Constructing a water quality safety guarantee system that aligns with national strategic water source zones constitutes an essential part of the operation and management of the South-to-North Water Diversion Middle Route Project in the new era. This paper proposes the establishment conception of four major systems—monitoring station network, water quality monitoring, risk prevention, and technological support—based on the new requirements and objectives for water quality monitoring in the Danjiangkou Reservoir and its upstream basin. We detail the fundamental concepts and elements of these systems. The four systems aim to ensure the sustainable northward flow of clean water by enhancing the water quality monitoring framework through comprehensive coverage, timely alerts, advanced intelligence, three-dimensional perception, focused monitoring, and scientific research.
The water replenishment inlet of the Yangtze-to-Hanjiang River Diversion Project is located approximately 5 kilometers from Anle River outlet downstream of the Danjiangkou Dam, with the replenishment volume matching the diversion volume. The project’s impact on the waterway primarily manifests in the water reduction section. Comprehensive management is essential to restore navigable water levels during dry season. The effectiveness of the management plan was evaluated using a river engineering model, and the plan was optimized and further verified. Results indicate that, under the tailgate water levels of 86.47 meters and 85.90 meters for the 212 m3/s water reduction-replenishment plan, the water level from the diversion channel entrance to Huangjiagang decreases, while the water level downstream Huangjiagang remains unchanged. Notably, the water level at the diversion channel entrance experiences the largest drop, decreasing by 0.08 meters and 0.19 meters, respectively. After the comprehensive management plan 1 is implemented, the water level at the diversion channel entrance is reduced by 0.02 meters. However, the water level in the water-reduction section does not recover to pre-diversion levels, primarily because replenished water from the Anle River estuary fails to enter the left main waterway. Based on these experimental results, it is recommended to optimize the management plan by installing two bottom protection belts along the lower edge of the Canglangzhou outlet. Experiments identified four elevation values for these belts, with a recommendation to set the elevation at 85.5 meters. Further detailed analysis supports this elevation. The optimized plan is expected to slightly elevate the water level from the diversion channel entrance to Huangjiagang above pre-diversion levels, with a maximum increase of 0.06 meters at the channel entrance.
The medium- and long-term optimal scheduling of water resources is a complex optimization problem characterized by non-linearity, multi-stage high dimensionality, and multi-constraints. To address the local optimization and low convergence efficiency of classical intelligent algorithms, this paper introduce a novel algorithm named the Adaptive Chaotic Elite Mutation Differential Evolution (ACEDE) algorithm. The algorithm leverages a chaotic search strategy to enhance the algorithm’s exploration capabilities while revising the traditional mutation approach to learn from elite individuals, thereby accelerating convergence. The proposed algorithm is applied to the medium- and long-term scheduling of the Pearl River Delta Water Resources Allocation Project (PRD WRAP) as a case study and is compared with classical intelligent algorithms. Results indicate that: 1) The ACEDE algorithm improves significantly in global exploration capabilities and convergence accuracy and speed, demonstrating good adaptability. For the June 2030 and June 2040 level year dispatches, respectively, the ACEDE algorithm, saves ￥742 300 and ￥235 500 in electricity costs compared to the traditional DE algorithm, reducing the cost of electricity by 6.68% and 1.52%. 2) For the medium- and long-term optimal scheduling of PRD WRAP, fully utilizing the reservoir storage capacity to meet high water demand while slowing down the replenishment at the end of month could effectively control the smooth operation of the pumping station and minimize electricity costs.
During the flood season of 2022, the Changjiang River Basin experienced an unprecedented basin-wide drought. From September to October, the runoff at Datong Station fluctuated around 11,000 m3/s. Since September, the Changjiang River Estuary has faced severe saltwater intrusion due to typhoons, jeopardizing the water supply security of Shanghai. Based on analysis of measured runoff, wind speed, and salinity data, we conclude that low runoff combined with typhoons triggered the saltwater intrusion. We employed a three-dimensional estuary and coastal numerical model to quantitatively assess the impact of emergent water supply from cascading reservoirs. The emergent water supply mitigated saltwater intrusion in the Changjiang River Estuary, reducing the upward distance of saline water and shifting the 0.45 psu isohaline towards downstream by 17 km in the South Branch-North Channel section. This action reduced the salinity of reservoir water intake and extended the water intake window for the Qingcaosha Reservoir by approximately 6 hours. However, two cold fronts in October weakened the effectiveness of the water supply to some extent. To enhance the reliability of the water supply, it is crucial to strengthen comprehensive monitoring of hydrology, tides, and meteorology in the estuarine area, thereby ensuring the safety of freshwater utilization in Shanghai.
