Numerical Study on the Effectiveness of the Grouting Cable Bolt in Deep Retained Goaf Side Gateroad

Abstract

Grouting cable bolt was employed to control the stability of the retaind goaf side gateraod (RGSG) in the Panyidong coalmine by considering severe stress disturbances and soft rock mechanics associated in deep mining environment. To have a deep insight of the effectiveness of the grouting cable bolt supporting on the stability control of the deep RGSG, a FLAC3D numerical model was built according to the geotechnical condition of the Panyidong coalmine, in which strain softening constitutive material was introduced to model the softening behavior of the surrounding rock supported by end-anchored cable bolt or grouting cable bolt. Simulated results demonstrated that: Confining stress release during roadway driving and stress concentration during longwall face retreating are the main driving force to the large deformation of the RGSG supported by end-anchored cable bolt; Grouting cable bolt supporting can improve the stability of the deep RGSG considerably thought providing high bolting strength and grouts injection, and ideally, the RGSG’s roof sag and right coal rib convergence making main contributions to the RGSG section shrinkage could be reduced by 22.0% and 23.0%, 26.6% and 29.4%, 30.2% and 34.9% when the RGSG is supported by grouting cable bolt I, II and III, respectively. Field application also verified that the integrity of the surrounding rock of RGSG was improved and the residual section of the RGSG was large enough to reserve for the second longwall panel mining when the grouting cable bolt technology was applied in the Panyidong coalmine with 850 m depth.