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01 February 2024, Volume 41 Issue 2
    

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  • Journal of Changjiang River Scientific Research Institute. 2024, 41(2): 0-0.
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  • Special Contribution
  • SHAO Jun
    Journal of Changjiang River Scientific Research Institute. 2024, 41(2): 1-6. https://doi.org/10.11988/ckyyb.20231020
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    The source region of Yangtze River is highly sensitive to climate change, leading to significant alterations in river runoff. According to hydro-meteorological data from Zhimenda hydrological station and five meteorological stations in the source region of Yangtze River spanning 1960 to 2022, we investigated the changes in annual and seasonal runoff in the source region of Yangtze River. Utilizing correlation analysis, cross-wavelet transform, and principal component analysis, we further examined the relationship between runoff fluctuations and key meteorological factors. Findings indicated a notable upward trend in annual runoff at Zhimenda station throughout 1960 to 2022, with a particularly substantial increase of runoff in the past two decades. The seasonal runoff trend in the source region remained relatively stable from 1960 to 2000, but exhibited an increasing trend from 2000 to 2022, persisting to the present day. Precipitation, temperature, and relative humidity emerged as the primary meteorological factors exerting the most significant influences on the runoff at Zhimenda station.
  • Comprehensive Management Of River Basin
  • XU Yang, LÜ Hao, LIU Shuai, FANG Wei, QIN Hui
    Journal of Changjiang River Scientific Research Institute. 2024, 41(2): 7-13. https://doi.org/10.11988/ckyyb.20221303
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    To address the time-consuming nature of traditional hydrodynamic model combined with scheduling model, we propose a surrogate model as an approximation to enhance efficiency. The research focuses on the practical scheduling of cascade reservoirs from lower Jinsha River to the Three Gorges. By combining hydrodynamics theory with the Kriging surrogate model, we established a multi-objective dispatching model for a multi-reservoir system, and subsequently solved the model using a multi-objective evolutionary algorithm. Ultimately, we identified the multi-objective Pareto front of the model by adopting the projection pursuit method in decision-making. Research findings demonstrate that the surrogate model exhibits an average simulation error of less than 1.5%, effectively replacing the time-consuming hydrodynamic model while generating a competitive Pareto front and providing reasonable compromise solutions. These outcomes lay a theoretical foundation for advancing the comprehensive benefits of cascade reservoirs.
  • River Lake Protection And Regulation
  • DUAN Guang-lei, PENG Yan-bo
    Journal of Changjiang River Scientific Research Institute. 2024, 41(2): 14-20. https://doi.org/10.11988/ckyyb.20221616
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    The Songzi River serves as the primary channel linking the Yangtze River and the Dongting Lake. Since the 1950s, the water diversion from the Songzi River has gradually decreased due to the completion of artificial cutoffs in the lower Jingjiang River, the Gezhouba Project, and the Three Gorges Reservoir (TGR). Based on measured hydrological data and prototype channel observation data, we analyzed the change and influencing factors of water diversion at Songzi outlet after the impoundment of TGR. Results indicate the following: 1) The annual split ratio has stabilized at 7% with no significant changes. 2) The water diversion capacity of Songzi outlet noticeably increases when the discharge at Zhicheng Station exceeds 25 000 m3/s, particularly during the first ten years following the TGR impoundment. 3) Operations during main flood season have a minimal impact, while impounding water after flood season in the TGR negatively affects water diversion at Songzi outlet. 4) Riverbed erosion in the mainstream of Jingjiang River leads to a decline of middle-low water levels near the inlet, posing an unfavorable impact on the flow diversion at Songzi outlet. 5) To a certain extent, the construction of the channel improvement project in Lujiahe Shoal Reach helps maintain middle-low water levels, and the sand dredging in the entrance reach improves inflow conditions during specific periods.
