01 January 2019, Volume 36 Issue 1

    

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SPECIAL CONTRIBUTION
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  Standard-reaching Rate of Water Quality in Water Function Regions in Changjiang River Basin in Recent Years

  CHEN Jin, LIU Zhi-ming

  Journal of Changjiang River Scientific Research Institute. 2019, 36(1): 1-6. https://doi.org/10.11988/ckyyb.20181063

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  According to the data of water resource quality bulletin and water resource bulletin of Changjiang River Basin in recent five years, the standard-reaching rate of water quality of first-class water function region and drinking water source area of second-class water function region in main streams and main tributaries of Changjiang River Basin was examined, and the change of main pollutants was also analyzed. Research findings are as follows:(1) in first-class water function region, the standard-reaching rate of water quality has improved apparently, of which the rate of river water quality is always higher than that of lake water quality. The standard-reaching rate of lake varies significantly during a year. (2) In second-class water function region, despite that the standard-reaching rate of water quality has raised by 11.6%, the rate of lake maintains a downward trend. (3) The standard-reaching rate of water quality has improved in main streams and tributaries of the Changjiang River, among which the Yibin-Yichang reach witnessed the most obvious improvement, followed by the Minjiang River and Tuojiang River. Except for the stream below Shigu of Jinsha River and mountainous rivers of the Jialing River, the standard-reaching rate of water quality in dry season is relatively poor in most river segments of the Changjiang River, indicating that the huge water environmental capacity of the Changjiang River contributes to the good water quality in recent years. The standard-reaching rate of river water quality in drinking water source area is relatively high, but varies sharply during a year. The rate of Yibin-Yichang reach and the main stream in the downstream of Hukou increases by 50.6% and 29.2%, respectively, while the rate of Wujiang River drops by 21.6%, with total phosphorus as the major standard-exceeding pollutant. (5) As the point-source pollution control works effectively, total phosphorus has replaced ammonia nitrogen and COD to be the most important standard-exceeding pollutant in almost all water bodies of the Changjiang River. In conclusion, further improving the water quality of Changjiang River requires precisely targeted, scientific and steady control of main pollutants in different water regions.
WATER RESOURCES AND ENVIRONMENT
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  Research of Oncomelania Snails’ Migration and Diffusion in Water: Review and Prospects

  ZHANG Lin, WANG Jia-sheng, YANG Qi-hong, MIN Feng-yang

  Journal of Changjiang River Scientific Research Institute. 2019, 36(1): 7-12. https://doi.org/10.11988/ckyyb.20170787

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  Schistosomiasis, severely harmful to the human health, is a most widely distributed chronic parasitic disease epidemic in 73 countries of Asia, Africa, and Latin America attacking 200 million people. As the only intermediate host of schistosome, oncomelania snails migrating and diffusing plays a fundamental role in the spread of schistosomiasis. Studying the migration and spread of oncomelania hupensis is of vital significance for the controlling of schistosomiasis. In this paper, the suitable habitats for oncomelania and influential factors, the diffusion modes, the effects of water conservancy projects on the migration and diffusion of oncomelania hupensis are reviewed and summarized based on previous researches. Furthermore, the remaining challenges and future development are discussed.
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  Investigation on the Feasibility of Centrifugal Simulation on Water Migration in Vadose Zone

  QIN Huan-huan

  Journal of Changjiang River Scientific Research Institute. 2019, 36(1): 13-20. https://doi.org/10.11988/ckyyb.20170593

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  As the main driving force of pollutant migration and the movement of water, vapour and heat, water movement in vadose zone is of very important significance to the “four water” transformation, groundwater source, water resources development and utilization, ecological protection, and human’s production and life. Nevertheless, it is still controversial whether centrifugal simulation can be applied to researching the water migration in vadose zone. In this paper, the feasibility of applying centrifugal simulation to researching water migration in vadose zone is investigated via establishing one-dimensional theoretical and numerical models and verification by four sets of data. Results demonstrate that: (1)numerical model could well reproduce the water migration process presented in the literature, matching well with experimental data; (2) the analysis of materials conservation error show that the quality of the numerical simulation results can be guaranteed to be excellent when the time step and space step are small enough; (3) it is feasible to apply centrifugal simulation technology to researching the water migration in vadose zone; (4) the uneven distribution of acceleration in the centrifugal simulation would result in the lag of water migration at the bottom of the model behind that of the prototype, which, however, can be alleviated by using higher centrifugal acceleration.
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  Remote Sensing Estimation of Chlorophyll-a and Total Suspended Matter Concentration in Qiantang River Based on GF-1/WFV Data

