Medical Journal of the Chinese People's Armed Police Forces
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01 April 2017, Volume 34 Issue 4
    

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    RIVER LAKE SEDIMENTATION AND REGULATION
  • Model Test on a Novel Scheme of Reservoir Desilting with Guide Wall
    KANG Feng,SHEN Zeng-yun,TAO Chun-jie
    Journal of Changjiang River Scientific Research Institute. 2017, 34(4): 1-4. https://doi.org/10.11988/ckyyb.20160081
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    As reservoir sedimentation is very serious in China, remarkable achievements have been made in the study of reservoir desilting, but few are about the desilting under small flow. In this article, hydraulic model test with movable bed was carried out and a scheme of desilting in the presence of guide wall was proposed. Guide wall is proved advantageous in desilting under small flow rate through analyzing the desilting effect in the presence of guide wall under different flow rates. Moreover, desilting tests in the presence and in the absence of guide wall under different flow rates suggest that water depth is influential in the scour effect, and the water depth should be less than 1m to achieve the optimal result. Under large flow rate, guide wall is not as effective as that in small flow rate; hence different measures should be taken in different conditions. This research provides a new idea for reservoir desilting both under small flow and comprehensive conditions.
  • Influence of Water Pressure on Incipient Velocityof Cohesive Undisturbed Soil
    FAN Li-yang, CHEN Guo-ping, MA Hong-jiao, LI Qing-yin
    Journal of Changjiang River Scientific Research Institute. 2017, 34(4): 5-8. https://doi.org/10.11988/ckyyb.20160124
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    In order to study the influence of water pressure on incipient velocity of undisturbed clay, we carried out test on the incipient velocity by using a closed rectangular pipe which could provide different water pressures. Results show that incipient frictional velocity of undisturbed clay in the presence of 4.35 m water column height is 2.52-3.06 times that under 0.35 m height. In other words, incipient velocity of undisturbed clay increases with the increasing of water pressure. Besides, water column height, grain gradation and compactness of undisturbed clay are also main factors affecting the incipient frictional velocity.The experimental results can provide reference for further studies on incipient velocity of cohesive undisturbed soil.
  • Water Scarcity Analysis of River Basins in ChinaBased on Water Exploitation Index Plus
    FAN Lin-lin, WANG Hong-rui, LIU Feng-li, LAI Wen-li, HONG Si-yang
    Journal of Changjiang River Scientific Research Institute. 2017, 34(4): 9-14. https://doi.org/10.11988/ckyyb.20160023
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    In the aim of assessing the water scarcity situation of river basins in China, Water Exploitation Index Plus (WEI+) developed by European Union was introduced to compute the water scarcity situations from 2003 to 2012 in ten first-grade districts of water resources in China. Results show that the WEI+ in rivers basin in Southwest China is the smallest, with the average value of 1.9%, and that of Haihe River Basin is the largest, with the average value of 130%. The WEI+ values of six basins in the North are larger than those of four basins in the South, indicating a severe water scarcity situation in North China. The WEI+ values of four basins in the South changed little during 2003-2012, while those of six basins in the North fluctuated greatly. Moreover, the WEI+ values of most river basins displayed a downward trend, showing the alleviation of water scarcity situation. In addition, the spatial distribution pattern of WEI+ is generally similar with that of water conservancy development and utilization degree, which indicates that WEI+ could effectively reflect the regional water scarcity situation in China.

    • WATER RESOURCES AND ENVIRONMENT
  • Characteristics of Nitrogen Pollution and Isotopic Tracer Analysis ofShallow Groundwater in the Sewage Irrigation Area of Kuihe River
    WANG Jin-guo, LI Qun, WANG Bi-ying, ZHANG Ying
    Journal of Changjiang River Scientific Research Institute. 2017, 34(4): 15-19. https://doi.org/10.11988/ckyyb.20160120
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    Nitrogen pollution in groundwater is mainly caused by the intrusion of ammonium nitrogen and nitrate nitrogen. Especially when ammonium (NH4+) is the major pollutant in groundwater, studying its distribution characteristics will be difficult as its migration law in aquifers is complicated and the pollutant is hard to be removed. Through boring holes at both banks of Kuihe River in Xuzhou city, we collected water samples to analyze nitrogen pollution. Test results showed that the main existence form of nitrogen in the study area was NH4+, followed by NO3-. Isotopic analysis of δ15N-NH4+ showed that 27.3% of NH4+ in the groundwater was from chemical fertilizer and the rest was from the sources with high δ15N, such as animal manure and domestic sewage, etc. On the other hand, isotopic analysis of δ15N-NO3- showed that 15.2% of NO3- was from chemical fertilizer and soil organic nitrogen and 63.6% of that was from animal manure and sewage. Test and analysis of groundwater also showed that about 21.2% of samples were with higher isotope values than the pollution source, reflecting the denitrification in shallow groundwater at the study area.