  • WANG Xi, LU Jin-you, ZHOU Yin-jun, CHAI Zhao-hui, HUANG Li
    Journal of Changjiang River Scientific Research Institute. 2024, 41(2): 21-26. https://doi.org/10.11988/ckyyb.20221720
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    A generalized flume experiment was conducted based on typical morphological parameters of alternative bars in midstream Yangtze River to investigate the longitudinal, transverse, and horizontal changes in scouring and silting of the bars under varying conditions. The aim was to comprehensively understand the evolution of alternate bars in straight channel under clear water scouring. The findings indicate that the bed experiences extensive erosion over a long distance in the longitudinal direction, with a greater discharge resulting in increased scouring depth. To be specific, the average thalweg scouring depth at a flow rate of 215 L/s is approximately 2.1 times that at a flow rate of 46.71 L/s. Additionally, the longitudinal gradient of the thalweg attenuates under larger discharge. In the transverse direction, the alternative bars primarily undergo scouring, with maximum scouring typically occurring at the edge. Other sections demonstrate fluctuating patterns of scouring, silting, and then scouring (e.g., at a discharge of 215 L/s, the average scouring depth outside section 2# ranges around 3.5 cm in (0,2] hours, followed by an average silting height of approximately 0.5 cm in (2,12] hours, and finally an average scouring depth of about 0.7 cm in (12,21] hours). Regarding the planar movement, the bar shifts downstream as a unified entity and becomes elongated, with deposition mainly concentrated within 1 m downstream of the bar. Furthermore, the presence of an upstream bar initially promotes sedimentation of the downstream bar, subsequently intensifying scouring of the downstream bar, particularly affecting the toe of the bar.
  • FAN Yang-cheng, LIU Ping
    Journal of Changjiang River Scientific Research Institute. 2024, 41(2): 27-36. https://doi.org/10.11988/ckyyb.20221297
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    The WRF-CMAQ model is employed to estimate the atmospheric nitrogen deposition of different nitrogen forms in four major lakes of China in 2018. The nitrogen forms include total nitrogen (TN), oxidized nitrogen (OXN), reduced nitrogen (REDN), nitrate nitrogen (NO-3-N), and ammonium nitrogen (NH+4-N). The annual nitrogen deposition fluxes in 2018 for Lake Qinghaihu, Lake Ulansuhai, Lake Donghu, and Lake Taihu were 3.02, 4.38, 64.25, and 21.67 kgN/hm2, respectively. Atmospheric nitrogen deposition contributed 0.9%, 22.3%, and 11.3% of the total nitrogen load in Lake Ulansuhai, Lake Donghu, and Lake Taihu, respectively. Lake Donghu and Lake Taihu were significantly more affected by atmospheric nitrogen deposition than Lake Qinghaihu and Lake Ulansuhai, highlighting the need for increased concern regarding atmospheric nitrogen deposition in developed regions. Sensitivity analysis revealed that the deposition velocity of nitrogen pollutants had an insignificant impact on local nitrogen deposition fluxes. However, reducing the source emission rate of nitrogen pollutants significantly decreased the nitrogen deposition fluxes. A 20% reduction in the source emission rate led to a decrease in nitrogen deposition fluxes by 11% to 22% in the four representative lakes. This demonstrates that nitrogen emission sources is the major factor that affects nitrogen deposition compared to deposition velocity. The findings provide a scientific foundation for further understanding the role of atmospheric nitrogen deposition in the total nitrogen load of lakes and developing effective control measures.
  • Water Resources
  • JIA Ben-jun, TANG Zheng-yang, CAO Hui, GUO Le, ZHANG Hai-rong, REN Jia-peng
    Journal of Changjiang River Scientific Research Institute. 2024, 41(2): 37-43. https://doi.org/10.11988/ckyyb.20221261
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    To express the characteristics of reservoir capacity through function, we have developed two models: the triangular pyramid model and the irregular cone model. These models accurately depict the general morphological features of reservoirs. On this basis, we have devised a three-parameter power function model to represent the reservoir capacity characteristics using mathematical integration techniques. Furthermore, by considering the mathematical properties of reservoir capacity characteristics, we gave the ranges of parameter values for the three-parameter power function. Finally, through rationality analysis and evaluation of the goodness of fit, we validated the broad applicability, high reliability, and clear physical significance of this model in characterizing reservoir capacity characteristics for hydropower stations with 37 reservoirs in the middle and upper reaches of the Yangtze River as case studies. The research finding serves as a fundamental support for generating precise function curves, enabling fine dispatching of hydropower reservoirs.
  • ZHANG Xiao-ying, HE Yi, WENG Xue-xian, SHAO Yi-ting
    Journal of Changjiang River Scientific Research Institute. 2024, 41(2): 44-51. https://doi.org/10.11988/ckyyb.20221351
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    The hydrological response to climate change and human activities holds significant importance in the study of water resource management within a basin. In this study, we applied eight elasticity methods based on the Budyko framework to evaluate and quantify the impact of climate change and human activities on alterations in runoff patterns. This assessment was based on precipitation, potential evapotranspiration, and runoff data spanning from 1960 to 2016 in the Duhe River basin. The Pettitt test method was utilized to identify abrupt shifts, while the Mann-Kendall test method was employed to assess monotonic trends. The results revealed the following key findings: 1) Annual runoff exhibited a significant declining trend (p<0.05), with a change point identified in 1994. However, annual precipitation and potential evapotranspiration showed an insignificant decreasing trend (p>0.1). 2) The hydrological response demonstrates a greater sensitivity to human activities than to climate change. Human activities contributed between 57.69% and 72.00%, whereas climate change contributed between 28.00% and 42.31%. 3) Changes in underlying surface characteristics, primarily attributed to human activities, were identified as the main cause of runoff attenuation. This suggests that increased forest and vegetation cover led to a reduction in runoff. The study underscores the dominant role of human activities in hydrological processes, providing crucial theoretical support for water resource management and integrated management within the Duhe River basin.
