01 September 2018, Volume 35 Issue 9

    

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SPECIAL CONTRIBUTION
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  Two Decades of Water and Soil Conservation Plan for Production andConstruction Projects: Retrospect and Prospect

  SUN Hou-cai

  Journal of Changjiang River Scientific Research Institute. 2018, 35(9): 1-5. https://doi.org/10.11988/ckyyb.20180442

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  In the aim of providing technical support for the “power delegation, fair supervision and efficient service” reform of production and construction projects in China, a systematic review is made on the past two decades of report compilation, examination and approval, and acceptance of water and soil conservation programs, as well as the enactment of related laws and regulations, standards and specifications. Problems, characteristics and development trend in different stages are also analyzed. Relevant data from river basin institutions, water administrative department of the government, and compilation agencies for water and soil conservation program are collected by searching periodical database and the official website of the Water and Soil Conservation Monitoring Center of the Ministry of Water Resources. Due to related policies, the water and soil conservation program for production and construction projects has experienced early stage, stable development stage and the ongoing stage of “power delegation, fair supervision and efficient service”. Despite that the editing techniques of water and soil conservation program had been basically perfected, the acceptance process is still complicated due to the misalign between plan compilation and acceptance. Over the past two decades since the implementation of the water and soil conservation program for production and construction projects, water and soil conservation programs have been compiled and implemented for more than 300,000 projects nationwide, preventing and controlling an area of water and soil loss over 150,000 km², reducing water and soil loss effectively. The “power delegation, fair supervision and efficient service” reform to the water and soil conservation work could improve work efficiency, and in the meantime enhance the responsibility awareness of construction organizations.
RIVER-LAKE SEDIMENTATION AND REGULATION
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  Morphological Features and Spatial-temporal Change of Braided Reachof Tongtian River in the Yangtze River Source Region

  LI Zhi-wei, WU Ye-zhou, HU Xu-yue, ZHOU Yin-jun, YAN Xia

  Journal of Changjiang River Scientific Research Institute. 2018, 35(9): 6-11. https://doi.org/10.11988/ckyyb.20170276

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  Braided rivers widely develop in the Yangtze River source, forming a huge cluster of braided rivers. Yet, the spatial-temporal variation of the braided channel morphology remains unclear owing to the shortage of flow, sediment, and riverbed topography data. In the present paper, braided channel morphology and branching intensity in the local braided channel of Tongtian River were studied using the Landsat remote sensing images in 1987-2016 to extract water area. The ratio of water area to riverbed area above water changed periodically associated with the hydrological cycle in a year, i.e., the ratio in flood season (April-September) gradually increased, while in non-flood season (October to next March) decreased and eventually remained unchanged. In the past three decades, the ratio of water area to riverbed area displayed a trend of increasing, which implies the increasing trend of runoff in the source region of the Yangtze River. Of the 36 cross sections of braided river reach, the index of branch number and index of branching length ranged in 4-10, and 5-12, respectively; but the mean values of the two indexes in 1994, 2005, and 2015 almost remained unchanged, indicating that the braided river reach is of holistic self-similarity and invariant river pattern.
WATER RESOURCES AND ENVIRONMENT
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  Dynamic Pollutant Absorption Capacity of East Dongting Lake Based onRelationship among Water Level, Area and Volume

  HUANG Yi-fan, WANG Jin-sheng, YANG Mei

  Journal of Changjiang River Scientific Research Institute. 2018, 35(9): 12-16. https://doi.org/10.11988/ckyyb.20180533

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  In an attempt to obtain the dynamic pollutant absorption capacity of East Dongting Lake in different hydrological and water quality conditions, a model of relationship among water level, area and volume was established according to MODIS remote sensing data in 2003-2016 and hydrological data. Some calculation parameters in the presence of different water levels, incoming flow rates, and incoming water quality indicators were acquired. According to the Code for calculation of water pollution absorption capacity, the coefficient of pollutant absorption capacity, together with the dynamic absorption capacity of COD and ammonia-nitrogen in different hydrological and water quality conditions was calculated. Authors insisted that the pollutant absorption capacity of East Dongting Lake varies with water level, discharge and water quality dynamically. The minimum absorption capacity of COD is 14 200 g/s, greater than the average emission intensity which is 1 837 g/s in 2016, brewing no risk of standard-exceeding; but the minimum absorption capacity of ammonia-nitrogen is 43 g/s, smaller than the average emission intensity which is 275 g/s in 2016, posing large risk of standard-exceeding of ammonia-nitrogen. Moreover, hydrology and water quality conditions which would result in the standard-exceeding of water quality were determined: when incoming concentration of ammonia-nitrogen stays below 0.95 mg/L, ammonia-nitrogen concentration in the Lake would not exceed standard. We concluded that (1) The established model provides support for the calculation of dynamic pollutant absorption capacity; (2) Pollutant emission could be rearranged reasonably according to the dynamic pollutant absorption capacity. (3) The incoming concentration of ammonia-nitrogen should be controlled under 0.95 mg/L in East Dongting Lake.
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  Dynamic Characteristics of Vertical Hyporheic Flux in the Downstream of Weihe River, China

