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01 February 2023, Volume 40 Issue 2
    

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    SPECIAL CONTRIBUTION
  • LI Jia-zheng
    Journal of Changjiang River Scientific Research Institute. 2023, 40(2): 1-6. https://doi.org/10.11988/ckyyb.20220228
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    Engineered Cementitious Composite (ECC) was first designed and proposed by Professor Li of the University of Michigan in the 1990s, and has been widely used in industrial and civil construction in recent years. Changjiang River Scientific Research Institute proposed the concept of Hydraulic Engineered Cementitious Composites (HECC) which is suitable for hydraulic construction.According to the functional requirements of different hydraulic structures, HECC should have the properties of mixtures and molding methods designed on demand, medium strength,low elastic modulus,elongation designed on demand,strong thermal stability,high durability,controllable crack widths and a wider choice of raw materials. On this basis, HECC is proposed to be applied in hydraulic structures such as the new dam foundation gallery of rockfill dams, the new anti-seepage face slabs of face-rockfill dams, the new core wall structures of rockfill dams, and the anti-seismic and anti-cracking structures of the foundation constraint area of arch dams. In addition, the future research direction of HECC is prospected.
  • RIVER LAKE PROTECTION AND REGULATION
  • LIU Zhao-xi, WANG Jun, ZHOU Yin-jun, CHEN Si-han, JIN Zhong-wu, CHEN Peng
    Journal of Changjiang River Scientific Research Institute. 2023, 40(2): 7-13. https://doi.org/10.11988/ckyyb.20210968
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    The characteristics of bank collapse of Jingjiang Reach and the physical and mechanical properties of cohesive soil in the upper part of the riverbank are studied based on field investigation, indoor geotechnical test and collapse model test in different hydrological periods for three consecutive years. The characteristics and influencing factors of the bank collapse process of composite structure are also examined. Results reveal that bank collapses occurred more frequently in lower Jingjiang Reach than those in the upper reach, and on left bank more than those on the right bank. The composite structure of riverbank undergone a process generalized as follows: the slope toe becomes steeper due to scouring, cracks occur and develop on bank top, the bank slope is eroded progressively, and bank instability leads to collapse, then the bank slope shape tends to be stable, and finally enters the next collapse cycle. The moisture content of cohesive soil responds more quickly to water level change than that to soaking time. The incipient shear stress of cohesive soil is 0.531 N/m2, and the critical moisture content affecting the cohesion value is about 16%. Affected by longitudinal flow and soil moisture content, the bank slope is of high stability in dry season, but is subjected to local collapse during water level rising; both the flood season and recession stage will see intense slope toe scouring and bank collapse.
  • CHEN Yi-ming, LI Yi, QU Geng, LUAN Hua-long, YIN Da-cong
    Journal of Changjiang River Scientific Research Institute. 2023, 40(2): 14-18. https://doi.org/10.11988/ckyyb.20211044
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    Local scour depth of bridge pier is an important parameter in bridge design. The empirical calculation formula of local scour depth for large-sized piers is prone to generate big errors. In view of this, we established an empirical formula of local scour depth of bridge pier in sandy river under the principle of unified dimension, and further modified the formula considering the influence of abutment exposed on bed surface on the scour. Comparison with Chinese and American calculation specifications verified that the formula proposed in this paper is of higher precision, uniform dimension and comprehensive consideration of factors. It is suitable for calculating local scour depth of large piers.
  • WATER RESOURCES
  • BAO Xin-ru, ZHANG Xing-nan, ZHANG Wen-ting, XU Yang, ZHANG Zeng-xin
    Journal of Changjiang River Scientific Research Institute. 2023, 40(2): 19-26. https://doi.org/10.11988/ckyyb.20211048
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    The characteristics and evolution trend of water use structure in the Yangtze River Economic Belt are analyzed according to the changes in water consumption of eleven provinces (cities) from 2003 to 2020 by using theoretical methods of information entropy and equilibrium degree. The driving forces are also examined via principal component analysis. Results manifest that on the time scale, the total water consumption of the Yangtze River Economic Zone is on the rise. The proportion of agricultural and industrial water consumption has declined, while the proportion of domestic and ecological water consumption has increased; the information entropy and equilibrium degree of water use structure have both increased, and the water use system is more balanced. On the spatial scale, the water consumption system in the lower reach of the Yangtze River Economic Belt is the most balanced, followed by that in the upper reach and the middle reach in sequence. With the adjustment of agricultural structure, it is expected that the area of arable land in the Yangtze River Basin may shrink, and the amount of agricultural water consumption will not rise sharply, with its proportion continue to drop. It is expected that industrial water consumption may fall, and its proportion will still decrease; domestic water consumption will continue to increase. The major driving forces for the evolution of water use structure are total industrial production value, GDP, water-saving irrigation area, and water consumption per 10 000 yuan of GDP, together contributing 96.8% to the changes.
