25 July 2016, Volume 33 Issue 8

    

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RIVERLAKE SEDIMENTATION AND REGULATION
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  Delayed Response of Snails’ Vertical Migration on the Bottomland to the Changed Water Level

  LI Ling-yun, LU Jin-you, FAN Bei-lin, WANG Jia-sheng

  Journal of Changjiang River Scientific Research Institute. 2016, 33(8): 1-5. https://doi.org/10.11988/ckyyb.20150378

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  As the only intermediate host of schistosome, snails generally live at the bottomland of lakes. The vertical migration of snails on the bottomland is closely related to the water level but usually delayed to the water level alteration, which has not yet been considered in previous studies. As a result, the snails’ vertical migration is always difficult to describe or predict accurately. A generalized model for the changes of snails’ vertical distribution was proposed in this study, and a calculation method is developed for predicting the theoretical distribution elevation of snails in the presence of altered water level. The calculation method reveals that 1). the elevation at which snails are distributed increases with the rise of water level and decreases with the decline of water level; 2). the distance between the snail distribution elevation and the water level decreases with the rising of water level, and increases with the descending of water level. According to the field data at the Dongkou bottomland of Dongting Lake, the calculation method based on the delayed response for predicting the snails’ distribution elevation was tested, and the results showed that the relationship between the snails’ vertical distribution and the water level alteration established in this paper can be used to accurately predict the snails’ distribution elevation.
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  Application of 2-D Numerical Model of Bed Load in Rivers of Mountain Area:Regulation Project in Wangmo River as An Example

  ZHOU Wei,GAO Hui-cai,WU Teng

  Journal of Changjiang River Scientific Research Institute. 2016, 33(8): 6-17. https://doi.org/10.11988/ckyyb.20150473

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  In order to utilize rich hydropower resources in southwest mountain area of China and decrease flow with high sand proportion and debris flow disasters caused by flash flood, we should establish suitable two-dimensional bed load mathematical models for rivers in mountain area. On the basis of finite volumetric method, we dispersed common controlling equations in sediment numerical model of two-dimensional flow, dealt with dry land boundary by using frozen method, and established a general two-dimensional bed load mathematical model. Xintun section in Wangmo river located in Guizhou province was taken as an example. We carried out numerical calculation of flow field, exploring scouring and deposition of bed load. Test results showed that, as for water level calculation and verification of scouring and deposition in the river bed, simulated data was in consistent with data from empirical formula; after regulation project of the river, most of water levels along the flow direction decreased, except for slight increase in few sections; meanwhile, in the condition of given discharge,water level after the regulation was smaller than that before the regulation, and sediment deposition into the water flume decreased, which is in favor of river flood control.
WATER RESOURCES AND ENVIRONMENT
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  Review of Urban Stormwater Management Models Based on GI Measures

  FU Heng-yang,LI Bang-yan,FU Jin

  Journal of Changjiang River Scientific Research Institute. 2016, 33(8): 11-17. https://doi.org/10.11988/ckyyb.20150543

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  In consideration of the application universality of models and the upgrading possibility of softwares, we make a review on eight urban stormwater management models based on green infrastructure (GI) measures. Thesemodels have been applied widely in recent years. Firstly, the eight models are classified in terms of the rain and runoff water quality control, GI economic benefit analysis, integrated model of GI stormwater management and economic analysis, respectively. Secondly, the eight models are described in detail with regard to five major criteria including representative GI measures, spatial scales, algorithms used for modeling, data inputs and outputs, and user interface and handling of the tool. Thirdly, the eight models are compared in terms of the number of GI measures they can represent, modeling approaches, data requirements, modeling accuracy, and regional limitations. Fourthly, the application of several models in China are analyzed, and the problems urgent to be solved are also pointed out. Finally, in view of the advantages and disadvantages of the current models, we proposed the direction and trend of the development of urban stormwater management models in future. This study is designed to help urban stormwater managers and researchers to understand the fundamental knowledge of different GI stormwater management models, and help them to select appropriate model in practice according to their needs.
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  A Wavelet-ANN Hybrid Model for Groundwater Level Forecasting

  ZHANG Jian-feng, LIU Jian-bao, CUI Shu-jun, XIE Yu-hua

  Journal of Changjiang River Scientific Research Institute. 2016, 33(8): 18-21. https://doi.org/10.11988/ckyyb.20150474

