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20 December 2016, Volume 33 Issue 12
    

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    RIVER-LAKE SEDIMENTATION AND REGULATION
  • YU Lei,LI Ling-yun,LU Jin-you,WANG Jia-hu,ZHENG Shan
    Journal of Changjiang River Scientific Research Institute. 2016, 33(12): 1-5. https://doi.org/10.11988/ckyyb.20150808
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    In order to study the adjustment of discharge and sediment concentration of inlet section from Dongting Lake to Yangtze River, we take Chenglingji hydrological section as an example. According to measured data from 1962 to 2010, we carry out multi-time scale analysis of flow discharge and sediment concentration of Chenglingji station in association with wavelet analysis method to obtain the periodic changes of water-sediment load at the section. Then, we select the section area of low water level as characteristic variables, and use wavelet coefficient of discharge to divide discharge and sediment concentration sequences into different periods. On the basis of delayed response principle, we establish an adjustment model with different time intervals, which is suitable for the response of the water and sediment concentration in the area of the Chenglingji station of Qilishan. Results show that the model could well simulate the regularities of inlet section’s adjustment of Dongting Lake, and the fitted coefficient R2 between calculated and measured data is 0.77, which demonstrates that the model has adequate accuracy.
  • WATER RESOURCES AND ENVIRONMENT
  • LIN Yong-sheng,PEI Jian-guo,DU YU-chao,LU Li,FAN Lian-jie
    Journal of Changjiang River Scientific Research Institute. 2016, 33(12): 6-9. https://doi.org/10.11988/ckyyb.20151049
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    With the underground river at Litang county of Guangxi province as a research object, we revealed the hydrochemical compositions of Yaocun underground river and discussed its temporal and spatial distribution by analyzing groundwater samples collected in wet season (June), normal flow season (September), and dry season (December). Results showed that 1) in space scale, the conductivity and the concentrations of Ca2+ and Mg2+ gradually increased from the upstream to the downstream, and in particular, the conductivity of the underground river’s outlet (point No.3) was higher than that of other positions, reaching 589 μS/cm in wet season, 634 μS/cm in normal flow season, and 614 μS/cm in dry season; 2) while in time scale, the concentrations of pH, SO42-, NO3- varied with season, and NO3- concentration at underground river’s outlet in dry season was higher than that in other seasons; 3) the hydrochemical characteristics of the research area are influenced by karst degree and agricultural activities.
  • WANG Dong, FANG Juan-juan, LI Yi-tian, YIN Zheng-jie
    Journal of Changjiang River Scientific Research Institute. 2016, 33(12): 10-16. https://doi.org/10.11988/ckyyb.20160301
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    The diverted flow from three outlets of Jingjiang River is an important part of inlet flow of the Dongting Lake. Its changes would affect the relationship between the Yangtze River and the Dongting Lake. Since the impoundment of the Three Gorges Reservoir, changes in the diverted flow from the three outlets has been closely related to incoming flow decrease and runoff process change in the Yangtze River. In this article, according to measured data, the relationship between discharge of mainstream Jingjiang River and diverted flow of three outlets was analyzed, and the durations of middle flow and high flow of mainstream Jingjiang River before and after the reservoir impoundment were compared. Moreover, the influence of runoff process change caused by reservoir storage on the three outlets was also researched. Results revealed that 1) the diverted flow from three outlets is dependent on the number of days of middle flow and high flow in mainstream Jingjiang River. The diverted flow from three outlets reduced due to decreases in incoming flow and middle-and-high-flow durations caused by reservoir storage and regulation; 2) in running period of 139 m water level, the reservoir runoff changed slightly, which had no big influence on the three outlets; 3) in typical year of running period of 156 m water level, impoundment process has the biggest influence on three outlets, with the total diverted flow decreasing by 770 million m3, whereas in other periods the influence was small; 4) in running period of 175 m water level, flood storage in flood season and impoundment in storage period significantly affected the duration of middle flow and high flow in Jingjiang River, causing a decrease of 8.31 billion m3 in total diverted flow of three outlets.