  HUO Ai-di, WEI Hong, GUAN Wen-ke, HOU Zhi-qiang, ZHENG Xiao-lu,
  DU Wei-hong, WEN Yi-ran, LI Cong-yi

  Journal of Changjiang River Scientific Research Institute. 2018, 35(9): 17-22. https://doi.org/10.11988/ckyyb.20170239

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  Hyporheic exchange has significant impact on the changes of water quantity in the hyporheic zone and residence time of various substances (oxygen and organic matters). Accurate calculation of hyporheic exchange flux and its dynamic change is of crucial importance for the integrated management and ecological restoration of rivers. In the present paper, the hyporheic flux in the hyporheic zone of the Caotan section of Weihe River is calculated by using heat transfer model as a case study. The spatial heterogeneity and dynamic change of hyporheic exchange are examined through temperature tracing. Results show that in the monitoring period, groundwater in the study area was recharged by river flow. Hyporheic flux varied in a range of 8.73×10^-7-8.90×10^-6m/s in shallow hyporheic zones of about 0.75 m thick at different locations, displaying complex dynamic feature. In the monitoring period, the overall trend of hyporheic flux at different depths was increasing, yet with some differences in vertical distribution varying with time. The results prove that temperature tracing method is simple and accurate in the calculation of hyporheic flux, and is suitable for the calculation of hydrodynamic exchange capacity in hyporheic zone.
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  Assessment of Groundwater Quality in Hamatong Drainage Basin byUsing Model of Set Pair Analysis Based on Entropy Weight Method

  GANG Shen-ting, JIA Tao, DENG Ying-er, LIU Wei-po, PENG Xin

  Journal of Changjiang River Scientific Research Institute. 2018, 35(9): 23-27. https://doi.org/10.11988/ckyyb.20170156

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  The evaluation of groundwater quality serves as a scientific basis for the exploitation and protection of groundwater resources. The indicators of traditional water quality assessment models are random, fuzzy and uncertain. In view of this, a set pair analysis model based on entropy method is established and applied to the groundwater quality assessment for Hamatong drainage basin. According to data of 86 monitoring points, six indicators, including NH₄⁺, NO₂^-, Fe²⁺,Mn²⁺, Zn²⁺, and COD_Mn are selected and given weight by using entropy weight method. The assessment result is compared with that of modified Nemerow index method. The results implies that the groundwater quality of Hamatong drainage basin is below average, with Ⅳ and Ⅴ levels accounting for a large water area, while Ⅱ and Ⅲ levels occupying a small area. The assessment result is consistent with that of the modified Nemerow index method, both comforting well with reality. The set pair analysis model based on entropy weight is proved rational and reliable.
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  Effect of Silty Loam Interlayer on Migration of Benzene andBr^- in Homogeneous Fine Sand

  GUO Lei-lei, XU Mo, LI Qing-shan, KANG Xiao-bing, WANG Zai-min

  Journal of Changjiang River Scientific Research Institute. 2018, 35(9): 28-33. https://doi.org/10.11988/ckyyb.20170195

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  To study the influence of silty loam interlayer on the migration of benzene and Br^- in unsaturated zone, we analyzed the laws of migration of Br^- and benzene in different soil columns by examining the adsorption of Br^-and benzene by silty loam and sand collected from a foundation pit in Jinniu District of Chengdu. Result showed that the adsorption of Br^- did not increase with the climbing of clay content; the adsorption of benzene increased linearly with the increase of clay content, hence weakening the migration of contaminants. The impact of the concentration of tracer bromide ion on the adsorption of benzene by soil sample was negligible. Moreover, the advancing of wetting front in homogeneous sand was nonlinear, almost consistent above the silty loam interlayer in both soil columns; once entering the silty loam interlayer, the advancing of wetting front weakened evidently. The results indicate that silty loam interlayer has an inhibition effect on infiltration by weakening the migration of Br^- and benzene downward and by adsorbing and purifying benzene.
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  Prediction of River Water Level by GA-Elman Model

