Influence of discontinuities on the rock mass stress-strain state around excavation

Engineering and construction of roads, subways, airfields, bridges and transport tunnels

Adequate mathematical modeling of selvage zone and natural fracturing as well as assessment of its impact on stress-strain state – urgent problems in calculation of hydraulic tunnels. Modern Russian regulations in fact give dependences only to solve the problems in plane deformation conditions. The specificity of work of the tunnel that crosses the discontinuity, as a space frame are not taken into account. This article presents influence of discontinuities and fracture characteristics on the rock mass stress-strain state around excavation. Fractured rock mass model was analyzed. Formula of modulus of elasticity for fractured rock mass at distance from the fault was deduced. Influence of discontinuities on the stress distribution was estimated with using experiment design method. On the basis of the conducted research it was established, that assessing rock stress-strain state around the fracture is necessary to consider rock mass fracture characteristics; and using principal stresses distribution in combination with Lode parameter we can clearly estimate the type of stress-strain state in each point, therefore, we can use different strength theories for different sections of the tunnel.