  • XIAO Xiao, QIU Xin-fa, XU Jin-qin
    Journal of Changjiang River Scientific Research Institute. 2023, 40(2): 27-33. https://doi.org/10.11988/ckyyb.20211079
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    High spatial resolution TerraClimate dataset is employed to analyze the characteristics of dry and wet climate change in China under the influences of geographical terrain and underlying surface. According to monthly precipitation and evapotranspiration data from 1960 to 2019 in the TerraClimate data set, the range of dry and wet areas, dry and wet climate boundaries and climate change trend in China are analyzed based on precipitation and humidity index. Compared with those in the first three decades, the area of arid and humid regions in the latter three decades showed negative increase, and the area of semi-arid and semi-humid regions positive increase. The dividing line fluctuated mainly in Heilongjiang province, central and northeast Inner Mongolia, and Huaihe River. In recent six decades, the precipitation and humidity index tended to increase in the west and southeast, indicating that the climate was getting wet, and vice versa. Comparison with meteorological data analysis manifests that the TerraClimate dataset is more applicable and well reflects the dry and wet conditions in China and their variation characteristics, and the applicability of precipitation data is more prominent.
  • ZHANG Hui, WANG Jing, FANG De-bin, WANG Yong-qiang
    Journal of Changjiang River Scientific Research Institute. 2023, 40(2): 34-43. https://doi.org/10.11988/ckyyb.20211007
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    During the allocation of initial water rights, the asymmetric information and different water use goals between basin governor and regional water users usually result to unreasonable allocation and inefficient utilization of water resources. To improve the allocation and utilization efficiency, we propose a framework for optimal allocation of initial water rights based on bankruptcy theory from the perspective of the basin governor. We take into consideration the demands of regional and industrial users, regional impact factors and industrial impact factors. Upon obtaining the initial optimization scheme in the first stage, we establish the supervision mechanism according to the reward and punishment rules in the second stage. We applied the model to the initial water rights allocation in typical basins, and investigated the implementation and effectiveness. Results demonstrate that the proposed model could improve the allocation efficiency of water resources on one hand, and restrain the behavior of over-users on the other. Hence, the model could support the reasonable allocation and efficient supervision of initial water rights. The research finding is conducive for watershed managers to rationally allocate and utilize water resources.
  • WANG Yuan, SU Bu-da, WANG Yan-jun, ZHAN Ming-jin, YANG Chen-hui, JIANG Tong
    Journal of Changjiang River Scientific Research Institute. 2023, 40(2): 44-51. https://doi.org/10.11988/ckyyb.20211201
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    In line with the carbon peaking and carbon neutrality, known as the dual-carbon goal of China, we divided SSP-RCPs into the dual-carbon scenario (SSP1-1.9, SSP1-2.6, SSP2-4.5, SSP4-3.4, and SSP4-6.0) and the high-carbon scenario (SSP3-7.0, and SSP5-8.5). In the aim of offering suggestions for basin water resources management under the scenario of dual-carbon goal, we analyzed the streamflow change in Fuhe River Basin (FRB) in the near-term (2021-2040), mid-term (2041-2060) and end-term (2081-2100) in the 21st century by using SWAT hydrological model. Results demonstrate that: 1) From 1961 to 2019, the annual average temperature climbed markedly at a rate of 0.18 ℃/(10 a), while the annual precipitation dropped significantly at -32.8 mm/(10 a). 2) Under the dual-carbon scenario, the increment of annual average temperature in the FRB is projected to intensify with the passing of time compared with that in base period (1995-2014). Annual average discharge is projected to fluctuate upwardly; monthly average discharge is expected to increase from September to next February but a decline from March to July. The extreme high discharge is expected to increase while extreme low discharge decline, indicating the alleviation of hydrological extremes. 3) In high-carbon scenario, the annual average temperature is estimated to rise more significantly than that in the double-carbon scenario; but the annual precipitation would fall in the near-term and the end-term. The increment of annual average discharge is projected to be greater than that in double-carbon scenario with average temperature rising more sharply from May to October. In addition, extreme high discharges in all three periods are projected to increase.