  YAO Zhen, XU Ji-ping, KONG Jian-lei, LIU Song-bo

  Journal of Changjiang River Scientific Research Institute. 2018, 35(9): 34-37. https://doi.org/10.11988/ckyyb.20170230

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  The fluctuation of river water level is a complex nonlinear process. Traditional neural network prediction is of slow convergence and poor stability with large error. To effectively predict river water level, a prediction model based on Elman neural network optimized by genetic algorithm (GA) is proposed. The effective combination of GA and Elman network solves the deficiencies of Elman neural network. The water level at Yongding river monitoring station is predicted by the proposed model and validated according to measured hydrological data, and the prediction results are compared with those obtained by Elman neural network and BP neural network. Results imply that the GA-Elman water level prediction model is of fast convergence and high precision. According to the prediction results, reservoirs and river barrages can be operated rationally for an effective allocation of water resources to meet the demands of irrigation, power generation and flood control.
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  Risk Analysis on the Influence of Xingou River Discharge onWater Quality of Yangtze River

  CHEN Jiang-hai, CHEN Xiang

  Journal of Changjiang River Scientific Research Institute. 2018, 35(9): 38-42. https://doi.org/10.11988/ckyyb.20170362

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  The construction of Xingou River dredging and expanding project would affect the water quality of the Yangtze River by increasing the load of discharge. To control the risk of pollution and ensure the safety of water quality, a 2-D hydrodynamic pollutant transport model is built to examine the influence of Xingou River discharge on the water quality of Yangtze River under unfavorable conditions. Meanwhile, the background concentration of NH₃-N in Yangtze River varies remarkably in different months, hence the maximum allowable discharge is also different in different months. The results show that Xingou River discharge has apparent influence on the local water quality of Yangtze River under unfavorable conditions, and a higher NH₃-N concentration would exert greater influence. To prevent from the risk of water pollution and protect the nearby water source conservation district, the maximum allowable discharges in the presence of different background concentrations are given.
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  Inter-annual Variations of Precipitation Concentration Degree andConcentration Index in Huaihe River Basin

  PANG Xin-xin

  Journal of Changjiang River Scientific Research Institute. 2018, 35(9): 43-47. https://doi.org/10.11988/ckyyb.20170185

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  The inter-annual variation of heterogeneous annual precipitation distribution over 1961-2015 was studied by using the precipitation concentration degree (PCD) and precipitation concentration index (PCI) previously defined by other researchers. Results revealed that precipitation concentrated in some seasons, indicating that the distribution of precipitation in Huaihe basin was quite uneven at annual scale. Annual PCD showed an increasing trend with apparent undulation since 1990. According to Mann-Kendall analysis on the data of monthly and seasonal PCI, most months in which the PCI values were averagely positive (from May to August) displayed an increasing trend, while most months in which the PCI values were averagely negative (in April and October) exhibited an decreasing trend, with only one month(November) changing in the opposite direction. The trend of seasonal PCI was similar to that of monthly PCI: in spring and autumn when PCI were averagely negative, PCI showed decreasing trends; in summer when PCI was averagely positive, an increasing trend; in winter, the change of PCI was insignificant. In general, the trends of seasonal and monthly PCI at annual scale exacerbated the polarization of precipitation distribution: wet periods are tending to be wetter and dry periods are getting dryer.
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  GIS-based Vulnerability Assessment and Comprehensive Treatment ofXijiang River Drainage Basin in Guangxi

  WANG Yu, HU Bao-qing

  Journal of Changjiang River Scientific Research Institute. 2018, 35(9): 48-53. https://doi.org/10.11988/ckyyb.20170386

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  The vulnerability of Xijiang River drainage basin in Guangxi, China is evaluated in this paper by using spatial principal component analysis and analytical hierarchy process in association with GIS technology.The evaluation index system comprises indicators involved in ecology, resource, and disaster. The vulnerability is classified into five levels in order: potentially vulnerable, slightly vulnerable, mildly vulnerable, moderately vulnerable, and severely vulnerable. The spatial distribution of vulnerability is examined, and comprehensive treatment suggestions are put forward. As the research shows, slightly vulnerable, mildly vulnerable, and moderately vulnerable area together cover 75.46% of the total basin area, among which moderately vulnerable area is the largest, accounting for up to 29.11%; potentially and severely vulnerable area covers 11.48% and 13.06% of the total area, respectively. The spatial vulnerability distribution is closely related with elevation. With the climbing of elevation, vulnerability exacerbates.
WATER-SOIL CONSERVATION AND ECO-CONSTRUCTION
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  Relations of Vegetation with Topography and Groundwaterin Yili River Valley of Xinjiang