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  Due to over-exploitation of groundwater in many cities of North China Plain, there is a tendency of lasting decrease in groundwater level, which results in serious problems, such as groundwater exhaustion, land subsidence and seawater intrusion. In order to accurately predict changes of urban groundwater level, based on artificial neural network (ANN) and analysis of multi-scale of wavelet transform (WT), we established a wavelet-ANN conjugate model and test its accuracy to predict groundwater level. Measured data of groundwater level at Pinggu district of Beijing were taken as research objects. We predicted groundwater levels at the district by back propagation (BP) model and hybrid model. Then, we calculated the prediction accuracy by using statistical parameters including root mean square error (RMSE), mean absolute error (MAE) and correlation coefficient (R). Results showed that the MAE of the hybrid model from the first month to the third month was 0.535, 0.598 and 0.634 m, respectively, whereas 0.566, 0.824 and 0.940 m for BP model. The MAE of hybrid model from the first month to the third month was 95%, 73% and 67% of that of BP model, respectively. Comparison of results reveals that the hybrid model has advantages of better prediction accuracy and longer effective prediction duration.
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  Hydrogeological Characteristics of Taojialongtan Water Source Area in Xiuwen County of Guizhou

  ZENG Hong-biao, SHAO Lian-fen, YU Hong-ming, LI Ya

  Journal of Changjiang River Scientific Research Institute. 2016, 33(8): 22-33. https://doi.org/10.11988/ckyyb.20150972

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  In order to study the hydrogeological characteristics of water source in the karst area of Guizhou Province, we take Taojialongtan water source area in Xiuwen country as study object. In association with investigation methods like hydrological surveying and according to the development law of karst groundwater, we obtain the characteristics such as general geological situation, factors affecting karst development, and boundary conditions. We divide impervious boundary conditions according to three aspects water blocking property of the boundary, development situation of karst along the boundary, and the groundwater emergence location.Moreover on this basis, we study the recharge boundary. Results show that the development area of water source has the characteristics of an independent hydrogeological unit; meanwhile, the development of Taojialongtan hydrogeological unit is mainly influenced by lithology and fissure structures; furthermore, discharges mainly takes the form of karst spring and artificial mining, which ultimately flows into the surface river; finally, the hydrochemistry type of Taojialongtan water source area is of HCO₃·SO₄-Ca·Mg, suitable for drinking water source.
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  Diel Greenhouse Emissions from an Eutrophic Pond in Summer

  ZHANG Cheng, LONG Li, Lü Xin-biao, LI Ying-chen, PENG Feng

  Journal of Changjiang River Scientific Research Institute. 2016, 33(8): 28-33. https://doi.org/10.11988/ckyyb.20150289

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  Methane (CH₄) and Carbon dioxide (CO₂) emission pathways in summer were quantified during a 48 hours online survey of a subtropical shallow pond in Yichang, China. We separated the diel bubble and diffusion gas fluxes measured by the DLT-100 Analyzer (Los Gatos Research, USA) thanks to its high sampling frequency. The total emission fluxes of CH₄ and CO₂ were 595.2 mg/(m²·d) and 1450.8 mg/(m²·d) respectively. Bubble emissions of CH₄ and CO₂ accounted for 99.7% of the total CH₄ emission and only 3.0% of the total CO₂ from the pond. Bubble emissions are highly time-variable in the observation period, with the biggest CH₄ bubbling rate of 424.28 mg/(m²·h), accounting for 35.75% of the two days’ total bubbling CH₄ emissions, but ebullition CH₄ flux was mainly located at <20 mg/(m²·h). The maximums of the diel diffusion CH₄ and CO₂ flux were 6.0 and 6.5 times of the responding minimums respectively.
WATERSOIL CONSERVATION AND ECOCONSTRUCTION
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  Ability of Heavy Metal Concentration of Several Herbs Suitably Growing on Eco-concrete in Honghe Prefecture

  DUAN Ji-hong, WANG Lin , ZHANG Xue-sen ,LI Guo-hong

  Journal of Changjiang River Scientific Research Institute. 2016, 33(8): 34-37. https://doi.org/10.11988/ckyyb.20150530

