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| Anisotropy research of excavated fractured rock mass based on slowness vector and polarization vector
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| LIU Xiaoping1，2，CHEN Zhanguo3，LIU Yonghua4，LI Ning1，WANG Yutao2，CAO Xiaoyi2，LI Linyuan2 |
| (1. School of Civil Engineering and Architecture，Xi'an University of Technology，Xi'an，Shaanxi 710048，China；2. Xi'an Research Institute，China Coal Technology and Engineering Group Corp，Xi'an，Shaanxi 710077，China；3. Sinopec Geophysical Research Institute，Nanjing，Jiangsu 211103，China；4. College of Geology Engineering and Geomatics，Chang'an University，
Xi'an，Shaanxi 710054，China) |
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Abstract The formation anisotropy induced by mining-induced fracture is one of the key scientific problems of mine disaster prevention and environmental protection. Based on the disturbance theory of seismic wave propagation in anisotropic media，artificial source excitation and Walkaround VSP three-dimensional three- component acquisition technology were used to extract the slowness vector and polarization vector of direct qP wave propagation in excavated fracture rock mass by using the algorithm of “five-point trinomial derivative” and “covariance matrix eigenvector method” respectively，and the trend of fracture and anisotropic coefficient of strata were predicted. The results show that the predicted fracture trend is consistent with regional geology，tectonic stress field and mining conditions. The trend of mining fracture will turn in the stratum，which is caused by the difference of lithology，strength and stiffness. The degree of anisotropy excavated fractured rock mass is closely related to the characteristics of “three zones” of overburden, from shallow to deep shows a small increase and then a smaller trend. The degree of anisotropy of bending subsidence zone and strata not affected by mining is less than 1%，fracture zone is less than 2%，and caving zone is 2%-4.5%，which provides a new index for quantitative evaluation of “three zones” of overburden.
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2020, Vol. 39 