  • WANG Ruo-chen, OUYANG Shuo
    Journal of Changjiang River Scientific Research Institute. 2016, 33(12): 17-21. https://doi.org/10.11988/ckyyb.20160900
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    As the first-stage project of the south-to-north water transfer project has been built, the scheduling of Danjiangkou reservoir has become an important issue. The aim of this research is to provide basic support for the scheduling which could make a trade-off among multiple users in the Hanjiang river basin. In the light of storage, water supply, and power generation tasks, a scheduling model for Danjiangkou Reservoir was built through setting objective functions (minimum abandoned water flow and maximum power generation) and water supply dispatching scenarios (in the presence and in the absence of the south-to-north water transfer project). The solution space which meets the dispatching operation mode of Danjiangkou reservoir was constructed. Dynamic programming algorithm and natural incoming runoff series of Danjiangkou between 1956 and 2015 were used for the simulation. The influences of objective function and operation mode on the water regime and water balance in the downstream were analyzed. Results show that in the presence of the first stage of middle route south-to-north water transfer project, the discharge of Danjiangkou reservoir’s optimization scheduling is more than 27.2 billion m3, which could meet the water demands in the lower reach of Hanjiang River.
  • LI Yun-jie, LÜ Hui-jin, BU Peng
    Journal of Changjiang River Scientific Research Institute. 2016, 33(12): 22-26. https://doi.org/10.11988/ckyyb.20150774
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    “A total of five waters treatment” was put forward in 2014 in Zhejiang province, and 2015 is an important year for the strategy.Zhejiang Province advocates the construction of an ecological province, and so the sustainable utilization of water resource is an important issue to be considered at this stage and the dynamic analysis of water resource can present its utilization actuality. Based on ecological footprint method, the analysis of ecological footprint, ecological carrying capacity and the dynamic change of water resources may provide references for water resources utilization, management and planning in Zhejiang Province.The results show that water ecological footprint in Zhejiang Province changed frequently from 2006 to 2013; the ecological carrying capacity of water was larger than the ecological footprint, giving rise to ecological surplus of water; the ecological pressure index of water ranged from 0 to 1, indicating a higher safe factor; water ecological footprint per ten-thousand-yuan GDP was also higher,which proved that water resources in Zhejiang Province was unsustaintable.
  • WATER-SOIL CONSERVATION AND ECO-CONSTRUCTION
  • HUANG Jin-quan,CHENG Dong-bing,WANG Zhi-gang,LIU Ji-gen,
    ZHANG Guan-hua,SUN Bei,ZHANG Ping-cang
    Journal of Changjiang River Scientific Research Institute. 2016, 33(12): 27-32. https://doi.org/10.11988/ckyyb.20160337
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    Dynamics of soil organic carbon(SOC) affected by water erosion plays an important role in accurate assessment of soil erosion role in carbon cycle.In this paper, we discuss the influence of erosion on the pattern of global carbon cycle, and clarify the significance of research on dynamic mechanism of SOC affected by water erosion. On this basis, we introduce the latest domestic and foreign progresses of SOC pattern and dynamic mechanism of SOC pool, and analyze problems in the current research and the development tendency in the future. Through the research, we conclude that soil microorganisms should be taken as the research objects for SOC mineralization affected by water erosion, which will help us to verify erosion role in soil carbon cycle at mechanism level. Furthermore, in order to fully investigate the dynamic mechanism of SOC affected by water erosion, we can employ model simulation method, and it is an urgent research direction for the research in future.
  • FLOOD PREVENTION AND DISASTER REDUCTION
  • ZHANG Hui, LI Hui-yun, CUI Zhan-feng
    Journal of Changjiang River Scientific Research Institute. 2016, 33(12): 33-36. https://doi.org/10.11988/ckyyb.20150943
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    With rapid economic and social development and population growth, rail transit project construction increases obviously at flood detention basin near big city, but few reasearchers turn their eyes to the influence of rail transit on usage of flood detention basin. In view of this, we take rail transit No. 21 in Wuhan as an example. We apply dynamic boundary simulation technology and establish a two-dimensional water flow mathematical model for the flood detention basin to analyze the influence on the basin. Results show that effective flood detention volume occupied by bridge pier or railway station is relatively small in Wuhu flood detention basin. Furthermore, project construction has little influence on flood diversion discharge, duration, water level and flow field. It is the same for flood fall discharge,so project construction doesn’t have obvious adverse impact on the usage of flood detention basin. Finally, the research method and results can be taken as reference for design companies and autorities of flood prevention.