  CHENG Chun-mei,LI Yuan,DING Yi, TU Qian-guang,QIN Peng

  Journal of Changjiang River Scientific Research Institute. 2019, 36(1): 21-28. https://doi.org/10.11988/ckyyb.20170701

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  In an attempt to explore the effect of Gaofen-1 (GF-1) satellite on remote sensing inversion of river water quality, the remote sensing estimation models of Chlorophyll-a and total suspended matter concentration were constructed to estimate the water quality in Hangzhou segment of Qiantang River by simulating the WFV bands by in situ spectral reflectance based on the GF-1/WFV data with 16 m resolution and the ground measured data. Results prove that the quadratic polynomial model based on the reflectance difference of B1 and B3 band (B1-B3) can be used to estimate the Chlorophyll-a concentration with R²=0.83 and RMSE=0.74 μg/L; the quadratic polynomial model based on the B3 band reflectance can be used to estimate the total suspended matter concentration with R²=0.92 and RMSE=1 mg/L. The models were applied to quasi-synchronous GF-1/WFV data, which well reflected the spatial distribution of Chlorophyll-a and total suspended matter concentration in the low-tidal Qiantang River. This research is a useful exploratory work to monitor the water color parameters of Qiantang River by the GF-1 satellite data, and the research methods and results offer reference for the study of water color remote sensing in other river basins.
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  A Novel Method of Sample Pre-treatment for Extraction of Arsenite from Water

  PENG Lian, WANG Li-fan, ZHANG De-bing, ZHAO Qi-chao

  Journal of Changjiang River Scientific Research Institute. 2019, 36(1): 29-33. https://doi.org/10.11988/ckyyb.20170835

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  Inorganic arsenic has been identified as a harmful pollutant to human health. However, the regulated standard of arsenite concentration set by administration exposes people to relatively high risk, partially due to the limitation of analysis method. In this work, a dispersive liquid-liquid extraction method was developed and applied to the extraction of arsenite from water. Ionic liquids (ILs) were selected as extraction solvent. Effect of key factors including sample volume, pH value, and amount of ILs on the extraction efficiency of the proposed method were studied. By using the proposed method, the extraction of arsenite can be completed in minutes with the enrichment factor reaching 210 and a good linearity in the range of 0.05-10 μg/L under optimized condition, yet an error only 1.5%. When coupled with atomic absorption spectrometer equipped with graphite furnace atomizer, the limit of arsenite detection was found as low as 10 ng/L. In addition, the proposed method consumes little organic solvents, making it more environmental friendly
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  A GIS Integrated Water Quality Model System Based on SWMM, ECOM, and RCA

  CHAI Jie, LIANG Jian-guo

  Journal of Changjiang River Scientific Research Institute. 2019, 36(1): 34-40. https://doi.org/10.11988/ckyyb.20170758

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  Water Quality Model System(WQMS) is an important approach to analyzing aquatic situation and supporting environmental decision. However, the usage and promotion of WQMS is largely limited by amounts of parameters, complex conditions and enormous operations. A GIS integrated system of urban water environment coupled with SWMM (storm runoff model), ECOM (hydrodynamic model) and RCA (water quality model) was constructed in this study, with the production and transformation of contaminants in large scale taken into consideration. This integrated system guaranteed an independent calculation and multi-model coupling calculation, including convenient pre-processing, fast and efficient model running and results visualization in different spatial and temporal scales, in the purpose of simplifying the usage and promotion of complex models and providing necessary understanding required in water resource managing and water pollution controlling, and ultimately improving decision making capability. The functionality of the proposed system was illustrated by a case of Wuhan city.
WATER-SOIL CONSERVATION AND ECO-CONSTRUCTION
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  Effects of Rainfall Intensity and Land Surface Roughness on Microtopography and Runoff and Sediment Yield of Slope

