Analysis and illustration on deviatoric stress strain energy generation of surrounding rock in circuar tunnel excavation

The stress in surrounding rock is the superposition of stress in virgin rock mass and deviatoric stress happened in circuar tunnel excavation.The breakage of rock mass by was dominates by the deviatoric stress or its strain energy.On condition that hydrostatic pressure and volumetric strain of rock mass equalled to zero,by using the stress distribution expressions of surrounding rock that its elastic,nonlinear hardening and nonlinear softening zones were linked glossily based on the constitutive model of Reference1,and using multiple integral,the strain energy of deviatoric stress,U d,was calculated in the elastic,hardened and softened zones of surrounding rock.It was proved that U d could be deduced concisely by integrating geo-stress with respect to displacement of tunnel wall,and multiplying by the perimeter of tunnel wall.Thereby,the variation of the deviatoric stress energy in surrounding rock in response to the displacement of tunnel wall could be expressed by the geometric form of the relation between geo-stress and displacement of tunnel wall as well as the area enclosed by them.The obtained results could deepen the understanding of mechanical response of surrounding rock due to the excavation and operation of tunnels.