  XIA Han-feng, XIE Hong-bo, LIU Hao, WEN Guang-chao, LI Ying

  Journal of Changjiang River Scientific Research Institute. 2018, 35(9): 54-57. https://doi.org/10.11988/ckyyb.20170133

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  The quantitative relations of vegetation with topography, groundwater depth and total dissolved solid(TDS) in Yili River Valley are examined using RS and GIS technologies based on Landsat 8 OLI data and field investigation achievements. Results reveal that: (1) Vegetation growth gradually worsens in the order from swamp plain, alluvial and fluvial fine soil plain, gently sloping gravel fine soil plain, loess hills, aeolian dune to strongly inclined gravel plain area. (2) Vegetation growth at the elevation around 750 m and 2 800 m is sound. (3) When TDS in groundwater is higher than 1 000 mg/L, vegetation growth is negatively correlated with groundwater salinity, with the coefficient of correlation up to 0.733 5. (4) Under small disturbance of human activities, the relationship of groundwater depth(within 0-4.3 m) and vegetation growth was quadratic,with the coefficient of correlation reaching 0.764 8. Groundwater depth within the range of 1.2-4.3 m is favorable for vegetation growth; in particular, when groundwater is around 2.8 m, vegetation growth is the best
ENGINERING SAFETY AND DISASTER PREVENTION
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  Causes of Abnormal Damage of M_s6.2 Earthquake in Norcia, Italy

  LIU Yong, WANG Yun-sheng, Janusz Wasowski

  Journal of Changjiang River Scientific Research Institute. 2018, 35(9): 58-62. https://doi.org/10.11988/ckyyb.20170323

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  At local time 3:36 on August 24, 2016, an M_s6.2 earthquake hit the town of Norcia in Lazio Rieti Province of central Italy. Despite that the earthquake magnitude was not big, some ancient towns were severely damaged. In this paper we revealed the causes of the abnormal damage by analyzing the architectural structure, geological structure, and topographic features in the study area according to monitoring achievements of seismic response of slopes in recent years in association with numerical simulation. Results uncover that terrain amplification effect could give rise to severe seismic disaster in spite of small magnitude and long distance to the epicenter. The poor seismic performance of aged buildings, the shallow seismic focus, the amplification effect of seismic wave induced by isolated topography are key factors resulting in the large number of casualties.
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  Sensitivity Analysis of Hazard-brewing Environmental Factors ofLandslides in Puge County of Sichuan Province

  WANG Wen-po, HAN Ai-guo, REN Guang-ming, YANG Lei, HUANG Wen-fang

  Journal of Changjiang River Scientific Research Institute. 2018, 35(9): 63-67. https://doi.org/10.11988/ckyyb.20170358

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  The west of Sichuan Proince is highly prone to geological disasters.In an attempt to quantify the sensitivityof landslide-brewing environmental factors (including fault, petrofabric, river, slope gradient, land relief, road, and elevation),the discrete degree of fractal dimension values of the abovementioned factors are measured by calculating the variance of fractal dimension values in association with ArcGIS. Landslide in Puge County of Sichuan Province are taken as research objective. The main results are concluded as follows:(1)Slope gradient, fault, and road have large impact on the development of landslide, while river and land relief has small influence on landslide development; (2) The variance of fractal dimension value of medium-sized landslide is the largest, followed by that of small landslide and large-scale landslide; (3) The sensitivity of landslide to hazard-brewing factors can be quantified by fractal dimension values, and the dicrete degree of the sensitivity can be measured by variance of fractal dimension values; (4)The variable dimension fractal theory provide a basis for obtaining the weights of hazard-brewing environmental factors in landslide risk assessment.
HYDRAULICS
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  Hydraulic Characteristics of Classic Baffles in Culvert Fishway

  HU Xiao, JING Pei-ran, HUANG Li-yan, SHI Xiao-tao

  Journal of Changjiang River Scientific Research Institute. 2018, 35(9): 68-74. https://doi.org/10.11988/ckyyb.20170155

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  As a special means of river restoration in hydraulic engineering construction, culvert mainly functions as a water channel for road and bridge system, and for local aquatic animals to passing through barriers. Since the hydraulic design of culvert fishway is rarely reported in China, theoretical basis for the construction of culvert fishway is insufficient. By analyzing some experiment data of culvert fishway abroad, we summarized the hydraulic characteristics and flow fields of classical baffle systems of culvert fishways,including offset bafe(OB),slotted-weir bafe(SWB) and weir bafe(WB).We obtained the expressions of dimensionless flow rate, water depth, slope against velocity, and compared the working performance of the three baffles.The research achievements would provide theoretical basis and reference for the internal transformation and hydraulic design of culvert fishway in China.
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  Model Test on Flow Diversion and Flow Capacity ofWater Delivery Tunnel with Long Distance

