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Modeling and Application of Optimal Water Supply Based on Coupling the Red Lines of Watershed’s and District’s Total Water Uses HUANG Cao, HE Si-zhong, FENG Di-zi, MU Long, LI Zhi-wei Journal of Yangtze River Scientific Research Institute    2022, 39 (6): 24-30.   DOI: 10.11988/ckyyb.20210168 Abstract （208）      PDF（pc） （1463KB）（1032）       Knowledge map    Save To refine the indicators of total water use and to optimize the water supply pattern for watershed-district coupling area, we built a water allocation optimization model with multiple water sources and multiple targets under the common constraints of the water usage red lines of watersheds and districts. We applied the model to Liuyang-Laodao River Basin to analyze the optimal scheme and the maximum volume of water supply from different water sources to different districts. Results reveal an excessive or insufficient water supply in Liuyang-Laodao River Basin in current years. The optimal water supply model compresses the water usage exceeding the red line in both normal and wet years and increases the water supply in both drought and extremely drought years. The water shortage rate of the Liuyang-Laodao River Basin in planning extremely drought years is 11.63% lower than that in current extremely drought years, which indicates that the optimal water supply model can optimize the patterns of water supply and determine the refined indicators of total water use in coupled watersheds and districts for years of different inflow frequencies. The results offer effective technical support for the monitoring of control process and the early warning of excessive total water usage. Reference | Related Articles | Metrics | Comments（0）

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Cause Analysis of Runoff Change in the Upper Reaches of Hutuo River Based on Time-varying Budyko-type Equation MIAO Zheng-wei, LU Mei, DING Zhi-hong Journal of Yangtze River Scientific Research Institute    2022, 39 (7): 29-35.   DOI: 10.11988/ckyyb.20210284 Abstract （614）      PDF（pc） （6930KB）（1017）       Knowledge map    Save The causes of runoff changes in the upper reaches of Hutuo River were analyzed to clarify the driving force of runoff evolution and furthermore to promote the sustainable utilization of water resources.Based on the one-parameter Budyko-type equation,the influencing factors of runoff are divided into two categories:aridity index and catchment properties.First,the time-varying Budyko-type equations were derived to describe the temporal variations in catchment properties via the time-varying parameters in the Budyko-type equations.In subsequence,the long-term trends in climatic variables were modeled using time as an explanatory variable.Finally,the impacts of aridity index and catchment properties on runoff were decomposed at annual scale and multi-year scale.The research results demonstrated that:(1) Time-varying Budyko-type equations improve remarkably the fitting capability for the upper reaches of Hutuo River basin.(2) In terms of quantifying the impacts between two periods of multiple years,the results based on the time-varying Budyko-type equations are similar to the Budyko-type equations with fixed parameter,implying that the time-varying Budyko-type equations proposed in this paper is reliable.(3) The contribution rate of aridity index decreased from 86.79% to 71.01%,while the contribution rate of catchment properties increased from 13.21% to 28.09%.Therefore,aridity index is the dominant factor of runoff reduction in the upper reaches of Hutuo River basin.(4) The apparent weakening of the influence of aridity index on annual runoff constitutes the major cause of increment in the contribution of catchment properties to the annual runoff change.In conclusion,the significant reduction of runoff in the upper reaches of Hutuo River is mainly caused by the change of aridity index,i.e.,precipitation and potential evapotranspiration. Reference | Related Articles | Metrics | Comments（0）