River system connectivity (RSC) is closely related with water security issues, including water resources allocation, flood and drought management, and the protection and restoration of aquatic ecosystems. Currently, there is a lack of comprehensive studies evaluating RSC at a national level, and few comparisons were conducted among different water resource zones. To address this gap, an RSC evaluation system is established by employing hierarchical analysis and the entropy weight method. The evaluation indices reflect the quantitative, structural, and hydraulic characteristics in line with the fundamental connotation of RSC. The spatial distribution map of RSC values on different scales (first-grade and third-grade national water resource zoning) is plotted. Results indicate that RSC values decline progressively from southeastern to northwestern China, categorizing into low (0.07-0.38), medium (0.39-0.50), and high (0.51-0.78) levels. Low RSC values primarily occur in the arid inland areas of northwest China, while medium values are found in hilly regions, and high values are concentrated in the plain river networks of the middle and lower reaches of the Yangtze and Huaihe River basins. This study contributes to enhancing RSC planning and development at both regional and catchment scales.
Assessing the risks and reducing the hazard level of water pollution emergencies in water diversion projects are of prominent significance to leveraging the benefits of such projects and enhancing regional water supply safety. The Drivers-Pressures-State-Impacts-Responses (DPSIR) model was employed to establish a risk evaluation index system that reflects the characteristics of risk sources and risk receptors. A method of evaluating the risk grades of water pollution emergencies was proposed by utilizing the cloud model to quantitatively assess the risk water pollution emergency in the Henan section of the Yangtze River to Huaihe River Diversion Project. Findings revealed low risks of water pollution emergency in the studied section. Specifically, the risks of two sections were classified as significant (Level II), while five were designated as general (Level IV). These results aligned with qualitative evaluations considering risk source magnitude, risk receptor vulnerability, and risk control effectiveness. Our study offers a novel approach for assessing the risks of water pollution emergencies in water diversion projects and lays a foundation for risk management in the study area.
The river diversion project from the Yangtze River to the Hanjiang River serves as a supplementary water source for the Middle Route of the South-to-North Water Diversion Project. To ensure water quality safety in the middle and lower reaches of the Hanjiang River and to safeguard urban and rural water supplies in Hubei Province, it is essential to delineate a drinking water source protection area around the project’s water intake. In comprehensive considerations on water quality protection requirements, transportation and shipping, port construction and development, as well as emergency response needs, this study designs scenarios for various operational conditions, including different water levels of the Three Gorges Dam, representative flow rates for engineering diversion, and corresponding water quality conditions. It integrates hydrodynamic and water quality model simulations with emergency response time analysis to define and recommend the drinking water source protection zone for the Longtan Creek intake. The results suggest that the protection zone radius around the Longtan Creek intake should be no less than 1.3 kilometers. This recommendation provides technical support for the future delineation of protection areas.
To strengthen the comprehensive treatment of groundwater overexploitation and land subsidence in North China, the Ministry of Water Resources initiated a pilot project in 2018, focusing on ecological water replenishment in sections of the Hutuo River, Fuyang River, and Nanjuma River. We monitored phytoplankton and water quality factors from 2019 to 2022 in the Hutuo River and Nanjuma River, which have received ecological water supplement for five executive years (2018-2022), to evaluate the effects of the replenishment and explore phytoplankton community responses. Results indicate that ecological water replenishment gradually improves water quality from inferior-V class to II-class, reaching optimal conditions by the third year. Phytoplankton communities significantly altered in response to changes in environmental factors. Specifically, the density, biomass, percentage of cyanobacterial species, and the dominance degree of dominant species decreased over time, while the percentage of diatom species and density, Margalef index, Shannon-Wiener diversity index, and Pielou index increased. The dominant phytoplankton species shifted from cyanobacteria to diatoms and chlorophytes. Redundancy analysis (RDA) revealed that total nitrogen and pH were the primary environmental factors influencing phytoplankton community structure.
