关键词: 原地应力测量, Shoerey模型, Hoek-Brown强度理论, 高地应力, 判据

Abstract:

To define the in-situ stress regime accurately is one very important basis for stability design and evaluation of underground project. By analyzing how to evaluate the in-situ stress state in the past, it is found that many used methods have totally different standards and criterions in China, and one new high stress criterion and analysis method is established by reference to the past findings. Here the internationally-widely-accepted Shoerey’s model is introduced into the modified high stress criterion; but this model does not take the difference between deformation modulus of rock mass and Young’s modulus of intact rock sample into consideration. For this reason, the authors introduce the deformation modulus from Hoek-Brown criterion into this model to better the Shoerey’s theory, and form the modified Shoerey’s model. A tunnel in Lufeng County, Yunnan Province, has burial depth up to 525m, the lithology of surrounding rock mass is sandy slate. Two boreholes, ZK5 & ZK9 for hydro-fracturing in-situ stress measurement, are arranged along the tunnel line, but the measurement results are rather scattered. The in-situ stress magnitude at the tunnel section, estimated with the methods suggested by this paper, is up to 19.29 MPa; but the global strength of rock mass is only about 5.243 MPa. According to the strength-to-stress ratio method and the criterion from modified Shoerey’s model, the tunnel section at the largest burial depth is under the high in-situ stress; and the project construction and design department should pay more attention to such a condition. Finally, the general method and procedures to evaluate the in-situ stress state are summarized to offer some references for other projects.

Key words: in-situ stress measurement, Shoerey’s model, Hoek-Brown criterion, high stresses, criterion