  • Experimental Investigation on Separating Algae from Water UsingMicro-nano Bubble Air Flotation Process
    WANG Jian,HU Shu-heng,ZHUO Sheng-jun,WANG Jia-quan
    Journal of Changjiang River Scientific Research Institute. 2017, 34(4): 20-23. https://doi.org/10.11988/ckyyb.20160061
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    Micro-nano bubble coagulation and air flotation process was adopted to treat the fresh and stale algae-laden waters coming from the algae and water separation port of Tangxi River in Hefei. Effects of coagulant and air retention time on the separation of algae and water were investigated. Through comparing the method with pressurized dissolved-air flotation which is in operation at present in the separation port, experimental parameters of the best treatment effect were explored to achieve the optimal process conditions. Results showed that the optimal dosage of coagulant PAC for fresh and stale algae-laden waters was 24 g/m3 and 36 g/m3, respectively, and the optimum air retention time in floatation pool was 30 min and 40 min,respectively. The removal rates of total phosphorus(TP), total nitrogen (TN), chemical oxygen demand (COD) and suspended solids (SS) of fresh algae-laden water reached 96.50%, 53.10%, 85.70%, 99.00%, respectively. And the removal rates of TP, TN, COD and SS of stale algae-laden water reached 98.40%, 62.40%, 65.60%, 99.80%, respectively. The treatment effect of micro-nano bubble air flotation was better than that of pressurized dissolved-air flotation.
  • Properties of Natural Zeolite in Adsorbing Iron andManganese in Groundwater
    TANG Chao-chun,DUAN Xian-yue,YE Xin,CHEN Hui-min,ZHONG Lü
    Journal of Changjiang River Scientific Research Institute. 2017, 34(4): 24-27. https://doi.org/10.11988/ckyyb.20160112
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    Adsorption is convenient and practical in removing iron and manganese in groundwater. Test of adsorbing iron and manganese by natural zeolite was carried out. Results reveal that the adsorption of iron and manganese by natural zeolite complies with Freundlich’s isothermal adsorption formula, and the removal rates of iron and manganese increase with the increase of zeolite dosage. The higher concentration of original solution is, the larger adsorption amount of iron and manganese is; but with the concentration of original solution increasing, the removal rate of iron gradually reduces, whereas the removal rate of manganese tends to decrease when solution concentration is greater than 5 mg/L. Moreover, the optimum duration of adsorbing iron and manganese is 30 min and 20 min, respectively. As adsorption duration exceeds the optimum, the adsorption amounts both decrease. The test lasts for 70 days and proves that the natural zeolite could not effectively adsorb manganese, with the lowest manganese content in the effluent water over 0.1 mg/L, not reaching national standard (which is ≤ 0.1 mg/L); while the effect of removing iron is better than removing manganese, and the lowest iron content in effluent water approaches 0.0 mg/L, within the national drinking water standard (0.3 mg/L).
    • WATER SOIL CONSERVATION AND ECO CONSTRUCTION
  • Impacts of Anti-seepage Channel Construction on River Ecosystemin Gobi Area of Qaidam Basin
    LI Shao-hua,WANG Xue-quan,CUI Xiang-hui,GAO Qi
    Journal of Changjiang River Scientific Research Institute. 2017, 34(4): 28-32. https://doi.org/10.11988/ckyyb.20160012
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    In order to investigate the impacts of anti-seepage channel construction on the river ecosystem in Gobi area and to provide reference for the sustainable development policy of agricultural oasis in Qaidam Basin, we compared the water quality of surface rivers, the riparian vegetation, and the physical and chemical properties of soil before and after the construction of anti-seepage channels in Dagele watershed through field sampling and laboratory analysis based on socio-economic surveys. Results reveal that 1) constructed anti-seepage channels could purify river water quality, but the effect is insignificant (P＞0.05); 2) anti-seepage channels are not conducive to the reproduction and growth of riparian vegetation in Gobi area, with the average coverage ratio decreased by 4.5%, biomass decreased by 330.2 kg/hm2, and vegetation mortality increased by 6.5%; 3) the soil texture displayed a degrading trend (P＜0.05), with the sand content increasing by 8.68% and organic substances decreased by 0.53 g/kg. Ecological sluices at the outlet of mountains are recommended for the flood diversion and irrigation in flood season. Ecological water conservancy projects should also be constructed to achieve a sustainable development of eco-environment in the basin.
