostructure Characteristics of Granite Residual Soil with Macropores

  YANG Peng-fei, LI Xian, QUE Yun, CAI Pei-chen

  Journal of Changjiang River Scientific Research Institute. 2022, 39(8): 99-104. https://doi.org/10.11988/ckyyb.20210341

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  The aim of this research is to reveal the distribution characteristics of macropores in granite residual soil in three-dimensional scale.The characteristics of macropores of undisturbed granite residual soil in Fuzhou are characterized quantitatively as a case study by extracting the parameters of macropores via three-dimensional reconstruction using the representative volume element (RVE) based on CT (computer tomography)scanning images of the soil.Results unveil remarkable difference in the number of connected pores in granite residual soil samples but small difference in pore structure due to the similar causes of pore formation with the pore radius mostly between 1 mm and 4 mm.The topological spatial structure of pores in soil at different locations varies notably,with the coordination number of some pores reaching over 40,which is rarely influenced by depth.The coordination number of pores is mainly concentrated within 20,and the coordination number of pores above 20 is distributed in discrete points.Comparison among different processing methods demonstrate that the average pore diameter obtained by two-dimensional image processing is the smallest,and the porosity is quite different;the average pore diameter obtained by pore network model processing is the largest,and the pore distribution is relatively uniform;the difference of average pore volume between 3D reconstruction processing and pore network model processing is over five times.
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  Stability Analysis for Anaclinal Layered Rock Slopes Subjected to Flexural Toppling under Earthquake Load

  QU Xin, SU Li-jun, XU Xing-qian, LÜ Qian, LOU Gao-zhong

  Journal of Changjiang River Scientific Research Institute. 2022, 39(8): 105-112. https://doi.org/10.11988/ckyyb.20210395

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  Current studies of flexural toppling failure rarely involve earthquake loading,and the influence laws of earthquake load on the stability of anaclinal layered rock slopes subjected to flexural toppling is unclear.In order to solve the above problems,we present a limit equilibrium method to evaluate the stability of anaclinal layered rock slopes subjected to flexural toppling under earthquake load.We consider that once the overall failure of a slope occurred,the stress of the slope reached the limit equilibrium state,i.e.,the residual sliding force (toppling force) of slope toe calculated along the failure surface was zero.Based on the idea of static equivalent substitution,the calculation formula of the non-dimensional height of the point of application of normal force was derived.The stable zone,potential failure zone and the failure modes of potential failed strata were determined via strict mechanical derivation,and the residual sliding force (toppling force) of slope toe was obtained with step by step analysis method.The calculation results for a slate slope in South Anhui as an engineering example demonstrate that the slope failure plane and the safety factor of the stability of the slope are credible.Through the sensitivity analysis of seismic coefficient,we found that with the increase of seismic coefficient,the residual sliding force of slope toe increase while the safety factor of the stability of the slope decrease,and consequently,the slope is subjected to shallow damage and becomes more unstable.
HYDRAULIC STRUCTURE AND MATERIAL
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  Stress-strain Response of Pre-stressed Concrete Cylinder Pipe under Rockfall Impact Load

  MAO Hao-ran, CHENG Lin, YANG Jie, MA Chun-hui, YUAN Xing-guo

  Journal of Changjiang River Scientific Research Institute. 2022, 39(8): 113-119. https://doi.org/10.11988/ckyyb.20210345

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  A finite element model of rockfall-soil-pipe was established to study the influence of rockfall impact on the safe operation of Prestressed Concrete Cylinder Pipe (PCCP).The process of spherical rockfall impact on buried PCCP was simulated on the basis of the calculation of static load condition.By changing the radius and height of rockfall,the stress and plastic strain of pipeline under different rockfall impact loads were examined.Results demonstrated that PCCP under rockfall impact mainly suffered from circumferential tensile plastic damage.Compared with the height of rockfall,the change of rockfall radius had a greater influence on PCCP.At a suspension height of 10 m,the falling rock with a radius over 1.4 m would cause visible cracks in the material with the plastic strain of concrete tube core exceeding 16.0×10^-4 and the plastic strain of mortar over 9.1×10^-4.Under rockfall impact load,concrete tube core first witnessed damage,and then mortar,steel tube,and prestressed steel wire in sequence.After the crack of concrete tube core,steel tube and prestressed steel wire saw rapid increase and yield failure of Mises stress.
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  Mechanical and Deformation Properties of Sulfate-attacked Concrete under Cyclic Loading and Unloading with Variable Amplitude

  XUE Wei-pei, XU Wei, LIU Xiao-yuan, ZHANG Han-wen

  Journal of Changjiang River Scientific Research Institute. 2022, 39(8): 120-125. https://doi.org/10.11988/ckyyb.20210412

