A Discontinuous Sub-Block Meso-Damage Evolution Model And Its Application

The discontinuous deformation and failure of rock mass is one of the important topics in the scopes of rock & soil mechanics and engineering at present. Rock mass which consists of joints and rocks is intervenient of continuous and discontinuous. The uncertainty of inner structure induces the complexity of its mechanic behavior in macroscopic view. The failure of rock mass is a multi-scale problem. It roots not only the propagation of joints in macroscopic view, but also the generation, propagation and transfixion cracks in meso-scopic view. The accumulation of the damage and cracks in mesoscopic view reduces the failure in macroscopic view. Therefore, the failure of rock mass is a progressive process.In this thesis, the research scale of the rock mass' failure first of all. Taking the continuous problem, the discontinuous problem and the conversion from the continuous to the discontinuous into account, a discontinuous sub-block model is brought forward from the view of multi-scale coupling. The discontinuous sub-block model is on the base of the method of discontinuous deformation analysis in theory. In the discontinuous sub-block model, rock from the cutting of rock mass by joints is defined as block. And the block is cut into smaller block which is defined as sub-block. The sub-block is isotropic and homogeneous. It's the basal element in numerical simulation. It is assumed that the rock mass and rock belong to the macroscopic view and the sub-block belong to the meso-scopic view. The contact between the sub-blocks is also redefined and divided into two kinds. One is the continuous contact and the other is discontinuous. And the continuous contact can change into the discontinuous one under some condition. The extended Lagrange is adopted to deal with the contacts and the exact contact force can be calculated.The sub-block can't failure or change into smaller blocks, but the damage in the sub-block also has effects on the failure of rock mass under outside load. Therefore, the meso-damage mechanics is introduced into the discontinuous sub-block model mentioned above. Considering the tensile and shear damage, a discontinuous sub-block meso-damage evolution model for rock mass failure is put forward. In the discontinuous sub-block meso-damage evolution model, the tensile strain and the shear strain are defined as the damage parameter and the tensile damage evolution equation and the shear damage evolution equation are built up separately. The effects of rock mass material's heterogeneity on the deformation and failure of rock mass is considered. And it is assumed that the heterogeneity of rock mass obeys the Weibull distribution.Based on the numerical method brought forward in this thesis, the numerical simulation program which takes the Tongji Shuguang graph flat roof as the pre-processing module is developed with the Visual C++ program language. Through some classical validation examples, the feasibility, validity and precision of the numerical simulation program are proved. At last, the numerical simulation program is applied to the failure of rock arc bridge and some discussions are made based on the simulation results.