Research On Mechanism And Large Deformation Control Technology Of Soft Rock Around A Tunnel In High Ground Stress Areas

Under highland stress self-stability of soft rock is relatively poor, prone to plastic defor-mation and showing a significant rheological characteristic. So soft rock tunnel showed a significant aging characteristic.it is prone to large deformations. With soft rock tunnel large deformation problems in high ground stress have become increasingly prominent. Exploring an effective and economic support programs are becoming increasingly important. This paper mainly researchs on soft rock tunnel in highland stress. A permanent support idea that combines cyclic interval lining with initiative pressure relief is presented. Study working mechanism and relief effect of the lining structure by heoretical analysis and model test method. The main research work is as follows.(1) Simplified reasonably the cyclic interval and pressure relief two underlying structure with visco-elastoplastic analysis method. Established the mechanical model of lining segments and non-lining segments of tunnel. On one hand, for the lining segments, based on the commonly creep model of surrounding rock, Mohr-Coulomb strength criterion, non-associated plastic flow rule, and visco-elastoplastic theory, elastic-plastic displacement solution of surrounding rock is obtained. On the other hand, for the non-lining segments, reference to the existing rock stress release model, the release coefficient of no supporting segment of surrounding rock is obtained, and then the visco-elastoplastic displacement solution of non-supporting surrounding rock is solved, furthermore, the relationship between the visco-elastoplastic displacement solution of non-supporting hole segment and the rock pressure of supporting hole section is built.The result proved the deformation of non-supporting hole can relieve a certain rock pressure of supporting hole.(2) Research on the cyclic interval and pressure relief two underlying structure with the model test method. Using three groups of the two underlying structure with different interspace interval. Research on the interspace interval have a influence on the relief effect. Study the deformation law and stress trends of the surrounding rock in the case of the increasing stress by gradual loading.(3) By comparing the deformation law and stress trends of the surrounding rock of the theoretical analysis with laboratory model test, obtained that the deformation of non-supporting hole can relieve significantly rock pressure of supporting hole under the cyclic interval and pressure relief two underlying structure. Large deformation occurs can be well controlled.And the structure have the effect of pressure relief with circulation. Ensure that the permanent use of the structure.