  LI Qing-xi, DING Wen-feng, ZHU Xiu-di, PANG Yan-jie

  Journal of Changjiang River Scientific Research Institute. 2019, 36(1): 41-47. https://doi.org/10.11988/ckyyb.20170619

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  Surface roughness is an important factor affecting sediment yield. Previous studies are focused on the effect of roughness on runoff and sediment characteristics rather than the relationship between microtopography changes and soil erosion and sediment yield process under different roughness conditions. In this study, the effects of rainfall intensity and land surface roughness on microtopography and runoff and sediment yield are studied by artificial rainfall experiments and Photoscan technique. Results reveal that in the experiment condition, four microtopographic factors, inclusive of surface roughness, relief amplitude, surface incision, and depression storage) decrease on both smooth and rough slopes after rainfall, and the decreasing trend aggravates with the further increasing of rainfall intensity. Under the same rainfall intensity and rainfall duration, microtopographic factors of rough slope change more dramatically than those of smooth slope.There is a significant positive correlation between the variation of topographic factors and the runoff and sediment yield parameters (runoff rate, sediment rate, accumulative runoff volume, and accumulative sediment yield), but the correlation is only based on the condition of the same initial slope treatment; under different slope treatments, the variation of microtopographic factors on the slope does not correspond with the amount of soil erosion.Compared with the smooth surface, the rough surface could effectively reduce runoff yield in the early stage of rainfall, and the yield on both slopes tends to be consistent with the elongation of rainfall duration.Under four rain intensities in the experiment, the runoff rates of rough slope and smooth slope both increase at first and then tend to be stable; the sediment yield and runoff rate of rough slope display the same trend; but on smooth slope, sediment yield increases rapidly at the early stage of runoff yield, and then decreases and finally tends to be stable. The research results provide reference for studying soil erosion mechanism and establishing hillslope erosion and sediment yield model.
ENGINEERING SAFETY AND DISASTERPR EVENTION
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  Deformation Mechanism of Outwash Deposit Body under Rainfall Condition in Huanxi, Lixian County, Sichuan Province

  FENG Wen-kai, BAI Hui-lin, HE Shan-yu, ZHOU Qiang, ZENG Xiu-shu, QI Hao

  Journal of Changjiang River Scientific Research Institute. 2019, 36(1): 48-54. https://doi.org/10.11988/ckyyb.20170739

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  The deformation mechanism and characteristics of outwash deposit body under rainfall condition are different from those of rainfall-induced landslides. The study area is featured with characteristics of dry and warm valley climate, with small rainfall amount but large evaporation. Through water-soil chemical effect tests, mineral composition detection, scanning electron microscopy (SEM), rainfall simulation and medium scale in-situ shear test, the structural damage mechanism of outwash deposit in water is examined, and the characteristics and amplitude of strength attenuation are also investigated. On this basis, the infiltration and saturation characteristics of groundwater and the change trend of pore water pressure are analyzed by using SEEP/W module. The deformation mechanism and process of outwash deposit body are concluded in summary in line with geoenvironmental conditions. Research results unveil that when outwash deposit contacts with water, the dissolution of mineral (mainly gypsum) together with the rearrangement of mineral particles weakens the soil structure, which further develops and mitigates the interactions among large particles, and finally results in the dramatic attenuation of overall soil strength under the lubrication and softening effect of water: the value of cohesion declines by 20.6%, and internal friction angle by 34.1%. Moreover, due to the special geological condition of the study area, the effect of rainfall infiltration in gentle slope is better than that in steep slope; and the differences in saturation time, range and depth brings about the variation of soil strength. Besides, favorable free surface gives rise to creep deformation in the direction of the free surface in the front edge and tensile cracks in the back edge of deformed body, providing passage for rainfall infiltration. Cumulative creep deformation diminishes the locked segment in the front edge of deformed body, and finally induces instability.
HYDRAULICS
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  Hydraulic Characteristics of Continuous Micro-bend Channel: Flume Experiment and Numerical Simulation