  • WATER ENVIRONMENT AND WATER ECOLOGY
  • JING Zheng, ZHANG Jue-hong, CAO Hui-qun, CHEN Hao, TANG Xian-qiang, LUO Hui-ping
    Journal of Changjiang River Scientific Research Institute. 2023, 40(2): 52-59. https://doi.org/10.11988/ckyyb.20211026
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    Changes in the spatial and temporal distribution of reservoir water temperature pose a significant impact on the environment and aquatic ecosystem in the reservoir area and its downstream rivers. We first made a review on the history of reservoir water temperature research in China and abroad, and introduced the methods of researching reservoir water temperature and discriminating the structure of reservoir water temperature. In particular, we expounded the latest developments and frontier progress of mechanism-based models and intelligent algorithm models for reservoir water temperature, and summarized the latest research findings in stratification characteristics and eco-environmental impacts of water temperature as well as improvement measures. Furthermore, we put forward some key research directions in future: the rules of water and heat transfer between reservoir and river, the flow-temperature coupling calculation based on non-static pressure, and the ecological scheduling of layered water withdrawal to improve downstream water temperature.
  • LIU Ye, WANG Cun-shi, WU Shao-kai, SHEN Wen-tao, XU Jian-bo, BAI Wang-jun, ZHU Jian-zhong
    Journal of Changjiang River Scientific Research Institute. 2023, 40(2): 60-66. https://doi.org/10.11988/ckyyb.20210960
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    The aim of this research is to verify the effectiveness of electrokinetic remediation technology in removing heavy metal pollution. The adsorption characteristics and the diffusion and migration of Cd2+ in sediments under electric field were studied by using the low-pressure DC sediment disturbance simulation device. Results manifested that the saturated adsorption of Cd2+ by silt under electric field increased from 0.438 mg/g to 0.498 mg/g. XRD analysis of sediment confirmed that the change of mineral crystal led to the decrease of Zeta potential and the enhancement of adsorption capacity. The migration of Cd2+ to solid phase and electrode network increased at 30 V voltage, and the Cd2+ atom content in cathode electrode network increased from 0.05% to 0.19% mainly due to the electrocoagulation of Cd2+ in liquid phase. In addition, the adsorption and electrochemical reaction of Cd2+ can be accelerated under the condition of disturbance.
  • AGRICULTURAL WATER CONSERVANCY
  • CAO Yong-qiang, YANG Xue-ting, ZHOU Shu-han
    Journal of Changjiang River Scientific Research Institute. 2023, 40(2): 67-74. https://doi.org/10.11988/ckyyb.20210993
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    In the aim of enhancing the efficiency of utilizing water resources in agriculture, we studied the spatial and temporal evolution of water footprint of summer maize in Hebei Province as well as the factors affecting the change of water footprint based on meteorological data from 17 meteorological stations and related agricultural data in Hebei Province from 2002 to 2018. Results revealed that in the study period, the water footprint of summer maize production in Hebei Province declined in a fluctuating mode, averaging 759.03 m3/t annually. By comparing the spatial evolution characteristics of green water footprint and blue water footprint of summer maize in Hebei Province among the year 2002 (low flow), 2003 (normal flow), and 2013 (high flow), we found that the green water footprint in different periods remained approximately the same level, while the blue water footprint differed significantly. Correlation analysis of 13 factors also suggest that the water footprint of summer maize is positively correlated with evapotranspiration and effective irrigation area; but significantly negatively corrlated with the total output value of summer maize.
  • HYDRAULICS
  • GUO Hui, YU Si-han, CHEN Wen, HUANG Ming-hai, CHEN Duan
    Journal of Changjiang River Scientific Research Institute. 2023, 40(2): 75-80. https://doi.org/10.11988/ckyyb.20210868
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    The aim of this study is to investigate the influence of rock type on dynamic radial-flow sedimentation of high concentration wastewater produced from processing aggregate system for hydropower project.On the basis of the scaling law for high concentration wastewater,a large-scale physical model of the radial-flow sedimentation tank of Baihetan Hydropower Project was established as a prototype to elucidate the effect of basalt and limestone on dynamic radial-flow sedimentation characteristics.Experiment results manifested that combined addition of PAM and PAC could improve the settling and thickening effect of wastewater with the removal rate of suspended substance in treated water exceeding 99%.For basalt wastewater,higher velocity was observed in the middle layer of radial-flow sedimentation tank,and solid particles presented linear sedimentation along water depth;for limestone wastewater,higher velocity was observed in the bottom layer of radial-flow sedimentation tank,and solid particles settled rapidly along water depth in the first phase,and then gradually concentrated in the bottom layer.Compared with limestone wastewater,basalt wastewater is of inferior natural sedimentation performance,posing higher control requirement for sludge discharge rate during radial-flow sedimentation.The research findings offer technical support for green construction of hydropower projects.