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Practices of Deep Excavation in Macau SAR Based on British Standard and the Standard of Hong Kong SAR XIE Wan-dong, LIN You-gao, WANG Zheng-liang Journal of Yangtze River Scientific Research Institute    2022, 39 (7): 126-130.   DOI: 10.11988/ckyyb.20210205 Abstract （259）      PDF（pc） （6450KB）（937）       Knowledge map    Save The standard system,design procedures,routine practices and other aspects of deep excavations design in Hong Kong SAR (Special Administrative Region) and Macau SAR of China and overseas regions are quite different from those in Mainland China. Based on the design practices of deep excavations in Barra Transportation Hub in Macau SAR,the design of deep excavation support in overseas projects is introduced in detail,including determination of the embedded depth of diaphragm wall,downward extension of diaphragm walls in hard rocks,strut system,structural calculation,verification of stability against overturning,etc. The stipulations of deep excavation design in British Standard and the standard of Hong Kong SAR are compared with those provided in the standards of Mainland China. During desk study,numerical modeling was adopted to calculate the force and deformation of bracing system of excavation; during construction,numerical method was also adopted for back analysis and predictions based on filed monitoring data,which guaranteed smooth construction. Reference | Related Articles | Metrics | Comments（0）

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Simulation on Water System Connected Dispatching under Multi-object Cooperation LIU Jin, HU Yong-hui, LIU Xia Journal of Yangtze River Scientific Research Institute    2022, 39 (6): 15-23.   DOI: 10.11988/ckyyb.20210248 Abstract （201）      PDF（pc） （2282KB）（929）       Knowledge map    Save The discharge of waste water and sewage in many cities in China continues to increase along with the rapid economic and social development, resulting in excessive pollutants in rivers and lakes and the deteriorating water ecological environment, which in turn hinders economic and social development. The basic theories and key technologies for water system connectivity in Zhongshun Protection Demonstration Site as a case study are studied in this paper with flood control and storage, agricultural water supply and water environment improvement as targets. Results demonstrate that: 1) with flood control and storage as major target, scheme 1 is the optimal with its average inrush capacity 100 000 m3 smaller than the current situation; 2) with agricultural water supply as major target, scheme 3 is the optimal solution with the water diversion volume increasing by 3.81 times; 3) with water quality improvement as major target, scheme 2 and scheme 3 are the optimal, with 90% of the overall water exchange period shortened by 58.17%. In addition, countermeasures and suggestions are put forward corresponding to the flood control and drainage safety in Zhongshun Protection, the water environmental problem brought about by urbanization, and the lack of unified dispatch and management of water conservancy projects. The research findings offer theoretical basis and technical support for the comprehensive improvement and restoration of Zhongshun Protection, water ecological protection and other projects. Reference | Related Articles | Metrics | Comments（0）

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Spatial and Temporal Characteristics of Water Resources in Qinghai-Tibet Plateau in Recent Two Decades ZHOU Si-ru, XIN Zhong-bao Journal of Yangtze River Scientific Research Institute    2022, 39 (6): 31-39.   DOI: 10.11988/ckyyb.20210212 Abstract （313）      PDF（pc） （3603KB）（928）       Knowledge map    Save The Qinghai-Tibet Plateau is renowned as the water tower of Asia and the third pole of the world. Changes in the water resources of the Qinghai-Tibet Plateau has a profound impact on the water resources security and people’s lives in China and its neighboring countries. The temporal and spatial changes of surface and groundwater resources in the Qinghai-Tibet Plateau from 1997 to 2018 are studied using linear tendency estimation, Mann-Kendall trend test and Pearson correlation coefficient method based on the data of Qinghai Water Resources Bulletin and Tibet Water Resources Bulletin. The results of the study indicate that: (1) water resources in the Qinghai-Tibet Plateau is extremely concentrated, mainly in Shannan, Nyingchi City, the Yarlung Zangbo River Basin and the river basins of southern Tibet. The south and east of Qinghai-Tibet Plateau boasts abundant water resources while the north and the west less. (2) From 1997 to 2018, the amount of surface water resources on the Qinghai-Tibet Plateau showed an insignificant upward trend, while the amount of groundwater resources (-16.64 billion m3/(10 a)) a significant downward trend. The change trends of water resources differed notably in spatial scale, with the surface water resources (9.83 billion m3/(10 a)) and groundwater resources (5.8 billion m3/(10 a)) in most areas of Qinghai Province in north Qinghai-Tibet Plateau displaying a significant upward trend, and surface water resources in most parts of the southern Tibet Autonomous Region an insignificant downward trend, groundwater resources a significant downward trend (-19.54 billion m3/(10 a)). (3) In recent years, the temperature in Qinghai-Tibet Plateau has had a very significant increasing trend, with the rising rate reaching 0.49 ℃/(10 a). The precipitation of Qinghai Province in the northern part of the Qinghai-Tibet Plateau showed a significant increase trend, while the southern part an insignificant downward trend. In conclusion, precipitation is the major factor that induces the changes of surface water resources and groundwater resources in the Qinghai-Tibet Plateau. Reference | Related Articles | Metrics | Comments（0）

