Question

A Circular Tunnel is located 1000 meters below the ground surface. The tunnel is subjected to vertical (p) and horizontal (kp) principal stresses. The stress p is equal to the depth stress, and the horizontal stress is defined as 0.28p. The unit weight of the rock mass γ = 27 kN/m. The uniaxial compressive strength of the rock is equal to σ.-63.1 MPa, the Tensile strength of the rock T,-0 MPa. (1) Plot the tangential stress σ00 around the boundary of the circular tunnel (2) What are the maximum and minimum tangential stresss at the boundary of the tunnel. Also show the locations of these stresses in the tunnel (3) If there are failures around the boundary of the circular tunnel, propose and alternative design for the excavation.

Answer 1