  • Influential Factors of Rainfall Detention of Green Roof Substrates
    ZHANG Hua, YUAN Mi, LIU Shuan, SHEN Ke
    Journal of Changjiang River Scientific Research Institute. 2017, 34(4): 33-37. https://doi.org/10.11988/ckyyb.20160861
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    The water storage capacity of saturated green roof substrates is defined as the maximum water content, which is important for evaluating the effect of rainfall detention. In this research, ceramics particles, peat, and coal cinder were selected to design the substrate of green roof by adjusting the combinations and mixing proportions. The influences of substrate thickness, rainfall intensity, and substrate type on the effect of rainwater detention were investigated through artificial rainfall experiments. Results suggest that thickness and rainfall intensity have no effect on the maximum water content in the presence of the same substrate. But with the increase of substrate thickness, the total capacity of water detention grows, and the delay time of runoff also extends; while when rainfall intensity increases, the delay time of runoff shortens. As for different substrates, the maximum water content of substrates of large total porosity is large correspondingly; and the water retention capacity is related with the coefficient of non-uniformity of substrate particles, which means that more even particles lead to lower water retention capacity.
    • ENGINEERING SAFETY AND DISASTER PREVENTION
  • Combinatorial Forecasting of Slope Deformation Based onRegression Analysis and Wavelet Transform
    YANG Zhen-xing,CHEN Fei-fei,MA Huan-yuan,LI Zhong-yan
    Journal of Changjiang River Scientific Research Institute. 2017, 34(4): 38-42. https://doi.org/10.11988/ckyyb.20160101
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    In order to effectively estimate the variation trend of slope deformation, we employed regression analysis and wavelet transform to decompose the trend term and error term of slope deformation. In subsequence we selected data of optimal decomposition and predicted series of trend term and error term by using BP and RBF neural network. Then, we obtained the forecast results of single term and analyzed the forecast results of fixed weight combination and non-fixed weight combination. Results showed that the results of decomposing trend term and error term by different methods are different.Among the methods, polynomial regression with power of six. Fourier regression with power of five and seven and wavelet transform of sym2 have better results. Moreover, partial prediction is prior to conventional prediction of single term, which verifies the effectiveness of partial prediction in the present research. According to combinatorial forecasting results, fixed weight and non-fixed weight both obviously improved prediction accuracy, and the prediction accuracy of the latter is better than that of the former.
  • Risk Assessment of Karst Surface Collapse in Wuhan RegionBased on AHP-Information Method
    WU Li-qing, LIAO Jing, WANG Wei, PI Wei, ZHOU Lan-lan
    Journal of Changjiang River Scientific Research Institute. 2017, 34(4): 43-47. https://doi.org/10.11988/ckyyb.20151128
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    Karst surface collapse is the main geological disaster in Wuhan area. We selected nine evaluation factors including formation lithology, groundwater exploitation, distribution of fault zone, thickness of overburden, structure of overburden, engineering activities and distance from the Yangtze River, development of karst caves, and karst collapse points to calculate their comprehensive information values by combining weights determined by analytic hierarchy process and information value calculated by information quantity method. Then the risk zoning assessment of karst surface collapse in Wuhan region was conducted. The accuracy of applying AHP-Information quantity method to the karst surface collapse risk assessment in Wuhan region is verified according to comparison with karst surface collapse already occurred. Points which have already seen karst surface collapse are almost in high risk zone. The evaluation results provide basis for the prevention and control of karst surface collapse in Wuhan region,and the evaluation method could also provide reference for the risk assessment of karst surface collapse in other areas.