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  The mechanical and deformation properties under cyclic loading and unloading with variable amplitude are crucial for concrete structures under sulfate attack. The evolution of the mechanical properties,deformation properties and dissipation energy of concrete specimens under chemical erosion immersed in 10%,15% and 20% sodium sulfate solution for 5 and 7 months in advance was examined via uniaxial compression cyclic loading and unloading test with variable amplitude. Results demonstrated that with the increase of sodium sulfate concentration and erosion time,the strength of the specimen declined,and the number of cycles at failure decreased. The cumulative residual strain increased with the rising of loading strain,and such increment intensified continuously. The loading strain difference was always larger than the cumulative residual strain difference,but approached closer gradually with the proceeding of cyclic loading and unloading. The dynamic elastic modulus and plastic deformation rate both increased with the cyclic loading. The dissipated energy also increased with the cyclic loading,and especially boosted in the later stage.
INFORMATION TECHNOLOGY APPLICATION
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  A Preliminary Study on Runoff Simulation of Salt Lake Basin with the Air-Space-Ground Stereoscopic Monitoring System and VIC Model

  LI Lin, WEN Xiong-fei, TAN De-bao, WANG Ying, LIU Xi-sheng, WANG Gang

  Journal of Changjiang River Scientific Research Institute. 2022, 39(8): 126-132. https://doi.org/10.11988/ckyyb.20210354

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  Hydrological simulation for the Salt Lake basin encounters many difficulties by using traditional methods due to the lack of basic data.An air-space-ground stereoscopic monitoring system for the Salt Lake was established using satellite remote sensing technology,unmanned ships and other technologies to study the changes of ecological environment and hydrometeorology.The water level-area-volume relationship curve was obtained,the monthly-scale lake area was interpreted through monthly remote sensing data,and the storage variable as well as the monthly-scale runoff into the lake were deduced.Furthermore,a VIC(Variable Infiltration Capacity)model based on multi-source data was constructed to simulate the lake runoff by collecting and sorting out the Chinese regional ground meteorological element-driven data set CMFD and MODIS LAI(leaf area index).Results reveal that the Nash coefficient NSE and relative error of the simulated runoff of the Salt Lake basin are 0.87 and 11.81%,respectively,which reflects the change of the actual runoff.The air-space-ground stereo monitoring system combined with the VIC model could simulate the monthly-scale runoff change process of the Salt Lake basin,and hence offering reference for the hydrological simulation of rivers and lakes in areas with no data.
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  Three-dimensional Visualization of Grouting for Water Conservancy and Hydropower Project Based on GIM: Analysis Method and Application

  SHI Yan, HUANG Can-xin, WANG Tuan-le, SHI Hua-tang, SUN Yun-shan

  Journal of Changjiang River Scientific Research Institute. 2022, 39(8): 133-139. https://doi.org/10.11988/ckyyb.20210180

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  The quality control of water conservancy and hydropower grouting project has been a difficulty in the industry for a long time because of its hidden operation, large amount of data and strong experience. Guided by the core values of BIM (Building Information Modeling), the three-dimensional visualization analysis method of grouting engineering based on GIM (Geological Information Modeling) is researched in this paper to improve the efficiency and effectiveness of grouting analysis following the idea of “real-time monitoring, rapid analysis and dynamic feedback” in the whole process. The analysis method includes the construction and analysis of GIM model, the parameterization and visualization of grouting engineering, the real-time monitoring and visualization of grouting process, etc. On this basis, a 3D visualization analysis system of grouting engineering based on GIM is developed. Engineering practice manifests that the present method could accomplish the prediction of geological conditions of grouting holes in advance, the real-time monitoring and abnormal diagnosis in the grouting process, and the rapid analysis and evaluation of the results after the process, hence offering reliable technical support for the quality control and management of concealed grouting project.
INSTRUMENTATION DEVELOPMENT AND TESTING TECHNIQUES
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  Experimental Study on Separation Efficiency of Hydrocyclones for Treatment of Waste Water with High Sand Concentration

  ZHANG Jun-peng, HUANG Wei, DONG Ya-kang, ZHU Ya-peng, CHEN Wen

  Journal of Changjiang River Scientific Research Institute. 2022, 39(8): 140-144. https://doi.org/10.11988/ckyyb.20210400

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  Hydrocyclone is a crucial device of waste water treatment in aggregate processing for hydropower projects. The separation efficiency of hydrocyclone determines the success of the whole processing system. To date,the operational parameters of hydrocyclone are empirical. To quantify the impact of inlet pressure and concentration as well as hydrocyclone parameters on separation efficiency,we carried out test on the separation efficiency of hydrocyclone with a diameter of 250 mm and 150 mm,respectively. Results demonstrated that the rising of inlet pressure cannot further obviously increase the production rate of underflow as it reached 0.1 MPa. As inlet concentration increased,the production rate of underflow decreased. Hydrocyclone with a diameter of 250 mm or 150 mm is not recommended to be used alone as the former has a production rate lower than design value,which results in unsatisfactory performance of some processing techniques,and the latter has a concentration of underflow lower than the requirement for the next dehydrate process. We recommend to use hydrocyclone with a diameter of 200 mm alone,or a diameter of 250 mm and 150 mm in parallel running. The research findings offer experience for the design and operation of waste treatment in aggregate processing.
UTILIZATION OF GROUNDWATER RESOURCE
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  Evaluation Index System for the Suitability of Groundwater Strategic Reserve Site in Middle and Lower Yangtze River

