Research On Highly-weathered Swelling Granite Roadway Support Technology

Abstract

Granite can be easily weathered and often gets disintegrated and argillated when wet. In this paper, we take the granite roadway support work as the research object. Through analysis by X-ray diffraction and scanning electron microscope (SEM), we find that granite contains a great amount of montmorillonite, which is a hydrophilic mineral, and that the rock mass will be rapidly disintegrated when absorbing water. We use the 3D non-linear finite element method to build an elasto-plastic numerical calculation model for the granite roadway, analyze the shotcreting-bolting support schemes with different support parameters, optimize the technical parameters of shotcreting-bolting support from the stress state of the surrounding rock, roadway safety factor and distribution of rock plastic zones, and recommend reinforcing the roadway with 1.8m anchor bolts with spacing of 1.0m í— 1.0m and shotcrete with a thickness of 5cm. At the same time, the support monitoring data show that the deformation of the roadway can be clearly divided into three stages - roadway excavation impact, deformation control and stable deformation stages. For a weathered roadway that can be easily disintegrated, it will take the support structure about 3 months to be stabilized. By that time, the anchor bolts and concrete will coordinate well with the deformation of the surrounding rock and have good supporting effects.