Studying the spatial distribution and influencing factors of biogenic elements is crucial for effective water quality management.We analyze changes in biogenic elements during dry season in the Guanshan River,a major tributary of the Danjiangkou Reservoir.We employed GeoDetector to assess the individual and interactive effects of meteorological conditions,terrain,land use,human activities,and other factors on biogenic elements. Findings indicate that during dry season,the Guanshan River is slightly alkaline and predominantly oxygen-rich,and exhibits significant spatial variability in parameters such as dissolved oxygen (DO) and total dissolved solids (TDS) along the main stream,though basic physical and chemical parameters do not differ notably between the main stream and tributaries. Inorganic carbon predominates in the river’s dissolved carbon content. The concentrations of carbon (C),nitrogen (N),phosphorus (P),and silicon (Si) are lower compared to some southern rivers in China,with notable spatial variations. The river does not exhibit eutrophication,and its water quality is generally good. A correlation exists among the concentrations of biogenic elements,with variations in dissolved inorganic carbon (DIC) and dissolved silicon (DSi) mass concentrations being effectively explained by precipitation,temperature,and elevation. Interactions among land use types and between land use and factors such as precipitation significantly enhance the interpretation of changes in biogenic element concentrations. These results are important for water environmental protection in the water conservation area of the Middle Route of the South-to-North Water Diversion Project.
As a research focus for ice-involved open channel projects, the roughness of ice cover is a fundamental parameter for determining the relationship between water level and discharge in open channels during freezing period. Given the current lack of data on ice sheet roughness in large-scale concrete channels, we investigated the channel section between Tanghe sluice gate and Fangshui sluice gate of the Middle Route of the South-to-North Water Diversion Project in the north of Shijiazhuang as a case study. Utilizing daily measured data of water level and flow rate from January to February 2016, we employed the Bernoulli energy equation and the Xie Cai-Manning formula to estimate channel roughness and analyze the changes in roughness before and after freezing, both qualitatively and quantitatively. The results are as follows: 1) The roughness coefficient nb of the studied channel during free-flow period is 0.016 7. The average comprehensive roughness nc of the ice sheet during freezing period is 0.014 6, and the average surface roughness ni beneath the ice sheet is 0.011 8. 2) Due to hydraulic abrasion, the roughness of ice sheet decreases over time during freezing. 3) Once ice sheet is formed in the channel, the water delivery capacity significantly diminishes, achieving only 66.7% of the designed flow rate. These findings provide a scientific basis for optimizing water transportation scheduling and designing similar engineering projects during freezing period.
Safe and controllable water hammer pressure is a necessary condition to ensure the stable operation of long pressurized piping system. However, in ultra-long pressurized pipeline system, extreme accidents such as local pipe bursts may paralyze the entire system or lead to secondary disasters due to the widespread propagation of water hammer pressure throughout the entire pipeline.To address this issue, we introduce a cylindrical overflow surge tower designed to block water hammer propagation. The surge tower features a vertical inlet pipe, which effectively segments the pipelines and prevents water hammer from spreading. We analyzed the hydraulic characteristics of this surge tower using both model tests and numerical simulations. Our findings indicate that the flow patterns within the tower are uniform, and the overflow water dissipates sufficient energy before entering the downstream pipeline. Finally, we describe the application of this surge tower to the Chaoer River to Liaohe River Diversion Project. Results demonstrate that the surge tower effectively blocks the propagation of water hammer in case of local pipe bursts, thereby mitigating the negative impact of water hammer on the entire pipeline system. The findings offer valuable insights into protection strategies against water hammer for ultra-long pressurized piping systems.
