| Transient Electromagnetic Methods(TEM), as an electrical branch approaches, has experienced rapid development in recent years. It has the advantages of deep detecting depth, strong adaptability, high sensitivity and resolution and in the wild the instrument deft, collecting data fast and low cost. TEM widely used in city construction, transportation, water conservancy, environmental protection, archaeology, etc. TEM which is one of the important methods in the fields of the geophysical exploration successfully solves many practical problems has the extremely broad application.The transient electromagnetic method is a kind of time domain electromagnetic induction method. TEM which is based on the process of transmitting the primary electromagnetic impulse to underground with ungrounded loop receives the induction secondary magnetic which is the unsteady magnetic field caused by the eddy of underground good conductive geological body driving with the same loop or another during off period of the primary field. Just theoretical basis is concerned, frequency domain electromagnetic method and the time domain electromagnetic method is the same, both are the research of electromagnetic induction secondary field. Because of the time domain method in nonexistent primary field cases is receiving the secondary field and the main noise source different from the frequency domain method, TEM shows more advantages.This thesis finished mainly based on the research project"The Application in Traversing Projects with the Geophysical Techniques"(Project Numbers: XN10D/WX39) of Southwest Branch of CPE. In the first chapter reviews the development history of TEM, and briefly introduces the current situation of the application of TEM on rivers. The second, third, and fourth chapters introduce the basic theory and characteristics and the field work method of TEM, and introduce the method and process of data processing with taking a kind of data processing software as an example. The fifth and sixth chapters mainly for the simulation studies of TEM on river with the different parameters contrast, and then applied TEM in two engineering example of the Jialing River and the Fujiang River for analyzing and evaluating application effect with geological data and borehole data. The last part is the conclusion. The main research results in this paper are as follows:(1) In order to further study the actual TEM exploration on river, we adopt ATEM-3 transient electromagnetic instrument and overlapping loop separately taked a series of device parameter contrast simulation tests of the superposition times, single circle coils area, connecting wires length and more circle coils size and so on. Through the simulation test, we have the in-depth understanding of Geophysical meanings of all kinds of parameters for the TEM equipment, and preliminarily track out the suitable parameter settings for application of TEM on river in the wild.(2) Based on the simulation test, the TEM applied to the Jialing River and Fujiang River exploration in practice, and to contrast the exploration results with the borehole data and explanation results of the seismic exploration in the same area. It shows that the transient electromagnetic method for engineering geology exploration on the river, TEM has great exploration depth, and high efficiency. TEM achieves good results in engineering investigation on rivers. Because of the river application of TEM is not very mature, the transient electromagnetic method still exists many drawbacks.(3) Summarizes the experience and effectthe of the transient electromagnetic method on river application, puts forward problems needing attention of data collection, data processing method and explanation in wild on river. And also points out the problems needed to improve and solve applied TEM on river, and lays the foundation for further work. |
PDF Full Text Request