Distribution Characteristics of In Situ Stress Field for a Deep-Buried Tunnel in the Fault Area

Understanding initial in situ stress is important for studying rock burst or large deformation problems in tunnels under high geostress. Field measurements and inversions of the in situ stress field in the Baima tunnel were taken to determine key controlling factors on disturbance of the in situ stress field in fault areas. The measured results showed that the magnitude of the maximum principal stress at the fault decreased and the direction deflected. Numerical experiments showed that the fault type, fault direction, fault width, rock bedding direction, elastic modulus ratio of the surrounding rock to the fault, and principal stress ratio all had different effects on the stress field in the fault area. The on-site rock mass parameters were obtained through the conversion of the geological strength index, and the in situ stress field distribution in the fault area under the influence of combined factors was clarified by using the inversion method of multiple linear regression. This study showed that the more the actual geological characteristics of the site are considered, the more realistic and accurate the inversion results of the site stress field are.