Abstract:

Aiming at the problem of the in-situ stress field in long and deep buried tunnels, taking the deep buried tunnel of  Yellow River to Xining diversion project in Qinghai Province as the background, the regional tectonic evolution analysis, on-site hydraulic fracturing testing, and numerical deduction methods were used to determine the in-situ stress characteristics of each section of the tunnel. The research results show that the tunnel of  Yellow River to Xining diversion project is affected by the compression movement of the blocks in the northeast margin of the Qinghai-Xizang Plateau, and the main compressive stress direction is NE-NEE direction; The stress field of the tunnel  can be divided into three regions, with the maximum horizontal principal stress lateral pressure coefficient of 2.0 in the Laji section; The maximum buried depth of the tunnel when crossing the Laji Mountain exceeds 1 400 m, and the maximum horizontal principal stress exceeds 70 MPa, which may have a significant impact on the stability of the tunnel surrounding rock.

Key words: Yellow River to Xining , diversion project；deep buried tunnel；in-situ stress field；in-situ stress； hydraulic fracturing test；numerical deduction