  • ROCK SOIL ENGINEERING
  • WANG Gui-lin, YANG Zheng-qin, ZHANG Liang, SUN Fan
    Journal of Changjiang River Scientific Research Institute. 2023, 40(2): 81-86. https://doi.org/10.11988/ckyyb.20210929
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    Dry-wet cycles cause irreversible cumulative damage to rocks,and the deformation and failure process of rock is accompanied by obvious acoustic characteristics.In order to explore the deformation and failure mechanism of jointed sandstone after dry-wet cycles,we monitored the acoustic data of damage and failure of jointed sandstone specimens under indoor uniaxial compression test by acoustic emission (AE),and further examined the evolution characteristics of acoustic emission parameters of intact single-jointed and double-jointed sandstone specimens in the deformation and failure process after different dry-wet cycles (0,1,5,10,15 and 20 cycles).Results elucidated that with the proceeding of dry-wet cycles,the post-peak plastic characteristics of sandstone rock specimens gradually increased,and the AE activities undergone weak,enhanced,steep increase,and intense stages;the duration of violent phase of acoustic emission,the decrease of cumulative ringing count,and the b value of AE in the process of deformation and failure gradually increased.The b values of AE of intact rock samples at any dry-wet cycle were larger than those of jointed rock specimens.The research findings offer reference for researching the deformation and failure mechanism of jointed rockmass under dry-wet cycles.
  • SONG Jia, BAI Yang, WANG Xiao-lin
    Journal of Changjiang River Scientific Research Institute. 2023, 40(2): 87-94. https://doi.org/10.11988/ckyyb.20210908
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    The aim of this study is to investigate the changes in the microstructure of loess under dry-wet cycles.The gray-scale image texture features of Xi’an loess were extracted based on the gray-level co-occurrence matrix,and the area of cracks and pores in the loess was calculated based on the percentage of the area of cracks and pores.The relationship between the gray-scale texture characteristics and the proportion of cracks and pore areas was established through the deep learning time-series regression prediction model,and the damage degree of loess under dry-wet cycles was determined by calculating the damage factor.Our study revealed that within two dry-wet cycles,the edge structure of soil aggregates was destroyed,and cracks and pores increased sharply;within five dry-wet cycles,the texturing trend of soil structure became more obvious,approaching the direction of parallel water migration;after four times of dry-wet cycle,the damage ratio of loess under dry-wet cycle reached 93.10%;after six dry-wet cycles,the damage no longer increased,which means that the microstructure texturing of the loess stabilized.
  • CHEN Guang-yao, WANG Ming-wu, JIN Ju-liang
    Journal of Changjiang River Scientific Research Institute. 2023, 40(2): 95-101. https://doi.org/10.11988/ckyyb.20210026
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    Since slope instability may cause huge economic losses and casualties, a rational and effective model for slope stability evaluation is of vital significance to disaster prevention. Considering multiple uncertainties of slope stability evaluation, we propose a slope stability evaluation model coupling fruit fly optimization algorithm (FOA), normal cloud model (CM), and support vector machine (SVM). The normal CM is used to optimize the FOA by describing the randomness and fuzziness in the foraging process of drosophila. The CM-based FOA, namely, CMFOA, is used to optimize the parameters of SVM classification model. The reliability of the proposed CMFOA-based SVM model is verified with a case study and comparisons with GA-SVM, PSO-SVM, and Grid Search-SVM. Results demonstrated that the proposed model is effective and feasible in slope stability evaluation. The accuracy and efficiency of parameter selection for classification using the CMFOA-SVM model are better than those of other models. It also overcomes the shortcoming of local optimal capability in traditional FOA and provides a new reference for other similar classification problems.