Bifurcated pipes constitute an essential part of water conveyance pipeline in water diversion projects. They are commonly used to connect large major pipes with branch pipes.To address the local low-pressure issue in bifurcated pipes, we propose using an elliptical arc chamfer design while maintaining the existing bifurcation angle. We investigated the flow pattern, pressure distribution, and head loss in both circular arc and elliptical arc chamfered bifurcated pipes using numerical simulations and verified the reliability of numerical results via model experiments. Our results reveal that, with only the main pipe in operation, the elliptical arc chamfered bifurcated pipe exhibits smoother water flow pattern and a 6.9% reduction in head loss coefficient compared to circular arc due to larger space and gradual change of flow section. This design significantly improves the local low-pressure distribution at the bifurcation, raising the minimum pressure by 1.47 meters compared to the circular arc chamfered pipe.On the contrary, when only the branch pipe is in operation, both circular arc and elliptical designs show similar internal flow pattern and pressure distributions; however, the head loss coefficient for elliptical arc chamfered pipe is 5.7% higher than that of the circular arc chamfered pipe.
Shihua sluice serves as the control hub for the Water Diversion Project from the Three Gorges Reservoir to the Hanjiang River. A double-layer gate layout is employed to address key technical challenges in hydraulic control such as high-head and long-pressurized water conveyance. Numerical calculations and hydraulic model tests were conducted to explore the hydraulic control technologies in the double-layer control gate. A one-dimensional and three-dimensional coupled mathematical model simulates the hydraulic transition process resulting from the opening and closing of the control gate, providing essential boundary conditions for engineering design. Physical model test analyzes the rationality of the control gate shape. Findings indicate that the maximum and minimum pressures throughout the system comply with relevant regulations. Parameters such as water flow patterns and pressure distribution are normal, and the shape configuration is appropriate. Overall, the design scheme for the Shihua sluice is effective. Its layout and our research methods offer reference for similar projects.
The Yangtze-to-Hanjiang River Diversion Project is the first large-scale project under construction subsequent to the South-to-North Water Diversion Project. Its diversion tunnel intersects the active creep Tongcheng River fault. Understanding the in-situ stress characteristics of the active fault is crucial for evaluating the project’s stability. The in-situ stress near the complex Tongcheng River active fault was measured, and the fault stability was analyzed to reveal the current geostress state and the critical conditions for fault slip instability. In-situ hydrofracturing tests were conducted in two nearly 1,000-meter-deep boreholes in the vicinity of the Tongcheng River active fault. The results indicate that the current stress state within the measurement depth is divided into two types. Specifically, the spatial principal stress state is hypothesized to transition from a composite (reverse and strike-slip) or reverse type to a normal type at approximately 900±20 meters depth. This suggests that the in-situ stress in the near field is influenced by intersecting faults. The direction of the maximum horizontal principal stress shifts from NW to NWW with increasing borehole depth, which aligns with the dynamic characteristics of active fault movement, the left-slip mechanism of intersecting faults, and the focal mechanism solutions. Finally, based on the measurement data and in line with the Mohr-Coulomb friction sliding criteria and Byerlee’s law, the stability of the active faults was analyzed. Findings reveal that the overall stress accumulation near the Tongcheng River active fault is relatively low and has not reached levels that would induce instability, suggesting that the crust remains relatively stable. These findings provide essential geological and mechanical data for assessing the stability of the Yangtze-to-Hanjiang River Diversion Project near the Tongcheng River active fault zone and offer valuable insights for engineering design across active faults.
High groundwater level is a most essential factor that threatens the safety of linings in large-scale, long-distance water diversion channels. Particularly when such channels traverse foothill plains, the lining stability is highly influenced by groundwater fluctuations in the foothill transition zone. A typical excavation channel section from the middle route of the South-to-North Water Diversion Project was taken as a case study. By utilizing groundwater monitoring data and a three-dimensional seepage model, we examined how groundwater changes affect the stability of the channel lining in line with the geological characteristics of foothill plain. For the first time, we elucidated the feedback relationship between water supply channel and groundwater in foothill plain and proposed relevant countermeasures. Our findings reveal that the channel intersects the surface permeable layer of foothill plain, creating a water-blocking effect. Rainfall and runoff from the foothill elevate the groundwater level between the foothill and the channel, directly resulting in uplift and damage of lining plate. The results offer theoretical foundation and technical support for designing, operating, and maintaining water diversion channels in similar foothill plain regions and for managing associated risks.