  • ENGINEERING SAFETY AND DISASTER PREVENTION
  • ZHANG Yu-chi,HUANG Hui-hong
    Journal of Changjiang River Scientific Research Institute. 2016, 33(12): 37-41. https://doi.org/10.11988/ckyyb.20160197
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    Structural flexibility matrix and element’s stiffness matrix are difficult be obtained accurately by sensitivity analysis of structural flexibility in practical vibration test.To solve this problem, an improved method which optimizes and reduces input data to meet the requirements of practical application is proposed. The first several low modals are collected and the structural flexibility matrix is calculated, and then the elements are assumed successively to be damaged and the matrix of flexibility variation before and after structural damage is built. The method is applied to the damage identification for a hydraulic radial gate, and the numerical simulation results prove that the proposed method could locate the damaged element accurately and avoid the misjudgment of symmetric unit. The research provides theoretical basis for the damage identification of hydraulic structures.
  • HAN Wen-qi, YU Hong-ming, CHEN Peng-yu
    Journal of Changjiang River Scientific Research Institute. 2016, 33(12): 42-45. https://doi.org/10.11988/ckyyb.20150492
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    Researching the relationship between rockfall’s impact force and rockfall velocity is of great significance for the prevention and remediation of rockfall hazard. The impact force of rockfall involves many factors, among which velocity is the most influential factor. In this article, the relationship between rockfall velocity and impact force was researched through indoor impact test. First, marble ball was released to hit rectangular slabs made of different materials. Second, the rockfall’s impact force was recorded through sensors and rockfall movement by using camera. Third, the instantaneous velocity at the moment of hitting was calculated, and some related data were obtained. Results reveal that the large rockfall movement velocity (V), the greater the impact force (F) of rockfall. According to the results and the fitted data, the velocity and impact force are in a power function relationship, i.e. F is positively related with V1.35.
  • AGRICULTURAL WATER CONSERVANCY
  • YANG Jun, LI Zheng, LI Wen-bo
    Journal of Changjiang River Scientific Research Institute. 2016, 33(12): 46-50. https://doi.org/10.11988/ckyyb.20150978
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    Pollution of rural cultivated land has restricted the healthy and sustainable development of agriculture, and has affected the national food security strategy. In order to analyze the response of farmers to farmland pollution and its impact on agricultural production, we investigate the situation of rural land pollution and construct an ordered Logit model. Rural land pollution in Poyang Lake region is taken as an example. Major conclusions of this thesis are as follows: 1) the proportion of arable land circulation and the improvement of agricultural products’ commercialization rate are beneficial to improving farmers’ participation in the management of farmland pollution; 2) whether farmers choose to continue the production at contaminated farmland or not is affected by the proportion of farmland transfer-in and the degree of commercialization; 3) the higher education level of main agricultural labor force is , the stronger willingness to change the mode of production in polluted farmland is. The results show that, promoting the transfer of arable land has positive significance to strengthen the prevention and control of farmland pollution from the microscopic main body. Furthermore, strengthening the knowledge of farmers’ land pollution and food safety is conducive to improve the current situation of food pollution.
  • HYDRAULICS
  • CAO Jing-jing, SHEN Hong-bin
    Journal of Changjiang River Scientific Research Institute. 2016, 33(12): 51-54. https://doi.org/10.11988/ckyyb.20150416
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    Trapezoidal section is widely used in the design of channels. The regularity of boundary shear stress distribution is an important factor in the research of flow structure and resistance.In this article, the expressions of the relative values of average bed and sidewall shear stress with width-depth ratio of flow section are derived through integration. Comparison between the present calculation method and Knight’s experimental data reveals relatively small error. The variation regularity of average bed and sidewall shear stresses of optimal hydraulic section in trapezoidal open channels with different side angels is analyzed. The result shows that the optimal hydraulic section in trapezoid open channel is narrow and deep, the average bed shear stress changes little while the average sidewall shear stress reduces with the decrease of side angel.