  LUO Ping-an, LI Mi

  Journal of Changjiang River Scientific Research Institute. 2019, 36(1): 55-59. https://doi.org/10.11988/ckyyb.20171098

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  The hydraulic characteristic of continuous micro-bend channel was researched on a continuous bend physical model with sinuosity of 1.07 and Reynolds stress model. The water line, flow velocity field, circulating flow in bend channels, and intensity were examined. Reynolds stress model is proved well simulates the flow in continuous bend. In a given section, the vertical longitudinal velocity distribution in the adjacent of convex bank approached to logarithmic distribution, while the vertical longitudinal velocity adjoining concave bank displayed a bulging shape, increasing firstly and then decreasing with the growth of relative water depth. Circulating flow in bends displayed asymmetric double circulation structure, with the flow intensity larger in the surface and bottom of flume than that in the central part, and larger at concave bank than that at convex bank.
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  Hydraulic Experimental Study on Concrete Dam Break with Different Break Modes

  GUO Hong-min, HU Hai-song, HU Wen-bing, ZHANG Tian-tian, ZHANG Shu-mei

  Journal of Changjiang River Scientific Research Institute. 2019, 36(1): 60-63. https://doi.org/10.11988/ckyyb.20170716

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  Concrete dam break generally occurs in a very short period of time. Previous studies seldom consider the process and mode of dam break. According to the structural characteristics of concrete dam and the stress characteristic, we assumed three possible dam break modes, namely, sliding, toppling over, and opening. We examined the hydraulic characteristics of breach under such three modes via physical model test, and compared the test results with empirical transient failure calculation results. Comparison revealed that the calculated values of peak flow rate at breach were higher than test values in general. Among the three break modes, sliding failure witnesses the maximum flow rate with the greatest harm.The results provide guidance for revising empirical formula of dam break by taking into consideration the influence of process and mode of dam break on the hydraulic characteristics of breach.
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  Influence of Atmospheric Pressure on Cavitation Characteristics of High Velocity Flow at High Altitude

  PANG Bo-hui

  Journal of Changjiang River Scientific Research Institute. 2019, 36(1): 64-67. https://doi.org/10.11988/ckyyb.20170742

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  To quantify the influence of low pressure environment at high altitude on the cavitation characteristics of water flow, single gas nucleus critical pressure under different pressure conditions was theoretically calculated. The influence degree of single gas nucleus critical pressure on the nuclear incipient cavitation number was analyzed, and the sensitivity of flow cavitation number at different elevations was evaluated. Research results showed that, in low pressure environment, both gas nuclear incipient cavitation number and water flow cavitation number decreased, but the water flow cavitation number decreased much more intensively than gas nuclear incipient cavitation number did. On the premise that other conditions are the same, the cavitation erosion risk of high velocity flow is correspondingly high in high-altitude area. The research conclusions provide reference for the design against and evaluation of cavitation erosion of high speed flow in high altitude area.
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  Numerical Simulation on Bubble Behavior at Nozzle of Vertical Flat Pipe

  WU Xuan, LI Song-yang, MA Jun, QIN Meng-zhu, JIN Guang

  Journal of Changjiang River Scientific Research Institute. 2019, 36(1): 68-73. https://doi.org/10.11988/ckyyb.20170750

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  VOF (Volume of Fluid) model is employed to study the behavior of single bubble at nozzle of vertical flat pipe. The process of bubble expansion and detachment is simulated, and the influences of immersion mode, nozzle diameter, gas velocity, liquid density, and surface tension on bubble expansion detachment time and detachment diameter are comparatively analyzed. Results demonstrate that the bubble expansion and detachment time shortens with the increase of gas velocity at the nozzle, and then tends to be gentle gradually under three different nozzle immersion modes. In the bottom-immersion and top-immersion mode, the bubble expansion detachment time and detachment diameter both increase with the growth of surface tension, while decline with the climbing of liquid density. In the side-immersion mode, the bubble expansion detachment time and detachment diameter both increase with the growth of surface tension, whereas the effect of liquid density is subtle. There is a positive correlation between the bubble expansion and detachment time and the bubble detachment diameter. The established mathematical model offers an effective research approach by simulating the formation and motion of bubbles truly.
ROCK-SOIL ENGINEERING
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  Laboratory Study on Structural Performance of Two Reconstituted Soil Samples