During tunnel construction, determining which advanced geological prediction method is most accurate and applicable under varying engineering geological conditions could be quite challenging. Single methods often lack sufficient accuracy and applicability. To address these issues, this paper introduces the principles and characteristics of advanced geological prediction technologies for long-distance tunnels using seismic wave methods and for medium- and short-distance tunnels using electromagnetic methods. We discuss the advantages and disadvantages of different advanced geological prediction methods based on their working principles, methods, and prediction ranges, and outline their most suitable scenarios. We propose a practical, comprehensive advanced geological prediction process, demonstrated through engineering examples from the Dali II section of the Central Yunnan Water Diversion Project. This process combines long-distance TSP method, medium- and short-distance TEM, and GPR to predict adverse geological features such as fault fracture zones and fissure water. Initially, we use long-distance prediction methods to classify the risk levels of geological disasters and identify high-risk sections. Subsequently, short-distance prediction methods more accurately identify and locate adverse geological features. By analyzing the geophysical response characteristics obtained from the three prediction methods, we evaluate the types and spatial distributions of adverse geological bodies. We also present a case study using GPR to detect dissolution, analyzing its wave-field characteristics to infer the physical properties, scale, and spatial distribution of dissolution features. The prediction results align closely with findings from tunnel excavation, validating the reliability of the three advanced geological prediction methods and confirming the practicality of the proposed comprehensive prediction process. This approach provides valuable guidance for geophysical exploration, enhancing the accuracy of geological predictions and ensuring tunnel construction safety.
At present, the reserved rock shoulder width of end-suspended piles and the embedded depth of support piles in foundation pits are mostly determined from the impact on internal forces and deformations of the upper support structure. This approach often overlooks the local stability issues near the bottom of the support structure. Based on the ultra-deep shaft project of the Pearl River Delta Water Resources Allocation Project, we identified three potential failure modes for end-suspended pile foundation pits with inclined structural planes or fractured rock masses. We employed the limit equilibrium method to calculate the stability safety factor and analyze the impact of various parameters on the safety factor under different failure modes, such as rock layer burial depth, mechanical properties of structural planes, rock shoulder width, and rock shoulder depth. Our findings reveal that the inclination angle of outward-dipping structural planes and the mechanical properties of structural planes or rock masses significantly affect the stability safety factor. This study offers valuable insights for similar projects.
In the aim of exploring the mechanical actions underlying the joint bearing of surrounding rock and stacked lining structure in cirlular hydraulic tunnel, this study focuses on the three-layer stacked lining used in the Pearl River Delta Water Resource Allocation Project. The lining structure comprises an outer concrete segment, a self-compacting concrete filling layer (SCC), and an inner steel tube. Using the power series solution of plane elastic complex function theory and stress function analysis, we established a mechanical model considering the interaction between surrounding rock and lining as well as stress boundary conditions. We derived and solved the stress components at any point within the surrounding rock and each layer of the lining under combined excavation load and internal hydraulic pressure. This approach elucidates the load transfer mechanisms and behaviors of the stacked lining structure. We verified the accuracy of our method by comparing boundary stress results with numerical simulations. Finally, through parameter analysis, we examined how increased internal hydraulic pressure affects radial and circumferential normal stresses in the surrounding rock and the three-layer lining. Results manifest that when the surrounding rock and the three-layer lining work together to bear loads, both the radial and circumferential normal stresses exhibit a cosine distribution, while the shear stress follows a sine distribution. As the water pressure inside the water conveyance tunnel increases, the three-layer lining and surrounding rock become increasingly compressed in the radial direction, while the circumferential normal stress tends to become tensile and increases. The research findings provide a theoretical foundation for the design and construction of multi-layer lining systems in hydraulic tunnels.