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  In order to determine herbs which can grow well in eco-concrete and can help us to restore environment, we select nine kinds of herbs according to the characters of climate and soil in Honghe prefecture of Yunnan Province. Then, we plant these herbs using the construction technology of eco-concrete and analyze the concentrations of heavy metals, including Pb, Zn, Cu, Cr, Hg and Cd. Experimental results show that (1) Cynodon dactylon ,Vetiveria zizanioides L., Carex ‘Evergold’ has the highest ability of enriching Pb, Zn, Hg, and Commelina communis has the highest ability of enriching Cu, Cr, Cd; (2) average concentration coefficient of heavy metal of Commelina communis is the highest, followed by Bidens pilosa L., Carex ‘Evergold’, Vetiveria zizanioides L., Ophiopogon bodinieri, Cyperus rotundus, Cynodon dactylon, Nephrolepiscordifolia(L.)Presl and Canna indica L. In these herbs, average bioconcentration coefficients of heavy metal of Commelina communis, Bidens pilosa L. and Carex ‘Evergold’ are all bigger than 1. In comprehensive consideration of the herbs’ ability of enriching heavy metals and the conditions of growing in eco-concrete, we decide that Commelina communis and Vetiveria zizanioides L. are the most suitable for eco-concrete engineering among the nine kinds of herbs.
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  GIS Network Analysis Technology for Flood Evacuation Routes

  YIN Dan

  Journal of Changjiang River Scientific Research Institute. 2016, 33(8): 38-41. https://doi.org/10.11988/ckyyb.20150537

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  In order to reduce life loss caused by flood dam-break and effectively organize staff to withdraw from dangerous area, we introduce in detail the technology of flood evacuation route analysis, and discuss the procedures of using GIS-based network analysis technology to calculate flood evacuation routes. These procedures include topological check and manipulation of road network, establishing of digital road network model, optimal matching between transfer unit and evacuation shelter, and optimal calculation of evacuation routes. Then, we take dam-break at the right bank of Hunhe river, located in Liaoning province, as an example. We realize the nearest route searching for evacuation and draw evacuation map. The results show that, GIS network analysis technology is convenient for calculating optimal evacuation route, and can help us increase the efficiency and save cost during evacuation. The flood evacuation map and evacuation method from GIS technology can be references for emergency plans on flood control.
ENGINEERING SAFETY AND DISASTER PREVENTION
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  Uplift Pressure at Dam Base of Concrete Gravity Dam Considering the Nonlinear Environmental Impacts

  XU Wei, FANG Chun-hui, WANG Xue,ZHU Kai

  Journal of Changjiang River Scientific Research Institute. 2016, 33(8): 42-46. https://doi.org/10.11988/ckyyb.20150478

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  In view of the lag effect and the nonlinear characteristics of the influence of upstream water level and rainfall on the uplift pressure of concrete gravity dam, a monitoring model of the concrete gravity dam considering the nonlinear environmental influence is established. The influential process is regarded as a normal distribution process and the lagging days and influential days are optimized by improved quantum genetic algorithm to raise the fitting and forecasting accuracy. Finally, a concrete gravity dam is taken as an example and the corresponding uplift pressure series of the measuring point A6-UP-01 are fitted and predicted with the proposed method. Through comparison between measured data and predicted data, the proposed method is verified superior to the traditional statistic model and it is of scientific and practical application value.
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  Landslide Susceptibility Assessment Using Support Vector Machine Based on Weighted-information Model

  AN Kai-qiang, NIU Rui-qing

  Journal of Changjiang River Scientific Research Institute. 2016, 33(8): 47-51. https://doi.org/10.11988/ckyyb.20150311

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  Three Gorges Reservoir is one of the landslide disaster-prone areas in China, and it is meaningful to as-sess the landslides susceptibility of Three Gorges Reservoir both for disaster prevention and reduction. The WI (Weighted-Information)-SVM(Support Vector Machine) model was adopted to assess the landslide susceptibility on the basis of entropy and SVM models. The SVM’s training dataset was comprised by the entropy of nine influence factors, including the stratum lithology, the geological structure, the slope gradient, the direction and structure of slope, the land use, the influence of water, and the NDVI (Normalized Difference Vegetation Index), together with the sum of them. The landslide susceptibility of the whole study area was evaluated, and the result of landslide susceptibility was ranked according to the zero value and abrupt change value of the decision value of model. The landslide susceptibility in Wanzhou district was assessed as an example to validate the WI-SVM model. The research result showed that the accuracy of the training dataset was 81.41% and verification dataset 91.11%, superior to commonly used models. Area with high and relatively high susceptibility accounts for 47.05% of the entire area, mainly in the mainstream and tributaries of the Yangtze River with strong human activities. The results are consistent with the distribution of landslides which has been known, indicating that the WI-SVM model has good applicability for the study area.
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  Spatial Distribution Characteristics of Landslides and Collapse Masses in Debris Flow Formation Region along the Yuzixi River Basin of Wenchuan County, Sichuan Province

  CHENG Xiao, ZHU Jing, WANG Shuai-yong, FANG Qun-sheng, ZHANG Wei-xu

  Journal of Changjiang River Scientific Research Institute. 2016, 33(8): 52-58. https://doi.org/10.11988/ckyyb.20150497

