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Illustration of well-logging with natural tracer: (a) on-site photo; (b) sketch of the logging process.
Source publication
Leakage is a common phenomenon in dams, and its early detection is critical for dam safety. In the present study, a new method based on tracer tests is applied to detect and quantify leakage in the Wanyao Dam, Jiangshan City, China. The objective is to detect the leakage zone of a dam wall by combining the natural tracer test and the artificial tra...
Contexts in source publication
Context 1
... automatic probe provided by Solinst Canada Ltd. was used to record temperature, EC, and water level at every second with a high precision level of 99.5%. Figure 4a is an on-site photo depicting the well-logging procedure. The probe connected to a cable was placed into the bottom of each borehole to log temperature and EC at various depths (Figure 4b). ...
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... 4a is an on-site photo depicting the well-logging procedure. The probe connected to a cable was placed into the bottom of each borehole to log temperature and EC at various depths (Figure 4b). ...
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... and EC profiles of all boreholes inside the dam are given in the Supplementary Material. These are illustrated the following figures: (1) Figure S2 for dam section III, (2) Figure S3 for dam section IV, (3) Figure S4 for dam section VIII and X, and (4) Figure S5 for dam section IX. Comparison of temperature and EC profiles show that temperature profiles have better performance in revealing the flow field in boreholes than EC. ...
Citations
... Rockfill dams exhibit excellent adaptability to various foundations and are widely used in areas with deep overburden. However, the complex geological and topographical conditions in these areas, combined with uncertainties in the materials used to build rockfill dams, have resulted in failures like cracking [8,9] and seepage [10,11] during construction and operation. These issues have hindered the development of high earth-rock dams and increased safety risks [12]. ...
Rockfill dams are the most competitive type of dam in complex geological environments. Identifying the failure modes and causes in high dams over 100 m is critical for better guiding high dam designs and implementing safety prevention and control measures. To this end, this paper investigated numerous cases of earth–rock dam breaches and failure modes in rockfill dams globally, with a particular focus on dams over 100 m in height, encompassing all such dams in China. The study categorized dam failure modes based on whether the dams were built before or after 1980. It also examined the causes of dam failures in terms of dam height, foundation characteristics and thickness, and failure time. Additionally, the paper analyzed a rockfill dam in China, with a height of 136 m and over ten years of operation, as a case study. We analyzed the spatial and temporal characteristics and causes of failures, such as dam crest cracking, high-level seepage, and gallery cracking, using the design situation, monitoring data, and numerical simulation. The paper also addressed issues related to dam design and foundation treatment, providing recommendations for improvement. The study indicated that the overall risk of total failure for dams over 100 m is already low. However, longitudinal cracks on the dam crest, core wall seepage, hydraulic splitting, and seepage damage to the dam foundation are primary issues in the current high core wall rockfill dams. These issues are mainly caused by uneven structural deformation of the dam and its foundation. A reasonable design of rockfill materials and foundations can mitigate these failures.
... In recent years, the tracer technique has been gradually applied in the seepage detection of the reservoir dams. Qiu et al. [20] implemented an enhanced tracer test methodology, integrating both natural and artificial salt tracers, to quantitatively assess the leakage at Wanyao Dam, and conducted a detailed analysis of the leakage rate. Hua et al. [21] developed an innovative dimension reduction model (DRM) based on tracer test results, which effectively characterizes fractured networks and predicts the flow and transport within the fractured aquifers, further demonstrating its applicability to fractured network characterization at the field scale. ...
