Abstract:
As the mining depth increases annually, the dilation ans shear deformation of roadway surrounding rocks have become increasingly significant, leading to frequent occurrences of surrounding rock instability, which seriously affects the safe and efficient exploitation of mineral resources. After roadway excavation and unloading, the plastic zone distribution of surrounding rocks, closely related to the deviatoric stress field and dissipative energy, is the primary factor affecting roadway stability. Therefore, this paper investigates the deformation, failure, and energy dissipation of deep roadway surrounding rocks under different working conditions in the Jinchuan mining area. Firstly, the causes of structural failure in deep roadway surrounding rocks in Jinchuan mine were summarised through on-site investigation, and the spatial distribution information of surrounding rock joints and fissures was obtained using 3D laser scanning technology. Subsequently, the RMR rock mass quality classification method was modified in combination with Unwedge software, and basic mechanical parameters of rock masses with different lithologies were acquired using RockData software. Finally, a numerical model of the roadway containing complex joints and fractures is developed based on FLAC
3D software. A risk coefficient and energy analysis module for deep roadway surrounding rocks was developed using Fish language to study the risk zones and dissipative energy evolution under different working conditions. The results show that the plastic zone, deviatoric stress field, and dissipation energy of surrounding rocks under different working conditions exhibit circular, elliptical and butterfly shapes. Lithology and burial depth only alter the plastic zone volume, as well as the magnitude of deviatoric stress and dissipative energy, without affecting their distribution patterns. In contrast, the roadway cross-sectional shape and lateral pressure coefficient influence both their distribution patterns and values. Based on the distribution patterns of the risk zones and dissipative energy of surrounding rocks, the length and quantity of energy-absorbing bolts were determined to inhibit further expansion of the plastic zone and reduce insufficient or excessive support in roadway surrounding rocks.