    • HYDRAULICS
  • Deduction and Verification of the Calculation Foumula for Lengthof Abruptly Expanding Hydraulic Jump
    FU Ming-huan,LU Zhi-nan, HUI Xiang-ming, ZHENG Yan, SUN Pei-xue
    Journal of Changjiang River Scientific Research Institute. 2017, 34(4): 48-51. https://doi.org/10.11988/ckyyb.20160088
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    As an important parameter for the design of abruptly expanding stilling basin, length of hydraulic jump has remarkable effect on the safety, stability and economy of the stilling basin. The variation of length of hydraulic jump in abruptly expanding stilling basin was researched through establishing motion equations of flow particle in hydraulic jump zone. Furthermore, a half-theoretical formula for the hydraulic jump length was put forward and measured data from existed literatures was employed to verify the formula. Result shows that the length of hydraulic jump is the function of four parameters, namely upstream Froude number, upstream mean flow depth, conjugate water depth ratio and abrupt enlargement ratio. With the increase of the four parameters, the length of hydraulic jump increases. The mean error of length of hydraulic jump calculated by the proposed equation is 4.32%. Among 48 working conditions of five patterns, the relative errors of only five conditions exceed 10%, with the maximum value of -12.5%.
  • Summary and Prospect of Researches on the Layoutof Water Flow Aerators
    WEN Lin-sen, HUANG Guo-bing, WANG Cai-huan, CHEN Dong-xin
    Journal of Changjiang River Scientific Research Institute. 2017, 34(4): 52-55. https://doi.org/10.11988/ckyyb.20151121
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    Cavitation damage often occurs in outlet structure under the action of high-velocity flow. Measures of aeration and cavitation mitigation are often taken in engineering to protect hydraulic structures. The availability and importance of different layout types of water flow aerators in outlet structures with high water head and large discharge were summarized. Their characteristics, advantages and disadvantages, the structure, principle and engineering application of aeration measures in different layout types were reviewed. And the optimal selection of layout types of aerators under different hydraulic conditions was also summarized.
  • Numerical Simulation on Slip-type Flip Bucket at Flood DischargingTunnel of Xiaowan Hydropower Station
    CHEN Rui-hua, YANG Ji-jian, MA Lin, HU Zhong-ke, GAO Lan-lan
    Journal of Changjiang River Scientific Research Institute. 2017, 34(4): 56-60. https://doi.org/10.11988/ckyyb.20160121
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    Although slip-type flip bucket is widely used in hydraulic projects, there is no mature method to design it. The bucket type is designed preliminarily according to similar projects, and is optimized through model test. However, model test features with long time, high cost,and low accuracy of conventional instruments. In this article, three-dimensional numerical simulation is carried out on the slip-type flip bucket at the flood discharging tunnel of Xiaowan hydropower station in association with RNG k-ε turbulence model and FAVOR technology of Flow 3D. The computation results of some main hydraulic parameters inclusive of water depth, water jet shape, point of jet entering water in the downstream and upstream, peak height of water jet, and angle of water jet are in accordance with model test and prototype observation. Flow 3D could save time and cost in designing slip-type flip bucket.
  • Stability of Cantilever Pipe Conveying Fluid with DistributedFollower Force on Two-parameter Foundation
    ZHENG Kun, GUO Chang-qing, WANG Fan
    Journal of Changjiang River Scientific Research Institute. 2017, 34(4): 61-65. https://doi.org/10.11988/ckyyb.20151119
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    Through analyzing the relationship between dimensionless complex frequency and critical flow velocity of cantilever pipe, the stability of cantilever pipe conveying fluid with distributed follower force on two-parameter elastic foundation was researched. The vibration of the cantilever pipe under actions of distributed follower force and flow velocity with four different values of foundation stiffness were also analyzed. On the basis of Euler-Bernoulli beam model, differential motion equations of pipes were established and the equations were solved by using transfer matrix method. Results show that 1) with given foundation stiffness, vibration characteristics of the cantilever pipes under the action of distributed follower force is obviously different from that of fluid velocity; 2) with given dimensionless distributed follower force and fluid velocity, the bigger foundation stiffness is, the more stable vibration condition of the pipes system is. In addition, the influence of shear stiffness is more obvious than that of linear stiffness.
    • ROCK SOIL ENGINEERING
  • Mechanical Parameters of Granite Pegmatite Dike in DamFoundation of Lenggu Hydropower Station
    WEI Xing-can,YANG Jing-xi, XIAO Hua-bo, WANG Gang
    Journal of Changjiang River Scientific Research Institute. 2017, 34(4): 66-70. https://doi.org/10.11988/ckyyb.20160099
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    Mechanical parameters of rock and soil at dam foundation are important for the design and stability calculation of dam structure. A large number of granite pegmatite dikes occurs at the dam foundation of Lenggu hydropower station. In view of this, the characteristics of deformation and strength of the dikes were studied by circular rigid bearing plate test and straight shear test. Test results show that stress-deformation curves obtained from bearing plate test are in two shapes, namely straight linear type (or quasi straight linear type) and concave type. The curves of τ-u obtained from direct shear test can be classified into three types brittleness, plasticity and composite type. According to the physical meaning of envelope modulus and secant modulus and the hydraulic project’s characteristics, as well as the representativeness of least square method and optimal slope method in analyzing strength test data, the principle of determining the standard value of rock mass is presented. Finally, mechanical parameters of pegmatite dike at the dam foundation are proposed.