  LI Chong-min, RU Rong, WANG Ke-zhong, YANG Jian-hui

  Journal of Changjiang River Scientific Research Institute. 2018, 35(9): 75-79. https://doi.org/10.11988/ckyyb.20171275

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  Hydraulic model test is an important means to verify the rationality of water building design.In this study, physical model test is carried out to research the water diversion tunnel of Yellow River Diversion Project in the Middle of Shanxi Province based on fluid theory and hydraulic model theory. Flow capacity of the main tunnel and flow distribution between west branch tunnel and east branch tunnel with different gate openings are studied; the relationships of gate opening and closing rate against water level in front of gate are obtained. Results demonstrate that the design flow discharge and discharge ratio can be achieved in the presence of east gate opening at 0.60 m and west gate opening at 0.56 m. Moreover, gate opening and closing rate is negatively correlated with upstream water level. The results are of theoretical significance for researching the flow capacity of non-pressurized water delivery tunnel, and provide reference for gate control system.
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  Preliminary Study on Hydraulic Characteristic of Stream Barbs forEcological Restoration of Medium and Small Rivers

  XING Yan, JIANG Bo-le, MA Dian-guang

  Journal of Changjiang River Scientific Research Institute. 2018, 35(9): 80-85. https://doi.org/10.11988/ckyyb.20170275

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  As river restoration idea transfers from canal-dominated back to nature-oriented, instream flow control structure, as a proactive bank protection measure, is drawing increasing attention due to its unique ecological benefits. The main categories, working characteristics, applicability and research progress of in-stream flow control structure in China and abroad are summarized in this paper.On this basis,the 3D hydraulic characteristics in a 193° sharp bending flume before and after stream barbs are arranged in backflow direction are studied and comparedthrough numerical simulation. The working mechanism and effectiveness of stream barbs in bend flume are investigated preliminarily. Results demonstrate that stream barbs could achieve the purpose of bank stabilization by adjusting the secondary flow structure and deflecting the high speed flow far away from the concave bank. Nevertheless, stream barbs would give rise to backwater in the bend and deviate the high speed flow on the convex bank side. The backwater level and deviation degree are closely related with the layout pattern of stream barbs. The study is of referential significance for upcoming researches on eco-hydraulic engineering structures in river ecological restoration field.
ROCK-SOIL ENGINEERING
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  Decoupling Inversion of Instantaneous and Rheological Parameters andDeformation Prediction of High Core-wall Rockfill Dam

  LI Shao-lin, WANG Zhao-qing, ZHOU Wei, MA Gang, YANG He

  Journal of Changjiang River Scientific Research Institute. 2018, 35(9): 86-91. https://doi.org/10.11988/ckyyb.20170326

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  High core-wall rockfill dam is featured with many partitions of different materials with varied instantaneous and rheological parameters. The inversion of instantaneous and rheological parameters simultaneously is accompanied with ponderous calculation. To improve the accuracy of material parameters in calculation model and deformation prediction, a decoupling inversion of instantaneous and rheological parameters was conducted in consideration of the decoupling relationship between instantaneous and rheological parameters. With Pubugou high core-wall rockfill dam as an example, the sensitivity of parameters to the deformation of rockfill dam was examined,and highly sensitive parameters were selected for inversion. Furthermore, the decoupling inversion of instantaneous and rheological parameters was conducted by adopting modified genetic algorithm and radial basis function neural network (RBF) according to the monitoring data of deformation during dam construction, first impoundment, and second impoundment. The inversion result proved that the calculated settlements agreed well in general with the measured data in terms of values and change rules.
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  Effects of Pore Solution’s pH Value on EngineeringProperties of Remolded Loess

  YANG Xiu-juan, WANG Yuan, FAN Heng-hui, XU Ning-rui

  Journal of Changjiang River Scientific Research Institute. 2018, 35(9): 92-97. https://doi.org/10.11988/ckyyb.20170357