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Numerical Simulation of the Force and Deformation Characteristics of Cantilever Retaining Structure with EPS Buffer in Expansive Soil WANG Xie-qun, KUANG Wen-zhuang, HAN Zhong, ZOU Wei-lie Journal of Yangtze River Scientific Research Institute    2022, 39 (7): 78-86.   DOI: 10.11988/ckyyb.20210166 Abstract （171）      PDF（pc） （7385KB）（917）       Knowledge map    Save The decompression effect of expanded polystyrene (EPS) buffer layer in cantilever retaining wall was examined when the expansive soil expands due to rainfall infiltration. The expansion characteristics of Nanyang expansive soil were tested to determine its expansion coefficient under lateral and vertical loads. On this basis, the expansive soil-EPS buffer layer-cantilever retaining wall system was numerically simulated using ABAQUS to explore the influences of EPS buffer layer (thickness, elastic modulus, and interface friction) on the stress and deformation of the system. Numerical results indicate that EPS buffer layer effectively reduces the lateral pressure on the cantilever retaining wall and changes the distribution of soil pressure on the wall back. The EPS buffer layer with larger thickness and lower elastic modulus has better effect. The friction between EPS buffer layer, wall and expansive soil affects the distribution of lateral pressure on the wall, but does not affect the resultant force of the lateral pressure. In addition, the compression stiffness of EPS buffer layer is inversely proportional to its load reduction performance. Reference | Related Articles | Metrics | Comments（0）

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Creep Constitutive Model of Cobbly Soil and Its Engineering Application LIU Jian, TANG Yang, YI Long, PENG Yuan-cheng, ZHOU Yue-feng Journal of Yangtze River Scientific Research Institute    2022, 39 (6): 107-112.   DOI: 10.11988/ckyyb.20210109 Abstract （132）      PDF（pc） （1995KB）（911）       Knowledge map    Save Cobbly soil is widely applied in geotechnical engineering construction by virtue of its good engineering characteristics. The inadequate research on cobbly soil, especially on its creep characteristics, results in improper ways in evaluating its long-term stability. In the present research, the creep properties of cobbly soil are studied via laboratory triaxial compression test, theoretical analysis and numerical simulation. The relations of creep versus time and stress are analyzed, and a creep model containing eleven parameters is put forward. The creep model is embedded in ABAQUS software to calculate the long-term deformation of the foundation of a bridge as a case study. Results manifest that the constitutive model presented in the paper well describes the rheological properties of cobbly soil. Compared with monitoring results of anchorage deformation, the result of settlement calculation in creep acceleration stage is larger, while in stable creep stage is smaller. Reference | Related Articles | Metrics | Comments（0）

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Hydraulic Characteristics of Stepped Spillway with Trapezoidal Concave Angle LI Shao-wei, ZHANG Wen-chuan, WANG Jun-xing, ZHOU Zhao Journal of Yangtze River Scientific Research Institute    2022, 39 (6): 56-63.   DOI: 10.11988/ckyyb.20210612 Abstract （158）      PDF（pc） （2310KB）（908）       Knowledge map    Save The flow circulation and flow energy exchange in the concave angle of stepped spillway is a key factor of flood discharge and energy dissipation. Current research of stepped spillway mostly focus on the combined actions of step’s slope and size as well as wide tail pier; the geometric shape of concave angle is rarely studied. In this paper, the flow pattern, flow velocity, intensity of pressure and concentration of entrained air in both traditional triangular concave angle steps and trapezoidal concave angle steps are examined via hydraulic model tests and numerical simulated calculations. Results demonstrated the similarity of flow state between trapezoidal concave angle steps and traditional triangular concave angle steps; but trapezoidal concave-angle step changes the shape of vortex shedding, which, therefore, moves into the main flow and promotes the turbulence of water flow. As a result, the initial point of aeration moves slightly forward, the average concentration of entrained air in the cross section of the main flow area increases, the total pressure fluctuation at the virtual bottom plate intensifies, and the average flow velocity of the step section reduces, beneficial to reducing the risk of step cavitation and promoting the energy dissipation of the step. Reference | Related Articles | Metrics | Comments（0）