  • Strength Parameters of Rock Mass Based on Hoek-Brown Methodand Application in Hydropower Engineering
    GUO Wei-xiang, ZHENG Ke-xun, HU Zheng, ZHU Huan-chun, LI Zhen, ZHU Yong-sheng
    Journal of Changjiang River Scientific Research Institute. 2017, 34(4): 71-77. https://doi.org/10.11988/ckyyb.20160050
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    Strength parameters are affected by lithology diversity, confining stress and other factors under high stress and complicated geological condition of hydropower engineering in western China. Hoek-Brown method to determining parameter values is helpful to the hydropower engineering practice. Hoek-Brown empirical method is compared with hydropower empirical method, and the specific basis and realization process of independent parameters such as lithology indicator and geological strength index which are related to the factors in Hoek-Brown method are introduced. Moreover, practical methods closely related to the hydropower engineering in western China are expounded and are applied to Jinping Ⅱ-stage and Ⅰ-stage hydropower stations for validation. It is proved that Hoek-Brown empirical method is of high adaptability in hydropower engineering in western China
  • Damage Characteristics of Rock under Cyclic Temperatures
    NIU Chuan-xing,FU Hou-li,QIN Zhe, FENG Bai-yan
    Journal of Changjiang River Scientific Research Institute. 2017, 34(4): 78-82. https://doi.org/10.11988/ckyyb.20160053
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    Uniaxial compression tests were carried out on altered rocks under different temperature cycles to investigate the damage patterns of mechanical properties under cyclic temperatures. Results show that the mechanical properties of the altered rocks are obviously weakened by effects of temperature cycles. With the increase of temperature cycle times, uniaxial compressive strength and elastic modulus decreased and the relationships between them and temperature cycles obeyed exponential distribution. The sensitivity of different rocks to the temperature cycles is different, and the higher the degree of alteration of weathering is, the stronger the sensitivity is. Uniaxial compressive strength is more vulnerable to temperature than elastic modulus does. The cumulative damage values of uniaxial compressive strength reached 35.69% and elastic modulus 29.57% after 20 times of temperature cycles. The relationships between damage values of mechanical properties and the temperature cycles also obeyed exponential distribution. Results of electron microscope scanning revealed that cracks were generated in rocks under cyclic temperatures, mineral composition and internal structure changed, connection force between the lattice was weakened and mechanical properties were changed.
  • Compression Characteristics of Dredging Soil Solidifiedby Lignin
    LIU Wen bai,ZHANG En-hua
    Journal of Changjiang River Scientific Research Institute. 2017, 34(4): 83-86. https://doi.org/10.11988/ckyyb.20160057
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    Compression tests of dredging soil solidified by different contents of lignin were conducted to study the compression characteristics. Through indoor consolidation tests and unconfined compression tests, the compressive properties of soil solidified by lignin and cement-lignin were studied. The effects of solidifying material content and curing age on the compressive properties of solidified soil were investigated. Test results showed that the optimum content of lignin was 10% and the compressive strength reached 8.6 MPa. Dredging soil solidified by lignin is similar to cement soil in an obvious structural yield point of their compression curves. The compressibility of the solidified soil is very small when the upper load has not achieved structural yield stress; while the compressive capacity is three times larger when the load exceeds the structural yield stress. With the increase of lignin and cement contents, the compressive strength of soil solidified by cement and lignin has significantly improved. With the cement content of dredging soil with 25% lignin increasing from 10% to 30%, the compressive strength increased by 8.9 times, of which the increase was the most obvious. The research results provide data reference for the strength of soil solidified by lignin in practical engineering.
