ELASTO-PLASTIC AND LIMIT STATE ANALYSES OF UNDERGROUND ROCK STRUCTURE

Based on the progressive failure behaviour of rock mass.an elastic plus tic and limit state analyss method for the undergrouna rock strucure is developed.In the case of a circular tunnel,an idealized elastoplastic soften-ing and plastic dilation material model is set up;and aclosed form solution is presented for the axisymmetric plane strain case.It shows that there is ia limit failure state in the progress of the plastic zone around a tunnel.It hs the strain-softening and the plastic dilation behavinor of rock mass that save a heavy effect on the limit fairure state of a tunnel The solution of this paper is more practical and has a wider application cope shan the solutions which have been made.