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Water Temperature Variation and Its Influencing Factors in the Upper Jinsha River SHAO Jun, DU Tao, GUO Wei, OUYANG Shuo, WANG Kun Journal of Yangtze River Scientific Research Institute    2022, 39 (8): 17-22.   DOI: 10.11988/ckyyb.20210380 Abstract （574）      PDF（pc） （2640KB）（907）       Knowledge map    Save As the source area of the Yangtze River,the upper Jinsha River is of special eco-environmental functions.The water temperature of the river is of great significance to the growth of aquatic organisms and the surrounding ecological environment.In this paper,the intra-annual and inter-annual changes as well as distribution along the flow direction of natural water temperature of the upper Jinsha River were examined according to measured water temperature data from hydrological stations of Gangtuo,Batang,and Shigu.Major hydrological and meteorological factors that affect the water temperature were also analyzed.Results unveiled that the monthly average water temperature at Gangtuo,Batang,and Shigu hit the highest from July to August in general,while the lowest in January.The annual water temperature at the three stations displayed a significant upward trend from 1961 to 2018,with abrupt changes in 1998,1992,and 2003,respectively.Air temperature had the largest influence on the monthly average water temperature,followed by precipitation and streamflow;relative humidity,evaporation and wind speed also had a certain impact on the change of water temperature;sunshine hour bore a weakest relationship to water temperature.From the upstream to the downstream,the coefficients of correlation between water temperature and runoff,wind speed,and water surface evaporation decreased,while those between water temperature and precipitation,temperature,and relative humidity increased.The hydrological and meteorological characteristics of the basin were closely related with water temperature changes.In addition,the main factors affecting water temperature were further verified through principal component analysis. Reference | Related Articles | Metrics | Comments（0）

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Spatial and Temporal Land Use/Cover Change Characteristics of Qinghai-Tibet Plateau PENG Hai-yue, REN yan, LI Qiong, WEI Jia-hua Journal of Yangtze River Scientific Research Institute    2022, 39 (8): 41-49.   DOI: 10.11988/ckyyb.20210470 Abstract （225）      PDF（pc） （5090KB）（880）       Knowledge map    Save The characteristics of land use change from 1992 to 2015 in the Qinghai-Tibet Plateau are analyzed by examining the spatial-temporal distribution and change rate of land use using the 300 m high-precision land use data (abbreviated as TPDC_LUCC) of Qinghai-Tibet Plateau Research Institute on the basis of evaluating the accuracy of public land use data set. The attribution of land use change is also analyzed based on climate data and social economic data. Results reveal that:1) Among the public datasets,the TPDC_LUCC dataset has the longest sequence and the highest accuracy,especially the classification accuracy of cultivated land,urban land and water bodies;the 300 m land use data (abbreviated as ESA_LUCC) of the European Space Agency has the highest classification accuracy for grassland and the worst for cultivated land;the 30 m land use data (abbreviated as CASearth_LUCC) of the Institute of Space Information Innovation,Chinese Academy of Sciences has a relatively accurate classification of glacier and urban land,yet with a large error of unused land. 2) Grassland is the most widely distributed in Qinghai-Tibet Plateau,with a multi-year average proportion reaching 70.02%,followed by unused land such as sandy land and bare land,accounting for 15.81%. Urban land expanded rapidly,with a growth rate of 2.34% from 1992 to 2005 and 4.69% from 2005 to 2015. From 1992 to 2015,9.14% of unused land on the Qinghai-Tibet Plateau was turned into grassland,3.27% of shrub and arable land into forest land,and 5.5% of glaciers into water. 3) From 1992 to 2018,the average temperature of the Qinghai-Tibet Plateau increased by 1.17 ℃,and the increase of precipitation and temperature was the main driving factor for the increase of grassland,shrub and forest land in the eastern region. The significant increase of temperature led to the melting of glaciers in the northwest,and urbanization resulted in the increase of urban land and the decrease of cultivated land. Implementing ecological protection policies has significantly promoted the restoration of grassland and forest land on the Qinghai-Tibet Plateau. Reference | Related Articles | Metrics | Comments（0）