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  In order to understand the characteristics of landslides and collapse masses transforming into debris flow, we researched the landslides and collapse masses in debris flow formation area. In this paper, we took Yuzixi river basin between Yingxiu county and Wolong county as research area and 23 debris flow gullies as research objects. Area of the study region is about 396 km², and total area of debris flow basin is about 208 km².On the basis of interpretation of the landslide and collapse points with high resolution remote sensing images, in association with field investigation, we confirmed the reliability of the remote sensing interpretation, and finally obtained 2 741 disaster points with an area of 23.6 km². Then we employed GIS to calculate the distribution of the landslides and collapse points in aspects of elevation, gradient, dip, lithology and distance from the river. Results show that, firstly, most landslides and collapse masses exist in the elevation of 1 500-3 000 m; secondly, the area ratio of landslides and the collapse masses with slope gradient of 40°-50° is the largest; thirdly, slope direction is concentrated in the range of 90°-180 °, and slope direction of the range is perpendicular to the earthquake fault; furthermore, under earthquake or heavy rainfall ,harder diorite easily leads to a large number of landslides and collapse masses; finally, landslide and collapse easily break out when mountains are near the river.
HYDRAULICS
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  Application of Model of Porous Media to Simulate the Effects of Wave-Attenuating Plants

  LIU Da, HUANG Ben-sheng, QIU Jing, TAN Chao

  Journal of Changjiang River Scientific Research Institute. 2016, 33(8): 59-63. https://doi.org/10.11988/ckyyb.20150404

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  To testify whether the model of porous media can be applied to accurately simulate the impacts of broken waves near-shore on plants, we proposed a generalized model of porous media. The model is based on two-dimensional facade free face turbulence model. The characteristics of tree crowns were taken into consideration. Tree crowns and tree trunks were partitioned into two zones of porous media and were given different void ratios. Furthermore, the simulated results of instantaneous flow regime, wave line, maximum wave run-up value and time-averaged wave pressure on dike foot obtained from the model were compared with those of physical model test. The results were in good agreement, which indicated that the model of porous media has high accuracy in simulating the effects of counter-wave plants under the condition of broken waves.
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  Flow Characteristics in Wide and Narrow Alternated Channels in Mountainous Areas under Different Discharges

  MIAO Shu-ting, LIN Hu, QI Li-jian, ZENG Yun, HUO Lei

  Journal of Changjiang River Scientific Research Institute. 2016, 33(8): 64-68. https://doi.org/10.11988/ckyyb.20150476

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  In order to study the flow characteristics in wide and narrow alternated channels under different discharges, we chose upstream reach of Baoxing river as research object and established a three-dimensional flow numerical model through simplifying the actual river. Results show that 1) under low discharge, backwater at upstream reach of narrow section was not obvious, and wide and narrow alternated channel showed characteristics similar to straight channel; 2) with the increase of discharge, backwater in the upstream reach of narrow section was intensive, and the distribution of cross-section average velocity showed a multi-stage regularity (stages of increasing, relatively stable, rapidly decreasing, relatively stable and finally increasing);3) affected by river width, backwater and reflux, cross-section flow characteristics in wide section was more complex than that in narrow section, and the velocity distribution at backwater area was obviously different from that at non-backwater area;4)under different discharges, dramatic changes of bed shear stress in wide section will lead to discontinuous movement of pebbles, and deformation of riverbed in wide section showed cyclical tendency, which is in favor of stability of the wide river bed structure; 5) while in the narrow section, riverbed structure was compatible with surrounding environment under long-term larger bed shear stress, then larger flow energy in narrow section can be expended and riverbed stability can be guaranteed.
ROCKSOIL ENGINEERING
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  Method for Calculating Active Earth Pressure of Unsaturated Soil Considering Arching Effect

  WANG Ding-jian, TANG Hui-ming, WU Qiong, ZHANG Ya-hui, WEN Tao

  Journal of Changjiang River Scientific Research Institute. 2016, 33(8): 69-74. https://doi.org/10.11988/ckyyb.20150904

