Research And Application Of Comprehensive Electrical Method In Dam Leakage Detection Of Qianyaozi Reservoir

Leakage will lead to the reservoir water level of hydraulic construction can not reach the designed normal storage level,affect the normal use of the reservoir function,reduce the benefits of water conservancy projects,serious leakage problems will lead to reservoir abandonment,sudden dam break will endanger the safety of production and life of downstream residents.Therefore,timely leakage detection of dams with potential safety hazards is of great significance to protect the lives and property of the downstream residents of the reservoir.In the process of reinforcing and removing dangerous embankments,it is a prerequisite to find out the causes of dam leakage and to judge the leakage passage for rational selection of anti-seepage measures.The comprehensive electrical method was used to detect the leakage passage in detail,including pseudo-random flow field method,transient electromagnetic method and high-density resistivity method.Qianyaozi Reservoir is located in Inner Mongolia Autonomous Region and Linger County.On Huanghe River,the first tributary of the Yellow River,the reservoir dam is a homogeneous earth dam with sandy loam soil.Due to years and various reasons,the dam has many leakage.The detection and research of leakage passage are mainly based on pseudo-random flow field method,transient electromagnetic method and high-density resistivity method.Firstly,based on the basic principles of three kinds of electrical methods,combined with the seepage detection area of Qianyaozi Reservoir,this paper establishes physical parameter model,carries out forward simulation and inversion calculation of TEM and high density resistivity method,and theoretically discusses the feasibility of different geophysical methods in seepage detection of different parts of dam.Secondly,according to the work practice and the site conditions,the criteria for anomaly discrimination of three geophysical methods are determined.The data acquisition and analysis of all parts of the dam are completed to determine the seepage area of the water surface in front of the dam and the location of the seepage area in front,top and back of the dam.The specific direction of the seepage channel and the elevation of the seepage channel in the seepage area are emphatically studied to provide the basis for the later reinforcement.Finally,through the field work research of dam seepage detection and the summary of other reservoir seepage detection experience,a comprehensive analysis system is established for the determination of seepage passage in dam seepage detection process: geophysical detection method is the main method,relying on regional geological conditions and field conditions can affect the objective conditions of instrument detection,eliminating the abnormal interference in the seepage area;and dam is the main method for the determination of seepage passage in dam seepage detection process.The post-outlet point is used as the reference point to judge the general trend of the leakage area;the influence of the reservoir storage height on the post-dam outlet point,or the height of the leakage passage can be judged by the change of the water level of the observation hole;and the previous survey data can be used as an effective reference.The specific direction of leakage area and passage is determined from many aspects.