Numerical code RFPA2D (dynamic version) based on mesoscopic damage mechanics is used to simulate the failure process of roadway in transversely isotropic rock mass subjected to dynamic loading, and the influences of rock heterogeneity on propagation of stress wave and failure pattern are analyzed. The results indicate that there exists some influence of rock heterogeneity on stress wave propagation, stress distribution of roadway structure and time-displacement curve, etc. Firstly, influence of the heterogeneity index m of layered rock mass on failure pattern of layered rock mass under dynamic loading is great, that is to say, the more homogeneous rock is, the more easily fracture face of layered rock mass extends toward direction of interface of layered rock mass, and here the spallation failure extent of roadway induced by stress wave reflection is reduced; Secondly, the more homogeneous layered rock mass, the less attenuation of stress wave amplitude, and the faster stress wave propagates, and here the bigger peak value of displacement of roadway roof caused by dynamic disturbance. On the whole, stability of roadway being reduced results from interface failure of layered rock mass.
It is well known fact that rock mass structure properties influence the stability of surrounding rock of roadway considerably[1]. For example, because the stability of layered rock mass is dominated by layers of rock mass, block instability often occur when excavating in layered rock mass, bringing about immense harm to engineering construction such as roadway excavation[2]. In dynamics investigations, it is also found that propagation of shock waves are partially restricted by joint planes[3]; In the other hand, the movement of block rock mass may often be strengthened by dynamic disturbance such as earthquake, blasting and machine vibration, and then the stability of the whole underground structure such as roadway is influenced. So studying on dynamic response, stability and failure of roadway in layered rock mass under dynamic disturbance have great realistic significance. Here, roadway in layered rock mass with transversely isotropic properties is considered. Both continuum-based and discontinuum-based analyses have been used to evaluate the stability of underground structures. The former refer to Finite Differences. Finite Elements, and Boundary Element approaches, for example. The latter refer principally to the Discontinuous Deformation Analysis, the Key Block Theory, and the Discrete Element Method(DEM). In document[1], based on mesoscopic damage mechanics, finite flement numerical code RFPA2D (dynamic version) is used to simulate the failure process of roadway in transversely isotropic rock mass subjected to dynamic loading, and the influences of 1208 mechanical properties, such as strength and elastic modulus of layered materials on propagation of stress wave and failure mode are analyzed. However, lots of facts demonstrate that heterogeneity feature of rock material plays a significant role in fracture patterns of the rocks under dynamic loadings, so on the basis of document[1], the influences of rock heterogeneity on propagation of stress wave and failure pattern in roadway in transversely isotropic rock mass are analyzed in this paper.
