Inversion method of initial geostress in coal mine field based on FLAC3D transverse isotropic model

In most inversion on initial ground stress field,the object rock mass is simplified to isotropic elastomer,but for coal-bearing strata with layered structure,varied dip angle and different directions of mechanical properties,such simplification will lead to a large inversion error. Also,it is difficult to model and select parameters for such multilayer interactive rock mass. In order to improve the inversion accuracy of initial ground stress field in coal measure strata with complicated geological conditions,a method of ground stress inversion based on FLAC3D transverse isotropic elas- tic model and isotropic elastic model was proposed. At the same time,to solve the problems of computational modeling and parameter selection in the coal strata with multiple layer interactions and changeable angles,according to the laws of rock interbed,lithologic characteristics,through the study of the geological sketch of complex formation,a calculation model is established,which is basically consistent with the actual rock situation. A numerical experiment is conducted and the multi-layer equivalent rock mass mechanics parameters for the numerical calculation is obtained. According to the numerical test results,the transverse isotropic elastic model and the isotropic elastic model of the local region are established,and the partial least square regression method is used to fit the ground stress field,and the ground stress field is precisely loaded into the calculation model and the force balance is realized,and finally the initial ground stress field is loaded. The results show that the method of constructing numerical model to calculate the equivalent mechani- cal parameters of each layer of rock mass optimizes the modeling process and improves the efficiency of numerical cal- culation. By comparing the two inversion results,the horizontal isotropic model can better reflect the directional differ- ence of the mechanical properties of coal measures strata with layered structure,and can effectively improve the ground stress fitting accuracy in local areas,and the ground stress inversion results are more in line with the measured values.