Study On The Application Of Comprehensive Geophysical Exploration In The Integrity Testing Of Cut-Off Wall Of Reservoir Dam

As an important part of water conservancy and hydropower projects,cutoff wall is mainly used for seepage prevention treatment of reservoir dams.In order to ensure that it can play a role in preventing reservoir dam leakage,it is very necessary to carry out integrity detection and quality evaluation on the cutoff wall.At present,Integrity testing of cutoff wall mainly includes geophysical methods,traditional core drilling and water injection test methods,etc.In contrast,traditional method has the limitations of low construction efficiency,easy damage to the wall and the like.However,geophysical methods are highly efficient,non-destructive and continuous,and are gradually being popularized and applied in actual water conservancy projects.In order to further improve the reliability of geophysical detection methods,On the basis of analyzing the research status of detection methods and combining with the construction characteristics of cutoff wall,it is determined that seismic imaging method and high density resistivity method are adopted to carry out application research on integrity detection of cutoff wall.The details are as follows:(1)For the complete and incomplete(defective)cutoff walls,The numerical model and indoor physical model are adopted for simulation analysis.The simulation results of seismic imaging method show that,The cutoff wall shows different seismic wave field response characteristics under the above two conditions.The response law of seismic wave field under the conditions of complete and incomplete(defective)of cutoff wall is revealed.According to the physical simulation results,Compared with the complete cutoff wall,the simulation results of the cutoff wall with defects show the characteristics of poor continuity of in-phase axis,abnormal waveform recording,etc.It provides the basis for anomaly discrimination in actual engineering inspection,and illustrates the effectiveness and reliability of this method in the integrity inspection of cutoff wall.(2)In this paper,the high density resistivity method is used to carry out the numerical simulation calculation and physical model experiment on the incomplete(defective)cutoff wall.The method mainly comprises the following steps of injecting saline water into one side of the cutoff wall,and collecting apparent resistivity data before and after injecting saline water on the other side.Based on the change of resistivity anomaly coefficient before and after brine injection,the integrity of cutoff wall is tested and evaluated.The simulation results show that,In the process of cutoff wall integrity detection by using the high density electrical method and the above observation system arrangement mode,With the increase of the amount of saline water injected and the increase of the water injection time,the apparent resistivity changes obviously before and after the water injection at the defects of the wall structure.This shows that this method and the arrangement of corresponding observation systems are effective in the application of wall integrity detection.Figure [51] table [0] reference [69]...