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Numerical Calculation of Flow Field at Blind Tee-junction and Influencing Factors of Local Resistance Coefficient WU Sen-lin, WANG Qiu-liang, GAN Du-fen, LI En, WANG Yi-fan, LIU Yun Journal of Yangtze River Scientific Research Institute    2023, 40 (9): 85-92.   DOI: 10.11988/ckyyb.20220526 Abstract （74）      PDF（pc） （12828KB）（534）       Knowledge map    Save Blind tee, as an essential component in pipeline networks for transmission and distribution systems, plays a crucial role in ensuring stable pipeline operation. In this study, a model was established using Solidworks 2019 and Fluent to perform three-dimensional flow field calculations. The local resistance coefficient of the blind tee was analyzed by combining orthogonal analysis tests and SPSS software analysis. Empirical formulas were derived to explain the influence of each factor on local resistance coefficient. An optimal runner structure model was developed. The results indicate that the local resistance loss coefficient (ζ) decreases quadratically with increasing Reynolds number (Re) and branch pipe diameter (d), and increases quadratically with increasing included angle (θ) of the branch pipe. Furthermore, ζ decreases linearly with increasing blind end length (L3). Through multivariate nonlinear regression, a correlation formula for the local resistance coefficient of the blind tee was derived. The fluid velocity near the right wall of branch pipe increases, and the distribution of turbulent kinetic energy at the bifurcation and branch pipe becomes more pronounced. Within the simulated range, the influence of each factor on ζ can be ranked as follows: Reynolds number > included angle > branch pipe diameter > blind end length. The smallest combination of local resistance loss coefficient was observed when the Reynolds number was 6.4×105, the included angle was π/6, the branch pipe diameter was 0.9D, and the blind end length was 4.0D. The research findings provide a theoretical basis for blind tee structure design and engineering applications. Reference | Related Articles | Metrics | Comments（0）

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Historical Channel Evolution of Zhenjiang-Yangzhou Reach in Lower Yangtze River QU Geng, HAO Jie-yu Journal of Yangtze River Scientific Research Institute    2023, 40 (9): 1-7.   DOI: 10.11988/ckyyb.20230546 Abstract （118）      PDF（pc） （6184KB）（479）       Knowledge map    Save As a typical bifurcating channel in the tidal reach of the lower Yangtze River(also known as the Changjiang River), the Zhenjiang-Yangzhou Reach has experienced long-term complicated evolution. By examining historical documents, ancient maps, modern topographic mapping, and hydrological data, we analyzed the long-term evolution of the Zhenjiang-Yangzhou Reach. According to our findings, prior to the Western Han Dynasty, the Zhenjiang-Yangzhou Reach served as the mouth of the Changjiang River. Sediment gradually accumulated in the ancient estuary, giving rise to the development of a sandbar along the north bank. The river channel generally shifted in a southerly direction, resulting in decreased river width. The sediment deposition eventually stabilized, forming the Shiye sandbar branching channel and the Hechang sandbar branching channel. Throughout history, hydraulic power and sediment transport characteristics played a key role in shaping and transforming the river. River nodes located on both the north and south banks played an essential role in controlling the river’s flow regime. Since the 1950s, the channel morphology of Zhenjiang-Yangzhou Reach has been in a relatively stable state. However, recent developments have shown adjustments in the flow regime within the branching channel. Human activities, such as the construction of various projects in the river, have become important external factors influencing the evolution of the riverbed. Reference | Related Articles | Metrics | Comments（0）