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Management System and Mechanism of Water Resources Protection and Utilization in the Yangtze River Basin in the New Era XU Ji-jun, CHEN Shu Journal of Yangtze River Scientific Research Institute    2022, 39 (7): 1-6.   DOI: 10.11988/ckyyb.20211375 Abstract （220）      PDF（pc） （5244KB）（866）       Knowledge map    Save Protecting and utilizing the water resources in Yangtze River Basin has seen many problems and difficulties. In view of this,we discussed the paths of reconstructing and improving the management system and mechanism in the new era. To break the system and mechanism barriers in sustainable development,the management of water resources in the Yangtze River Basin should conform to the integrity and complexity of the basin. In the framework of coordination across the basin,we recommend to 1)build a sound system which integrates unified and separate management with overall linkage and interactions to forge a governance community for the basin with multiple stakeholders;2)enhance the mechanisms of diversified ecological compensation,cross-provincial river-lake-chief supervision,unified dispatch and management of controlling water projects,as well as spatial control and market operation. With such endeavors,the governance of water resources in Yangtze River Basin is expected to be further modernized. Reference | Related Articles | Metrics | Comments（0）

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Blasting Damage Characteristics of Rock Mass Near Blast Hole of Hydropower Engineering Slope LIANG Rui, BAO Juan, ZHOU Wen-hai Journal of Yangtze River Scientific Research Institute    2022, 39 (8): 71-76.   DOI: 10.11988/ckyyb.20210269 Abstract （160）      PDF（pc） （3056KB）（848）       Knowledge map    Save Single-hole blasting damage models were established by using HJC (Holmquist-Johnson-Cook) model and RHT (Randomized Hough Transform) model respectively for comparison to study the dynamic response of rock mass blasting in the vicinity of the blast hole of hydropower engineering slope under different damage models.The blasting damage distribution,the seismic wave energy characteristics,and the threshold of damage particle peak vibration velocity (PPV) of rock mass under the two models were investigated based on the simulation result and calculation analysis.The results demonstrated that the blasting cracked area in the RHT model is approximately twice that of the HJC model under the same working condition.The smaller the damage range,the greater the proportion of explosive shock wave transformed to elastic vibration wave.The damage PPV thresholds of HJC model and RHT model were obtained by fitting the relationship between damage degree and PPV as 13.09 cm/s and 27.29 cm/s,respectively.In conclusion,the RHT model reflects more accurately the blasting damage effect of rock mass in the vicinity of actual slope. Reference | Related Articles | Metrics | Comments（0）