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  With the assumption that the trace of the principal stress arching is a semicircle, the relationships of average vertical stress and interlaminar shear stress of soil differential element vs. counterforce of wall were established, respectively. Then, a static equilibrium equation based on the extended unsaturated soil shear strength formula was set up to solve the active earth pressure. The interlaminar shear action was considered in the process, to make up the shortage of force imbalance of traditional static equilibrium equation. Compared with the earth pressure formula of unsaturated soil deduced from classical approach, principal stress deflection is considered in this study, and the active earth pressure is nonlinear along the height which is closed to the true stress distribution. Compared with the conventional earth pressure calculations considering arching effects, factors on active earth pressure are analyzed in the new method. These factors include the properties of unsaturated soil and groundwater level. The result can provide theoretical basis for earth pressure study and reference for the design of retaining wall.
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  Regularity of the Damage of Altered Rock’s Mechanical Properties Under Water-Rock Interaction

  NIU Chuan-xing, QIN Zhe, FENG Bai-yan,FU Hou-li

  Journal of Changjiang River Scientific Research Institute. 2016, 33(8): 75-79. https://doi.org/10.11988/ckyyb.20150590

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  In order to research the effect of water level fluctuation on the mechanical properties of slope rock at altered zones, we carried out uniaxial compression test on rock samples from open-pit slope in Cangshang under different saturation-dehydration cycles. Moreover, we established the function which describes the variation pattern of mechanical properties of altered rock under water-rock interaction. We also analyzed the influence of circulating times on the mechanical properties of altered rock through introducing the concept of damage rate. Besides, the damage mechanism of water-rock interaction on altered rocks was also analyzed by scanning electron microscopy(SEM). The result indicated that the mechanical properties of altered rocks were obviously weakened by water-rock interaction, and with the increase of water-rock interaction, the phenomenon was more obvious; with the increase of circulating times, the elasticity modulus decayed rapidly while the peak intensity was decaying continuously. As the degree of alteration and fragmentation increased, the degree of damage increased regarding the water-rock interaction to the mechanical properties of rock, and after fifteen saturation-dehydration cycles, the damage rate of elasticity modulus reached 60%, while that of peak intensity was 45%.
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  Large Direct Shear Test on the Influence of Stone Size on the Strength of Gravel Soil

  WU Rui, DENG Qing-lu, FU Min, ZHANG Teng-fei, ZHU Jia-chang

  Journal of Changjiang River Scientific Research Institute. 2016, 33(8): 80-85. https://doi.org/10.11988/ckyyb.20150397

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  The influence of stone size on the shear strength of gravel soil was investigated through large direct shear test on three groups of remolded gravel soil specimens of different stone sizes. The gravel soil in the slope of Daqianshiling Tunnel in the Tianshifu-Huanren railway was taken as research object. On this basis, the characteristics of grain size distribution of the gravel soil specimens were researched by using fractal theory. The fractal dimension of gravel soil with different stone sizes was obtained, and the relationship between shear strength parameters and fractal dimension was studied. Results indicate that when stone content is the same, shear strength and internal friction angle increase with stone size increasing; on the contrary, cohesion decreases along with the increase of stone size. With the increase of stone size, fractal dimension increases, and as fractal dimension gets bigger, the particle distribution is more uneven, and vice versa. There is a certain degree of correlation between shear strength parameters and fractal dimension. With the increase of fractal dimension, cohesion decreases whereas internal friction angle increases; cohesion and internal friction angle have approximately parabolic function relationship with particle fractal dimension.
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  Triaxial Compression Test Analysis of Weakly Cemented Mudstone in West China

  WANG Lei, LI Zu-yong

  Journal of Changjiang River Scientific Research Institute. 2016, 33(8): 86-90. https://doi.org/10.11988/ckyyb.20151116

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  In order to solve the roadway support problem of weakly cemented soft rock in west China, we collected typical weakly cemented mudstone samples in Luxin coal mine in Inner Mongolia, and conducted indoor triaxial compression test on the soft rock at different states (natural state, saturation state, dry state) under different stress levels. We analyzed the relations of strength characteristics, fundamental mechanical indexes vs. confining pressure. The results are as follows firstly, the peak strength and residual strength of weakly cemented mudstone are very low under natural condition. With the increasing confining pressure, the peak strength and residual strength of mudstone both have a larger increase, and the relationship between peak strength and confining pressure is logarithmic. Secondly, as mudstone is very sensitive to water, peak strength and residual strength decreases with the increasing moisture content, while peak strength decreases more significantly. Thirdly,softening coefficient decreases with the increasing confining pressure, and the elastic moduli of mudstone under three different states increase linearly with the increasing confining pressure. Lastly, we established the triaxial compression stress-strain relationship by analyzing the four-stage triaxial compression stress-strain fitting curve of mudstone.
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  Experimental Research on the Influence of Particle Size and Gradation on Repose Angle of Rockfill