  • Water Environment And Water Ecology
  • LIU Yi, CHEN Yan, SU Ting, TAN Fu-ya, LIU Yong-lin, ZHANG Xue-yan, KUANG Xia, YIN Feng, ZHAO Jia-yu
    Journal of Changjiang River Scientific Research Institute. 2024, 41(2): 52-60. https://doi.org/10.11988/ckyyb.20221301
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    In order to evaluate the concentration of trace elements in drinking water and assess their potential hazards to human health, we collected a total of eighty terminal tap water samples from residents’ homes, along with three river water samples from water sources in the urban area of Chongqing. Subsequently we measured the concentrations of As, Ba, Cr, Cu, Mo, Ni, Sb, Se, and Zn in these water samples, and assessed the health risks of these elements in drinking water by using the health risk assessment model recommended by USEPA. Results revealed that 1) The average (arithmetic mean, the same hereinafter) concentrations of the nine trace elements in drinking water meet the national standards for drinking water quality. 2) The total health risks of trace elements to children and adults are 8.72×10-5 a-1 and 3.56×10-5 a-1, respectively, which falls within the maximum acceptable standard (10-6-10-4 a-1) recommended by USEPA.However,the total health risks to children are higher than those for adults.3) The carcinogenic risks posed by Cr and As for children and adults are 8.54×10-5 a-1 and 1.62×10-6 a-1, 3.48×10-5 a-1 and 6.74×10-7 a-1, respectively, lower than the maximum acceptable levels (10-4 a-1) set by USEPA. In conclusion, Cr and As are primary sources of health risks in the drinking water of main urban area of Chongqing. Thus, monitoring and management of Cr and As shall be strengthened in future.
  • FU Yu, TONG Si-chen, WANG Xiao, JIANG Pin-feng, HUANG Guo-xian
    Journal of Changjiang River Scientific Research Institute. 2024, 41(2): 61-66. https://doi.org/10.11988/ckyyb.20221122
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    To investigate the traceability of oil spills in inland rivers, we developed a mathematical model for the spread and drift of oil spill and inverse time tracking based on Fortran by utilizing the oil particle model in Lagrange theory. By using this model, we simulated the possible oil spill pollution process in the Three Gorges Reservoir during typical operation. Results indicate that the model could well simulate the spread and drift of oil spill and track the approximate location of the pollution source, thereby offering reference for the emergency investigation of unknown oil spill source pollution accidents in inland waterways.
  • Hydraulics
  • DUAN Wen-gang, LIU Bei, HUANG Wei
    Journal of Changjiang River Scientific Research Institute. 2024, 41(2): 67-75. https://doi.org/10.11988/ckyyb.20230104
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    Embankments play a vital role in flood control engineering systems, and any breach in these embankments can result in severe disaster losses. Therefore, it is crucial to understand the relationship between the development rate of embankment breaches and hydraulic factors to accurately predict breach processes and flood evolution. By analyzing experimental data from series breach tests of non-cohesive sandy embankments, we obtained the relationship between hydraulic factors (discharge and unit-width discharge) and breach development rates (transverse widening rate and vertical down-cutting rate). Findings reveal two major developments of breach, namely, transverse widening and vertical down-cutting. Breach discharge rate is positively correlated with breach development rate, although the specific relationship depends on inflow conditions, making it difficult to express uniformly for all experimental scenarios. Nonetheless, an exponential relationship exists between unit-width discharge and breach development rate. Based on this relationship, a calculation model is established with unit-width discharge as a parameter to simulate and analyze the development process of breaches, including transverse widening and vertical down-cutting. The results demonstrate a strong agreement between the simulated situation and the actual breach development process, thus confirming the accuracy, scientific validity, and simplicity of the calculation model.