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  With the rapid development of society, foundation soil pollution caused by vast waste water discharge has arising as a severe geoenvironmental problem. The changes in engineering properties of remolded loess polluted by hydrochloric acid and sodium hydroxide solutions are investigated via geotechnical test and resistivity test. The solutions are prepared at five different pH values. Result demonstrates that with the increase of acidity of the solution, the liquid limit,plasticity index, permeability coefficient, cohesive force and internal frication angle gradually increased, while electrical resistivity decreased; with the increase of alkalinity of the solution, the clay content, cohesive force, internal friction angle, and permeability coefficient increased, while liquid limit, plasticity index and electrical resistivity gradually decreased. Researching the effect of pH value of pore solution on properties of loess would offer reference for geoenvironmental practice.
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  Stability Analysis of Foundation Pit Based on CuspCatastrophe Theory and Spearman Rank Test

  LI Chang-mao, XUE Xiao-hui, LIU Sheng-hui

  Journal of Changjiang River Scientific Research Institute. 2018, 35(9): 98-102. https://doi.org/10.11988/ckyyb.20170643

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  Stability evaluation and prediction is of crucial significance for the safety evaluation of foundation pit as it gives timely feedback to the deformation behavior of the foundation pit. In the present research, the stability of foundation pit is analyzed by using cusp catastrophe theory and Spearman rank test; furthermore, the influence of data dependency on stability result is investigated through decorrelation of original deformation sequence by AR(1) model; finally, the correctness of stability analysis is verified by grey model. Case study demonstrates that the stability result obtained from cusp catastrophe analysis agrees well with that of Spearman rank test, both indicating that the deformation of foundation pit tends to stabilize. Decorrelation processing of the data could make the result conservative. In the meantime, the deformation obtained by grey model extrapolation of four cycles all tend to decrease, conforming with the stability analysis. The abovementioned three methods could all evaluate and preduct the stability of foundation pit, and the results are consistent.
ROCK-SOIL ENGINEERING
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  Orthogonal Experiment and Regression Analysis on Ultra-fine Fly AshGrouting Material for Teating Coal Mine Goaf

  PANG Jian-yong, YAO Wei-jing, WANG Ling-yan

  Journal of Changjiang River Scientific Research Institute. 2018, 35(9): 103-108. https://doi.org/10.11988/ckyyb.20170283

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  Grouting material is of crucial importance for the treatment of coal mine goaf by grouting. The physical and mechanical properties of fly ash cement grouting material with large volume ultra-fine fly ash are tested through orthogonal experiment. The influences of water-solid ratio, solid phase ratio, and dosage of sodium silicate on the setting time, water separating proportion, concretion rate, and unconfined compressive strength at different ages are also examined.Results showed that the performance of the slurry material is significantly affected by water-solid ratio, followed by solid phase ratio and dosage of sodium silicate. The 28-day compressive strength of grouting slurry with varying mix ratio is generally higher than 1 MPa and continues to grow; the strength at the 90^th day is larger than that at the 28^th day by over 60%. The regression formula of compressive strength along with mix proportion and the predictor formula of compressive strength along with age are obtained by curve fitting.
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  An Auto-classification of Rockmass Discontinuities Based on K-meansCluster Analysis and Cluster Validity Index I: Researchand Application

  WANG Jun-zhi, DU Peng-zhao, NIU Zhao-xuan

  Journal of Changjiang River Scientific Research Institute. 2018, 35(9): 109-113. https://doi.org/10.11988/ckyyb.20170290

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  Classifying the orientations of rock discontinuities is a fundamental but critically important routine of engineering geology and hydrogeology. The commonly-used rose diagrams of dip directions and strikes and poles to orientations are subjective. It is appreciated to resort to mathematical approaches. In this paper, an automatic grouping method is proposed based on the algorithms of K-means cluster analysis and cluster validity index I, and a Rock Discontinuities Auto-classification Program (RDAP) is developed. By comparing with Shanley and Mahtab’s result (1976), the reliability of the new grouping method or RDAP is verified. In the end, RDAP is used to cluster the gushing fractures to aid in the selection of the optimum position of grouting drillings of a project, which provides a basis for the prevention and control of water gushing.
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  Dynamic Deformation Characteristics and Modeling of Loess

  SHI Jiao, ZHANG Xi-dong

  Journal of Changjiang River Scientific Research Institute. 2018, 35(9): 114-120. https://doi.org/10.11988/ckyyb.20170678

