One plastic gradient model of zonal disintegration of rock mass near deep level tunnels

In the present paper zonal disintegration phenomenon is investigated within the framework of gradient theories of elastic-plastic solids. Gradient of effective plastic strain is introduced as additional internal variable. Equilibrium equation and boundary conditions are obtained by using virtual work principle. Evolution equations for internal variables are obtained by using Clausius—Duhem inequality. For circular tunnels the governing equation for effective plastic strain is obtained from the above model. Solution of the governing equation for ideal brittle rock mass model is obtained. The obtained solution may describe zonal disintegration phenomenon very well.