  • Physico-mechanical Properties of Cement-modifiedExpansive Soil under Freeze-thaw Cycles
    XU Lei, LU Yang, XUE Yang, SONG Ying-jun, YANG Qi
    Journal of Changjiang River Scientific Research Institute. 2017, 34(4): 87-91. https://doi.org/10.11988/ckyyb.20160070
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    all described as “shrinking in frost and expanding in thaw”. The bigger the cement ratio was, the less the variation of volume change was, and the smaller the maximum frozen shrinkage and maximum thaw expansion were. Yet there was an optimum cement ratio. Freeze-thaw cycles had a great effect on the mechanical properties of cement-modified expansive soil, especially for the initial freeze-thaw cycle. With the increasing of freeze-thaw cycles, strength and elastic modulus of samples with different cement ratios decreased gradually and then tended to be stable. The larger the cement ratio was, the smaller the attenuation of strength and elastic modulus were. The toughness of cement-modified expansive soil improved after freeze-thaw cycles.
  • Simulation of Base Soil-filter System with Two TypicalGradations Based on PFC
    LI Xiao-qing,QI Yang,TANG Xin-jun, GAO Qiang
    Journal of Changjiang River Scientific Research Institute. 2017, 34(4): 92-97. https://doi.org/10.11988/ckyyb.20160692
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    Seepage model of base soil-filter system which takes into account the coupling of solid and fluid was established in association with the built-in FISH programming language of PFC3D software. Piping-typed soils of continuous gradation and discontinuous gradation were simulated in the presence of various coefficients between layers. The variations of porosity, permeability, loss fraction of base soil filter material, as well as the interface between the two with seepage duration were traced and recorded, and then the water-retaining performance and permeability of the base soil-filter system were evaluated. Results show that there is an optimal range for the coefficient between layers (D15/d85*) of different piping-typed soils in the base soil-filter system. When values of the coefficient between layers are in the range , permeability of the infiltration system gradually increases along seepage direction, displaying good performances of conserving soil and permeability. Furthermore, base soil of continuous gradation has better filtration ability and a wide range of the optimal coefficient between layers, whereas the optimal range for soil of discontinuous gradation is narrow.
  • Analysis of Shear Strength of Sand-soil Reinforced with FiberBased on Response Surface Methodology
    SUN Hao,FENG Wen-quan,MA Fu-quan,LI Xiang,HE Yu-long,HAN Chun-peng
    Journal of Changjiang River Scientific Research Institute. 2017, 34(4): 98-103. https://doi.org/10.11988/ckyyb.20160068
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    In order to study the influence of fiber content on the shear strength of sand-soil, we carried out direct shear tests on sand-soil reinforced with fiber of different fiber lengths, sand contents and fiber contents, and determined the levels of influential factors through single factor experiment. Furthermore, we employed response surface methodology to establish the regression equation of cohesion and analyzed the variance, and then verified the optimization scheme of response surface analysis. Results show that 1) fiber content has insignificant influence on internal friction angle of sand-soil reinforced with fiber, but has obvious influence on cohesion; 2) data simulated by the cohesion model are significantly correlated with test data, and the difference of lack of fit is not significant, indicating that the model is reliable; 3) the effect of sand content on cohesion is very significant, while the effects of fiber content and fiber length on cohesion is relatively significant, and insignificant, respectively; 4) the cohesion obtained from verification test shows little difference with the theoretical predicted value, which suggest that response surface methodology for theoretical analysis accords with the actual cohesion.
  • Exploring Mesoscopic Deformation Mechanism of Sand in Direct ShearTest by Numerical Simulation Using Discrete Element Method
    LI Shuang, LIU Yang, WU Ke-jia
    Journal of Changjiang River Scientific Research Institute. 2017, 34(4): 104-110. https://doi.org/10.11988/ckyyb.20151006
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    Direct shear test of sand was simulated using discrete element method and the macro-and-mesoscopic responses of sand during shearing were analyzed in this research. The development of sand deformation was observed through strip partition method; and the relationship between shear stress and shear displacement was recorded to analyze the macroscopic behaviors of sand. In mesoscopic scale, the development of contact status was researched through analyzing contact force chain, contact fabric distribution, coordination number and sliding contact percentage; the evolution of granular distribution under shearing was observed through the analysis of porosity variation;
  • Applicability of Heat Transfer Model of Energy Pile with BuriedSpiral Pipe and Its Experimental Verification
    ZHAO Hai-feng,GUI Shu-qiang,TANG Rong-bin,DU Jin-long
    Journal of Changjiang River Scientific Research Institute. 2017, 34(4): 111-116. https://doi.org/10.11988/ckyyb.20160098
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    Accuracy of heat transfer model is directly related to the computational accuracy of heat transfer efficiency of energy pile, which influences the design of energy piles. Taken energy pile with buried spiral pipe as the research object, an in-situ test was conducted in Xinyang area, Henan province. Then, measured data such as temperature field around the pile was acquired, and calculation results of the cylindrical heat source model and the coil heat source model are respectively compared with measured data. Research results show that the computational accuracy of heat source model with finite length is higher than that of heat source model with infinite length. Coil heat source model with finite length is more accurate than cylindrical surface heat source model with finite length. The calculation error of tube wall temperature in coil heat source model with finite length is less than 1.5%, the calculation error of temperature field around the pile is less than 2.5%, and the water temperature at inlet and outlet of buried pipe less than 2.2%, respectively. In view of this, coil heat source model with finite length is recommended for calculating temperature field in energy pile with spiral buried tube. The applicability of different heat transfer models for the spiral pipe pile was explored, and can be taken as reference for the design of energy pile with buried spiral tube.
