Experimental Study And Application About Transient Electromagnetic Method In The Detection Of Underground Cavity

At present, with the establishment and improvement of the economic system, the infrastructure investment in China’s central and western regions is expanded gradually and the underground engineering construction has obtained rapid development, but it also has accompanied some problems by underground space. These common adverse geological bodies, such as faults, fissures, karst and other large cavitation, often become the most important and difficult problems in the construction field of underground space in China. If the underground space is rich in groundwater resources, and has a large area of fissure karst, there will be serious accidents and will have seriously impact on the quality and schedule of construction. Therefore, it is very necessary and pivotal to use the rapid, efficient, and lossless detection method for advance geological prediction to solve the cavitation problems in construction of underground engineering.The transient electromagnetic method (TEM) has the characteristic that it’s very sensitive to low resistivity body, so it has important significance and broad development prospects that the transient electromagnetic method is applied to advance geological prediction for the bad water-bearing geological body. Although domestic and foreign experts and scholars have research more on the transient electromagnetic technology, but it still has certain limitations to advance geological forecast, and so far, it has no unified interpretation mark and interpretation method that is the biggest bottleneck of prediction results, and this also greatly reduces the prediction accuracy. Therefore, in the study about TEM for advance geological prediction, first of all, a comprehensive interpretation method should be summarized to find the regularity of interpretation and explore the signs of interpretation, and it has very important significance to advance geological prediction using TEM.In this paper, the study on advanced geological forecast is carried out in domestic common large hole, such as coal mine goaf, loess holes and tunnel karst, by using the transient electromagnetic method based on the previous analysis of research results about the transient electromagnetic method. Then, the forecasted results are analyzed and compared with that forecasted by TEM combined with the geological conditions, original drilling conditions and actual excavation. On this basis, the data interpretation is summarized, and it obtains a good application effect. At the same time, the general rules of geological interpretation are found based on interpretation maps which are received through the analysis on large holes of different types and combining with the corresponding transient electromagnetic response characteristics, and the experience of practical application. Finally, interpretation methods of TEM are analyzed and summarized combined with the application of transient electromagnetic method in the existing research results and the general rules, and a set of interpretation marks are explored.The researches in this paper make detection have the further understanding which is about the common large holes problems in the underground engineering construction field and provide the basis for future design, construction and management. It can maximumly increase the precision and speed of advance geological forecast to this kind of problem and explore the deep study of advance geological forecast in china.