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  With SDT-20 dynamic triaxial apparatus, the dynamic deformation properties of both intact and remolded loess are explored. The effects of different test parameters on the dynamic shear modulus and the accumulation of dynamic shear strain are qualitatively analyzed. In the prerequisite of small strain and taking no account of radial strain during loading, the void ratio of sample is derived according to axial dynamic strain, and the dynamic compression behavior of loess samples is analyzed with e-σ_d curves. Different from those under static loading, the characteristics of compression of loess are not revealed under dynamic loading, and the structure of intact loess is not obviously reflected as both intact and remolded loess experience a similar deformation process under dynamic loading. A turning point exists in e-σ_d curve of intact loess as well as that of remolded loess, which implies a critical dynamic stress for both intact and remolded loess. When dynamic stress is less than critical dynamic stress, the dynamic deformation of loess develops slowly; but when dynamic stress is greater than critical stress, the dynamic deformation increases dramatically and loess samples are destroyed quickly. In addition, a hyperbolic model is established to modeling the accumulation characteristics of dynamic strain of loess, and the model parameters are calculated with differential evolution method. By comparing the estimation of hyperbolic model with experimental data, we conclude that the proposed hyperbolic model could well describe the deformation properties of loess under dynamic loading.
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  Influential Factors of Stability of Silica Stone Cuesta Cutting Slope

  ZHANG Ying, SU Sheng-rui, YU Guo-xin, SU Yi, LI Jing-shan

  Journal of Changjiang River Scientific Research Institute. 2018, 35(9): 121-126. https://doi.org/10.11988/ckyyb.20170279

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  In the aim of investigating the influential factors of stability of silica stone cutting slope, field survey was conducted to conclude that the failure modes of cutting slope are mainly dominated by sliding-tension and discontinuities. In the meantime, the physical and mechanical parameters of silica stone were obtained through uniaxial compressive test, tensile strength test, and direct shear test. On this basis, the influences of four factors, namely, slope gradient, spacing between discontinuities, cutting rate, and platform width, on slope stability were examined through strength reduction in finite element simulation. Results show that among the four factors, slope gradient plays a biggest role in slope stability, followed by cutting rate. Due to the special failure mode of silica stone and the diversity of cuesta cutting slope’s failure mode, various factors, rather than single factor, should be considered while evaluating the stability of silica stone cuesta cutting slope.
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  Fractional-order Visco-elasto-plastic Constitutive Model forRock under Cyclic Loading

  LIU Han-qing, PU Shao-yun, LIU Xi-jin, CHEN Ze-nan, LI Qin, HAO Zhi-cheng, LI Lei

  Journal of Changjiang River Scientific Research Institute. 2018, 35(9): 127-132. https://doi.org/10.11988/ckyyb.20170333

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  In order to study the fatigue deformation characteristics of rock under cyclic loading, we established
  one-dimensional and three-dimensional Fractional-order Visco-Elasto-Plastic Constitutive Model (FVEPCM) by replacing the common dashpot in viscoplastic body of Nishihara’s model with the fractional-order dashpot and connecting a viscous element in series in Nishihara’s model. Under high dynamic stress, the model is a FVEPCM reflecting the three states of rock fatigue deformation: deceleration stage, constant velocity stage, and acceleration stage; otherwise, it is a Burgers Model which reflects the two states of rock fatigue deformation: deceleration, and constant velocity stage. Fitting of the existing rock fatigue test results shows that the fatigue constitutive equation for rock based on FVEPCM can be used to better describe different deformation characteristics of rock under cyclic loading, and the effect of fitting to various types of deformation curves of rock is good, with the fitted correlation coefficients above 0.96.
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  Simulation of the Whole Process of Slope Failure Based onGravity Increase Method

  LIU Chen-ling, CHANG Xiao-lin, TANG Long-wen, ZHOU Wei, MA Gang

  Journal of Changjiang River Scientific Research Institute. 2018, 35(9): 133-138. https://doi.org/10.11988/ckyyb.20170376

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  Traditional slope stability analysis methods could not reflect the whole process of progressive failure from crack initiation, sliding, to piling up. In view of this, a combined finite-discrete element method based on gravity increase method (FDEM-GIM) is proposed to study the slope failure of Red Rock Landslide in Yunnan Province of China. Interface elements are introduced into the surface rock mass of the slope model to build the combined finite-discrete slope model and simulate the critical failure state of slope. The safety factor and the sliding surfaces of the slope are acquired, and then are compared with those obtained by rigid body limit equilibrium method. By increasing the gravity continuously, the progressive failure process of the slope is obtained. The results demonstrate that the proposed FDEM-GIM is feasible in slope stability analysis because the safety factor, the position and shape of the most dangerous sliding face obtained by FDEM-GIM are consistent with those by rigid body limit equilibrium method. Moreover, rigid body limit equilibrium is only suitable for the critical instability state of slope as it could not predict the formation of subsequent sliding blocks, while the proposed FDEM-GIM could further simulate the whole process of slope failure.
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  Experimental Study on Natural Limestone Particles inContact Damage and Fractal Characteristics