  • ZHOU Wang-wu, WEI Jie, MIAO Bao-guang, DAI Xiao-bing, REN Wei-chen
    Journal of Changjiang River Scientific Research Institute. 2024, 41(2): 76-81. https://doi.org/10.11988/ckyyb.20221196
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    An experimental study was conducted to investigate the scour prevention of downstream slopes in steep narrow valleys based on the ski-jump energy dissipation of the overflow tunnel at Lawa Hydropower station. The hydraulic characteristics of the slopes were analyzed using both fixed bed and moving bed tests. The experimental findings indicate that the water flow pattern, near-bank velocity, and fluctuating pressure of the skew bucket are superior to those of beveled flip bucket. Additionally, the elevation of the maximum impact pressure point on the riverbank is close to the lowest elevation of bedrock’s capacity to withstand scouring velocity. The scour pattern on steep slopes simulated with granular soils aligns well with the flow velocity law observed in fixed bed banks, thereby providing a more accurate representation of the damage caused by water scour on steep bedrock slopes. These research results hold significant reference value for determining bank slope support, protection depth, and support structure design in similar projects.
  • Agricultural Water Conservancy
  • YU Lei, ZOU Zhi-ke, LIU Feng-li, LUO Wen-bing, WANG Wen-juan
    Journal of Changjiang River Scientific Research Institute. 2024, 41(2): 82-90. https://doi.org/10.11988/ckyyb.20221141
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    Precise estimation of meteorological yield is a premise of accurately assessing the impact of meteorological conditions on rice yield. This study delves into the time series variation of meteorological yield for single-season rice in the irrigated areas of Zhanghe, Hubei Province. Four methods, in specific, three-point moving average method, HP filtering method, single exponential smoothing method, and quadratic exponential smoothing method, were applied to decompose the rice yield data from 1975 to 2020 into trend yield and meteorological yield. Through correlation analysis, eight meteorological factors associated with rice growth stages were identified and used to construct a rice prediction model alongside the separated meteorological yield. The findings indicate that the four methods effectively capture the regional consistency between meteorological yield series and productivity level in Hubei Province. The annual average meteorological yield accounted for approximately 3.39% of the total output, and after 2008 the figure exceeded 10.1%. Via correlation analysis, the key factors influencing meteorological yield were identified as follows: minimum temperature at heading and flowering stage, maximum temperature at jointing and booting stage, average temperature at late tiller stage, minimum temperature at returning-green stage, evaporation at milk grain stage, and minimum temperature at seedling raising stage. During calibration period (1976-2014) and validation period (2015-2020), the model exhibited relative errors less than 5%, and a determination coefficient (R2) reaching 0.994. The proposed model holds potential for facilitating the study of regional rice production under future climate change scenarios.
  • Rock Soil Engineering
  • ZHANG Yu-chuan, GAO Xu-long, LIU Dong-fa, HUANG Hong-wei
    Journal of Changjiang River Scientific Research Institute. 2024, 41(2): 91-97. https://doi.org/10.11988/ckyyb.20221052
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    Fractal three-dimensional model has long been used to study soil microstructure. However, the acquisition of parameters necessary for calculating the fractal dimension through conventional geotechnical tests poses challenges, thereby limiting the utilization of fractal theory in soil research. To address this issue, a combined approach integrating three-dimensional processing and triangular grid principle is proposed in this study based on the scanning electron microscope (SEM) testing of undisturbed soil samples collected from Dingbian, Shaanxi Province, and Lanzhou, Gansu Province. This approach enables the calculation of surface area and volume values corresponding to various measurement scales of soil particles (or pores), facilitating the determination of fractal dimensions. The effectiveness and reliability of the proposed method are validated by applying fractal theory to analyzing soil-water characteristics. Moreover, the three-dimensional processing technique allows for the determination of other soil microstructure parameters, such as apparent porosity and specific surface area. Consequently, it can be regarded as a novel method for quantitatively investigating soil microstructure.
  • FAN Yong-feng, ZHAO Yang, SHI Xian-li, LU Zheng, YAO Hai-lin
    Journal of Changjiang River Scientific Research Institute. 2024, 41(2): 98-104. https://doi.org/10.11988/ckyyb.20221094
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    Geocells, characterized by a three-dimensional honeycomb structure, are commonly utilized as a specialized geosynthetic material to restrict lateral soil deformation in the reinforcement of subgrades, slopes, and retaining walls. Throughout the operational lifespan of geocell-reinforced soil structures, the geocells are subjected to varying angles and layers of shear forces, potentially leading to the penetration of potential sliding surfaces through the geocell reinforcement layer. In order to examine the actual stress distribution within the geocell-reinforced layer, we analyzed the stress-strain behavior under different shear angles, layers, and width-to-height ratios using numerical methods based on direct shear tests. The findings demonstrate evident anisotropy within the geocell-reinforced layer. The geocell enhances the cohesion and internal friction angle of the soil, exhibiting disparities from existing triaxial test outcomes. Maximum shear strength of the reinforcement layer is observed when the shear plane passes through the middle of the geocell in parallel. As the angle between shear plane and geocell increases, the shear strength gradually diminishes. Furthermore, an increase in the width-to-height ratio of geocell corresponds to a linear rise in shear strength.