  • FANG Shi-long, CHEN Hong,SHI Xiao-fei
    Journal of Changjiang River Scientific Research Institute. 2016, 33(12): 55-60. https://doi.org/10.11988/ckyyb.20150991
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    Although submerged vertical circular cylinders have been widely applied in engineering fields, there are no systematic study on the flow pattern and turbulence characteristics in the flow field around the submerged vertical circular cylinders.In view of this,we carried out indoor flume experiment with different slopes and accurately measured the instantaneous velocity field around the submerged vertical circular cylinders. According to the test result, we analyzed the impact of the submergence ratio on the vertical distribution of three-dimensional flow velocity and turbulence intensity along upstream and downstream vertical symmetry plane of the submerged vertical circular cylinders.On this basis, we researched the variations of scour strength of downstream flow, horseshoe vortex and tail flow vortex with submergence ratio, and revealed the mechanism of submergence ratio affecting local scour by clear water around the submerged vertical circular cylinders. Research results show that 1) increasing submergence ratio could reduce the effective length of vertical circular cylinder above water surface and weaken the resistant flow and disturbance of the cylinder on water; 2) the scour capacity of downward flow in the upstream of cylinder, horseshoe vortex around the cylinder, and tail flow vortex obviously decreases, which reduces the probability of sediment around vertical circular cylinder being eroded by vortex.
  • ROCK-SOIL ENGINEERING
  • YANG Xin-guang ,ZHOU Mi, ZHANG Wei, PAN Jia-jun
    Journal of Changjiang River Scientific Research Institute. 2016, 33(12): 61-67. https://doi.org/10.11988/ckyyb.20150680
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    Three-node triangular elements together with the linearized yield criterion are commonly used in the finite element upper bound limit analysis. Therefore, the method is of low calculation precision. Aiming at this problem, a method of upper bound limit analysis using six-node triangular elements and second-order cone programming is developed to investigate the slope stability subjected to pore water pressure and earthquake loads. The proposed method formulates the slope stability problem as a second-order cone programming with constraints based on the yield criterion, flow rule, boundary conditions, and the energy-work balance equation. The optimization problem is solved by a state-of-the-art interior-point method, and the strict upper bound solutions can be obtained. Finally, the results of two numerical examples are compared with published solutions, which demonstrate the validity of the proposed method. The results also indicate that the mesh-dependence phenomenon is overcome and the calculation precision is improved even for large internal friction angel of materials.
  • LI Dong-dong,LIU Han-dong,WANG Zhong-fu,DUAN Su-zhen
    Journal of Changjiang River Scientific Research Institute. 2016, 33(12): 68-71. https://doi.org/10.11988/ckyyb.20150757
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    In probabilistic slope stability analysis, the selection of slip surface for calculation usually varies from critical deterministic surface to critical probabilistic surface. The reliability index for the former is not the minimum based on a deterministic surface, the latter is closer to the actual failure probability as a similarity to reliability of the slope system. In this paper, a technique put forward by Hassan and Wolff for the determination of slip surface with the minimum reliability index is presented. The critical probabilistic surface could be simply determined by several stability calculations according to specific combinations of soil parameters, which requires no special programs. The method’s validity is examined by two cases including simple homogeneous and heterogeneous soil slopes. Besides, the orthogonal design is applied to slope stability analysis for comparison. The results show that the critical probabilistic slip surface corresponding to the minimum reliability index conforms well with the surface corresponding to a minimum safety factor according to the combinations of soil parameters. Therefore, the critical probabilistic slip surface could be determined by this method in engineering applications.
  • XU Zhen-kai,ZHANG Lin,WEI Bo-wen,HUANG Hai-peng,WANG Feng
    Journal of Changjiang River Scientific Research Institute. 2016, 33(12): 72-77. https://doi.org/10.11988/ckyyb.20150760
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    In view of the uncertainty such as hierarchy and fuzziness of assessing rock slope’s safety and stability, we considered the stability assessment as a fuzzy system and took geological conditions, engineering status, environmental conditions and monitoring performance as well as their influence factors into account, hence building an index system which contains multiple layers including target layer, criterion layer and index layer. Principal component analysis and the improved analytic hierarchy process were combined to present a method which takes into consideration the subjective and objective weights at the same time and improves the accuracy and rationality of index weights. Membership functions were constructed by using fuzzy theory. Finally the comprehensive multi-level fuzzy model for assessing rock slope safety and stability was established. Practical application shows that the model is feasible and easy to operate and the result is in accordance with the reality. The model provides a new approach for the assessment of rock slope’s safety and stability.