  WU Qing-hua, WANG Xiao, FAN Yue

  Journal of Changjiang River Scientific Research Institute. 2022, 39(8): 145-151. https://doi.org/10.11988/ckyyb.20220060

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  The middle and lower reaches of the Yangtze River is endowed with abundant surface and groundwater resource. However,when cities suffer from emergencies or extreme regional drought,the surface water resource could be depleted,which seriously threatens the social stability. Groundwater could be pumped from a relatively safe groundwater strategic reserve(GSR)to deal with the problem of water shortage. In this paper,the principles of choosing the site for GSR are put forward from utilization and security perspectives. An evaluation index system for the suitability(EVISS)of location selection of GSR was established by integrating expert advice and hierarchical analysis. The system contains 16 influence factors in aspects of groundwater supply capacity,impact of emergency use,social and economic development,and environmental disasters’ impact,etc. The weights of the influence factors were determined:aquifer storage capacity and emergency water supply time boasts the largest weight,reaching 0.2138 and 0.1530,respectively,while economic cost of emergency water supply has the minimum weight,only 0.0057. The research finding offers technical support for the planning and emergency use of GSR in the Yangtze River Basin.
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  Evaluation Index System and Emergency Use of Groundwater Strategic Reserve:A Case Study on the City of Wuhan

  WU Qing-hua, WANG Xiao, CUI Hao-dong, FAN Yue, ZHANG Wei, WANG Jin-long, XIAO Li

  Journal of Changjiang River Scientific Research Institute. 2022, 39(8): 152-158. https://doi.org/10.11988/ckyyb.20211187

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  Emergencies or extreme climate events would pose potential risks to the water supply security in cities with only surface water source. In cities with abundant groundwater resource,groundwater strategic reserve can be built to cope with the problem of water shortage arising from emergencies. Nevertheless,systematic basis for evaluating the site selection of strategic reserve area is still in lack at present. In view of this,an evaluation index system of the suitability of site selection for strategic reserve of groundwater resource was established by using analytic hierarchy process. The index system involves groundwater supply capacity,impact of emergency use,socio-economic development,and environmental disaster impact. With the city of Wuhan,a typical city in the middle and lower reaches of the Yangtze River Basin,as a case study,the suitability of five target sites of groundwater strategic reserve was evaluated in consideration of the scale of water supply and the water-richness of aquifers,and the results showed strong suitability of target sites. On this basis,Feflow was employed to evaluate the emergency utilization scheme from the perspective of layout of mining wells and emergency time. The results manifest that with the increase of emergency time,the influence of pumping scheme on groundwater dynamic became more significant,but such influence attenuated with the increase of pumping well spacing. The research finding could provide reference for the site selection of groundwater strategic reserve in the Yangtze River Basin.
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  Decoupling Trend and Spatial Aggregation Between Groundwater Supply and Economic Development in China

  FENG Li, WU Guang-dong, ZHAO You-lin

  Journal of Changjiang River Scientific Research Institute. 2022, 39(8): 159-166. https://doi.org/10.11988/ckyyb.20220065

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  Studying the decoupling relationship between groundwater supply and GDP in provinces of China is of great significance for optimizing and adjusting the water supply structure and strengthening the protection and restoration of groundwater resources in the future. Based on the data of water supply,GDP and population of 31 provinces in China from 2000 to 2020,we investigated the decoupling between groundwater supply and GDP and the main driving factors of decoupling in the past two decades via decoupling analysis,driving effect analysis and spatial correlation analysis,and further discussed the spatial aggregation characteristics of each driving factor at provincial scale. The results manifest that the relationship between groundwater supply and economic development in China has gradually evolved from weak decoupling to strong decoupling,and the year 2013 is the dividing point from weak decoupling to strong decoupling. The increase of water use efficiency is the main factor driving the decrease of groundwater supply,while the rising of per capita GDP is the main factor driving the increase of groundwater supply. Provinces in China mainly experienced weak decoupling in the period from “The Tenth Five-Year Plan” to “The Eleventh Five-Year Plan”,while from “The Twelfth Five-Year Plan” to “The Thirteenth Five-Year Plan”,provinces with strong decoupling were dominant. From “The Tenth Five-Year Plan” to “The Thirteenth Five-Year Plan”,the main factors influencing decoupling state gradually evolved from economic level to water use efficiency and water supply structure;at the end of “The Thirteenth Five-Year Plan”,the contribution rate of each driving factor showed H-H aggregation or L-L aggregation characteristics.