  SUN Kai-chang, LIU Lin-feng, MING Hua-jun ,XU Xiao-feng, LI Quan, TONG Jia-xin

  Journal of Changjiang River Scientific Research Institute. 2016, 33(8): 91-95. https://doi.org/10.11988/ckyyb.20150632

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  In order to explore the influence of gradation and particle size on repose angle of rockfill, we conducted accumulation model test of granular mixtures slope and analyzed the accumulation phenomenon. Then we measured the repose angle of rockfill material with different particle sizes and gradations by improved measuring method. The results show that repose angle increases gradually with the increase of particle size of homogeneous rockfill. The influence of average particle size on repose angle is weakened gradually with the increase of non-uniform coefficient, while the influence of non-uniform coefficient on the repose angle increases firstly and then keeps stable. Besides, the repose angle of granular mixtures becomes larger when the particle size distribution is more uneven.
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  An Improved Fast Clustering Analysis Method for Attitude of Structural Plane in Rock Mass

  LI Jun,HU Bin,ZHU Kai,KOU Tian,WANG Wei

  Journal of Changjiang River Scientific Research Institute. 2016, 33(8): 96-99. https://doi.org/10.11988/ckyyb.20150519

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  Dominant attitudes of structural plane in rock mass are fundamental to the research and analysis of geotechnical engineering. Conventional rose diagram and pole isodense diagram are of poor accuracy, just with results of the number of dominant groups. In order to accurately obtain the dominant attitudes of structural plane, we proposed an improved fast clustering analysis method to turn structural plane attitudes into points on hemisphere surface of the unit space. According to structure density functions, we calculated the weighted values of every data point and classified the attitudes of structural planes. Furthermore, we applied the method to the statistical analysis of dominant structural plane of a slope near a mine transportation road. Results show that this method is reliable and reasonable. We can use it to determine the dominant attitudes of structural plane, and effectively avoid adverse effect of isolated points on the clustering result.
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  Experimental Study on Sandstone Weathering in the Ancient Battlefield Relics of Fishing Town in Hechuan District of Chongqing

  YAN Shao-jun,HE Kai,SUN Peng, DOU Yan, CHEN Jia-qi

  Journal of Changjiang River Scientific Research Institute. 2016, 33(8): 100-104. https://doi.org/10.11988/ckyyb.20150507

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  Fishing Town in Hechuan District of Chongqing,as an ancient battlefield, has important cultural, historical and military values.In order to avoid geological disasters, protect cultural relics and scenic spots ,and make sure the safety of surrounding residents and tourists, we should research the features of sandstone weathering of this site. According to the geological environment of Fishing Town, we divided rock mass of the cultural relics into 6 layers, and analyzed the water quality of surface water and groundwater of the area. Meanwhile ,we obtained rock coring samples at different depths of stratum No.6 and conducted half quantitative X-ray diffraction(XRD) test and X fluorescence chemical composition test. Since the cultural relics were mainly found in sandstone stratum No.6, we carried out identical tests of weathered samples at different positions of this layer, in association with analysis data and comprehensive comparison. Test results show that the contents of quartz and calcite in weathered samples are larger than those in rock core samples; moreover, reducing of feldspar content at different degrees and soluble salts such as gypsum play a significant role in rock flake weathering.
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  Influencing Factors of Geological Environment at Underground Tunnel in Chongqing

  DU Yan-fei, YANG Le, LIAO Yun-ping, PENG Hai-you, WEN Guang-ju ,LIU Si-chuan

  Journal of Changjiang River Scientific Research Institute. 2016, 33(8): 105-108. https://doi.org/10.11988/ckyyb.20150426

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  In order to determine the influencing factors of geological environment at underground tunnel, we carry out specific investigation by using methods such as in-situ interview and indoor statistical analysis. Engineering geological environment at 28 typical tunnels in Chongqing is taken as example. Results show that geological environment at underground tunnel is influenced by hydrogeological condition, lithology, waterproofing measure, construction method, geological structure, buried depth of tunnel and so on. In particular, hydrogeological condition is the controlling factor and lithology is the main factor. Meanwhile, we give suggestions to protect underground geological environment, which offer reference for administrators to specify the protection techniques of underground geological environment in Chongqing.
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  System for Evaluating Geological Environment Negative Effect in Chongqing Tunnel Engineering Construction Process

  REN Xiu-wen, PENG Hai-you, YANG Le, SHANG Hong-guang, HU Xiao-jun, FENG Fan

  Journal of Changjiang River Scientific Research Institute. 2016, 33(8): 109-113. https://doi.org/10.11988/ckyyb.20150806