  • ZHANG Jia-fa, WU Qing-hua, ZHU Guo-sheng
    Journal of Changjiang River Scientific Research Institute. 2016, 33(12): 78-85. https://doi.org/10.11988/ckyyb.20160400
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    The significance of researches on the clogging mechanism and performance improvement was expounded for typical infiltration facilities of sponge city, such as well, tube, and pond. Factors of clogging were classified as three kinds: clogging material properties, hydrodynamic conditions and filter properties. In this article, the advances of research on clogging mechanism were summarized and discussed in terms of these three kinds of factors. The drawbacks which need to be overcome by further studies were summarized: the characteristics of clogging material is unclear, the simulation of hydrodynamic condition is non-holistic, studies on real filter structures, intermittent operation and time effects are inadequate, understandings of the clogging mechanism are inconsistent, attention on new filter structures and filter maintenance is insufficient, and prototype and in situ studies are in lack. According to the status of sponge city construction in China, it is urgent to monitor the storm water for typical urban areas, especially the first storm water after a long dry period. On the basis of research on similar problems, the approaches of improving the performance of infiltration facilities were analyzed. It was proposed that replaceable filters would be a practical solution to break through clogging problem and to promote the application of infiltration facilities and would guarantee the long-term efficiency of sponge city construction.
  • WANG Yi-dong, XU Yong-fu, XI Yue
    Journal of Changjiang River Scientific Research Institute. 2016, 33(12): 86-90. https://doi.org/10.11988/ckyyb.20150779
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    A large number of experimental studies have shown that marble particle crushing has fractal characteristics. The fractal model of particle crushing was described in this paper. Through crushing tests on single particle, the particle size distribution was obtained, and three patterns of particle crushing damage were described, and the relationship between crushing pattern and particle shape was presented. According to the results, the relationship between deformation when particle crushed and particle size was established. This research is the first attempt to determine the relathionship between particle crushing energy and fractal dimension through the use of fractal theory. The fractal dimension D obtained from the test is 2.48. All conclusions are based on experiments, and all the theory and derivation are verified to be well consistent with experimental results.
  • WANG Chuang-ye,WANG Hong-qi
    Journal of Changjiang River Scientific Research Institute. 2016, 33(12): 91-93. https://doi.org/10.11988/ckyyb.20150761
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    The damage value of rock changes dynamically in the process of rock damage. By improving the Harris function,a damage constitutive model of rock under three-dimensional stress is established,and the parameters of the model are determined through triaxial test on sandstone. The relationships among confining pressure,critical damage value,and peak strain are analyzed qualitatively. Research results show that: 1) the model curve of sandstone’s damage constitutive model based on improved Harris function is well fitted with the measured curve,and has good applicability;2) the critical damage value is not a fixed value for the same kind of rock under different confining pressures,indicating that the mechanical properties of rock are related to its three dimensional stress state;3) the critical damage value increases correspondingly when confining pressure increases, which proves that confining pressure has a restraining effect on rock damage. The analysis results have a certain reference significance for the study of damage mechanism of rock under three-dimensional stress condition.
  • RAO Yu, ZHAO Gen, WU Xin-xia, LI Peng, HU Ying-guo, LI Wei-chao
    Journal of Changjiang River Scientific Research Institute. 2016, 33(12): 94-98. https://doi.org/10.11988/ckyyb.20150795
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    Based on the elastic wave theory, the numerical simulation model of stress waves across slipping joint has been built, and transmission, reflection and absorption coefficients are calculated to analyze the propagation characteristics of stress waves. Results show that propagation characteristics of normal incident longitudinal wave are affected by joint’s tensile strength, and if the tensile stress produced on the joint by normal incident longitudinal wave exceeds the tensile strength, the interface will separate, transmitted wave disappears instantaneously, and then total reflection occurs, with the reflected wave and absorbed energy increasing. The propagation characteristics of normal incident shear wave are affected by the ratio of tangential joint stiffness and the product of shear strength and normalized tangential joint stiffness. With the increasing of the ratio, the reflection coefficient increases, transmission coefficient decreases, and absorption coefficient increases at first and then decreases, then ends with total reflection.