  LIU Sheng, XU Yuan-jie, LI Hai-teng, REN Ling

  Journal of Changjiang River Scientific Research Institute. 2018, 35(9): 139-142. https://doi.org/10.11988/ckyyb.20170138

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  Contact compression test was conducted on natural limestone particles from Lianghekou to study the mechanical behavior and fractal characteristics of contact damage of irregular rock particles. The micro-morphology of particles was characterized by surface fractal dimension, roughness and undulation. The study revealed that the first damage force decreased with the increase of initial fractal dimension; the fractal dimension of particles in local contact range decreased after loading, which implied the influence of micro-morphology of rock particles on mechanical behavior of contact damage. Furthermore, the strain and displacement on specimen surface were traced dynamically by non-contact digital imager, which revealed the changes of strain and displacement in the whole process of particle contact test. The result shows that local stress level is much higher during contact compression between irregular rock particles. The contact damage first appears in local contact zone.
HYDRAULIC STRUCTURE AND MATERIAL
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  Variation Law of Water Pressure in Crack under Earthquake Loads

  YANG Kai-gang, LI Zong-li, ZHANG Guo-hui

  Journal of Changjiang River Scientific Research Institute. 2018, 35(9): 143-147. https://doi.org/10.11988/ckyyb.20170219

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  Water-containing cracks on concrete gravity dam are susceptible to instability due to additional water pressure generated by water compression caused by the rapid opening and closing of cracks under seismic load. In an attempt to obtain the variation law of water pressure in cracks under seismic load, we deducted the formula of additional water pressure in cracks under seismic load based on the assumption that the crack is oval. By case study, we analyzed the changes of additional pressure and factor of stress intensity at crack tip in different directions in the presence of varying crack size and drainage rate. Results revealed that the maximum additional water pressure of the calculation case reached 7.55 times of initial water pressure under seismic load. Meanwhile, with the increase of initial crack width, the maximum additional water pressures and the factor of stress intensity at crack tip declined rapidly; with the decrease of initial crack width, the influence of drainage rate on additional water pressure became more evident. In addition, the inclination angle of crack had no obvious impact on the factor of stress intensity at crack tip.
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  Mechanical Properties of Cemented Sand and Gravel MaterialAdded with PVA-fiber

  JIN Guang-ri, FANG Tao, WANG Jun-feng, ZHANG Xin-yue

  Journal of Changjiang River Scientific Research Institute. 2018, 35(9): 148-153. https://doi.org/10.11988/ckyyb.20170330

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  Research on the mechanical properties of cemented sand and gravel (CSG) materials has been increasing along with the application of CSG Dam. In order to improve the mechanical properties such as strength and deformation rate of CSG materials, we added fibers into natural sand and gravels with identical aggregate gradation and sand ratio, and investigated into the mix proportion by adjusting cement content and age through orthogonal experimental design. According to tests and regression equation, we conclude that the dosage of PVC-fiber effectively improved the ductility of CSG material, and converted the brittle fracture of CSG specimens into ductile fracture. In particular, the compression and split strength of specimens reached the maximum when PVC fiber proportion was 3%.
CONSTRUCTION AND MANAGEMENT OF WATER CONSERVANCY PROJECTS
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  Construction and Operation Management of IrrigationExperiment Station

  LI Ya-long, YUAN Nian-nian, FAN Lin-lin, QIAO Wei, FU Hao-long

  Journal of Changjiang River Scientific Research Institute. 2018, 35(9): 154-158. https://doi.org/10.11988/ckyyb.20170269

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  Irrigation experiment is an essential basis for developing highly efficient water saving irrigation and promoting irrigation area modernization. According to experiences of irrigation experiment and management of irrigation experiment station for many years and in light of the demands of irrigation area modernization, we made an in-depth exploration on the construction and management of irrigation experiment station. The main functions of irrigation experiment station should include experimental research, data collecting, technique popularizing and training, academic exchanging, and water saving science education. The construction of irrigation experiment station should involve field experiment area, leaching-pond experiment area, lysimeter experiment area, meteorological observation station, laboratory, water source project, irrigation and drainage project, and office and living quarter. The location selection, designing, construction and quality acceptance management should be enhanced. Finally, suggestions on the operational management of irrigation experiment station were put forward from the points of group construction, financial support, scientific research cooperation, and assessment and evaluation. The results provide reference for the construction and planning of new irrigation experiment stations, and for the upgrading and reconstruction of existing experiment stations.