  ZHENG Yun, MA Wei, LI Guo-yu, MU Yan-hu

  Journal of Changjiang River Scientific Research Institute. 2019, 36(1): 74-77. https://doi.org/10.11988/ckyyb.20170928

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  Natural clays are generally structural clays, and reconstituted soil samples also have some structural characteristics due to different sample preparation processes. Structural reconstituted soil samples are usually used in laboratory studies, and the sample preparation conditions have great influences on samples’ structural characteristics. Two kinds of reconstituted soil samples (with the same size, soil type, dry density, and moisture content, yet with different saturation methods) were prepared and the structural characteristics were analyzed by uniaxial compression and uniaxial loading-unloading compression tests. It was found that vacuum suction saturation could weaken the structures and uniformities of reconstituted soil samples, and the soil samples without vacuum suction saturation had very good initial uniformity and typical structural characteristics.
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  Stability Analysis of Rock Slope Based on Finite Elements with Joint Network

  LI Yuan-liang, REN Guang-ming, LIU Yan-ling, FAN Rong-quan, XIAO Hong

  Journal of Changjiang River Scientific Research Institute. 2019, 36(1): 78-83. https://doi.org/10.11988/ckyyb.20170823

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  Traditional numerical analysis could not reflect the intermittent and random discontinuities in rock slope because the slopes are generalized into continuous homogeneous body or discrete rigid units, of which the former neglects the impact of discontinuities while the latter exaggerates the control effect of discontinuities. Finite element simulation with joint network could overcome the limits by giving more reliable results such as slope stress, displacement, plastic zone, stability coefficient, as well as the evolution and range of deformation failure. In this paper, the basic principle and method of finite element simulation with joint network are introduced, and its application to a granite slope is expounded. Result suggests that the studied slope is stable in general, with the stability coefficient under natural condition and seismic condition reaching 1.57 and 1.46, respectively. Strongly-weathered loose rockmass with surface joints is of low stability. Practices show that the method provides a new idea and method for the study of rock slope stability.
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  Feasibility of Pull-out Cone Penetration Test in Offshore Engineering

  SHEN Hong, XU Jing, HU Sheng-gang, CHENG Yong-hui

  Journal of Changjiang River Scientific Research Institute. 2019, 36(1): 84-87. https://doi.org/10.11988/ckyyb.20170517

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  Due to the complex environment of oceans, present in-situ test methods are of some limitations in obtaining the physical and mechanical properties of undisturbed soil in offshore engineering applications. A novel pull-out cone penetration test (CPT) is proposed to solve the problems. In order to verify the feasibility of this method, we conducted CPT, pressuremeter test, and pull-out CPT and compared the curves of test parameters against depth as in different in -situ test methods. We found that the test result obtained by the pull-out CPT was of similar variation trends with those of other test methods, implying that pull-out resistance is able to reflect soil’s physical and mechanical properties, and that the proposed pull-out CPT is feasible. The research results lay the foundation for further research and application of pull-out CPT.
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  Cyclic Loading and Unloading Test on Fracture Mechanism of Combined Model of Surrounding Rock and Backfill Based on Field Strain

  WANG Zhi-guo,LI Zhu-ying , LI Yue-long

  Journal of Changjiang River Scientific Research Institute. 2019, 36(1): 88-94. https://doi.org/10.11988/ckyyb.20170764

