Coal Mine Abutment Pressure Distribution Based on a Strain-Softening Model

Abstract

The coal in front of the mining face presents strain softening deformation characteristics. An analytical model is proposed to simulate the abutment pressure distribution over the coal in front of the mining face under elastic and inelastic conditions. A new theoretical formula is derived from calculating the abutment pressure distribution and its width in elastic and inelastic regions of the coal under the limit equilibrium condition. The influences of UCS, residual strength, mining height, softening modulus, and deformation angle on the abutment pressure distribution are discussed. The study results show that (1) the stress gradient in the plastic area is larger than that in the crushed zone; (2) the width of the plastic region is independent of the peak abutment pressure, but it is dependent on UCS, residual strength, mining height, softening modulus, and deformation angle; (3) the width of the crushed zone in the inelastic area is closely related to the peak abutment pressure, coal-floor interface cohesion, and friction coefficient; (4) the width of the elastic zone is dependent on the mining height, coefficient of horizontal pressure, coal-floor interface friction coefficient, and peak abutment pressure, where the coefficient of horizontal pressure has the highest impact, in that the width of the elastic zone undergoes logarithmic decrease with the increase in the coefficient of horizontal pressure. A case study was carried out at longwall panel 07 of No. 5 coal seam in Dongjiahe Coal Mine to verify the analytical model. The abutment pressure distribution and the widths of the elastic and inelastic zones under the limit equilibrium condition are calculated based on the relevant parameters. The theoretical results are compared with the field monitoring data and show a very good fit. It is proved that the proposed analytical model has high accuracy, and the feasibility of the model is verified. The study results can provide guidance for similar engineering applications.

A Control Approach of the Roof in No-Pillar Roadway Formed by Roof Cutting and Pressure Releasing

“…By substituting the parameters into Equations ( 1), ( 5), (13), and ( 14), the following equation can be obtained: the peak advanced abutment pressure of the main roof is 12.92 MPa, which appears 9.16 m ahead of the working face, and its influence range is 32.43 m ahead of the coal wall. The advanced cutting distance is 27.45 m. The theoretical calculation results are in good agreement with the simulation results.…”

“…Relevant studies have been carried out by many scholars. Zhang et al [12,13] mainly apply continuum theory, elastic theory, and damage mechanics to study the distribution characteristics of abutment pressure and gradually consider the effect of rock beam movement on the evolution characteristics of abutment pressure. Yu et al [14][15][16] used experimental method, similar material simulation, numerical simulation, and other methods to study the distribution characteristics, influence range, peak position, and the change rule of abetment pressure with the roof's movement.…”

Study on Evolution of Front Abutment Pressure at Working Face in Repeated Mining of Close-Distance Coal Seams

“…Y. Li studied the law of abutment pressure when a longwall panel passes through the abandoned roadway in a damaged coal seam [17]. A. Li proposed an analytical model to simulate the front abutment pressure distribution under elastic and inelastic conditions [18]. P.S.…”