  • YANG Xiao-feng, LI Wei, YAO Zhao-ming
    Journal of Changjiang River Scientific Research Institute. 2023, 40(2): 102-108. https://doi.org/10.11988/ckyyb.20210980
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    As pile foundation is usually deeply buried underground,the horizontal deformation of pile-soil is not easy to be observed in field tests. Model test of a single pile subjected to lateral load on pile head was carried out in sandy soil by using Particle Image Velocimetry (PIV) to study the deformation mechanism of soil-pile under lateral loads. Factors such as bending stiffness of pile, relative density of soil, and size of scour pit were taken into consideration in the model test. The soil displacement and strain around the pile were obtained, and the horizontal pile-soil interaction modes of a flexible pile and a rigid pile were discussed. The influence of local scour on lateral pile-soil interaction were also examined. Results demonstrate that: 1) the displacement and shear strain of soil around the pile gradually develop along the horizontal direction and depth direction; therefore, the assumption that the soil strain in the strain wedge developes evenly in the strain wedge model for analyzing laterally loaded pile needs to be modified. 2) Pile-soil interactions were observed mainly in the passive compressed area of soil in front of pile and the active pressurizing area of soil behind pile above the first zero-point of lateral displacement of pile body, while those below the first zero-point for a laterally loaded rigid short pile shall not be ignored. 3) Scoured soil layer above the bottom of the scour pit still plays a due role in reducing the lateral deformation of the pile-soil system.
  • DONG Jia-xing, ZHANG Sheng-wei, CHENG Juan, YANG Run-xue, MI Jian, ZHAO Yong-chuan, HUANG Xin-ping, SHEN Zhen-luo
    Journal of Changjiang River Scientific Research Institute. 2023, 40(2): 109-114. https://doi.org/10.11988/ckyyb.20221009
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    Sandy dolomite stratum is widely distributed in the water conveyance tunnel of Yuxi segment of the Central Yunnan Water Diversion Project. Geological disasters such as collapse, water inrush and sand gushing often occur in the tunnels built in this stratum, which seriously affect construction safety. It is of great significance to scientifically and reasonably classify the level of dolomite sandification for disaster prevention and control in the construction process. In this paper, a hierarchical structure model consisting 12 indexes that accurately describe the degree of dolomite sandification is established by using the Fuzzy AHP method. The level of dolomite sandification is divided into slight sandification, weak sandification (lower section and upper section), strong sandification (lower section and upper section), as well as severe sandification. The upstream segment of Xiaopu 2# main tunnel is selected for model establishment and sandification level division. Results demonstrate that the method accomplishes the classification of dolomite sandification level by both qualitative and quantitative approaches, and the classification results are basically consistent with the current situation of the project.
  • HE Qi, CHEN Shi-wan, YANG Fu-bo, TIAN Yun-lei
    Journal of Changjiang River Scientific Research Institute. 2023, 40(2): 115-123. https://doi.org/10.11988/ckyyb.20210927
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    Brazilian splitting tests were conducted on Beishan granite (the potential host rock for China’s high-level radioactive waste repository) at different temperatures (25 ℃,60 ℃,90 ℃,120 ℃,200 ℃,and 300 ℃).The cracking process of granites was investigated using acoustic emission (AE),section analysis and particle flow code (PFC).Results reveal that:1) Temperature at 120℃ has a significant strengthening effect on granite,while the strength of granite at other temperatures is lower than that at 25 ℃.2) The AE data shows that the number and size of cracks in granite both increase with rising temperature in mild temperature range (60 ℃~120 ℃),which consumes more energy produced by loading and gradually improves the strength of granite.(3) Affected by the differences in thermodynamic properties of feldspar,quartz and mica,cracks of granite tend to propagate along the boundary of feldspar with the increase of temperature between 25 ℃ and 120 ℃.When temperature is higher than 120 ℃,the proportion of cracks at the boundary of non-feldspar particles begins to rise.(4) PFC2D model was established based on the distribution of minerals on granite surface,and the simulation suggest that temperature could reduce the bond strength between mineral particles and makes the rock more prone to fracture.
  • ENGINEERING SAFETY AND DISASTER PREVENTION
  • ZOU Hao, HE Fei, BAI Jun-long
    Journal of Changjiang River Scientific Research Institute. 2023, 40(2): 124-130. https://doi.org/10.11988/ckyyb.20210841
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    Huanggang City is located in a low mountainous and hilly area subjected to frequent small-scale landslide disasters. Rainfall is a major external cause of such landslide disasters. Analyzing the contributions of influencing factors to the number of rainfall-induced landslides and the relation between landslide and rainfall is of vital significance for the disaster prevention and mitigation in Huanggang. According to observation data of 238 meteorological stations in Huanggang from 2011 to 2020 together with landslide disaster data, the regional distribution of rainfall-induced landslide in Huanggang was examined. The contribution rates of monthly average rainfall, engineering rock formation, and slope gradient to the number of rainfall-induced landslides were obtained, and on such basis, the rainfall-induced landslides in the area were classified as highly susceptible, moderately susceptible, and lowly susceptible. Moreover, the reference values of rainfall corresponding to three levels, namely, forecast, early warning, and alarm were given with daily average rainfall in critical period and daily average rainfall in previous period as the rainfall threshold judgment criteria. The research findings offer basic data and scientific basis for the prevention and control of regional landslide disasters.