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  A combined model of surrounding rock and backfill was designed to simulate the failure evolution of backfilled mining stope. Cyclic loading and unloading tests were conducted on model specimens of three different rocks (marble, granite, and basalt) by using RLW-3000 microcomputer-controlled shear creep test machine under varying lateral pressure; VIC-3D non-contact full-field strain measurement system was employed to simultaneously monitor the damage process and failure of the combined model. Analysis result demonstrates that backfill enhances the integrity and strength of surrounding rock; the combined model undergone a volume dilatation process. The stress-strain curves of the loading and unloading in every cyclic loading process are non-coincident, forming plastic hysteresis loops which becomes more remarkable with the increase of rock’s softness. Strain field approximates uniform field under low cyclic load, while changes between non-uniform field of loading and uniform field of unloading under the condition of high load, exhibiting features of strain localization. Tensile strain firstly appeared in the region of backfill body of low strength, and gradually moves towards two sides of surrounding rock with the climbing of loading. The deformation and failure of backfill body and surrounding rock are asynchronous in spatial-temporal evolution with different failure modes. The failure mode varies with surrounding rock type: rock of low strength exhibits shear failure, and rock of high strength, tensile failure. The results suggest that the evolution of strain field could well reflect the fracture process of the combined model of surrounding rock and backfill.
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  Ground Subsidence Caused by Earth Pressure Balanced Rectangular Pipe Jacking Construction

  YIN Ying-zi,ZHAO Qiang,CUI Fang-jing,JIA Qi,LIU Bin

  Journal of Changjiang River Scientific Research Institute. 2019, 36(1): 95-101. https://doi.org/10.11988/ckyyb.20170699

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  The ground subsidence caused by rectangular soil pressure balanced pipe jacking construction in large section would damage the pavement structure layer, which has always been a difficulty and hot topic in geotechnical engineering. With the underground passage project in the Inner Mongolia University of Science and Technology as a case study, we analyzed the measured data of subgrade deformation and the applicability of Peck’s formula in predicting ground subsidence caused by rectangular pipe jacking, and also simulated the influence of pipe jacking construction in the presence of different soil depths on ground subsidence numerically. We found that, in general, measuring points in longitudinal direction on the jacking axis bulged at first, and then subsided and subsequently tended to be stable; in terms of cross section, pipe jacking affected an area within 10 meters of the axis, where the volume of settling trough occupied 90% of the total volume. When soil strata loss rate equals 0.4% and width parameter K of settling trough equals 0.4, the measured value agrees well with the results predicted by Peck’s formula. With the increase of overburden soil depth, the surface subsidence decreased gradually, and the settlement range gradually increased. The research results provide theoretical reference and application value for the construction of large cross-section soil pressure balanced rectangular pipe jacking and similar projects.
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  Durability of Mountain Road Slope under Dynamic Loads

  XU Xu-tang, JIAN Wen-bin, WU Neng-sen, XU Xiang, LUO Yong-peng

  Journal of Changjiang River Scientific Research Institute. 2019, 36(1): 102-106. https://doi.org/10.11988/ckyyb.20170825

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  Weibull distribution function is employed to describe the survival rate of micro-units of rock slope before and after damage; fatigue damage model and strength reduction FEM are also established to reflect the relationship between survival rate, cumulative damage factor and stability coefficient so as to achieve the staged early warning for mountain road slope in its whole life cycle. Results show that the coefficient of fatigue stability in the whole life cycle of slope would decrease under fatigue life reduction, changing sensitively in the early stage, attenuating slowly in middle stage and dropping rapidly in the later stage. The survival rate of slope declines with the reducing of residual life and safety factor. The early warning could be divided into four stages, namely initial creep, steady development, rapid development, and sliding failure. In the four stages, the stability coefficient, survival rate, and operation life of mountain road are all attenuating along with the development of deformation until slope failure. In addition, the concept of slope durability factor is proposed to evaluate the durability of road slope during its whole life cycle. In the durability design of slope engineering, fatigue-resisting measures should be adjusted continuously to make it in steady state development stage.
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  Laboratory Experiment and Mechanism of Solidified Soil of Biopolymer

  ZHOU Tian-bao, ZHANG Fu-hai, ZHOU Bing-sheng, WANG Yuan-hang

  Journal of Changjiang River Scientific Research Institute. 2019, 36(1): 107-110. https://doi.org/10.11988/ckyyb.20170797

