Instability Criterion for Surrounding Rock of Water-Rich Roadway in Sandy-Gravel Stratum Based on Catastrophe Theory

Abstract

In order to solve the problem of instability discrimination for water-rich roadway in sandy-gravel stratum, taking the displacement function and damaged area function as potential functions of the roadway surrounding rock system based on catastrophe theory, the instability criterions of the roadway in sandy-gravel stratum under seepage were established, i.e. the criterion for extremal modulus of displacement and criterion for the damaged area. Then the specific process for stability discrimination was further proposed. A PFC2D numerical model for a shaft bottom roadway in a large coal mine in Xinjiang was established. The calculation results show that as seepage pressure increases, modulus of displacement and damaged area in surrounding rock present irregular fluctuations and similar change rule. In the latter stage of the increase of seepage pressure, the deformation and damage of the roadway all have experienced a sharp sudden raise. And the conclusion of instability discrimination obtained from the calculation results of catastrophic eigenvalues for modulus of displacement and damaged area are consistent with damage evolution and instability process of the surrounding rock, which verifies the feasibility and applicability of the instability criterions.