Research Of Karst And Soil Caves Exploration With Geophysical Method

In engineering construction and mine mining, because dewatering from underground unceasing increase, the karst collapse disaster is day by day prominent. In the collapse disaster, some of was caused by groundwater, karst scour cause, the other was caused by mining and drainage. Whatever the case, they were all for underground by "tunneling", and finally formed after empty, and then because of roof instability collapses, causing the geological disaster happening. So, how to use geophysical techniques found that has not been formed before the collapse of cavity or Dong Ti development degree, space scale, is the main purpose of this research. Because of geophysical techniques have its conditional, limitations, redudced, a reasonable choice and use one or several detecting karst and soil caves geophysical exploration methods and the methods of research and evaluation, is the main content of this paper. Based on detailed summary and analysis of geophysical exploration methods researches in domestic and abroad including respectively the GPR (GPR), borehole wave method, resistivity method, shallow earthquake reflection method, imaging method and rayleigh wave method, try to find out their respective merits theoretically applied in cavities or mined-out area,.The author analyzed geological forming mechanism of karst and soil caves, the development of karst collapse features and forming mechanism, karst collapse and the development of soil caves. Summarizes the karst and soil hole embryonic stage and stable stage of geophysical characteristics, and listed under various conditions electrical differences abnormal, wave impedance abnormal, dielectric constant abnormal geophysical typical profile. A detailed discussion on the electrical method of the high density resistivity method of theory and its principle, installation; Dielectric constant difference method of GPR method and borehole wave method of the basic principle and practical use of case; Wave impedance differences method of shallow seismic reflection method and imaging method and Rayleigh wave method of general survey principle and application scope. Through analysis and comparison, finally to karst and soil caves detection methods are summarized and selection, determine the karst and soil caves the best combination method to detect. This paper also from karst and soil caves detection task departure, the normally requirements to geological tasks and technical requirements of geophysical techniques are formulated, briefly introduced the selection principle and geophysical prospecting work arrangement principle, carry out high-density electrical method and high density seismic imaging method requirements of the geophysical instruments and parameter setting, general specification of the requirements, geophysical data processing and interpretation methods to do a detailed design points. Papers were selected for two typical project cases were analyzed:GuLian city work xiangtan baishi survey base selection and hunan fenghuang new bridge are very geophysical survey. Theoretical analysis is verified the results of reasonable and effective.