Research On Methods Of Detecting Wall Leakage And Groundwater By Spontaneous Potential And Artificial Potential

The leakage of the water stop curtain can be detected by measuring the water distribution under the soil layer by using the spontaneous potential and the artificial potential in the foundation pit,because the leakage will cause the charged ions in the water to aggregate and diffuse to generate an electric field.Such a weak electric field requires a high-precision potential measurement system,which can be obtained by measuring the potential distribution of a certain area(with the help of a multi-channel system).Potential anomaly locations and distributions were found from the measured potential distributions,and leakage points were obtained in conjunction with the curtain structure.Before excavation of the foundation pit,the potential anomaly caused by the leakage of the water-proof curtain buried in the soil layer is detected by spontaneous potential.The deeper the burial,the smaller the potential anomaly measured on the ground.At this time,an artificial potential is applied in the borehole outside the foundation pit,and the applied current flows into the foundation pit through the leakage site,generating a strong electric field,so that the potential anomaly generated at the leakage point or the weakened surface is amplified to achieve active tracking.Based on the theory of stable current field,the related theories and field experiments are studied in this paper.The method of combining artificial potential and spontaneous potential is adopted.Firstly,the electric field distribution in a homogeneous medium is analyzed,the electric field distribution in a three-layer medium is studied by the mirror method,the water-stop curtain is simulated,and finally the electric field caused by leakage is added.According to the superposition theorem of the electric field,the actual measured potential signals are divided into useful signals and unwanted signals,and the measured potential distribution is comprehensively analyzed.The interference of the electric field excited by the electrode to the useful signal was eliminated,and the abnormal potential distribution caused by the leakage was obtained.Then,the location of the leakage was comprehensively judged by the relationship between the spontaneous potential and groundwater leakage.Using the developed experimental equipment,experimental tests were performed at two construction sites,and the theoretical model was experimentally verified.The difference between the collected potential distribution curve and the theoretical model was found,and the theoretical model was repeatedly improved.Finally,the spatial distribution of groundwater was successfully explained.