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  The geological environment problems which become increasingly prominent in Chongqing tunnel engineering construction process are taken as research objects in this paper. Applying methods of anlaytic hierarchy and scoring by experts,we establish a comprehensive evaluation model by selecting indices and determining the weights of indices. Then, we evaluate the geological environmental negative effect of Yufengshan tunnel of highway-ring around Chongqing; according to the comprehensive evaluation grading standard, we divide the negative effect area into four grades, which are serious area, relatively serious area, medium area and relatively minor area. Through investigation and verification, we found that the evaluation results are basically in accordance with actual situation and the study lays a foundation for the popularization and application of the evaluation method.
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  Influence of Intermittent Drawdown of Reservoir Water Level on the Stability of Accumulation Landslide

  XIAO Zhi-yong, DENG Hua-feng, LI Jian-lin, HU An-long, LI Chun-bo, CHANG De-long

  Journal of Changjiang River Scientific Research Institute. 2016, 33(8): 114-119. https://doi.org/10.11988/ckyyb.20150486

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  Rapid drawdown of reservoir water level is adverse to landslide stability. In view of this, we propose that the reservoir water level declines intermittently. On the basis of traditional analysis of persistent drawdown of water level, we analyzed the influences of intermission and intermittent drawdown of water level on the stability of landslide by using Geo-Studio software. An accumulation landslide in Three Gorges reservoir area was taken as an example. Research results show that intermission is in favor of the dissipation of pore water pressure in the landslide; meanwhile, lag effect of groundwater level’s decrease caused by rapid drawdown of reservoir weakens and hydraulic gradient decreases; when we compare reservoir intermittent drawdown with reservoir persistent drawdown, landslide stability factor of the former is bigger, but stability factor is not in proportion with intermission; under the multistage intermittent drawdown of reservoir, stability factor has obviously improved,which is greater than 5%. Finally, in order to optimize the landslide’s stability, we should reasonably arrange reservoir drawdown and intermittent time.
HYDRAULIC STRUCTURE AND MATERIAL
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  Influences of Mineral Admixtures on the Strengths of Corroded Concrete and Corresponding Correlation Analysis

  PENG Jian, DENG Tong fa,ZHU Nan hai, YI Dao xin

  Journal of Changjiang River Scientific Research Institute. 2016, 33(8): 120-124. https://doi.org/10.11988/ckyyb.20150282

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  In view of the environmental problem of ammonium sulfate residue caused by rare earth mining in thesouthern part of Jiangxi, we tested the mechanical properties of corroded concrete and analyzed the regularity of strength deterioration of corroded concrete through tests of corrosion (by ammonium sulfate solution) on concretes mixed with fly ash, slag, and both fly ash and slag, respectively. Furthermore, we employed the theory of gray correlation to analyze the correlation between strength and mineral admixtures of concrete. Results show that the concrete mixed with fly ash and slag replacing cement in equal amount could significantly increase the resistance of concrete to ammonium sulfate corrosion; the strength of concrete with high content of mineral admixtures grows slowly, but the resistance to ammonium sulfate corrosion is better; mineral admixtures have good effect in delaying the decline of compressive strength of corroded concrete, but shows worse effect for flexural strength. The results of grey analysis reveal that concretes C1 (10% dosage of fly ash), C4 (40% dosage of slag), and C5 (50% dosage of slag) have the best performances in resisting ammonium sulfate corrosion.
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  Determination of Critical Damage Point and Evolution Equation of Concrete’s Dynamic Splitting Damage under Stress Space

  WU Bin, HU Wei-hua, TANG Ke-jing

  Journal of Changjiang River Scientific Research Institute. 2016, 33(8): 125-129. https://doi.org/10.11988/ckyyb.20150462

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  In order to explore the features of concrete dynamic splitting, we carried out splitting test under different strain rates and established the relationship between stress level and AE(acoustic emission) energy number. Then, we put forward the concept of critical damage point and determined the evolution equation of dynamic splitting damage of concrete. On the basis of determining optimal critical point by using medical ROC(receiver-operating characteristic) curve, we gave the stress level of concrete at critical damage point in splitting test. Results showed that 1) under high strain rate, stress lags when emission signal occurs at the first stage of damage; 2) AE phenomena at the second stage were similar to those with low strain rate after stress level exceeded a given value; 3) with the increase of strain rate, the stress level at critical damage point increased, and its range was ; 4) there is a linear relationship between stress level at critical damage point and logarithmic function of strain rate, and the strain rate of concrete at critical damage point in splitting test under stress space was 0.75.
INFORMATION TECHNOLOGY APPLICATION
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  Development of A Multi-source Information Management System for Groundwater Monitoring