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Impact of Water Storage in Three Gorges Reservoir on Local Climate Change ZHAO Zi-hao, JIANG Xiao-dong, YANG Shen-bin Journal of Yangtze River Scientific Research Institute    2022, 39 (6): 40-49.   DOI: 10.11988/ckyyb.20210221 Abstract （178）      PDF（pc） （6239KB）（814）       Knowledge map    Save Due to special underlying surface properties, large water bodies have impacts on local water thermal cycle and climate. The Three Gorges Project is the world's largest water conservancy project. In the present research, we analyzed systematically the characteristics of climate change in the Three Gorges Reservoir over the past 66 years and the impacts of water storage on local climate by means of climate tendency rate and CVM test. Results demonstrated that the local temperature of the Three Gorges Project has declined after impoundment, affecting an area of 299.83 km2 near the dam, reaching 12.65 km away from the dam. The temperature of Zigui station, which is the closest to the dam, changed abruptly in 1997. The average annual temperature of Zigui two decades after the impoundment was 1.15 ℃ lower than that before the impoundment. Local precipitation has increased, affecting an area of 2 914.88 km2, reaching 109.15 km away from the dam. The precipitation of Zigui station also changed abruptly in 1997, and the average precipitation of Zigui two decades after the impoundment increased by 245.90 mm compared with that before the impoundment. Water storage also led to the rise of local relative humidity. Zigui and Xingshan witnessed abrupt changes in relative humidity in 1997 and 2003, respectively, of which the former rose by 5.29% two deades after the impoundment. The number of sunshine hours reduced, affecting the nearby area of 2 045.66 km2, extending 41.06 km away from the dam. The sunshine hours of Zigui changed abruptly in 2002, reducing by 33.87 hours compared with that two decades before the impoundment. In conclusion, water storage in the Three Gorges Reservoir has had a small scope of influence on meteorological elements, affecting an area of only 75.27 km2 on all the elements; only Zigui station experienced abrupt changes in all the elements during water storage. Reference | Related Articles | Metrics | Comments（0）

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Spatial and Temporal Variation Characteristics of Blue and Green Water Resources in the Yangtze River Basin Based on GLDAS-NOAH SHI Meng-qi, YUAN Zhe, SHI Xiao-liang, LI Yi, CHEN Fei Journal of Yangtze River Scientific Research Institute    2022, 39 (10): 38-44.   DOI: 10.11988/ckyyb.20210526 Abstract （214）      PDF（pc） （63525KB）（790）       Knowledge map    Save The blue and green water resources in the Yangtze River basin (YRB) were simulated by using the GLDAS (Global Land Data Assignment System) Noah hydrological model,and then the distribution of blue and green water resources and their temporal and spatial changes were revealed. Results demonstrate that from 2000 to 2019,the multi-year average blue water resource and green water resource in YRB was 420.24 mm and 686.95 mm,respectively,and the latter was about 1.62 times of the former. Over the past two decades,the blue water resource,green water resource and green water coefficient in the YRB showed insignificant increasing trends,and in particular,the change rate of blue water resource and green water resource was 3.26 mm/a and 2.27 mm/a during 2000-2019,respectively. On monthly scale,the blue and green water resources expanded in July and August,accounting for 29%-32% of the whole year,while shrank in January and February,accounting for 5%-6% of the whole year. On spatial scale,blue water resource distributed in a pattern of higher in the southeast and lower in the northwest,while green water resource higher in the east and lower in the west,and green water coefficient higher in the northwest and lower in the southeast. Scientific and comprehensive evaluation of blue and green water resources can provide scientific basis for optimizing water resources utilization mode and improving water resources utilization efficiency. Reference | Related Articles | Metrics | Comments（0）

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Protection and Repair Technology for Hydraulic Concrete in High and Cold Region: Research and Application LI Zhen, XIONG Ze-bin Journal of Yangtze River Scientific Research Institute    2022, 39 (6): 1-8.   DOI: 10.11988/ckyyb.20210924 Abstract （185）      PDF（pc） （8606KB）（772）       Knowledge map    Save Due to complex conditions such as large temperature difference, extremely low temperature, strong radiation, strong wind and drying, hydraulic concrete structures in high and cold region are prone to suffer from deterioration diseases represented by freeze-thaw damage. Protection and repair technology is a commonly used preventive measure against deterioration. The degradation process and the law of influence on hydraulic building materials under freezing-thawing cycle are simulated by finite element method. Results suggest that the frost heave stress caused by freezing of pore water is the main factor leading to the decrease of its durability under cyclic varying temperature-caused load. In addition to improving the antifreeze capacity of concrete, surface anti-seepage treatment such as surface coating protection should also be taken to control the interior water content and frost heaving stress in concrete and to improve freeze-thaw resistance. Moreover, the selection principles, types and characteristics as well as construction techniques of protective repair material for hydraulic structure in high and cold region are summarized, and some typical engineering applications of protective repair technology in high and cold region are introduced for reference. The development trends of material performance, equipment, technique extension, and standard formulation are also discussed. Reference | Related Articles | Metrics | Comments（0）