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Experimental Study on the Strength of Cemented Soil in Baishan Navigation Lock of Yangtze-Huaihe Water Diversion Project WANG Zhi-yong, DU Guang-yin, ZHANG Ding-wen, SONG Tao, YANG Yong Journal of Yangtze River Scientific Research Institute    2023, 40 (6): 147-153.   DOI: 10.11988/ckyyb.20211403 Abstract （104）      PDF（pc） （1482KB）（450）       Knowledge map    Save Intelligent bidirectional cement-soil mixing technology has been applied in the Baishan navigation lock of the Yangtze-Huaihe water diversion project. To investigate the strength variation of the cemented soil in the Baishan navigation lock and assess the effectiveness of the new technology, we prepared cemented soil specimens with varying shapes, cement ratios, and curing ages. These specimens underwent unconfined compressive strength tests and triaxial unconsolidated and undrained tests, allowing us to obtain the stress-strain relationship, compressive strength, and shear strength parameters. The results of the laboratory tests indicate that the stress-strain relationship of the cemented soil exhibits strain softening behavior. The unconfined compressive strength increases with the growth of cement ratio and curing age, showing an approximate linear correlation with the logarithm of curing age. Under the same conditions, 90-d age cylindrical specimens display a strength approximately 13% higher than cubic specimens. The ratio of deformation modulus to unconfined compressive strength ranges from 55.6 to 96.2 and is significantly influenced by the age of the specimens. Cohesion and unconfined compressive strength can be described as approximate linear growth relationship, and the internal friction angle ranges from 22° to 33°. The in-situ core samples exhibit a strength exceeding 70% of that of laboratory cemented soil, demonstrating that the strength ratio expression helps compensate for the strength discrepancy between laboratory and in-situ cemented soil. Scanning electron microscope (SEM) results also unveil the mechanism behind the strength growth of cemented soil from a micro perspective. Reference | Related Articles | Metrics | Comments（0）

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Application of Bankruptcy Theory to Basin Water Resources Allocation under the Scenario of Supply and Demand Change SUN Dong-ying, YU Meng-ling, MA Jian-feng, WANG Hui-min Journal of Yangtze River Scientific Research Institute    2023, 40 (9): 17-23.   DOI: 10.11988/ckyyb.20220642 Abstract （75）      PDF（pc） （6773KB）（447）       Knowledge map    Save Amidst population growth and rapid economic development, the demand for water resources is continuously increasing. However, the uncertain water demand and total supply caused by environmental changes have led to an intensified mismatch between water supply and demand. In view of this, the bankruptcy theory was applied to water resources allocation at basin scale. Four bankruptcy theory rules - the proportional rule (PRO), constrained equal awards rule (CEA), constrained equal losses (CEL), and adjusted proportional rule (AP) - are employed to address water allocation problems in the basin under various supply and demand scenarios. The stability of the bankruptcy criteria was evaluated. Additionally, the Fallback bargaining method was utilized to select consistent and satisfactory results. The findings indicate that the AP rule exhibits the best stability in all scenarios, followed by the PRO rule. The application of Fallback bargaining demonstrates that the results obtained by the PRO rule achieve unanimous satisfaction. In view of the disparity between the two rules, the PRO rule is considered to yield satisfactory result. Based on these findings, an analytical framework that combines the bankruptcy criterion and Fallback bargaining was established to offer a scientific decision-making basis for water resources management in changing basin environments. Reference | Related Articles | Metrics | Comments（0）

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Experimental Study on Jet Trajectories and Scour Regularities of Narrow Slit-bucket in Asymmetrical River XU Li-zhe, YUAN Hao, HE Xiao-long Journal of Yangtze River Scientific Research Institute    2023, 40 (9): 93-97.   DOI: 10.11988/ckyyb.20220488 Abstract （56）      PDF（pc） （8489KB）（438）       Knowledge map    Save The jet trajectory and scour characteristics of a narrow slit-bucket with different shrinkage ratios in an asymmetric river channel were examined via model test of a hydropower station. The findings demonstrate that the shrinkage ratio of the narrow slit-bucket significantly influences the morphology of the scour pit. As the shrinkage ratio decreases, the sidewalls of the bucket constrict the water flow, while the jet disperses more effectively in the air, thus increasing energy dissipation, and consequently resulting in a decrease in scour pit depth and an increase in scour extent. For asymmetric riverbeds, the scour depth amplifies with an increasing β value at a given flow rate. However, the lateral spread of scour notably reduces. Furthermore, a comparative analysis was conducted to calculate the jet trajectory. The results reveal that the calculation result of Chen Zhongru’s formula agrees well with test values when shrinkage ratio (β) is greater than 0.2. When β=0.2, the modified formula from the hydraulic calculation manual proves to be a better choice for calculating the jet trajectory. Reference | Related Articles | Metrics | Comments（0）