  ZHANG Lei,YUAN Ai-jun,FENG Jian-hua

  Journal of Changjiang River Scientific Research Institute. 2016, 33(8): 130-133. https://doi.org/10.11988/ckyyb.20150555

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  With economic development and continuous population growth, groundwater has been over exploited and the groundwater level depth declines significantly, and the over-exploitation resulting environmental and geological problems. In order to realize the scientific management and rational planning of groundwater, we develop a new groundwater information system. Some key technical issues such as data acquisition, transmission, management and remote control can be solved by the system. Moreover, we can use the system to analyze real-time monitoring data, synchronously update data, display, query, manage apparatus device and communication equipment (including the information of monitoring well), give an alarm and so on. The system is compatible with a variety of equipment and the monitoring data with different formats can be also processed by the system. Users can access this system via Internet, so the system is of good convenience and high versatility.
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  BIM-based Visualization and Application Demonstration of Sci-Tech Achievements in Hydropower Engineering

  LIN Wei

  Journal of Changjiang River Scientific Research Institute. 2016, 33(8): 134-137. https://doi.org/10.11988/ckyyb.20150538

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  It is difficult to learn, understand and refer to the traditional 2-D display of sci-tech achievements in hydropower engineering. In order to solve this problem, we analyzed the limitations in the traditional form of paper carrying in transmission and expression of information, and proposed the concept of BIM(Building Information Modeling)-based visualization. We established a digitized model of hydropower engineering construction objects with scene reconstruction technology, 3-D simulation technology and 3-D interactive technology. Through this model, construction methods and construction process of sci-tech achievements are visually simulated, and all-round and multi-angle interactive browsing of the virtual construction objects is realized. The model could exactly transfer a large number of sci-tech information achievements in a short time, and offers a completely new and highly efficient learning experience to the sci-tech achievements. It is also beneficial for the assessment and promotion of scientific and technological achievements.
INSTRUMENTATION DEVELOPMENT AND TESTING TECHNIQUES
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  Parameters Identification of Hydro-turbine Governing System Based on Chaos Particle Swarm Optimization and Modeling Experiment

  FENG Yan-min, WANG Zhan, ZHANG Xue-yuan,ZHANG En-bo, LIU Chun-lin

  Journal of Changjiang River Scientific Research Institute. 2016, 33(8): 138-143. https://doi.org/10.11988/ckyyb.20150482

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  To overcome the shortcomings of standard Particle Swarm Optimization(PSO), for example, prone to local optimum and slow later convergence and so on, shrinkage factor and chaos idea were adopted to improve standard PSO in the study. A novel design method for satisfactory function of hydro-turbine governing system was put forward. Chaos PSO was applied to parameters identification of controlled object for governing system. Quality parameters, such as rise time, settling time, hydro-turbine’s reverse peak power and reverse peak time, were directly measured, and the overall satisfaction level of system was taken as fitness function. On the basis of the new method, the control parameters of a hydro-turbine governor were measured in association with parameter identification of hydroelectric turbine-conduit system. Test results show that the simulated data correctly reflect the response characteristics of cascade frequency disturbance for the unit load, and meet the requirements of power grid stability calculation. Furthermore, under large interference, the algorithm still has accurate parameter identification and high convergence efficiency.
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  Development and Optimization Skills of Simple Particle Image Velocimetry Technology

  KE Sen-fan, SHI Xiao-tao, WANG En-hui, HE Hui-ling, HU Xiao,WANG Zhi-qiang, RAO Dong-wei, FAN Hou-yan

  Journal of Changjiang River Scientific Research Institute. 2016, 33(8): 144-150. https://doi.org/10.11988/ckyyb.20150549

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  As a measurement technique of instantaneous 2-D velocity flow field, particle image velocimetry(PIV) has received much attention in detailed flow field measurement, but mature product of PIV is still expensive. In view of this, we introduce a simple device which consists of high-speed digital camera, laser transmitter, cylindrical lens and tracer particle. The fuctions of business PIV product can be achieved with low cost. To verify the simple PIV performance in this paper, we designed a simple device and analyzed the advantages and disadvantages of this simple device by software Fluent. Furthermore, we optimized the particle size and the tracking performance of particle. Results show that corn flour particle is suitable as the tracer particle of this simple device. Moreover, we should choose the frame rate of high-speed digital camera according to the maximum inlet water velocity which the tracking performance of tracer particle can reach. During this process, we can get a better flow field measurement, and develope and optimize the PIV technique. The analysis result offers important reference for further study.