In areas with complex hydrogeological conditions, the tracer test method is often used as an effective means in hydrogeological surveys. According to the results of tracer tests, hydrogeological parameters, including hydraulic gradient and permeability coefficient, fracture network leakage passages and their scale, and groundwater flow rate and direction can be quantitatively determined. This paper takes the upper reservoir of Yongxin Pumped Storage Power Station in Jiangxi Province as the research object, and focuses on the complex hydrogeological conditions of the upper reservoir. Three sets of tracer tests and multiple sets of single-hole flow rate and direction tests were conducted on the left and right banks of the reservoir and near surface gullies. The results showed that ZKS18 received tracers in all three tests, which indicates a close hydraulic connection between ZKS18 and the left bank, right bank, and surface gullies within the reservoir. Based on the single or multiple peak values of the tracer, it was determined that there are 1–6 leakage passages in the fractured rocks, with leakage passage sizes of 0.1–0.4 mm. According to the single-hole flow rate and flow direction tests, a self-developed instrument was used to determine the groundwater flow rate and flow direction at different depths in the test holes, which yielded results that were basically consistent with the results of the three-hole method. These results provide a basis for the use of tracer tests in hydrogeological surveys for water conservancy and hydropower engineering, and anti-seepage design of upper reservoirs.
... While geophysical methods for dam investigation, such as radar (Hui & Haitao, 2011;Bigman & Day, 2022), micro-seismic (Hickey et al., 2010), and resistivity (Kukemilks & Wagner, 2021;Zumr et al., 2020), focus on providing a visual representation of the seepage zone, the tracer method is considered an empirical technique that enables the determination of flow path direction and water velocity in the dam body and foundation (Bedmar & Araguas, 2002;Qiu et al., 2022). A tracer test is conducted by introducing artificial tracers like saline, ethanol, or fluorescent substances at a known upstream location and monitoring their concentration over time at target sites such as piezometers and downstream leakage points. ...
The local pore water velocity along the preferential flow path signifies the hydraulic parameter responsible for erosion within an earthen dam. This study introduces an empirical approach to ascertain the local pore water velocity within the earth dam's leakage zones by monitoring the travel time of the salt tracer through the corresponding electric potential anomalies in the ground. The alignment of electric potential anomalies with the movement of the salt tracer plume over time was confirmed through experiments on a physical model coupled with numerical simulations. The pore water velocity, calculated based on the location of the maximum electric potential anomaly, demonstrated excellent agreement with the experimental value, with an error of under 6%. For illustrative purposes, a field-scale salt tracer test was conducted at a leaking earthen dam in Vietnam. The tracer breakthrough curve originating from the leakage point revealed that the seepage water's travel time is approximately 40 days. The results of electric potential anomalies over time indicate that the pathway of seepage flow from upstream to the leakage point forms a horizontal V-shape, with the local pore water velocity ranging from 1.7 to 9.9x10-5 m/s. These local pore water velocities are subsequently compared with the critical seepage velocity to assess in-situ information regarding the internal erosion status of the target dam.
... Using different environmental isotopes, electrical conductivity and hydrochemical analysis to comprehensively determine the source and path of leakage will undoubtedly enhance the reliability of the investigation results (Qiu et al. 2022). However, this method of artificial comprehensive judgment is still not totally comprehensive and objective (Wang et al. 2015). ...
Earth/rock-fill dams and embankments are the main water retaining structures in hydraulic projects, and they can effectively resist floods and are of great significance for protecting people's lives and property. Leakage is a common problem in these structures. Investigation activities, including geotechnical, geoelectric, and tracing methods, are required to locate the leakage path and provide a basis for risk mitigation and reinforcement. These three methods provide information on different leakage characteristics, uncertainties, and spatiotemporal distributions. This work first introduces the micro-mechanism of internal erosion and then, provides a site case base for leakage investigation of earth/rock-fill dams and embankments from all over the world. For each investigation method, the basic principle, investigation process, data interpretation, and future potential are summarized. It should be emphasized that geotechnical, geoelectric, and tracing methods are placed on an equal level to assist dam managers and researchers in selecting the most appropriate method to assess dam leakage against specific geological backgrounds and structural types. Finally, the advantages, disadvantages, and applicable conditions of each investigation method are compared. The role of surface investigation methods and internal investigation methods in different stages of leakage is explained. The application of combined methods is discussed at four levels, and a new combined method is proposed.