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Influence of Fracture and Heavy Rainfall Infiltration on Seepage Field and Stability of Accumulation Landslide FU Jing, AI Kai, SHI Hua-tang, GAO Yang-yang, TAN Hai, WU Yong-jin Journal of Yangtze River Scientific Research Institute    2023, 40 (9): 112-117.   DOI: 10.11988/ckyyb.20220564 Abstract （80）      PDF（pc） （10466KB）（431）       Knowledge map    Save Rainfall infiltration temporarily increases water pressure in the unsaturated area above the groundwater level of a landslide, reduces matrix suction, and weakens the shear strength of the slope. Meanwhile, cracks in the landslide facilitate rapid rainwater infiltration. During rainy season, intense rainfall accumulates and forms a transient water source in areas with more developed cracks in the slope. Continuous recharge results in high pore dynamic water pressure, leading to a rise in the groundwater level of deep landslide. This transient movement of groundwater and the associated additional water load become controlling factors for slope instability during rainy season. In this study we focus on large-scale accumulation landslides. Based on the saturated-unsaturated seepage theory of soil mass, we examined the influence of transient water sources formed by heavy rainfall at the end of cracks in the slope on the seepage field and groundwater level of landslide using finite difference method. We evaluated the adverse effect of transient water supply on the stability of the landslide by using the strength reduction method. The research findings provide a scientific basis for landslide prevention and the design of drainage treatment. Reference | Related Articles | Metrics | Comments（0）

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Effects of Herb Root Type and Distribution on Unconfined Compressive Strength of Root-Soil Composites LIU Xiang-feng, ZHANG Qiang, HAO Guo-liang, WANG Yi-teng, SUN Ying-cong, WANG Lai-gui Journal of Yangtze River Scientific Research Institute    2023, 40 (9): 106-111.   DOI: 10.11988/ckyyb.20220407 Abstract （54）      PDF（pc） （6269KB）（429）       Knowledge map    Save To investigate the impact of herb root type and distribution on the unconfined compressive strength of root-soil composites, the root distribution characteristics of cluster-root Viola philippica, tiller-root Ixeris polycephala, and rhizome-root Triglochin Palustre within different soil depths were determined using an image pixel conversion algorithm. Stress-strain curves of the three herb-root-soil composites were obtained through unconfined compressive tests. The relationship between root parameters and cohesion increment of the failure surface of the root-soil composites was examined by quantifying the compressive strength. Results indicated that within the 0-8 cm soil depth range, the root length density (RLD), root surface area density (RASD), and root area ratio (RAR) of Viola philippica and Triglochin Palustre gradually decreased with increasing soil depth, while Ixeris polycephala displayed an increasing trend followed by a subsequent decrease. Quantitative root distribution parameters of Viola philippica ranks first, followed by Triglochin palustre and Ixeris polycephala in sequence. Rhizome-root Triglochin palustre exhibited the highest ability to improve soil compressive strength, with the cohesion increment of its root-soil composite being 1.42 and 2.6 times those of Viola philippica and Ixeris polycephala, respectively. Triglochin palustre has the largest RLD, RASD and RAR of the failure surface, followed by Viola philippica and Ixeris polycephala in sequence. No correlation was observed between root parameters and cohesion increment of the failure surface of Ixeris polycephala. For cluster-root and rhizome-root herbs, RAR has larger correlation with cohesion increment than RLD and RASD do. Therefore, RAR can serve as an important predictor of soil compressive strength improvement for cluster and rhizome root types. Reference | Related Articles | Metrics | Comments（0）

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Extracting the Dynamic Change of Lake Area in the Three-River Headwaters Region Based on Google Earth Engine QI Chang-xian, REN Yan, PENG Hai-yue, WEI Jia-hua, WANG Yong-qiang, LI Qiong Journal of Yangtze River Scientific Research Institute    2023, 40 (7): 179-185.   DOI: 10.11988/ckyyb.20220806 Abstract （305）      PDF（pc） （8885KB）（425）       Knowledge map    Save Based on Google Earth Engine (GEE) remote sensing cloud computing platform and Landsat TM, ETM+ and OLI satellite image data, a comprehensive water body identification algorithm with multiple indices such as Modified Normalized Difference Water Index (MNDWI), Normalized Difference Vegetation Index (NDVI) and Enhanced Vegetation Index (EVI) was used to extract the area of lakes larger than 1 km2 in the Three-River Headwaters region (source region of the Yangtze River, the Yellow River, and the Lancang River) from 1990 to 2020. In association with meteorological, glacier cataloguing and permafrost distribution data, the changes of lake area along with their influencing factors were analyzed. The findings of the study reveal a 15% increase in the overall lake surface area from 10 811.8 km2 to 12 449.53 km2, with 46 new lakes in the Three Rivers area since 1990. Specifically, the increase in lake area differed across sources, with more visible changes observed in the Yangtze River source area (29%) compared to the Yellow River source area (10%). Rising average temperature and increased precipitation were identified as the primary factors behind the increase in lake area. Specifically, increasing temperature caused glacier retreat and permafrost degradation, resulting in a faster increase in the area of glacier-replenished lakes and lakes located in permafrost areas. Precipitation was more closely related to the increase of lake area in the Yellow River source area. Reference | Related Articles | Metrics | Comments（0）