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Variation Characteristics of Total Phosphorus Concentration in the Yangtze River Basin in the Thirteenth Five-Year Plan Period JI Xiao-yan, PENG Dan Journal of Yangtze River Scientific Research Institute    2022, 39 (8): 1-9.   DOI: 10.11988/ckyyb.20220083 Abstract （252）      PDF（pc） （5414KB）（769）       Knowledge map    Save The spatial-temporal variation characteristics of total phosphorus (TP) in the Thirteenth Five-Year Plan period are examined in this paper based on the TP data of 590 river sections and 116 lakes and reservoir points in the Yangtze River Basin monitored by the National Examination Network. Results revealed a decline trend of TP concentration in the Yangtze River Basin in the Thirteenth Five-Year Plan period,with the annual average concentration dropping from 0.106 mg/L in 2016 to 0.072 mg/L in 2020. TP concentration in 93.2% sections of the mainstream of Yangtze River decreased,with the annual average concentration reducing from 0.092 mg/L in 2016 to 0.059 mg/L in 2020. Minjiang River,Tuojiang River and Wujiang River witnessed apparent decrease (over 50%) of TP concentration,while the mainstream of Yangtze River experienced a rise of TP concentration due to the inflow of major tributaries including Minjiang River,Tuojiang River,Wujiang River and Hanjiang River. TP concentration at 62.9% of lake and reservoir sites decreased compared with that in 2016. Taihu lake and Chaohu Lake suffered from high TP concentration in autumn,Dongting Lake,Poyang Lake and Danjiangkou Reservoir in winter,and Dianchi Lake in summer. The research finding reflects the positive results of water pollution prevention and control in the Yangtze River Basin on the one hand,and offers reference for the in-depth control of TP pollution in the Yangtze River Basin on the other. Reference | Related Articles | Metrics | Comments（0）

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A Calculation Model for Lining Crack Width Based on Bond Slip HE Huan Journal of Yangtze River Scientific Research Institute    2022, 39 (7): 149-153.   DOI: 10.11988/ckyyb.20210301 Abstract （109）      PDF（pc） （5412KB）（763）       Knowledge map    Save On the basis of the bond-slip theory,a force transmission system of “solid element to shadow node and to beam element” is proposed and applied to the separated modelling of a reinforced concrete lining structure.The stress of the stressed steel bar is calculated by finite element method,and the maximum width of crack is obtained in association with the calculation formula specified in code.Compared with test results,the feasibility of calculating the maximum crack width of lining by using the force transfer system of finite element modeling in association with code formula is verified.The research offers a novel calculation method for the maximum crack width of similar projects. Reference | Related Articles | Metrics | Comments（0）