... The objective was to locate water leakage paths at the dam [18]. Qiu et al. [19] employed a new method based on tracer tests to detect and quantify leakage in the Wanyao Dam in Jiangshan City, China. By combining natural tracer tests and an artificial tracer test with salt, the leakage zone of the dam wall can be identified. ...
Based on the hidden karst exposed in Jurong Pumped Storage Power Station, combined with the field exploration data, the temporal and spatial development characteristics of hidden karst in the power station area are analyzed using the methods of specific solubility and specific corrosion, water chemical composition analysis, borehole television imaging, tracer test, and water pressure test. The results show that the karst development in the study area can be divided into three periods: pre-Cretaceous, Pleistocene, and modern karst. Karst development is controlled by soluble rock, non-soluble rock, and their combination, and the development direction is basically consistent with the fault strike. Karst caves are mainly distributed below the elevation of 100 m, with different shapes and scales and randomness. Non-soluble rocks and impure carbonate rocks are widely distributed in the study area, and surface karst is not developed. The underground karst caves are filled with red clay, and the rate of groundwater circulation is slow. The existence of geological bodies such as rock veins causes the groundwater levels to have obvious double-layer characteristics, which results in weak connectivity between karst caves. Although the karst in the power station area has a certain hydraulic connection with the surface water outside the area, the hydraulic connection of karst in the power station area is generally weak. The research results provide a scientific basis for the anti-seepage measures of underground powerhouses.
Accurately exploring whether fractures are interconnected and whether water can flow through them, as well as quantitatively describing how underground water systems are affected by mining activities, is crucial for the safe exploitation of mineral resources and for protecting ecological water resources. Traditional groundwater level monitoring and geophysical techniques are unable to visualize many of these mining-triggered effects on the hydrological system, as well as the sources and vertical seepage paths of water inflow. A method combining particle-magnetic heading optical tracking technology (PMHOTT) and an artificial tracer test was proposed to address this problem. This method tracks and calibrates the water flow rate, velocity, direction, and dynamic composition of water flowing into the working face through in-situ monitoring and multi-aquifer tracer penetration flux-time relationship analysis. By analyzing hydrological metrics, the impact of mining activities on the groundwater system and the dynamic changes of the flow field within the effective influence area can be determined. The results indicate that the PMHOTT monitoring data, after correction, overcame the deficiency of insufficient observation boreholes in traditional water level monitoring, and accurately captured flow field changes in the area most affected by mining activities. Meanwhile, by considering the interaction between multiple tracers, we successfully identified the sources of water inflow entering the mine as well as the groundwater seepage path. This study accurately evaluated the development height of water-conducting fractures and quantified groundwater flow time, expanding the applicability of artificial tracer test in the fractured aquifer. This will be useful for predicting and preventing mining water hazards under complex hydrogeological conditions.
As the first barrier of flood control, the integrity and continuity of dams are of the utmost importance. However, with the influence of natural weathering, running water erosion, and humanistic factors, various degrees of damage are prone to occur inside and outside dams. Therefore, it is necessary to detect the integrity of dams and evaluate their flood control capacity. Different from the previous detection of water-filled imperfect areas, we used numerical simulation and measured data analysis and considered the influence of actual noise to conduct DC resistivity detection and 2D inversion research on the high-resistivity imperfect areas existing in dams. The research results show that both the calculated apparent resistivity and the resistivity obtained by 2D inversion deviate from the real resistivity of the dam. A dam with a height less than 5 m has a relatively small influence on the 2D inversion results of the DC resistivity method, and the inversion results can accurately show the spatial information of the high-resistivity imperfect areas. The distance between the river and dam has a major influence on the inversion results, but the influence on the inversion results can be ignored when the distance is greater than 20 m in the model of this paper. The 2D inversion of the DC resistivity method can be used to detect high-resistivity imperfect areas of dams, and the 2D spatial information of the 3D geological bodies can be accurately obtained.
