The Research And Application Of Integrated Geophysical Methods On Accumulation Body

Accumulative ground was an unreasonable geological phenomenon in hydrogeology engineering whose existence greatly affected the safety of reservoir and dam. To efficiently deal with this, a clear recognition for the thickness, size, structure and morphology of these deposits was needed. The commonly used method for detection was based on the single geophysical method due to which the creditableness and accuracy were relatively low. Nowadays, the report for synthetic geophysical method which was used to detect the accumulative body was few. Once a thesis was discussed the synthetic detection by employing both the direct current method and seismic prospecting. However, besides both of the two methods were confined to some certain cases, no further research was implemented. Meanwhile, this technique only aimed to dealing with some special accumulative bodies due to which the generality was lost. The other reports which adopted the synthetic technique for detecting accumulative bodies were relatively few. Moreover, no systematical study and summary was reported. Aiming at solving these problems, our achievement has made a distinctive breakout; a novel idea named synthetic detection with synthetic interpretation was carried out. With this method, the accuracy of geophysical prospecting for the accumulative bodies was dramatically improved by which the development of geophysical prospecting for accumulative bodies was greatly promoted. The main content and some novel result were list as follows:1. A systematical summary was executed based on the amount of experiments for analyzing the topography, geomorphology, thickness and the characteristics of the combination for the accumulative bodies. By combining geophysical properties of accumulative bodies, a new division was made. We divided the common accumulative bodies in to four types, namely loose-bridge-type(I-type),slumping-type(II-type),ice-waterand moraine-type(III-type) and huge-thickness-type(IV-type). This division which has a breakthrough for the conventional division method made selecting suitable method of geophysical prospecting easy. 2. A detailed geological study was made according to the divided accumulative bodies by geophysical rule. Based on this the corresponding geological models (including the typical geological profile) and geophysical models was presented. Meanwhile, the simplification for the geophysical models was implemented by which two classes of simplified geophysical modes were formed. With this work, we had provided a basis for the study of prospecting method.3. A systematical study for seven kinds of commonly used method for detecting the accumulative bodies was made with their principles, technique features, field work method and data processing. Through combining the two kinds of simplified geophysical models from the four kinds of accumulative bodies which were obtained by the general geophysical rules, the forward modeling was implemented. The results have shown that each geophysical method could be used for all the four kinds of accumulative bodies.4. Based on this, a novel thought which had a great breakthrough for interpretation by using only single geophysical method was made. Meanwhile, a synthetic method of geophysical prospecting for detecting accumulative bodies (including detecting method and interpretation) was presented. Moreover, an optimal combination for detecting each kind of accumulative bodies by synthetic geophysical method and each weighted coefficient of each prospecting method was provided.5. A whole process for the computation of the thickness and size of the accumulative bodies by synthetic method was implemented with the computational method and the required formulas for the thickness and volume size of accumulative bodies by using synthetic geophysical method being deduced. The software used for practical application was developed which has won the first prize of annual project survey and design computer program, Yunnan, 2008.To validate the generality of the system of synthetic geophysical prospecting method, we had an experimental summary based on the four kinds of accumulative bodies. Finally, with this guideline of the theory, two engineering application for prospecting accumulative bodies were executed. With the examples, the priority and accuracy were demonstrated again for prospecting accumulative bodies by synthetic means.