Abstract: As the main load of underground engineering,the theoretical analysis and regression method of in-situ stress have always been a research hotspot in geotechnical field. Influenced by the uncertainty of geological evolution process,geological conditions and in-situ stress test accuracy,the problem of non-uniqueness of solution and local optimization is easy to appear in the process of in-situ stress field regression. Therefore,this paper proposes a fine in-situ stress field inversion method considering unloading stress. Firstly,the values of original rock in-situ stress and unloading in-situ stress are obtained through field test. Then,the geological evolution and mining disturbance process are simulated by numerical calculation,and the boundary conditions of the model are inverted by neural network by using the stress values at key nodes on the rock mass path. Finally,the boundary conditions obtained by inversion are input into the calculation model,and then the in-situ stress field in the engineering area is calculated. According to the method proposed in this paper,the in-situ stress field in deep mining area of Sishanling is inverted,and the scientificity and applicability of the method proposed in this paper are proved by the in-situ stress test value and ground pressure failure phenomenon,which also provides reference for the stability analysis of deep mining area of Sishanling Mine. 

Key words: in-situ stress field,deep mining,unloading stress,inversion