Water and mud inrush in tunnels crossing high-pressure water-rich faults is highly destructive with low groutability. To address this challenge, we examined the geological characteristics, disaster processes, and causes associated with water and mud inrush in the Xianglushan Tunnel of Central Yunnan Water Diversion Project as a case study. We propose a combined management strategy consisting of drilling, grouting, pressure relief, and support all in advance. To tackle the high content of fine powder in the surrounding rock of the tunnel’s lower half section, which impedes the diffusion of grouting slurry, we introduce a replacement grouting reinforcement technique. This technique involves dividing the grouting holes into top holes and back (or horizontal) holes. Grout is injected through the top holes, while pressure is released through the back or horizontal holes to flush out rock powder. This approach facilitates the removal of rock powder and improves slurry diffusion. Our method successfully resolves the water and mud inrush disaster in DLI3+681.5 section of Xianglushan Tunnel. The research findings offer valuable insights for managing water and mud inrush disasters in tunnels with similar geological conditions.
Evaluating the damage risk level of water and mud inrush during the construction under water-rich, high-pressure, and unfavorable geological conditions is a challenge for the construction design of underground tunnels. Analyzing the interactions between excavation stress and seepage is crucial for accurately simulating the evolution of water and mud inrush during tunnel construction. We propose a method to calculate the damage coefficient of surrounding rock corresponding to the damage characteristics in different deformation stages based on its damage evolution during excavation load release, and further examines how this damage affects the rock’s permeability coefficient. Furthermore, we introduce a calculation method for determining the critical water inrush coefficient of surrounding rock based on its failure characteristics and water inrush mechanisms. According to the damage and permeability of surrounding rock, we categorize the water and mud inrush damage into four risk levels, providing the basis for assessing the risk of such damage in underground tunnel construction. Finally, we present a coupling calculation method that integrates variable damage stiffness, weighted grading of excavation load, and iterative application of seepage load. This method simulates the evolution of water and mud inrush during tunnel excavation. Application of this method in engineering practice demonstrates its effectiveness, offering a viable approach for assessing water and mud inrush risks in underground tunnel projects.
To enhance the understanding of regional winter temperature variations and provide a scientific basis for optimizing water transfer and management during the ice period of the South-to-North Water Diversion Middle Route Project, we analyzed the daily mean winter temperatures from 1981 to 2021. Data were gathered from 10 national meteorological stations located along the section north of the Anyang River within the main canal of the Middle Route Project. We investigated winter temperature changes over the past 41 years using various methods, including the climate tendency rate method, cumulative anomaly method, Mann-Kendall mutation test, and Morlet wavelet analysis. The results are as follows: 1) From 1981 to 2021, mean winter temperatures at stations north of the Anyang River declined gradually from south to north. This trend is strongly synchronized especially among adjacent stations, with correlation coefficients exceeding 0.9. 2) Over the past 41 years, mean winter temperatures at each station showed a clear warming trend with fluctuations. Significant temperature changes occurred notably in the mid-late 1980s, early 2000s, and early-mid 2010s. 3) Within the analyzed time domain, most stations north of Anyang River followed a 40-year cycle as the primary temporal scale. Mean winter temperatures displayed a cyclical pattern of low→high→low→high and are expected to remain elevated for a period in the future. Such conditions facilitate effective dynamic scheduling during the winter ice period.
Tunnel lining concrete is a typical example of thin-walled, large-volume concrete. During construction, the high hydration temperature of pumped concrete and the significant constraints imposed by the surrounding rock often lead to temperature-induced cracking. To explore reasonable temperature control measures, we employed three-dimensional finite element software to analyze the temperature field and thermal stress distribution in a typical tunnel lining section of the Central Yunnan Water Diversion Project. Contact elements were used to model the interactions between the surrounding rock and the lining. Based on on-site monitoring data, we performed a feedback analysis on the surface insulation coefficient of the lining section, which was 16.7 kJ/(m2·h·℃). We investigated how different pouring temperatures, section lengths, seasons, and the autogenous volumetric deformation of concrete affect the thermal stress field of the concrete lining. Our findings indicate that higher pouring temperatures increase thermal stress; specifically, a 4°C rise in pouring temperature reduces the minimum anti-cracking safety factor by 0.30. The maximum stress exceeded 3.5 MPa when concrete was poured during high-temperature seasons. Appropriate segment lengths for the lining structure and micro-expansion concrete can enhance crack resistance. The findings offer valuable insights for temperature control in tunnel lining concrete for the Central Yunnan Water Diversion Project.
