Abstract:

Finite element program for damage additional displacement is worked out on basis of damage mechanics, rock mechanics and finite element analysis methods. A group of stochastic fractures with NW45° dip are selected so as to analyze the damage of different dip angles, densities (damage factors) and filling conditions (transfer coefficients of tensive and compressive shear stress) on the surround rock mass of tunnels. The study shows that: 1) The absolute value of damage additional displacement of tunnel crown (floor slab) increases as the damage coefficient increases and the relationship between them is nolinear. 2) The damage influence of tunnels has nothing to do with the transfer coefficients of tensive and compressive shear stress when the dip angle is 0° and 90°. 3) The damage influence on the key points of tunnel crown and floor slab imposed by stochastic fractures with the same dip angle is almost opposite. 4) The damage influence on the crown settlement and the floor slab heave increases as the dip angle decreases. 5) The damage influence on the tunnel caused by the tensive shear stress transfer coefficient is larger than that caused by the compressive shear stress transfer coefficient. 6) The damage influence on the tunnel caused by the variation of the tensive shear stress transfer coefficient is less than that caused by the compressive shear transfer coefficient.

Key words: stochastic fracture, damage additional displacement, damage factor, dip angle, tensive and compressive shear stress transfer coefficient