  • WANG Gui-lin, REN Jia-shan, CAO Tian-ci, YANG Zheng-qin, WANG Run-qiu, LUO Guang-dong
    Journal of Changjiang River Scientific Research Institute. 2024, 41(2): 105-114. https://doi.org/10.11988/ckyyb.20220970
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    To investigate the impact of dry-wet cycles on damage and failure characteristics of karst-fissured limestone, we prepared limestone specimens with fracture-shaped, elliptical, mushroom-shaped, and dumbbell-shaped karst fissures for uniaxial compression test. Digital Image Correlation and Acoustic Emission techniques were also employed to monitor the damage and deformation characteristics of karst-fissured limestone after 0, 3, 6 and 10 dry-wet cycles. The results showed that the dry-wet cycles and the karst fissure damage degree of limestone samples were defined based on the peak strength. The damage degree was proportional to the number of cycles and the water-rock contact area, ranging from 33.31% to 64.86% during dry-wet cycles. We expressed the coupling relationship between the damage degree of karst fissure and the dry-wet cycle. Under dry-wet cycles, the failure mode of karst-fissured limestone changed from tensile failure to tensile-shear mixed failure, and the local zone of surface strain transitioned to ductile extension. The shape of karst fissure had a dominant guiding effect on the failure path. In addition, the cumulative ringing counts of acoustic emission, as well as the crack initiation stress σci and crack damage stress σcd decreased with the proceedings of dry-wet cycles. The research results provide scientific basis for analyzing the failure mechanism of karst-fissured limestone in the Three Gorges Reservoir area.
  • HAN Chao, YU Yue-zhong, BAI Bin, XIAO Han, FAN Zhou, WU Wei, SUN Ke
    Journal of Changjiang River Scientific Research Institute. 2024, 41(2): 115-122. https://doi.org/10.11988/ckyyb.20220930
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    The construction of pile group foundations and underground diaphragm walls generates a significant amount of waste mud. Similarly, the development and utilization of urban underground space, as well as the process of shield tunneling, result in the production of high-moisture mud-like slag. Conventional yard treatment is limited due to cost and environmental concerns. Thus, an efficient dewatering method is needed to reduce waste mud volume. To evaluate the dewatering effect of flocculant conditioning on waste mud and enhance dewatering efficiency, we employed single and composite flocculants to examine the influences of type and dosage of flocculants on mud-water separation and sought to establish a basis for assessing dewatering effectiveness. Our findings demonstrate that organic flocculants enhance dewatering performance and promote mud-water separation, with an optimal dosage. Moreover, composite flocculants exhibit a synergistic effect from both organic and inorganic components, further enhancing dewatering capacity. Specifically, PAM composite flocculant has excellent dewatering performance. The combination of PAM and CaO composite flocculants could reduce the water content in sedimentary layer by 82.75%.
  • SUN hui, LI Cong-an, QIU Jin-wei
    Journal of Changjiang River Scientific Research Institute. 2024, 41(2): 123-127. https://doi.org/10.11988/ckyyb.20230173
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    To remediate low-permeability kaolin contaminated with heavy metals like zinc and cadmium, we developed a model test apparatus with electrokinetic geosynthetics (EKG) drainage plate as the electrode material. The study aimed to investigate the impact of potential gradient, electrification time, and moisture content on the removal rate of heavy metals during electric remediation, and on this basis, to determine the optimal experimental conditions. Under the optimal conditions, we conducted experimental studies to examine the effects of electrode materials and potential gradients on the removal efficiency of various heavy metals. Findings revealed that with increasing remediation time, heavy metal pollutants at the anode gradually decreased, while their concentration at the cathode gradually increased. Under the same experimental conditions, the removal rate of cadmium (Cd) was significantly higher than that of zinc (Zn). Moreover, a higher potential gradient resulted in a greater removal rate of Zn ions. Notably, using EKG as electrodes exhibited a more effective remediation effect on heavy metal-contaminated soil compared to graphite electrodes. This research contributes to the understanding of the effects and mechanisms of EKG remediation on heavy metal-contaminated soil, and provides important technical support for the application of EKG remediation technology.