  • Formation Mechanism of Landslide in the Reservoir Area ofa Hydropower Station of the Yellow River
    WANG Yun-nan, REN Guang-ming, QIU Jun
    Journal of Changjiang River Scientific Research Institute. 2017, 34(4): 117-121. https://doi.org/10.11988/ckyyb.20151048
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    Toppling-deformation is usually found in anti-dip bedded slopes. But recent engineering investigations revealed that toppling-deformation mode could also appear in steep dip bedding slope. Analyzing the formation mechanism is of importance for the correct assessment of slope stability. In this article, the landslide III# on the right bank of a hydropower station in the Yellow River Basin was researched by means of numerical simulation and qualitative analysis based on geological surveys. The process of landslide formation was displayed by UDEC (Universal Distinct Element Code). Results indicated that the failure process of the landslide could be divided into three stages rock mass unloading, toppling deformation, and sliding-tension fracture. The result obtained from finite element method consists with that from discrete element method, which proves that the conclusion is rational.
  • Influence of Rainfall Infiltration on Slope Stability at Shallow Layer
    WANG Yi-zhao, SUI Yao-hua
    Journal of Changjiang River Scientific Research Institute. 2017, 34(4): 122-125. https://doi.org/10.11988/ckyyb.20160107
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    In the aim of investigating the influence of rainfall infiltration on slope stability at shallow surface, the permeability coefficient and pore water pressure of slip surface of shallow layer in rainy period and non-rainy period were analyzed based on unsaturated seepage theory. The rule of slope stability variation in shallow layer was also researched. Results showed that in rainy period pore water pressure at slope toe increased to saturation, and at slope top increased until approaching saturation. After rainfall stopped, the decline margin of pore water pressure at slope top was larger than that at slope toe. In the early stage of rainfall, the stability of slip surfaces decreased continuously, and in the later stage of rainfall the safety factor of slip surface at slope top tended to convergence; whereas the safety factor at slope toe kept decreasing.After rainfall stopped, the safety factors of slip surfaces in shallow layer all increased; while the safety factor of deep layer fluctuated.
  • Numerical Study of Effect of Roots Morphology onShallow Stability of Slope
    CHEN Chao,ZHANG Jun-yun,ZHAO Xiao-li,GAO Sheng-jun,MING Ming
    Journal of Changjiang River Scientific Research Institute. 2017, 34(4): 126-130. https://doi.org/10.11988/ckyyb.20160025
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    In the aim of investigating the anchorage effect of roots of different morphology when functioned as “live nail” within the slope, numerical calculation and analysis was carried out in association with strength reduction method. The influences of number and tiller angle of lateral roots on shallow stability of slope were analyzed. Results of numerical calculation show that vegetation roots have obvious reinforcement effect on shallow slope. Roots could improve the stress state of slope body and control the displacement variable. Safety factors of slope gradually improved with the increases of the number and tiller angles of lateral roots displaying a trend of progressive failure that bulging deformation gradually occurred on the central section and vertical upheaval deformation appeared on the toe area with no reinforcement.
