Integrated Application Of Geophysical Methods In Yungang Grottoes

In recent years, Yungang Grottoes suffered serious geological diseases. In order to effectively curb the development of grotto disease, we need to comprehensively and accurately detect the rock mass strength and spatial distribution of abnormal geological body inside the grotto, and provide scientific basis for the management of various geological diseases such as water erosion and weathering. However, conventional method has difficulty to fully reflect the rock mass of the grotto and easily damage the grotto.To overcome the shortcomings above, this study will introduce a variety of geophysical methods into the protection of Yungang Grotto. Take the No. three cave in Yungang Grottoes as the research object, use three kinds of geophysical methods such as the high density electrical method, multi-channel transient surface wave method and seismic wave CT method to detect the grotto. The main work is as follows:investigate moisture content and thickness of rock by using the high density resistivity method; survey the wave velocity of rock by using multi-channel transient surface wave method and analyze the stratification thickness of the covering rock; investigate the cave walls by using seismic wave CT methods and analyze the spatial distribution of broken rock mass.Main conclusions are obtained as follows:1.According to different water contents,there may be a water flow path on the top of the cave, the direction is from the south to north.2.The distribution of rock quality is layered in the vertical direction:the upper rock mass is loose and weathering; the quality of central rock mass is relatively good; the lower rock mass is poor because of long-term weathering.3.Overall, rock strength of the No.three Yungang Grottoes decreased from north to south and decreased from west to east.There is a low velocity zone to the southeast of the grotto, this area have adversely influence to the stability of rock mass.This study adopts the method of comprehensive geophysical prospecting. Comprehensive considering three kinds of methods,the results are more reliable and more complete. It provides a certain basis for the protection and governance of Yungang Grottoes.