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Influence of Dynamic Load on Stability of Deep Foundation Pit Excavation with Micro-piles WANG Chun-jing, BU Yi-ming, WANG Jin-xing, LIANG Bin Journal of Yangtze River Scientific Research Institute    2023, 40 (9): 139-146.   DOI: 10.11988/ckyyb.20220334 Abstract （64）      PDF（pc） （9277KB）（420）       Knowledge map    Save To investigate the impact of dynamic loading on the stability of adjacent bridges with micro-pile deep foundation pits, this study focuses primarily on the Ubisa-Shorapani (F3) section of Georgia E60 Expressway, which is a significant project contributing to China’s “Belt and Road” initiative. Numerical simulation is employed to analyze the effects of train loads on the foundation pit soil as well as the internal forces and deformation of the supporting structure. The results obtained from the numerical calculations are then compared with the data collected from on-site monitoring. The findings reveal that under the influence of train loads, the maximum displacement of pile near the train side and the maximum settlement of the soil increase by approximately 14.5% and 20%, respectively. Moreover, the overall safety factor of the foundation pit decreases by 0.1. Therefore, it is crucial to fully consider the impact of train loads on the stability of the foundation pit during the excavation process. The initial support is particularly affected by different loading modes, and the range of change in axial force for each support gradually decreases as the excavation progresses from top to bottom. When the train load is positioned 5 m away from the boundary of the foundation pit, the settlement of the soil near the train side is 3.61 mm greater compared to a load distance of 20 m. At a load distance of 20 m, soil settlement experiences minimal influence from the train load, resulting in improved stability of the foundation pit. The dynamic load exerted by the train greatly affects the internal forces of the neighboring pile. The magnitude of bending moment and the depth at which the maximum bending moment occurs increase gradually as the load distance decreases. Specifically, when the dynamic load speed is set at 120 km/h and the distance is 5 m, the pile experiences significant load-induced effects. The bending moment increases by 210 kN·m, and the depth at which the maximum bending moment occurs rises compared to the scenario without train load. Reference | Related Articles | Metrics | Comments（0）

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Inversion of Water Quality Parameters in Jianghan Plain Based on Sentinel2-L1C Image ZOU Zhi-ke, YU Lei, ZHANG Yu, WANG Wen-juan, ZHAO Yong-li, SUN Jian-dong, CHENG Qing-lei Journal of Yangtze River Scientific Research Institute    2023, 40 (9): 181-187.   DOI: 10.11988/ckyyb.20220515 Abstract （88）      PDF（pc） （7650KB）（412）       Knowledge map    Save Remote sensing technology has emerged as a powerful tool for monitoring inland water quality. To investigate changes in concentrations of total phosphorus (TP), total nitrogen (TN), and chemical oxygen demand (COD) in the aquaculture area of Jianghan Plain, we developed inversion models utilizing Sentinel2-L1C remote sensing data. These models are based on three optical active substances: water transparency, suspended matter concentration, and Chl-a concentration. By correlating the calculated water transparency, suspended solids concentration, and Chl-a concentration with TP, TN, and COD concentrations at regional water fitting points, we established indirect inversion models to estimate the concentrations of these substances and validated the models using fitting points data. Our results demonstrate a strong correlation between water transparency and TP concentration. Higher water transparency indicates better water quality and lower TP concentration. The concentration of suspended matter in water is highly correlated with the TN concentration. Increased suspended matter concentration indicates inferior water quality and higher TN concentration. Additionally, higher water Chl-a concentration corresponds to higher COD. The deterministic coefficients of the indirect fitting models for TP concentration, TN concentration, and COD were all greater than 0.6. Furthermore, the TP concentration, TN concentration, and COD concentration in water bodies of monitoring points in Jianghan Plain were simulated. The results align with the expected patterns in feeding period and reflect the spatio-temporal evolution of water quality parameters in the aquaculture areas of Jianghan Plain. This research contributes practical insights into understanding the dynamics of large-scale water quality parameters in aquaculture areas. Reference | Related Articles | Metrics | Comments（0）