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  Traditional cement soil is of high alkaline, high carbon emissions and dependency on water conservation, and also has adverse effects on the desertification in northwest region of China. Indoor experiment was conducted to investigate the curing effect of biopolymer (xanthan gum) on northwest silty soil and the curing mechanism. Compared with plain soil, xanthan gum as a biopolymer curing agent has good curing effect on silty soil. The compressive strength of dry-mixed soil is higher than that of wet-mixed soil. With the decrease of water content, the ionic bond strength between the molecular chain of xanthan gum and the soil particles increases rapidly, resulting in the growth in strength of solidified soil. The molecules of xanthan gum are firmly adsorbed on the surface of soil particles, playing a very strong cementation role. Moreover, biopolymer solidified soil is neutral, environmental-protecting and renewable, whose strength is formed in natural environment. It is of prominent application prospect and research value, for arid area of northwest China, in particular, as it has functions of moisturizing and anti-desertification.
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  Slope Stability Model Based on Fuzzy Analytic Hierarchy Process and K-means Clustering Method

  ZHANG Xiang-dong,BAI Ren-yu,HUANG Jian-guo

  Journal of Changjiang River Scientific Research Institute. 2019, 36(1): 111-116. https://doi.org/10.11988/ckyyb.20170669

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  In practical engineering, the safety factor of slope could not describe the slope state precisely. In view of this, a slope stability model is established based on FAHP (Fuzzy Analytic Hierarchy Process) and K-means clustering which integrates qualitative and quantitative analyses. The key factors of slope samples are evaluated and clustered, and the vectors of connection numbers are constructed. According to the key slope factors, the slope stability model based on FAHP and K-Means clustering is used to predict the unknown slope samples. The model is applied to analyze the Nanchang-Ganzhou high-speed railway project and the results are in line with actual situation. The proposed slope stability model based on FAHP and K-means clustering could offer reference for the design, construction, and monitoring of slopes as it reveals the nonlinear relationship between some key factors (height, slope angle, and pore water pressure) and slope stability.
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  Experimental and Numerical Study of Scrap Tire Columns Filled with Different Geomaterials under Cyclic Shear

  WANG Yao-ming, LU Yang, WANG Tao, REN Zeng-le

  Journal of Changjiang River Scientific Research Institute. 2019, 36(1): 117-122. https://doi.org/10.11988/ckyyb.20170584

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  To investigate the effect of filler types on cyclic shear behavior of scrap tire columns (STC) reinforced geomaterials, a series of horizontal cyclic shear tests, with a vertical pressure of 100 kPa and a maximum shear strain of 2%, were conducted on STC reinforced river sands, gravels and loam soils, respectively. Test results show that STC reinforced river sands and gravels almost have the same values of equivalent dynamic shear moduli and equivalent damping ratios, which are better than those of STC reinforced loam soils. In consideration of dynamic behavior and construction convenience, STC reinforced river sands have a good advantage in practical application. Moreover, the stress-strain hysteresis curves were reasonably established based on the FEM simulation by the code of ABAQUS. Constitutive models of Mohr-Coulomb, Mooney-Rivlin and Rebar were selected to simulate the mechanical behaviors of geomaterials, rubbers and rebars, respectively. From the simulated energy-time variation curves during the cyclic shear, it is found that the inside filling geomaterials mainly play a role of energy dissipation, and scrap tires mainly act for reinforcement.
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  Sensibility Analysis of Influencing Factors of Reservoir Slope Stability Based on Grey Correlation

  NIE Bing-qi,TANG Ming-gao,SHAO Shan,MA Xin-jian,LI Yun-jie,YANG He

  Journal of Changjiang River Scientific Research Institute. 2019, 36(1): 123-126. https://doi.org/10.11988/ckyyb.20170712

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  Orthogonal experiment and grey correlation analysis method are coupled to make sensitivity analysis on six main influence factor for a homogeneous slope in reservoir area using GeoStudio-based limit equilibrium analysis method. The sensitivity of slope stability factors ranks in the order of internal friction angle, cohesive force, permeability coefficient, rate of reservoir water level drawdown, slope angle, and degree of declining in reservoir water level. The combination of orthogonal design and grey correlation method could, to a large extent, eliminate the errors generated by tests by taking the interactions among factors into consideration, and could also overcome the shortcomings of traditional mathematical statistics analysis. The results offer reference for the support of reservoir slope and prevention works.
HYDRAULIC STRUCTURE AND MATERIAL
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  Review on the Influence of Alkali on Hydration and Hydration Products of Cement-based Materials