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Experimental Study on Strength Deformation and Micro-characteristics of Improved Chloride Saline Soil SEMERJAN Memetyusup, TAO Shi-chao Journal of Yangtze River Scientific Research Institute    2022, 39 (6): 113-119.   DOI: 10.11988/ckyyb.20210066 Abstract （154）      PDF（pc） （4385KB）（759）       Knowledge map    Save The unfavorable engineering characteristics of saline soil such as salt expansion and solution subsidence have extremely adverse effects on the construction of transportation infrastructure and its safe operation. The mechanism of improving saline soil by adding sodium silicate, cement, lime, fly ash and fiber and the microscopic characteristics of improved soil were investigated via unconfined compression test and SEM-EDS test on the chloride saline soil of subgrade in south Xinjiang. Results manifest that with the 28 d compressive strength as the evaluation standard, the optimal combination in scheme 1 (cement content 8%, lime content 12%, fiber content 0.2%, and fiber length 18 mm, with a salt content of 3%) is suitable for improving medium chloride saline soil; the optimal combination in scheme 2 (fly ash content 20%, lime content 6%, fiber content 0.2%, and fiber length 12 mm, with a salt content of 1%) is suitable for improving weak chlorine saline soil. The improved saline soil modified by the aforementioned two schemes could both retain high compressive strength after reaching stress peak, and the stress-strain curves display strain softening feature with brittle failure. Microstructure and EDS analysis illustrate that the mineral particles of the modified and solidified saline soil are relatively large with sound particle integrity. The cementitious material is composed of flocculent calcium silicate hydrate and acicular ettringite with dense microstructure. The contact mode between particles is mainly face-to-face contact. Compared with those in scheme 2, the improved soil specimen in scheme 1 is of dense internal structure, good internal integrity, and superior strength performance. Reference | Related Articles | Metrics | Comments（0）

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Evaluation of Available Rainwater Resources in the Guanlan River Basin of Shenzhen City XIE Shuai, LIN Hang, WANG Yong-qiang, XU Ji-jun, CHEN Jin Journal of Yangtze River Scientific Research Institute    2022, 39 (7): 17-22.   DOI: 10.11988/ckyyb.20210373 Abstract （185）      PDF（pc） （6266KB）（755）       Knowledge map    Save Evaluating the available amount of rainwater resources is a crucial part of utilizing rainwater resources in solving the water problems in the process of urbanization.In order to support the utilization of rainwater resources in the Guanlan River basin in Shenzhen,we calculated the amount,the theoretical potential and the practical potential of rainwater resources in different typical years based on the daily rainfall data of Shenzhen from 1984 to 2018 by using a calculation method based on classifying the types of underlying surface.Results demonstrate that the Guanlan River basin has a large potential in the utilization of rainwater resources,with the theoretical potential in normal flow year reaching 374 million m3 and the practical potential at a 70% control rate of total annual runoff amounting to 242 million m3.Under equivalent rainfall conditions,the underlying surface and the urban construction conditions both exert remarkable influence on the available rainwater resources.Expanding underlying surface area such as landscaping area and water area and raising the control rate of total annual runoff are conducive to improving the practical potential of available rainwater resources. Reference | Related Articles | Metrics | Comments（0）

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Experimental Study on Improving the Swelling Characteristics of Expansive Soil Using MICP Technology LIU Hao-lin, LI Dan, HU Bo, CHENG Zhan-lin Journal of Yangtze River Scientific Research Institute    2022, 39 (6): 150-156.   DOI: 10.11988/ckyyb.20220049 Abstract （142）      PDF（pc） （1522KB）（754）       Knowledge map    Save The effectiveness and mechanism of MICP (Microbial Induced Calcium carbonate Precipitation) improving the expansion characteristics of expansive soil were investigated via test of expansive soil mixed with urease-producing bacteria CGMCC 1.368 7. The effects of reaction solution ratio and Ca2+ molar concentration on the free expansion rate, unloaded expansion rate, and percentage generation of CaCO3 of expansive soil treated with MICP were studied by orthogonal experiments, and the microscopic properties of MICP-modified expansive soil were revealed. The swelling characteristics of expansive soil treated with MICP can be improved remarkably: when the ratio of reaction solution is 1∶1 and the concentration of Ca2+ is 2.0 mol/L, the free expansion rate of expansive soil is reduced by 44.4% at most; when the ratio of the reaction solution is 1∶3 and the concentration of Ca2+ is 2.0 mol/L, the volumetric expansion rate is reduced by 92.2%, and the expansion moisture content is reduced by 24.9%. MICP technology reduces the hydrophilicity of expansive soil particles, hinders the repulsion between soil particles, and weakens the expansion potential of expansive soil by cementing soil particles, filling soil pores and ion replacement. The research results verify the feasibility of improving the swelling properties of expansive soil by mixing based on MICP technology. Reference | Related Articles | Metrics | Comments（0）