  • WANG Li, SUN Wen-duo, WANG Shi-mei, HU Qiu-fen, CHEN Yu-shan, NAN Fang-yun
    Journal of Changjiang River Scientific Research Institute. 2024, 41(2): 128-134. https://doi.org/10.11988/ckyyb.20221071
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    The deformation of reservoir landslides exhibits a significant coupling effect between seepage and creep. In this study, we investigated the influence of seepage on creep and the impact of deformation on seepage using a self-developed seepage and creep coupling triaxial apparatus. By redesigning and improving the GDS triaxial apparatus, we conducted seepage and creep coupling tests with precise control and measurement. Our findings reveal that under the influence of seepage, the volume deformation of soil samples gradually increases with time and then slowly decreases. This behavior is attributed to excess pore water pressure leading to the unloading of confining pressure, resulting in rebound deformation of the soil sample. Despite this, the ongoing effects of seepage pressure continue to act on the soil, contributing to a gradual decrease in sample volume. Furthermore, we obtained the data of volume changes of soil samples during the seepage process and established the void ratio-permeability coefficient (e-k) relationship curve before seepage and after achieving seepage stability. The results demonstrate that considering the influence of deformation yields a more accurate e-k relationship curve, better reflecting the fluid-solid coupling effect of the soil. These research findings are expected to contribute to the development of a more scientific and rigorous theory and method for predicting the evolution of deformation in reservoir landslides.
  • XU Guo-quan, WANG Xin-yu
    Journal of Changjiang River Scientific Research Institute. 2024, 41(2): 135-141. https://doi.org/10.11988/ckyyb.20221277
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    The prediction model which integrates non-destructive testing and machine learning has emerged as a hotspot for predicting tensile strength of rock. This paper presents a data-driven modeling approach for predicting rock’s tensile strength based on Multivariate Adaptive Regression Splines (MARS). An experimental dataset comprising 80 data sets, including Schmidt hammer rebound number, dry density, point load strength index, and Brazilian tensile strength, was collected. The dataset was randomly divided into training (70%) and testing (30%) sets. Additionally, artificial neural network (ANN), support vector machine (SVM), and decision tree (DT) techniques were utilized to develop machine learning models. The performance of the MARS model was compared with those of the DT, ANN, and SVM models. The predictive accuracy of the developed models was evaluated using Root Mean Square Error (RMSE), Mean Absolute Error (MSE), coefficient of correlation, and coefficient of determination. The results manifested the satisfactory predictability of the machine learning models, with the MARS model exhibiting optimal performance, followed by SVM model, ANN model, and DT model in descending order. Notably, MARS was able to assess the relative importance of each variable through ANOVA decomposition. The model presented in this paper is conducive to rapidly obtaining the tensile strength of rock.
  • PEI Shu-feng, HAO Wen-feng, FAN Yi-lin, CHEN Hao, LI Wen-tao
    Journal of Changjiang River Scientific Research Institute. 2024, 41(2): 142-150. https://doi.org/10.11988/ckyyb.20220933
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    To ensure the effective long-term operation of anchoring systems for large-scale water conservancy and hydropower projects, we conducted statistical analysis of anchoring systems monitoring data from six hydropower stations under the Three Gorges Group and clarified the time-history evolution law of anchor cable load and anchor bolt stress as well as the factors affecting these characteristic changes. Results demonstrate that the anchor cable loads and anchor bolt stresses of high slope and underground cavern are mainly within designed ranges, with significant changes occurring primarily during the construction period, gradually stabilizing after the completion of excavation and support. Anchor cable loads on slopes exhibit three distinct stages, rapid decline, followed by slow decline, and eventual stability or periodic change. Anchor cable loads in underground caverns exhibit similar characteristics, yet with more complex variation. Bolt stress demonstrates a significant negative correlation with temperature. Anchor cable load in underground cavern exhibits a diameter effect, with cavern size in direct proportion to the average cable load value and a more significant loss rate change range. Fully unloaded areas, such as intersection portals in the underground cavern group, blocks, and retained rock piers, display the largest anchor bolt stresses, and the loss rates in block section are generally higher than those in other engineering parts. Load loss rates of fractured anchor cables are relatively high. Rock mass quality negatively correlates with anchor cable load loss rates. Failure characteristics of anchor cable projects during construction include steel strand breaks, anchor cable breakage through anchor covers, and steel strand shrinkage. Long-term failures of anchor cable operation include anchor pier head corrosion and calcium carbonate precipitation.