  • HYDRAULIC STRUCTURE AND MATERIAL
  • ZHU Yu-liang, LIN Ming-ze, CHEN Lei, JIANG Chao-hua, SUN Jian-wei
    Journal of Changjiang River Scientific Research Institute. 2023, 40(2): 131-135. https://doi.org/10.11988/ckyyb.20210971
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    To explore an effective way of utilizing fine dredged sand as a replacement of ordinary concrete, cement-based material was prepared by using fine dredged sand with fineness modulus of 0.1-0.3 from the downstream of the Changjiang River as the main raw material. Dredged sand with varied mud content (6.5%-25.8%) was made into cement-based materials by adopting vibration and semi-dry pressing methods, respectively. In the vibration case, the increment of mud content has an adverse impact on the durability and mechanical properties of the tested material. The 28-day compressive strength and splitting tensile strength of cement-based materials with low mud content (6.5%) reached 35.1 MPa and 3.98 MPa, respectively, and the abrasion resistance strength and mass loss rate amounted to 12.5 h/(kg/m2) and 8.4%, respectively. In the semi-dry pressing case, however, the rising of mud content is conducive to the material strength. The 28-day compressive strength and splitting tensile strength of prepared materials with high mud content (25.8%) reached 37.0 MPa and 4.4 MPa, respectively, up by 36.5% and 25.7% respectively compared with those prepared by vibration method. Moreover, preparing cement-based material with vibration or semi-dry pressing molding techniques using dredged sand is environmental-friendly and of notable ecological effect by cutting the costs by 33.0%-40.5% compared with that using ordinary C30 concrete.
  • ZENG Guo-hua, XIAO Cheng-jing
    Journal of Changjiang River Scientific Research Institute. 2023, 40(2): 136-140. https://doi.org/10.11988/ckyyb.20221179
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    The rock mass under the impervious wall of Nianpanshan Water Conservancy and Hydropower Project is moderately permeable red sandstone containing argillaceous siltstone, siltstone, medium coarse sandstone, and gravel-containing medium coarse sandstone (K2P3-1), etc. As the rock mass absorbs a small amount of slurry, cement grouting has unsatisfactory result with the water permeability after grouting still over 10 Lu. To tackle this problem, according to previous engineering experiences, we adopted acrylic chemical grouting and carried out indoor pressurized and pressureless groutability tests of rock samples and on-site chemical grouting tests. Test results demonstrate that the CW520 acrylate grouting material has good groutability for the red sandstone curtain. When the grout gelling time of the acrylate grouting material is controlled within 35-45 min and the unit grout consumption is 80 kg/m, the anti-seepage requirements of project design can be met, the grouting amount can be effectively controlled, and the project cost can be cut. The research findings have been applied to the design and construction of anti-seepage curtain grouting for the main works of Nianpanshan Water Conservancy and Hydropower Project.
  • DONG Fu-qi, ZHANG Fu-qiang, FU Shu-lin
    Journal of Changjiang River Scientific Research Institute. 2023, 40(2): 141-146. https://doi.org/10.11988/ckyyb.20210919
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    In this paper,the mechanical properties of the new steel aqueduct structure with steel truss beam-arch composite system across the canal are evaluated by means of numerical calculation and field test.The studied 110-metre steel aqueduct of Pihe River main canal of the Hanjiang-Weihe River Water Diversion Project has the largest span in the world.First,the strain and deformation of the key sections of the steel aqueduct structure under super varying water load are monitored through field water filling test,and the static performance of the structure is analyzed and evaluated by comparing the monitoring data with the numerical calculation results.Second,the natural vibration frequency of the structure under different water levels is tested by field pulsation test,and later compared with the numerical analytical results.The dynamic performance of the structure is also analyzed and evaluated.The results of water filling test demonstrate that the new steel aqueduct of Pihe main canal is in safe condition and the bearing capacity meets the design requirements.The research results could serve as a technical reference for similar projects.
