After excavating tunnel in rock mass, secondary stress presents in the wall rock with water-bearing,because the in-situ rock stress distribution and the infiltrative hydraulic pressure action is disturbed. The unbalanced stress is the major reason of rock mass deformation, displacement and even destroy. Based on Mohr-Coulomb and elastic-plasticity theory and rock damage caused by rock strain-softening, taking circular section of underground deep tunnel as example, the paper calculates and analyses the relationship between plastic range and supporting force in the case of limit equilibrium. The study establishes theoretical foundation for actual underground project construction and support engineering.%在岩体内开挖巷道后,由于干扰了原岩应力分布和渗透水压力的作用,巷道含水围岩中呈现次生应力,这种新出现的不平衡应力是引起岩体产生变形、位移,甚至破坏的主要根源.以圆形截面巷道为例,结合莫尔-库仑理论从围岩弹塑性变形的角度出发,在考虑了围岩应变软化所引起围岩损伤的基础上,计算和分析了地下巷道含水围岩达到极限平衡时围岩塑性区范围与相应支护抗力之间的关系,为实际地下工程施工和支护提供了理论基础.
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