  • HU Min, CAO Wen-gui, CUI Peng-lu, XU Zan, LI Hui-xin, LI Zhao-shuai
    Journal of Changjiang River Scientific Research Institute. 2024, 41(2): 151-158. https://doi.org/10.11988/ckyyb.20220973
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    To investigate the nonlinear consolidation behavior of soft soil under varying loads in one dimension, we introduce a novel one-dimensional nonlinear compression model to establish the one-dimensional nonlinear consolidation equation in consideration of non-Darcy flow for saturated soft soil subjected to variable loads. The equation is solved using the finite difference method. The excellent agreement between the obtained results and the analytical solution confirms the validity and reliability of the equation. Based on the solution of the consolidation equation, we thoroughly examine the effects of non-Darcy seepage parameters (represented by m and i1), the initial compressibility coefficient of the soil, the ratio of compression index to permeability index, as well as the rate and form of external load, on soil consolidation. The results demonstrate that an increase in the non-Darcy parameters (m and i1) and the ratio of compression index to permeability index leads to a decrease in the consolidation rate of the soil. Moreover, a higher initial compression coefficient or larger loading rate results in a faster consolidation rate. In comparison with existing models, the established model in this study eliminates the need for measuring the initial effective stress of the soil. Consequently, it can be more easily applied to engineering.
  • QIAN Lei, SUN Ji-zhu, WANG Yong, LI Kun
    Journal of Changjiang River Scientific Research Institute. 2024, 41(2): 159-166. https://doi.org/10.11988/ckyyb.20220990
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    Particle size distribution (PSD) is a fundamental physical property that significantly influences the engineering properties of soil. Various methods exist for measuring PSD in marine sediments; however, the consistency and correlation between different measurement results need to be discussed. We deduced the relationship between sedimentation analysis method and laser diffraction method, and proposed a conversion method based on their testing principles. By employing the two methods, we analyzed the PSD of deep-sea sediment samples from the South China Sea and the Shenhu Sea area, and then converted the PSD obtained from laser diffraction method according to the conversion relationship. Results reveal that the difference between sedimentation analysis method and laser diffraction method mainly lies in the content of clay and silt particles.After the conversion, the measured percentages of clay and silt particles align well between the two methods,validating the reliability of the proposed conversion.
  • Engineering Safety And Disaster Prevention
  • ZHOU Fang-fang, ZHANG Feng, DU Ze-dong, HU Chao
    Journal of Changjiang River Scientific Research Institute. 2024, 41(2): 167-172. https://doi.org/10.11988/ckyyb.20221224
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    Safety monitoring plays a crucial role in ensuring the safe and stable operation of water conservancy projects, serving as a fundamental prerequisite for achieving intelligent water conservancy. By directly capturing the displacement (or deformation) response of building structures under external loads, deformation monitoring offers a direct reflection of building safety. Currently, automatic monitoring of dam horizontal displacement primarily relies on the tension line method, vacuum laser alignment method, and vertical line method. The CCD vertical coordinate instrument has seen widespread use in dam engineering practice; however, it suffers from drawbacks such as the lack of on-site configuration and real-time data reading capabilities, and the absence of direct remote interaction function. This necessitates the use of auxiliary acquisition devices or switching devices for remote communication. To address these limitations, we designed an intelligent CCD vertical coordinate instrument with a microprocessor and Ethernet interface, eliminating the need for connection to additional acquisition equipment and enabling direct connectivity to the software system. This solution effectively resolves issues related to complex instrument integration and the unstable nature of traditional communication modes. To address field parameter configuration, real-time acquisition and display challenges, we employed bluetooth communication and a smartphone APP in designing this instrument. Furthermore, we propose an adaptive dimming technique to enhance the instrument’s self-adaptability and stability.
  • TANG Dong, JIAN Hui-xiang, WANG Cun-li, LI Yi, JIANG Zhong-ming
    Journal of Changjiang River Scientific Research Institute. 2024, 41(2): 173-180. https://doi.org/10.11988/ckyyb.20221138
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    The key to the operation of underground water-sealed oil storage cavern is to maintain a certain thickness of water seal, which is dependent on the behavior of oil vapor migration under varying water seal depth. To determine a proper water seal depth, we developed a finite element numerical simulation method based on gas-liquid two-phase flow theory to model the evolution process of oil vapor leakage from an underground water-sealed oil storage cavern in China during its operation. Results showed that in construction stage in the absence of water curtain system, a large drainage area at the top of the cavern made oil storage inoperable. However, the construction of a water curtain system enabled the maintenance of a certain thickness of water seal above the coal seam. The range and volume of oil vapor leakage in the surrounding rock displayed positive power function correlation with operation time, with smaller leakage range and volume observed at thicker water seals. However, excessively thick water seals greatly increased engineering costs. Our study suggests an economically and reasonably safe water seal thickness of 30 m, which meets recommended standards and provides a sound basis for water-sealed oil storage cavern design and oil vapor leakage control.