  LI Yang, WANG Shu-yin, YIN Hai-bo, HE Zhen

  Journal of Changjiang River Scientific Research Institute. 2019, 36(1): 127-133. https://doi.org/10.11988/ckyyb.20170736

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  The effects of alkali as different alkali metal ions and as combined with different anions on the hydration characteristics of cement-based materials are reviewed. Besides, in the light of the microstructure and composition of hydration products of cement-based materials, the interaction between alkali and hydration products of cement-based materials are analyzed and compared. The effects of alkali on the hydration characteristics of cement-based materials are different according to different forms of alkali. Alkali changes the structure and composition of cement hydration products, and hydration products in turn absorb hydration products selectively, and thus the cement-based materials exhibit different macro-properties. Moreover, considering the equivalent weight of alkali content as the alkali content in cement-based material is of some deficiencies. Therefore, the effect of the alkali-based form cannot be neglected for the fine control of the performance of cement-based material.
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  Causes of Header Bolt Fracture of a Pumped Storage Power StationZ

  HAO Qiang,CHAI Jian-feng,MA Chuan-bao,DING Jing-huan,LI Bo

  Journal of Changjiang River Scientific Research Institute. 2019, 36(1): 134-138. https://doi.org/10.11988/ckyyb.20170754

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  Fractures were found in the header bolts of a pumped storage power station. According to bolt fracture analysis, fatigue cracks originated in the thread root were found in most of the bolts. Tip stress concentration induced by the source of cracks led to bolt fracture. To analyze the cause of bolt fracture, the diameter of the bolt was calculated and checked. It was found that the bolt diameter was small when the preloaded condition of the bolts was satisfied, and the fatigue strength calculation safety factor was small as well, which would lead to fatigue damage. Increasing the bolt diameter could not only meet the bolt preloading requirement, and also meet the requirement of bolt fatigue design.
INFORMATION TECHNOLOGY APPLICATION
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  Research Status of River-Leader System in China Based on Visualization Analysis of Literatures

  REN Jun-lin, PENG Zi-qian, KUANG Yang, CHEN Jiao-ni

  Journal of Changjiang River Scientific Research Institute. 2019, 36(1): 139-144. https://doi.org/10.11988/ckyyb.20171488

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  The research status of river-leader system in China is investigated by CiteSpace tool of bibliometrics.Research data comes from 500 papers indexed by CNKI from 2009 to 2017.The distribution of research time, author’s location,periodical location,research area, and author’s institution are analyzed in detail, and the research hotspot and trend are expounded. Visualization results imply that the research of river-leader system in China is still in its infancy, with a small number of literature and inadequate academic level. The research content focuses on theoretical review and policy interpretation rather than quantitative research; scientific research institutions in water conservancy sector instead of higher educations are major contributors; in terms of research trend, the number of research literature will witness a steady growth due to the promotion of river-leader system nationwide and the implementation of “one strategy for one river” policy. The research results are expected to offer reference for researchers in this regard.
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  Management Information System of Dynamic Flood in Hongze Lake Area Based on WebGIS

  KOU Jia-wei, DONG Zeng-chuan, LUO Yun, ZHU Zhen-ye, LÜ Hao-yang

  Journal of Changjiang River Scientific Research Institute. 2019, 36(1): 145-150. https://doi.org/10.11988/ckyyb.20170759

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  Discharging a flood of 158 000 km² from the upper and middle reaches of Huaihe River, Hongze Lake is mainly surrounded by plain and depression which are subject to flood disasters. In the aim of reducing regional flood risk and alleviate flood losses, a B/S-structured management information system of dynamic flood is developed based on WebGIS by constructing flood routing models for three types of risk source including external river flood, regional flood and rainstorm waterlogging. On this basis, the dynamic flood risk map is generated by using dynamic layer. With this system, the rainfall and water information, static and dynamic flood risk information, as well as disaster loss information under planning and simulated conditions can be managed comprehensively, and the 2-D flood routing process can be displayed dynamically, which is conducive to strengthening regional flood control and establishing evacuation schemes.