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Regularities of Particle Gradation Change Before and After Soft Rock Fill Tests SUN Xiang-jun, PAN Jia-jun, DING Li-hong, ZHOU Yue-feng, LU Yi-wei, ZUO Yong-zhen Journal of Yangtze River Scientific Research Institute    2023, 40 (9): 133-138.   DOI: 10.11988/ckyyb.20220355 Abstract （67）      PDF（pc） （3552KB）（411）       Knowledge map    Save To investigate the variation law of particle grading in soft rock fill before and after testing, a series of large-scale experiments were conducted on soft rock fill in the construction of two reservoir dams. Quantitative analysis was performed using the Marsal particle crushing rate and grading equation parameters. Results are as follows: 1) In the compaction tests, the Marsal particle crushing rate reaches its maximum value near the optimum moisture content. 2) With increasing confining pressure, the Marsal particle crushing rate increases in the triaxial tests. However, such rate increase becomes less significant when a specific confining pressure is reached. 3) The Marsal particle crushing rate in super-large-scale compaction tests is higher than that in large-scale compaction tests. The rate of Marsal particle crushing after wetting and creep tests is lower than that in saturated triaxial tests. The Marsal particle crushing rate in large-scale lateral compression tests is also lower than that in triaxial tests. 4) Parameters of the grading equation show a monotonic change before and after the tests, tending to converge to a specific value. These research findings provide a scientific basis for optimizing the grading design. Reference | Related Articles | Metrics | Comments（0）

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Measurement and Influencing Factors of Green Efficiency of Water Resources in Urban Agglomerations in Middle Yangtze River XIAO Yi, CI Xiao-hu, YANG Bing, ZHANG Li-ping, XIA Jun Journal of Yangtze River Scientific Research Institute    2023, 40 (9): 8-16.   DOI: 10.11988/ckyyb.20230206 Abstract （87）      PDF（pc） （7927KB）（409）       Knowledge map    Save The high-quality development of the Yangtze River Economic Belt constitutes a crucial strategy tied to overall national growth. Ensuring ecological priority and green development necessitates addressing the fundamental issue of improving the green efficiency of water resources in urban agglomerations. This study introduces the concept of “green development” into traditional research on water resources utilization efficiency. A comprehensive indicator system for evaluating the green efficiency of water resources is constructed. The super-efficiency EBM-DEA (Epsilon-Based Measure - Data Envelopment Analysis) model and panel Tobit model were employed to calculate and analyze the green efficiency of water resources in urban agglomerations in the middle Yangtze River. The findings reveal: 1) Changes in GDP have a significant impact on the economic efficiency of water resources, and the measurement results for the environmental efficiency and green efficiency of water resources are more reflective of actual conditions. From 2009 to 2020, comparisons among various city clusters reveal that the green efficiency of water resources in the Wuhan city cluster consistently outperformed that of the Poyang Lake urban agglomeration and Changsha-Zhuzhou-Xiangtan urban agglomeration. 2) Cities with thriving economies also exhibit high values of water resource utilization efficiency. Areas with abundant water resources in urban agglomerations in the middle Yangtze River demonstrate slightly lower water use efficiency than areas with scarce water resources. Rapid urbanization exerts a restraining effect on green efficiency of water resource, underscoring the need for urban agglomerations in the middle Yangtze River to adhere to a green and new type of urbanization development path. Reference | Related Articles | Metrics | Comments（0）