  • HUANG Da-guan, NIU Di-tao, LIU Yun-he, SU Li, XIA Qian
    Journal of Changjiang River Scientific Research Institute. 2023, 40(2): 147-152. https://doi.org/10.11988/ckyyb.20211046
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    The mechanical properties, permeability and pore structure of basalt-polypropylene fiber reinforced concrete with varied fiber content were studied.Results reveal that in the range of 0-0.2% volumetric content of fiber,as fiber content grows, the compressive strength improves first and then declines;compressive strength increases by 9.2%,reaching the maximum, when the volumetric content of basalt fiber and polypropylene fiber is 0.05%. The splitting tensile strength increases with the addition of fiber,and the improvement effect of basalt fiber is better than that of polypropylene fiber. Both basalt fiber and polypropylene fiber can effectively reduce the impermeability of concrete,but would have an adverse impact on the impermeability of concrete once exceeding the optimum dosage. In addition,the fractal dimension of basalt-polypropylene fiber reinforced concrete was calculated.The fractal dimension has a good positive correlation with compressive strength and a good negative correlation with electric flux.
  • WATER CONSERVANCY INFORMATIZATION
  • CAO Yue-qi, LIN Li, PAN Xiong , DONG Lei
    Journal of Changjiang River Scientific Research Institute. 2023, 40(2): 153-160. https://doi.org/10.11988/ckyyb.20220298
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    With the core set of Web of Science and CNKI database as data source, we studied the status and emerging trends of freshwater microplastics research by using CiteSpace to examine the keywords cooccurrence, keywords clustering, highlight words, author cooperation and institutional cooperation based on literatures of microplastics in freshwater environment published from January 1, 2007 to July 24, 2021. The number of published papers in this regard has been on the rise over the past two years, mainly in China, the US, and Germany, attracting increasing concern. In terms of keywords cooccurrence and clustering, we found that the research directions both in China and abroad are similar in general; the distribution of microplastics in freshwater environment, the distribution of microplastics in sediments and the pollution characteristics, as well as the impact of microplastics on freshwater environment are of widespread concern. Analysis of keywords and highlight words reveals that the ecological risk of microplastics in freshwater environment, such as the impact on freshwater organisms is an emerging trend. In addition, nanoplastics is also a key research direction in the future.
  • SUN Wen-liang
    Journal of Changjiang River Scientific Research Institute. 2023, 40(2): 161-168. https://doi.org/10.11988/ckyyb.20210958
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    Traditional management systems for environmental conservation usually have defects such as backward data management mode, lack of multi-source dynamic association, and unsatisfactory visual effect. With digital control of environmental conservation for river basins as the target, we put forward the design idea of digital environmental management platform for river basin by systemically analysing problems we face. The fusion management and dynamic linking of data were realized through data classification storage, multi-source data cleaning and unified data encoding. On this basis, functions of the digital management of environmental conservation can be met by integrating Internet of Things (IOT) data collection, numerical simulation model and statistical analysis algorithm. Hence, environmental conservation of the basin can be displayed in three dimensions based on three-dimensional Geo-information System(3D-GIS) and Building Information Modeling (BIM) fusion technologies. The management platform was applied to the Yalong River Basin, and especially to the realtime monitoring and 3D query of data and operation scenes in the water intake facilities of Jinping-I hydropower station. The platform improved the operation efficiency of the water intake facilities and reduced the eco-environmental risks for the basin.
  • LIAO Guo-qing, ZHU Ye, WU Guang-dong, WANG Wen, LIU Yi, ZHU Ling-ling
    Journal of Changjiang River Scientific Research Institute. 2023, 40(2): 169-176. https://doi.org/10.11988/ckyyb.20220754
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    Using precipitation and temperature observations from national meteorological stations in China during 1961-2017, the weekly standardized Palmer drought severity index was proposed, and heat waves were recognized by using the relative high temperature threshold method. On this basis, the spatiotemporal evolution features of droughts and heat waves, as well as their concurrences were analyzed. Results reveal that: 1) droughts and heat waves occurred frequently in summer. The annual series of the percentage of meteorological stations under droughts and heat waves both indicated a downward tendency before 1995, and an upward tendency afterwards. 2) Heat waves took place much more frequently at most stations, and so did drought events in northeast and north China and east Yunnan Province. The freqency of heat waves changed abruptly in the 1980s and 1990s. Such changes presented a similar spatial pattern with droughts. 3) Yunnan suffered the most concurrent droughts and heat waves, followed by the northeastern region, the northern region, and coastal areas of Guangxi and Guangdong. In contrast, the Changjiang River basin and northern parts of Xinjiang experienced least concurrent events. 4) Among concurrent events, approximately 65% of heat waves occurred in the onset-development stage of droughts, whereas for Yunnan and southern parts of the Changjiang River basin, heat waves mostly occurred in the recovery stage of droughts. 5) Except for the Huaihe River basin and the middle and lower reaches of the Changjiang River, concurrent droughts and heat waves significantly increased for the majority of China.