    • HYDRAULIC STRUCTURE AND MATERIAL
  • Curing Kinetics of CW Epoxy Resin Grouting Material
    LI Jia-xiang, WEI Tao, WANG Zai-qin
    Journal of Changjiang River Scientific Research Institute. 2017, 34(4): 131-135. https://doi.org/10.11988/ckyyb.20160066
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    CW epoxy resin grouting material has been widely used in water conservancy projects such as Three Gorges Project, Gezhouba Project and Danjiangkou Project. At present, there are few studies on its curing kinetics. In this article, experiments were carried out to study the process of curing reaction of CW epoxy resin grouting material by using non isothermal DSC(Differential Scanning Calorimetry). The DSC curves at five different heating rates(5, 10, 15, 20, 25 K/min) were obtained. According to Kissinger function and Crane function, the apparent activation energy Ea, apparent frequency factor A and reaction order n of CW epoxy resin grouting material were obtained, and the n-tier curing kinetic model was established. The model can be used to predict and analyze the curing reaction characteristics of CW epoxy resin grouting material, and could guide the theoretical researches and engineering practice of the modification of grouting material combined with test data.
  • Influence of Sand’s Fineness Modulus on Slurry Strength ofBackfill Grouting
    MU Xin,CHEN Xi-kun, CHEN Hong-xiang
    Journal of Changjiang River Scientific Research Institute. 2017, 34(4): 136-139. https://doi.org/10.11988/ckyyb.20160135
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    Backfill grouting is a critical step in the process of shield tunneling construction. In order to explore the development of slurry strength, we obtained sands of three different fineness modulus(1.652,1.096,0.773) by using different sieving methods and prepared inert slurry and rigid slurry by using the sands. Through setting time test, direct shear test and cubic compressive test, we observed the effect of fineness modulus of sand on the setting time and strength of inert slurry and rigid slurry. Results show that strengths of the two slurries decrease with the increasing of fineness modulus of sand. Moreover, cement hydration in rigid slurry mainly promotes the increase of cohesion and the decrease of internal friction; while the action of fly ash in inert slurry can be ignored.
  • Experimental Study on the Triaxial Test of the Shield BackfillGrouting Material at Initial Stage
    CHEN Xi-kun, ZHU Wei, WANG Rui
    Journal of Changjiang River Scientific Research Institute. 2017, 34(4): 140-143. https://doi.org/10.11988/ckyyb.20150494
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    Deformation and mechanical properties of backfill grouting material directly affect soil stress release, ground subsidence and late stress situation of segment lining. Based on triaxial test method of non-independent material, we take the rigid slurry and inert slurry as research objects, carrying out consolidated non-drained triaxial shear test. Results show that, 1) high confining pressure contributes to the consolidation and drainage of the slurry, and the ultimate volumetric strain of the slurry increase with confining pressure; 2) in the shearing process on the non-drained condition, slurry shows tendency of strain hardening, and the volume shrinks first, then with obvious shear dilatation. On the premise of deformation and construction requirements, we can suitably increase grouting pressure and use slurry with smaller water-glue ratio to ensure the construction quality of grouting body.
    • INFORMATION TECHNOLOGY APPLICATION
  • Information Extraction and Dynamic Changes ofWetland in Jiangsu Coastal Area Based on RS and GIS
    ZHANG Jian, HE Qi-sheng, CUI Tong, SHI Peng-fei, YANG Tao
    Journal of Changjiang River Scientific Research Institute. 2017, 34(4): 144-150. https://doi.org/10.11988/ckyyb.20160051
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    Mastering the distribution and dynamic change characteristics of wetland could provide scientific basis for better protection of wetland. In this research we processed the remote sensing data of Jiangsu coastal wetlands in 1999, 2002, 2012 and employed maximum likelihood method to extract wetland information. On this basis we investigated the dynamic change of coastal wetland and analyzed the driving factors. Results showed that the total area of wetland in Jiangsu coastal area presented a declining trend. The proportion of artificial wetlands increased by 22.43%, and the proportion of natural wetlands decreased, accordingly. In addition, natural wetland presented a tendency that communities of Aeluropus littoralis and Artemisia halodendron reduced greatly, and Spartina experienced the process from widespread diffusion to relative stabilization. During the process of transfer, the biggest transfer-in area was artificial breeding pond, while the biggest transfer-out ratio changed from barren wetland to shallow waters. The main driving factor of coastal wetland change was the influence of human activities.
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Journal Information
Founded: 1984
Publication Frequency: Monthly
Governing Body: Changjiang Water Resources Commission, Ministry of Water Resources
Sponsor: Changjiang River Scientific Research Institute, Changjiang Water Resources Commission
ISSN 1001-5485
CN 42-1171/TV
Postal Distribution Code: 38-147
Subscription: Available at post offices nationwide
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