Development of a numerical model of rock failure mechanisms associated with the impact of lateral displacement

Ground subsidence due to mining has been the subject of research for several decades, and it remains to be an important problem, which confronts the mining close to ecologically sensitive areas. This thesis is concerned with the development of a numerical simulation model of ground deformation, extended to ground movement under river channel systems present at the base of valleys. A number of numerical models have been developed for better understanding of the strata interactions using the two- imensional explicit finite difference code FLAC Version 4.0. The proposed model simulation is focused on the ground deformation, down to 30 meters below the river valley. Ground displacement, mainly lateral displacement has been observed by field monitoring and accordingly, artificial lateral displacement was created to study the deformational behaviour beneath the bottom of the valley. Lateral displacement around valley areas caused the closure of the valley and bulging of the valley floor, known as upsidence. Most of the numerical simulations carried out with FLAC demonstrated that valley closure and valley floor bulging were dependent on the shape and dimension of modelled geometry, strata properties, loading rate of lateral displacement, the magnitude and shape of loading, the presence of bedding planes and the presence of an underground water table. The inclusion of bedding planes or joints with known rock types was recommended for ground deformation simulations. The use of UDEC instead of FLAC was considered as an alternative to provide a better understanding of the effects of joints and bedding planes on subsidence and upsidence. Further studies are required for strata interaction when an underground water table is introduced to the model.