  • FORUM OF CHANGJIANG RIVER PROTECTION AND INNOVATIVE DEVELOPMENT, THE 2022ANNUAL ACADEMIC MEETING OF CHANGJIANG TECHNOLOGY AND ECONOMIC SOCIETY
  • QU Geng, LU Jin-you, MA Yue-hua, YIN Da-cong, LEI Wen-tao, LUAN Hua-long, LI Meng-yu
    Journal of Changjiang River Scientific Research Institute. 2023, 40(2): 177-185. https://doi.org/10.11988/ckyyb.20221416
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    With the rapid development of social economy, strong human activities including the Three Gorges Project have had a great impact on the natural evolution of the lower Yangtze River, and further affected the river’s natural and social functions. In this research we establish an evaluation system containing fourteen indicators to represent the impact of river channel evolution on five major functions of river channel, namely, flood control, navigation, bank and shoal protection and utilization, water resources, and water ecological environment. In subsequence, we determine the weights of the indicators by integrating expert scoring method and AHP method, and formulated the quantification and scoring standards of each indicator. Application to the Shiye sandbar branch in the lower Yangtze River manifests that, after the impounding of the Three Gorges Project (2019), most indicators have improved to varying degrees compared with those before the impounding (2002). Yet, problems still exist. Such problems include the stability of river bank, the impact of water-involved project groups, and the reduction of aquatic biodiversity. The evaluation index system and conclusions of this paper is of popularization significance for the protection and governance of the Yangtze River.
  • LU Yang, WANG Yu-xuan, CAO Lei, ZHANG Qian-zhu, ZHAO Dong
    Journal of Changjiang River Scientific Research Institute. 2023, 40(2): 186-191. https://doi.org/10.11988/ckyyb.20221497
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    The aim of this research is to obtain the evolution characteristics of Chongqing segment of Wujiang River and its influence on navigation in recent years. On the basis of prototype observation of sediment from 2016 to 2020 together with the change of runoff and sediment characteristics, the characteristics of sediment erosion and deposition and the law of river evolution are analyzed. The research findings are presented as follows: 1) In addition to the main flood season, the water level fluctuation period of the Three Gorges Reservoir and the end of flood season see most sediment transport. 2) In Wulong Gorge segment in the upstream, the river bed showed a declining trend, while the estuary bed an upward trend, and the river channel slope in general a gentle trend. 3) The annual sediment scouring and silting in wide reaches changes more significantly than that in canyons. 4) Perennial backwater channel is subjected to inferior sand conditions, basically in siltation. 5) The erosion and deposition of river sediment in the upstream of the fluctuating backwater area is mainly controlled by river morphology. In conclusion, from the perspective of evolution trend, the current incoming water and sediment conditions are conducive to reducing river sediment deposition. The erosion and deposition in some critical dangerous shoal segments develops gently, the river regime is generally stable, and the river evolution has little impact on shipping.
  • LIU Gao-feng
    Journal of Changjiang River Scientific Research Institute. 2023, 40(2): 192-198. https://doi.org/10.11988/ckyyb.20221431
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    In the study of branching rivers, flow and sediment diversion ratio is an important factor. The flow and sediment diversion ratio at Fujiangsha river reach in the Yangtze River Estuary was calculated according to in-situ data from 2012 to 2019 by using a 3D tidal-sediment numerical model ECOM-Sed. Result demonstrate that runoff increase in the upstream or tidal range decrease in the downstream would both intensify the imbalance between flow and sediment diversion. The factor of such imbalance is positively correlated with the amount of dredging maintainance of navigation channel. It’s difficult for the 30% discharge in Fubei channel to convey about 40% sediment flux. Such impbalance would result in severe silting in Fubei navigation channel. To alleviate the silting, engineering measures such as lengthening or heightening of the three existing groins at Fujiangsha reach can be taken to reduce the imbalance.