关键词: 滇中红层; 软岩; 挤压变形; 强度应力比; 围岩应变;

Abstract: Extrusion deformation of soft rock is a difficult problem for deep buried or high stress tunnel project.Because of the very diversified characteristics of different soft rocks, extrusion deformations degree of tunnels under different conditions are diverse.According to the rheological property of soft rock in the red beds of Central Yunnan area and the existing classification methods for extrusion deformation of soft rock, the classification standard for extrusion deformation of soft rock in the red beds of Central Yunnan area was put forward.The side pressure coefficient and the direction of the maximum horizontal principal stress of tunnel project region were determined based on the statistical results of ground stress test of Central Yunnan Water Diversion Project.On this basis, the limit depth of different extrusion deformation of different stratum in this diversion tunnel was calculated, and the extrusion deformation of this diversion tunnel was predicted.At last, numerical simulation of extrusion deformation was carried out for the tunnel section of maximum burial depth in this diversion tunnel without support, the result of numerical simulation were basically in agreement with the prediction result based on strength-stress ratio, verifying the effectiveness of prediction based on strength-stress ratio for extrusion deformation of soft rock in the red beds of Central Yunnan area.

Key words: red beds in Central Yunnan area; soft rock; extrusion deformation; strength-stress ratio; surrounding rock strain;