  • GAO Chun-yan, GAO Quan-chen, NIU Jian-guang
    Journal of Changjiang River Scientific Research Institute. 2016, 33(12): 99-104. https://doi.org/10.11988/ckyyb.20150797
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    The rheological property of surrounding rock is one of the key factors affecting the safety and stability of tunnel engineering. Research of constitutive model is the most essential and important part of rock rheological mechanics theory and is a necessary step to apply the results to practical engineering. A research method integrating experimental investigation, theoretical analysis and numerical simulation is applied in this paper to analyze the rheological mechanics characteristic and the establishment of constitutive equations of the sandrock of kilometers deep shaft roadway in Huainan Mining Group’s Zhuji coal mine. Based on a large number of relevant theoretical and experimental data,a nonlinear creep model expressed as an exponential function of stress and time is constructed to combine with Burgers model. The new creep model of six elements demonstrates the three phrases of rock creep process and takes into consideration the accelerated creep characteristic. Triaxial compressive rheology test under high confining pressure condition was performed on sandstone taken from Zhuji deep mine. Creep parameters for the proposed model were identified from the test creep data to verify the rationality of the model.
  • CAI Jia-yuan,ZHOU Chuan-bo,WU Cao
    Journal of Changjiang River Scientific Research Institute. 2016, 33(12): 105-108. https://doi.org/10.11988/ckyyb.20150614
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    In order to speed up the construction of double line subway tunnel,two shield machines are used in the excavation at the same time.Under the condition of invariable transverse spacing of the two shields,small longitudinal spacing will aggravate the disturbance of surrounding soil and affect the safety of surface building(structures).In this paper,with Wuhan Metro line 3 as engineering background,the characteristics of transverse and longitudinal surface deformations of shield tunnel excavation are analyzed through field monitoring and numerical simulation,and the regularity of longitudinal influence of double-line parallel tunnel excavated in the same direction is revealed.Results show that the numerical results accord with the field monitoring data;surface subsidence trough forms after the shield passes.The surface deformation above the tunnel vault remains the biggest,and the farther away from the axis of the tunnel,the smaller the surface deformation reaches.In the process of excavating,the surface uplift value above the front of shield reaches the maximum;the surface settling velocity increases rapidly after the shield passes and finally tends to be stable.In the process of shield excavating in same direction of double line metro tunnel,the secondary disturbance of shield contributes to the final surface deformation,but the longitudinal spacing of shields has no effect on the final surface deformation.With the increase of longitudinal spacing of shields,the total surface settling velocity slows down.It is safe and reliable when the longitudinal spacing of shields exceeds 50 m.The research result of this paper is expected to provide a basis for the safe and rapid construction of subway tunnels.
  • ZHOU Li-ming, WANG Fa-gang, XIAO Guo-qiang, FU Dai-guang, LUO Rong
    Journal of Changjiang River Scientific Research Institute. 2016, 33(12): 109-112. https://doi.org/10.11988/ckyyb.20160174
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    Well logging technology has been proved to be a reliable method to researching the rock mass structure and quality in hydropower project. In order to estimate the geological conditions and structural characteristics of rock mass, we took the south bank expansion project of Kariba power station as an example and carried out rock mass test at position Sd01, upstream cofferdam of water inlet and gate shaft of water inlet. By adopting acoustic and optical logging technology, we conducted in-site test and obtained the thickness of covering layer, weathering degree of bedrock, fissures development degree, and acoustic velocity of rock mass. The experimental results show that the water level at these places is 11.7, 13.1, 14.1-16.5 m,respectively, and average wave velocity is 3 200, 3 500, 2 000 m/s ,respectively,and the thickness of the covering layer is 21, 26 m, and above 30 m. Furthermore, the rock mass at Sd01 site and the gate shaft is relatively complete, with 12 and 11 fractures,whereas the rock mass of upstream cofferdam is broken and strongly weathered.