  • Hydraulic Structure And Material
  • CAO Fu-bo, YANG Zhen, WANG Chen-xia, WANG Gao-feng, LIU Tao, WANG Xiao-yun, LI Xiao-li
    Journal of Changjiang River Scientific Research Institute. 2024, 41(2): 181-187. https://doi.org/10.11988/ckyyb.20221223
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    To investigate the impact of equal volume replacement of coarse aggregate by industrial steel slag stone on the mechanical and durability properties of concrete, we produced 144 specimens with varying steel slag replacement ratio, water-cement ratio, and concrete strength grade to test the mechanical properties, frost resistance, and carbonation resistance of the specimens. The results indicate that the greater the steel slag replacement rate, the larger the difference in carbonization depth between the top surface and the bottom surface. G-0.45-100 (here 0.45 represents the water-cement ratio and 100 means that the replacemen ratio is 100%) exhibited the largest difference, at 53.4%. Moreover, steel slag concrete demonstrates better strength and frost resistance at the same age. At a steel slag replacement rate of 100%, the 28-day compressive strength of steel slag concrete with a water-cement ratio of 0.45 increased by 13% compared with that of ordinary concrete. The splitting tensile strength and the flexural strength increased by 12.6% and 7.1% respectively. SEM test revealed that the interface transition zone (ITZ) of steel slag and cement stone was denser than that of ordinary aggregate, less affected by freeze-thaw cycles, and exhibited superior interface bonding. Additionally, through multiple regression analysis and the least square method, we established a numerical model for compressive strength and a freeze-thaw damage model of steel slag coarse aggregate concrete with good fitting accuracy.
  • YANG Tao, ZHANG Yu-qi, FU Chun-jian, ZHAO Hua-dong
    Journal of Changjiang River Scientific Research Institute. 2024, 41(2): 188-197. https://doi.org/10.11988/ckyyb.20221098
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    Predicting the remaining useful life (RUL) holds great significance in ensuring the operational safety of complex structures. To enhance the accuracy of RUL prediction for hydraulic gates, we propose a multi-feature information fusion-based approach. Initially, we employ the gamma process to simulate the corrosion evolution of gates and analyze the corrosion-caused degradation of characteristic parameters, including stress, natural vibration frequency, and dry/wet modal shapes through numerical simulations. Subsequently, we screen the feature parameters considering monotonicity and discreteness. We construct a health index by fusing these features based on principal component analysis. To model the gate degradation process, we employ a non-linear Wiener process and utilize the particle filtering method to obtain RUL prediction results for the gate at different operating times. Finally, we validate the reliability and effectiveness of our proposed method through engineering examples and finite element simulations. Our results demonstrate that the fusion of multiple information sources enables a more comprehensive reflection of the gate’s degradation state. The root mean square error (RMSE) of the prediction accuracy evaluation index is 1.395 5, the mean absolute error (MAE) is 1.262 8, and the absolute error of variance (VAE) is 0.352 8, showcasing high accuracy. This method can serve as a basis for gate health management and safety assessment.
  • Water Conservancy Informatization
  • NIE Wen, CHEN Yuan-ming, SHEN Xiao-ying, WEN Zhen-xing
    Journal of Changjiang River Scientific Research Institute. 2024, 41(2): 198-202. https://doi.org/10.11988/ckyyb.20221135
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    By searching published research papers affiliated with the Changjiang River Scientific Research Institute (CRSRI) from 2016 to 2020 included in three major index databases, namely SCI, EI, and CPCI, we conducted a bibliometric analysis on the number, discipline, author, and author group distribution of these papers. The author group distribution includes author’s age, education level, and professional titles. By comparing the statistical data with those in the previous five years, we further examined the scientific research, discipline development, and personnel structure of CRSRI in recent years from the perspective of research papers. We observed a significant enhancement in research strength and international influence. While maintaining the research strength in traditional fields, emerging fields have shown rapid improvement in research capacity, and external collaborations have been strengthened. A higher level of research talent has emerged, with a tendency towards younger researchers. This study aims to provide valuable data for discipline construction and research performance evaluation of CRSRI.