Comprehensive Research On Weathering Sand Barrier Pillar Of Yungang Grottoes

Yungang Grottoes has a very high historical and cultural status among Chinese Grottoes, which is the treasures of Chinese Grottoes art culture. With a thousand years history, the weathering of number 9 and 10 Caves in Yungang Grottoes before the column column is more and more serious. The external stone has been completely lost.weathering has affected the stability of the grotto structure, therefore, the degree of its weathering survey is a matter of great urgency which promote the processing of stability of the pillars to be assessed is particularly important.Based on the previous study of ultrasonic and steady-state rayleigh waves and according to the principle of ultrasonic and steady-state surface wave propagation,this paper theoretically and experimentally verified that the ultrasonic method and the steady-state rayleigh waves method can theoretically determine the degree of weathering And the high-resolution and high-efficiency and non-destructive characteristics of ultrasonic wave and steady-state rayleigh wave were used to verify the weathering of the east column of Yungang Grottoes. After field investigation and verification, the data were collected. through data preprocessing, data analysis, data processing, and combined with the region of drilling data, the final analysis results have been further verified. The results show that the ultrasonic method can be used to detect the weathering degree of the rock, and the steady-state rayleigh waves method can be used to detect the weathering degree under the condition of coupling.After field investigation, the following conclusions are drawn. Firstly, the overall pillar from top to bottom, surface strong weathering layer in turn is increasing. The top surface of the pillars in south of the south, the east of the south, the east of the east is strongly weathered, and the others is middling weathered; The bottom of the stone pillars,surface weathering is more serious,only the west,southwest of the surface is middling weathered,the rest of the south,south,east,north east, north north, northwest and other directions are strongly weathered; Secondly, the weathering of the south side of the pillar is more serious than that on the north side, and the degree of weathering on the east side is more serious than that on the west side. The bottom of the weather is more severe than the top. Northeast of the survey area are characterized by strongly weathered, which is easy to fall off the surface of loose. West, north-north direction are middling weathered, which surface is hard and hard to fall off. Thirdly, the pillars as a whole from top to bottom, unweathered column core cross-sectional area gradually increased; weathering layer gradually thickening. The depth of the non-weathered layer is about 49 ?53cm,and the depth of the non-weathered layer is about 48-72cm,and the depth of the non-weathered layer is about 43?77cm.Through the investigation of the internal velocity of the stone pillars, the distribution of the weathering layer of the stone pillars is acquired. This result provides the basis for the determination of the mechanical stability of the pillars, which can promote the scientific protection of the Yungang Grottoes column. At the same time,this research can provide some reference for the non-destructive testing and protection of other stone cultural relics.