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Experimental Study on Physical and Mechanical Properties of a Frost Susceptible Silty Clay in Freezing Processs HU Kun, GAO Zhao-guo, WANG Shao-wei, YANG Zhao, WU Yan Journal of Yangtze River Scientific Research Institute    2023, 40 (8): 127-132.   DOI: 10.11988/ckyyb.20220313 Abstract （64）      PDF（pc） （6209KB）（407）       Knowledge map    Save To address the issue of foundation stability in construction engineering in cold regions, an experimental study was conducted to investigate the physical and mechanical properties of a frost susceptible silty clay in freezing process. Parameters such as the critical water content for frost heaving, frost heave forces, and shear strength of warm frozen soils were determined. The results indicate that frost shrinkage occurs when the water content of soil samples is below the critical water content for frost heaving. This phenomenon is attributed to the combined effect of frost shrinkage of the soil skeleton and phase transformation of pore water. The vertical displacement curves of soil samples exhibit three types with varying water content: frost shrinkage, frost shrinkage followed by rebound, and frost shrinkage followed by frost heave. The curve of frost heave forces can be divided into two stages, namely rapid growth and stable growth, due to the development of the temperature field. The frost heave force increases as the freezing temperature decreases. The increase in temperature gradient within the active zone of freezing soils, based on the theory of segregation potential, is the cause of higher frost heave forces. When compared to soil samples at normal temperature, the cohesion of frozen silty clay at -3℃ increased from 7.34 kPa to 29.56 kPa, and the internal friction angle increased from 6.40° to 9.18°. However, the shear stress curves did not exhibit brittle failure of frozen soils, but rather displayed characteristics of strain hardening. Reference | Related Articles | Metrics | Comments（0）

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Effect of PVA Fiber Mixed with Nano-SiO2 on Fatigue Resistance of Concrete and Its Microscopic Mechanism KONG Zheng-yu, LU Jing-zhou, WANG Jian-wei, WANG Wei-liang, HAN Wen-yu, XIAO Ying Journal of Yangtze River Scientific Research Institute    2023, 40 (9): 170-175.   DOI: 10.11988/ckyyb.20220356 Abstract （64）      PDF（pc） （7819KB）（405）       Knowledge map    Save This paper presents an experiment aimed at investigating the influence of blending PVA fiber and nano-SiO2 on the fatigue resistance of concrete.The experimental specimens are divided into three groups: blending PVA fiber only (Group P),nano-SiO2 only (Group S),and PVA fiber mixed with nano-SiO2 (Group SP).Uniaxial compression tests were performed on the specimens subjected to multiple-cycle fatigue loading, and the resulting data were used to assess their fatigue resistance.The relative dymanic elastic modulus and compressive strength of specimens after the tests were taken as the assessment indices.Additionally,SEM was employed to observe and analyze the microscopic action mechanism.The findings reveal that all three concrete groups exhibit a notable improvement in fatigue resistance compared to ordinary concrete,although the manner of improvement differs.Group S demonstrates the most notable enhancement in concrete strength, while group SP effectively suppresses the development of internal degradation in concrete. In terms of the underlying mechanisms,PVA fibers enhance the tensile capacity between concrete elements,effectively reducing damage and failure under fatigue loads, thereby prolonging the concrete’s failure process.Nano SiO2 participates in the reaction to generate C-S-H (calcium silicate hydrate) gel,filling the weak areas of the concrete and improving its compressive strength,thus raising the starting point of failure under fatigue loads.These findings provide valuable insights for the design of fatigue-resistant concrete structures. Reference | Related Articles | Metrics | Comments（0）

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Quantitative Analysis of Flood Peak Attenuation Capacity of the Three Gorges Reservoir Facing Historical Floods WANG Suo-ping, MA Yi-yang, ZHU Di, YAO Hua-ming, WANG Xian-xun Journal of Yangtze River Scientific Research Institute    2023, 40 (9): 73-77.   DOI: 10.11988/ckyyb.20220545 Abstract （67）      PDF（pc） （5285KB）（403）       Knowledge map    Save To quantify the peak-cutting of flood control storage capacity of the Three Gorges Reservoir (TGR), an optimization-fitting framework was employed to calculate the historical storage flood data. Various maximum water level schemes during scheduling were set at first, and a dynamic planning algorithm within the framework was utilized to optimize and solve different incoming floods. By doing so, the flood peak reduction curves under different flood control storage capacities were obtained. Furthermore, regression analysis was employed to quantify the peak-cutting of flood control storage capacity of TGR. Results demonstrate that the correlation between the utilization of the flood control storage capacity in TGR and the reduction of flood peak flow can be classified into three types: “flat curve following an increment”, “segmented increment”, and “linear increment”. The first two types exhibit inflection points, suggesting that the flood control storage capacity should be maintained below a specific threshold to fully maximize its efficient peak-cutting capacity. As for the third type, the flood control storage capacity can be planned rationally for dispatching in line with the flood peak reduction target. The findings provide valuable insights for the scientific and rational allocation of flood control storage capacity in the Three Gorges Reservoir. Reference | Related Articles | Metrics | Comments（0）