The study aims to investigate the influence of maximum grain size of coarse aggregate on the deformation of hydraulic concrete, and assess whether the aggregate sizes specified by national standards meet the performance requirements for hydraulic concrete. Based on the Yangtze-Huaihe River Diversion Project, we conducted deformation tests on concrete with maximum coarse aggregate sizes of 31.5 mm and 40.0 mm and examined the evolution law of long-term durability performance of both aggregate sizes. Results indicate that concrete with a maximum aggregate size of 31.5 mm exhibits slightly higher ultimate tensile strength and modulus of elasticity, along with improved dynamic fatigue performance. In contrast, concrete with a maximum aggregate size of 40 mm shows reduced drying shrinkage and autogenous volumetric deformation, with comparable creep behavior to that of concrete with a 31.5 mm aggregate size. However, concrete with a 31.5 mm aggregate size demonstrates superior long-term impermeability and frost resistance compared to concrete with a 40 mm aggregate size. Therefore, using a maximum aggregate size of 31.5 mm in hydraulic concrete not only meets the performance requirements but also enhances dynamic fatigue life and durability. Nonetheless, attention should be given to potential concrete cracking issues.
Compared to concrete dams, the thin-walled mass concrete structures of ship lock heads and pumping stations are relatively smaller in size. However, their structural forms and stress patterns are more complex, with significant constraints. These structures are constructed using pumped high-performance concrete, which generates more heat and heats up faster during the early stages than regular concrete. As a result, they are more prone to temperature-induced cracks during construction, making crack prevention a significant challenge in quality control. With the upper lock head project at Zongyang shiplock of the Yangtze-to-Huaihe River Diversion Project as a research background, we simulated and assessed the impacts of environment, materials, structure, and temperature control measures by using three-dimensional finite element approach. By analyzing temperature field, stress field, and crack resistance, we developed temperature control measures for the project. Our research identifies some functional areas of the upper lock head structure as more prone to cracking. These areas include the bottom plate, water conveyance gallery, pier wall, mass concrete around the empty box and the hoist room. Implementing a combination of temperature control measures, such as temperature-controlled pouring, water cooling, and surface insulation, with differentiated control strategies, can significantly reduce the risk of cracking. The findings offer valuable reference for crack prevention design in thin-walled structures of the Yangtze-to-Huaihe River Diversion Project.
The Tianjin mainline of the South-to-North Water Diversion Project established a settlement monitoring system in 2021, which includes 102 domestically produced BDS (BeiDou Satellite) monitoring stations. Approximately 6.4 GB of raw observation data and 2 125 settlement monitoring results are added daily. Due to the large span of the project and the consequent low efficiency of manual inspections, it is difficult to quickly and promptly diagnose the health status of monitoring stations. To address this issue, we propose an automated health diagnosis technology for stations with massive BDS deformation monitoring data. By assessing whether the multi-path error exceeds a threshold for a long time and whether the subsidence patterns change abruptly, we can timely diagnose the observation environment and stability around BDS monitoring stations. This enables rapid analysis and diagnosis of vegetation growth changes and abnormal soil subsidence changes around BDS monitoring stations at a lower manpower cost.
To address the high computational burden and low efficiency of time-series InSAR as well as the inadequate accuracy of traditional D-InSAR methods, we propose a TD-InSAR approach using continuous image pairs. This method enables rapid analysis of land surface deformation along long-distance water diversion and transfer projects through the HyP3 cloud computing platform. We validated the accuracy of the TD-InSAR land surface deformation detection by applying it to the Pearl River Delta Water Resources Allocation Project and comparing the results with traditional PS-InSAR monitoring data. Results demonstrate that TD-InSAR’s land surface deformation rate closely aligns with the trends observed in PS-InSAR, with a determination coefficient R2 greater than 0.7. Furthermore, TD-InSAR improves accuracy by 52.6% compared to traditional D-InSAR methods. The cloud computing-based TD-InSAR approach significantly reduces the computational burden of time-series InSAR analysis, enhances time efficiency, and is well-suited for large-scale, rapid survey of land surface deformation.