  • ZHANG Jun-xian
    Journal of Changjiang River Scientific Research Institute. 2016, 33(12): 113-118. https://doi.org/10.11988/ckyyb.20150908
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    Though fracture grouting technique has been widely used in underground engineering, the theoretical study lags far behind engineering practice. Based on the assumption of power-law fluid and narrow plate model of grouting diffusion, a formula for calculating the maximum diffusion radius of a power-law fluid is deduced. The scope of application and the method to determine parameters are analyzed, and the formula is validated by means of filed grouting tests. The findings are as follows: 1) the maximum diffusion radius of fracture grouting is related to grouting pressure, front surface pressure, crack width, viscocity coefficient, average flow rate of grout and flow behavior index; 2) the maximum diffusion radius increases with grouting pressure difference, and grouting pressure difference reduces with the increase of crack width; 3) according to field test results, the error between theoretical calculation value and actual measured value of the maximum diffusion radius of the power-law fluid is obtained, which proves that the formula is correct and applicable. The results provide theoretical and technical support for similar grouting projects.
  • HYDRAULIC STRUCTURE AND MATERIAL
  • LI Jian-wei, WANG Zhi-hong,HONG Zhen-guo
    Journal of Changjiang River Scientific Research Institute. 2016, 33(12): 119-123. https://doi.org/10.11988/ckyyb.20160967
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    Thin concrete panels act as the main impervious body of CFRD (Concrete Face Rockfill Dam), and it is particularly important to prevent leakage at the panel seam joints. If a large amount of leakage occurs, the engineering safety and economy will be severely affected. In the aim of improving the sealing performance of surrounding joints of panels, we compared several typical sealing structures from aspects of structure design, sealing principle, deficiencies of structure and materials. Furthermore, we present a novel structure consisting five sealing levels for the surrounding joints of CFRD panels. Results reveal that the proposed structure retains the strengths of other structures, and also makes up for their deficiencies.
  • HOU Shu-peng, CHEN Li-yi, WANG Sheng, WAN Yu-hao, DING Xiu
    Journal of Changjiang River Scientific Research Institute. 2016, 33(12): 124-127. https://doi.org/10.11988/ckyyb.20150763
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    Cemented soil materials have been widely used in engineering construction in cold regions where climate and temperature have great influence on the properties of cemented soil. Researching the degradation and deterioration behaviors of cemented soil under cyclic freezing-thawing is of valuable reference for the construction and design of similar projects in cold regions. In this article, we mixed undisturbed soil from a slope in Xinjiang with ordinary cement to prepare the cemented soil for test, and conducted cyclic freezing and thawing tests of 0, 3, 9 and 15 times with the freezing temperature at -20 ℃ and thawing temperature at 20 ℃. Uniaxial compressive strength tests and quality analysis were performed after different cycles. On this basis, the microscopic structural changes of cemented soil were analyzed by using scanning electron microscopy (SEM) to investigate the degradation and deterioration mechanism of cemented soil under cycles of freezing and thawing. Results showed that the compressive strength and residual quality of cemented soil samples decreased with the increase of freezing-thawing cycle times, and the regularity of changes between freezing-thawing cycle times and compressive strength can be expressed with the fitting relation: Rc=-0.11n+3.29.
  • ZHANG Zhi-chuan,WU He-gao,SHI Chang-zheng
    Journal of Changjiang River Scientific Research Institute. 2016, 33(12): 128-132. https://doi.org/10.11988/ckyyb.20150772
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    Cracks are very likely to occur due to complex loads endured by concrete spiral case during the operation of hydropower station. Seepage control design is hence a big problem needs focus. Owing to insufficient research of seepage control at present and more applications of concrete spiral case in low and middle and even high head power stations in the future, some seepage control measures for concrete spiral case were analyzed by nonlinear finite element method with a hydropower station in river channel as the research background. The research results indicate that high strength concrete, steel fiber-reinforced concrete and epoxy mortar materials could solve the cracking problem for the concrete spiral case structure, but they have some limitations in practice. Steel liner coating on the inner wall of concrete spiral case and pre-stressed reinforcement have good effect in dealing with seepage problem and they are recommended to be preferentially used in practical projects.