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Spatio-temporal Evolution of Net Primary Productivity in Beijing-Tianjin-Hebei Region Based on MOD17A3 Data GUO Hao, YUAN Jin-guo, WANG Jing-zhi, WANG Xiao-xin, LI Yan-cui, LIU Bo-han Journal of Yangtze River Scientific Research Institute    2023, 40 (7): 66-72.   DOI: 10.11988/ckyyb.20220164 Abstract （107）      PDF（pc） （34617KB）（398）       Knowledge map    Save This study explores the spatio-temporal changes in vegetation net primary productivity (NPP) across the Beijing-Tianjin-Hebei region based on MOD17A3 data. Univariate linear regression method was employed to analyze the temporal and spatial evolution of vegetation NPP in 20 years (2000-2019). Additionally, this study analyzed the correlation between NPP and climate factors. The results show that vegetation NPP in the Beijing-Tianjin-Hebei region mainly falls within the range of 200-400 gC/(m2·a). The mean and maximum values of NPP exhibited gradual increase from 2000 to 2019, with a peak in both mean and maximum values occurring in 2016 at 385.10 gC/(m2·a) and 908.40 gC/(m2·a), respectively. The area with significantly increased NPP in the region from 2000 to 2019 was found to account for 97.12% of the study area, while the area with NPP decrease mainly occurring in areas surrounding urban centers. Furthermore, the four types of vegetation cover in the region ranking from smallest to largest in terms of NPP mean were as follows: cropland, shrub, grassland, and forest. The study also found that from 2000 to 2019, the stability of NPP in the region was characterized by high-low fluctuations, with lower fluctuations being dominant. Finally, NPP was found to be lowly correlated with the average annual temperature and highly correlated with annual precipitation. The findings can serve as reference for ecological civilization construction, ecological environmental restoration, and management and protection in Beijing-Tianjin-Hebei region. Reference | Related Articles | Metrics | Comments（0）

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Numerical Study on Influence of Hydraulic Lifting Dam Group on Variation of Channel Erosion and Deposition in the Erba-Yitang Segment of Fenhe River ZHANG Xiao-ya, REN Chun-ping, YANG Fan Journal of Yangtze River Scientific Research Institute    2023, 40 (8): 16-23.   DOI: 10.11988/ckyyb.20220501 Abstract （104）      PDF（pc） （10056KB）（396）       Knowledge map    Save Building continuous hydraulic lifting dams in small and medium-sized rivers will affect the hydrodynamics and sediment erosion and deposition process of the river. The variation characteristics of river erosion and deposition resulting from different combined operation schemes of hydraulic lifting dams also differ. To address this issue, four typical flood processes were selected for a 2D numerical simulation of water and sediment dynamics in Fenhe River (Erba-Yitang segment) using Delft3D FM model. Under the four operation schemes of hydraulic lifting dam group, the influence of hydraulic lifting dam group on the variation characteristics of erosion and deposition of river channel was analyzed. The findings provide valuable insights for the scheduling of hydraulic lifting dam groups in the midstream of Fenhe River. Results reveal that, under the schemes 1-4 in four flood scenarios, the water depth in front of dam 14# ranges from approximately 0.5 to 1.4 m, 1.3 to 2.8 m, 0.6 to 1.8 m, and 0.5 to 1.6 m, respectively, at the end of the simulation period. The maximum local velocity behind the dam is approximately 1.5-2.5 m/s, 2.0-6.0 m/s, 2.0-3.0 m/s, and 2.0-2.5 m/s, respectively. The range of erosion and deposition is approximately -0.5 to 1.4 m, -0.3 to 1.9 m, -0.5 to 1.6 m, and -0.5 to 1.5 m, respectively. The total amount of sediment deposition in the river reaches approximately 4.9×104 to 242.3×104 m3, 5.3×104 to 323.5×104 m3, 5.0×104 to 252.5×104 m3, and 4.95×104 to 245.1×104 m3, respectively. The conclusions are as follows: hydraulic lifting dams exhibit the greatest influence on the hydrodynamic field and the change in bed elevation when operating at full capacity. Moreover, the sediment deposition volumes of hydraulic lifting dams are approximately 1.08 to 1.36 times that of non-dam operation under the four flood scenarios. Reference | Related Articles | Metrics | Comments（0）

