The application of distinct lattice spring model to zonal disintegration within deep rock masses

Jianjun Ma & Peijie Yin & Linchong Huang & Yu Liang

Zonal disintegration has been frequently encountered in many tunnelling projects such as deep mining and watertunnels in hydropower stations. The mechanisms of this phenomenon cannot be explained reasonably throughconventional mesh-based numerical approaches. Thus, in this study, a dual coupled Micro-Macro ContinuumDiscontinuum approach named as Distinct Lattice Spring Model (DLSM) has been applied to investigate themechanisms of zonal disintegration within deep rock masses. Firstly, the 3D numerical modes are built up, withfixed boundaries being set for far fields and displacement loading being applied along the tunnel axis. Thisnumerical mode is then validated through comparing model simulation with laboratory model tests, wherereasonable agreement has been achieved for all cases considered (normal rock mass and layered rock mass withdifferent joint spaces). To cater for real tunnels within various rock masses, tunnels excavated in deep rockmasses with different sizes, shapes and material heterogeneities are investigated. Numerical study demonstratesthat, the DLSM is capable to reproduce the process of zonal disintegration explicitly, along with which themechanical responses have been captured reasonably. It shows that, the occurrence of zonal disintegrationmainly depends on the material heterogeneities and the in-suite stress level. The fracture patterns formed duringzonal disintegration rely on tunnels’ shape, size and the distribution of local weakness in surrounding rockmasses.