Continuous-discrete coupling-based stability study of surrounding rock of limestone roadway in acid environment

Abstract

To investigate the influence of acid environment on the stability of parallel limestone roadway, we carry out limestone mechanical characteristic degradation test, obtain the degradation rule of limestone, and utilize the FLAC and PFC2D softwares to construct the parallel roadway macroscopic–microscopic coupling computational model based on the continuous element and discrete element theory, thus analyzing the rock mass stress in the middle pillar, floor, and arch foot of the roadway, as well as the variation and failure pattern in the plastic zone under the long-term action of the acid environment from the macroscopic and microscopic points of view. Our results indicated that, relative to the neural water environment, the strength characteristic of limestone would basically show a linear degradation trend after the action of acid environment at pH 5 and 3 and that the influence on cohesion was greater than that on the internal frictional angle. Besides, under the acid environment, the middle pillar was subject to the greatest influence, which was likely to induce cutthrough of the plastic zone in the rock pillar, thus resulting in instability of the roadway. Additionally, the particle disruption distribution, displacement vector, and contact force chain in the discrete domain also revealed the deformation development rule of the plastic zone in the surrounding rock. This study has verified the feasibility of the coupling analysis method in studying the roadway macroscopic–microscopic deformation mechanism which is of reference significance to research on the parallel roadway stability under acid environment.