  • INFORMATION TECHNOLOGY APPLICATION
  • ZHOU Li-feng, LIU Wen, ZHANG Zhi-zhong
    Journal of Changjiang River Scientific Research Institute. 2016, 33(12): 133-137. https://doi.org/10.11988/ckyyb.20160957
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    In order to promote the information construction of the Yangtze River Scientific Research Institute during the 13th five-year planning period, the Internet Plus Water Sci-tech Action Plan of the Yangtze River Scientific Research Institute is prepared, in which the construction target of “Yangtze Science Clouds” in 2018 is proposed. The “Yangtze Science Clouds” consist of OA cloud, management cloud, scientific research cloud, technical service cloud and intelligent river basin research cloud, covering the main work of the institute. OA cloud means cloud-based working environment, and management cloud refers to cloud-based management flow, and scientific research cloud, as the core business, means cloud-based scientific research process, while technical service cloud and intelligent river basin research cloud refer to cloud-based information platform for sci-tech support. At present, the infrastructure construction of “Yangtze Science Clouds” is completed and the initial application is being carried out orderly. After construction, the level of management standardization, scientific research process informationalization, technical consultation networking and sci-tech support intelligentization will be improved significantly.
  • QI Wen, QIU Bing-wen, FAN Zhan-ling
    Journal of Changjiang River Scientific Research Institute. 2016, 33(12): 138-143. https://doi.org/10.11988/ckyyb.20150765
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    Researching the pattern of vegetation cover is of great significance for the sustainable development of eco-environment.In this article, the characteristics of vegetation cover pattern and its driving mechanism were investigated and analyzed using geographically weighted regression (GWR) model based on vegetation cover index data of 30m resolution.Fujian Province and Jiangxi Province were selected as study area, and natural and human factors were considered in the analysis. Research results revealed that 1) in Fujian and Jiangxi provinces, topography is a main factor affecting the vegetation cover degree which has the strongest correlation with elevation within the range of [100,300) m and [300,500) m respectively, and weak correlation with slope gradient, above 25 ℃ and 10 ℃ respectively; 2) the correlation between vegetation cover degree and distance from river for the two provinces differ greatly. In Jiangxi Province, the mainstream is surrounded by towns and cropland, while in Fujian Province, the mainstream is surrounded by towns and woodland; 3) the distance to residence at 5 km and 4 km has the weakest correlation with vegetation cover degree in Jiangxi and Fujian, respectively.
  • LÜ Xin,HAO Lian-xiu,GUO Qing-biao
    Journal of Changjiang River Scientific Research Institute. 2016, 33(12): 144-147. https://doi.org/10.11988/ckyyb.20150794
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    In view of the air quality situation in China, the air qualities of 16 cities of Anhui Province where monito-ring stations are located were analyzed. The temporal and spatial distributions of air quality of Anhui Province are preliminarily obtained based on monitoring data of air quality index from January to June in 2015 by using ArcGIS and SigmaPlot. Results show that 1) air quality in each city of Anhui Province improves with time; 2) the air quality of cities in southern Anhui is better than that in northern cities, worst in Hefei and Huaibei and best in Huangshan and Chizhou. The development of urban industry is an important factor which affects the air quality; 3) the AQI (air quality index) of each city fluctuates to different extents in different months. The value range of AQI concentrates in months of good air quality, and gets discrete in months of poor air quality.
  • INSTRUMENTATION DEVELOPMENT AND TESTING TECHNIQUES
  • WANG Bin, WANG Wu-hui, ZHANG Cheng, ZHU De-lan
    Journal of Changjiang River Scientific Research Institute. 2016, 33(12): 148-152. https://doi.org/10.11988/ckyyb.20140999
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    Nonlinear motion of hydro turbine’s governing system (HGS) will lead to unstability of the power units. In order to solve the problem, we study the stability control of HGS. Firstly, we establish a predictive model of HGS via the fuzzy linearization theory. Secondly, we design the fuzzy predictive controller for HGS. Finally, we use numerical simulations to verify the effectiveness of the proposed method. Results show that the method is effective with advantages such as small over-regulation amount and short transitive time, which is in favor of the stability of HGS. Finally, it can be referenced for stability governing of hydropower system in other projects.