Experimental Study On The Shallow Transient Electromagnetic Of Prospecting Technology

The problem of city underground space foundation condition has been paid more and more attention,especially shallow geological problems such as old cities cluttered urban pipeline,karst distribution area of ground foundation and disease dams,caused harm more and more serious,therefore,it’s appear more important and urgent that detecting shallow geological problems with the high precision and high efficiency.Based on above-mentioned current situation and the theory of the whole course transient electromagnetic method,The paper deals with the study of detecting shallow surface geological problems with shallow surface transient electromagnetic prospecting technique.Based on theory of the whole course transient electromagnetic method,compiled program which simulate the whole transient electromagnetic field response to shallow surface geological problems,and then visualization treatment and analysis for simulated data with post-processing software(Voxler),the shallow surface transient electromagnetic prospecting method is done to validate the feasibility and validity of detecting shallow problem in theory.According to the type of shallow geological problems,using the physical model experiment this paper mainly studies the variation regularity of several special abnormal body(sphere,cylinder,plate body,fault),high and low resistivity of the pipeline,the basis of the limestone foundation in building fields,and the corresponding relationship between whole course apparent resisitivity abnormal response and targets; Compared with the results of DC electrical method and test in fields,further validation feasibility and effectiveness of the method of detecting in shollow geological problem fieldsAfter numerical simulation and physical model experiment,detecting application comparison experiments were conducted in field.Results of comparison experiments show that shallow TEM technology can reflect the depth of the shallow target body and spatial distribution characteristics accurately and detecting the high,low resistivity target body accuracy in laterally positioning,respond of low resistivity deeper than the actual vertical position,vice verse is reverse.The results of experimental make great guiding significance on scene detection test.Finally,after thinking about the existing problems of the shallow transient electromagnetic exploration technology with low resistivity layers of target detection problems and shallow transient electromagnetic instrument development,the paper provides research ideas for well develop of the shallow transient electromagnetic exploration technology in the future.