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Application of Partially-closed Impervious Curtain to Foundation Pit Dewatering YAN Bo, TAI Jun, HU Ke, XU Wei, HAN Shuai Journal of Yangtze River Scientific Research Institute    2023, 40 (9): 98-105.   DOI: 10.11988/ckyyb.20220477 Abstract （67）      PDF（pc） （18427KB）（396）       Knowledge map    Save Numerical simulation is employed to analyze the groundwater control effect of super-large deep foundation pit dewatering using partially suspended impervious curtains and partially closed impervious curtains. The influence of different rates of closed impervious curtain (Rc) on the dewatering process and its impact on adjacent subway tunnels are investigated. The findings reveal a gradual decrease in the influence of dewatering on the surroundings at a given Rc as the insertion ratio (L/M) of the suspended impervious curtain increases, with a distinct turning point. Therefore, an economical and reasonable insertion ratio can be determined based on the descending depth variations of the pressure water head. L/M exhibits minimal influence on the water pumping capacity (q) per unit area. In contrast, Rc significantly affects q, showing a good linear correlation when Rc ranges from 0% to 80%. A comparison between calculated results and field monitoring data indicates a notable difference in water head between the inside and outside of a foundation pit, favoring the closed impervious curtain side over the suspended impervious curtain side. Consequently, partially closed impervious curtains prove effective in controlling groundwater seepage in sensitive surrounding areas. Furthermore, deformation calculation results of subway tunnels under different values of Rc could help determine the minimum Rc required to meet deformation requirements. Therefore, partially closed impervious curtains can be employed flexibly in the impervious curtain design for large foundation pits depending on the sensitivity of the surroundings. Reference | Related Articles | Metrics | Comments（0）

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Constructing a Compensation and Balancing Mechanism for Natural Ecological Space Occupation in Hubei Province JIA Bao-jie, ZENG Wen-hao, ZHANG Ya-quan, MENG Han-long, HUANG Zhuo, CHEN Jin Journal of Yangtze River Scientific Research Institute    2023, 40 (9): 68-72.   DOI: 10.11988/ckyyb.20220582 Abstract （74）      PDF（pc） （4817KB）（396）       Knowledge map    Save Constructing a compensation system for the occupation of natural ecological space is an important approach to address the imbalance between economic and social development and environmental protection. First, the current status and issues related to natural ecological occupation compensation, the characteristics of natural ecological space, and the classification of occupation behavior were analyzed. Subsequently, three modes of compensating natural ecological space occupation were proposed: in-situ compensation, off-site compensation, and financial compensation. Furthermore, the paths and procedures for the compensation were outlined within the policy system of Hubei Province. Differentiated compensation schemes should be selected based on different occupation behaviors. Control measures should be applied at four levels: avoidance, minimization, restoration, and compensation. Additionally, ecological expropriation and replenishment repository, monitoring and information sharing system, and public participation mechanism are recommended to ensure a smooth compensation. Reference | Related Articles | Metrics | Comments（0）

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Inverse Analysis of Arch Dam Thermal Parameters Based on Cross-Global Artificial Bee Colony Algorithm MAO Da-wei, ZHANG Ao, WANG Feng, ZHOU Yi-hong, TAN Tian-long Journal of Yangtze River Scientific Research Institute    2023, 40 (9): 162-169.   DOI: 10.11988/ckyyb.20220456 Abstract （62）      PDF（pc） （6364KB）（396）       Knowledge map    Save Affected by factors such as ambient temperature, cooling water, and surface insulation, the actual thermal parameters of arch dam during construction differ remarkably from laboratory test results. Based on temperature data obtained by using distributed optical fiber sensor, we employed the cross-global artificial bee colony (CGABC) algorithm determine the concrete thermal parameters of Baihetan double-curvature arch dam and capture their real-time variations. To address the slow convergence and susceptibility to local optimals encountered by traditional artificial bee colony (ABC) algorithm in obtaining the optimal function value, we developed the CGABC which integrates the concept of global optimal solutions from particle swarm optimization (PSO) and the cross-operation strategy of genetic algorithm (GA). By considering the influence of multi-stage cooling water and environmental temperature, we employed CGABC for the inversion of concrete thermal parameters of Baihetan arch dam. The inversion results demonstrate a favorable agreement between CGABC-calculated values and measured temperatures. In conclusion, CGABC exhibits excellent adaptability in the thermal parameter inversion of arch dams. Reference | Related Articles | Metrics | Comments（0）