Distribution Law of Principal Stress Difference of Deep Surrounding Rock of Gob-side Entry and Optimum Design of Coal Pillar Width

Abstract

The optimum design of deep-coal pillar width at the gob-side entry is the key to control surrounding rocks. Existing studies on this issue are based on the distribution law of mining abutment pressure without considering the principal stress difference distribution, which is related to the shear failure of surrounding rock. This study aimed to optimize the design of deep-coal pillar width at gob-side entry based on the distribution law of the principal stress difference. With FLAC 3D numerical simulation, the distribution characteristics of principal stress difference in the side mining stress field of the deep mining face and the distribution laws of the principal stress difference of the surrounding rock at the gob-side entry under different coal pillar width were explored. According to the distribution characteristics of the principal stress difference, the coal and rock mass on the goaf side in the deep mining face could be divided into three zones, i.e., decreasing, increasing and stable zones. Results show that the principal stress differences of the deep surrounding rock on the roof, floor, and coal wall rib at the gob-side entry present a single-peak curve distribution under different coal pillar width. However, the principal stress difference of the surrounding rock on the coal pillar rib displays a single-peak curve when the coal pillar width is less than or equal to 8 m, but a double-peak curve appears when the coal pillar width is greater than 8 m. The peak value of the shallow surrounding rock is obviously smaller than that of the deep surrounding rock. The width of the coal pillar of the gob-side entry in 11030-tunnel was optimized according to the theoretical calculation. This work provides a novel idea and method for the arrangement of deep coal pillars of gob-side entry.

A study on the reasonable width of narrow coal pillars in the section of hard primary roof hewing along the air excavation roadway

“…Wu et al studied the large deformation of the tailing plate caused by the failure of the coal pillar 7 . Li optimized the width of the deep coal pillar in Goaf according to the principal stress difference distribution law 8 . Yang et al analyzed the change of strata structure in the Goaf, the evolution of coal pillar stress and the mechanism of coal pillar‐induced rock burst, and studied the root cause of coal pillar rock burst 9 .…”

“…7 Li optimized the width of the deep coal pillar in Goaf according to the principal stress difference distribution law. 8 Yang et al analyzed the change of strata structure in the Goaf, the evolution of coal pillar stress and the mechanism of coal pillar-induced rock burst, and studied the root cause of coal pillar rock burst. 9 Yang et al established a mechanical model of coal pillar support under a double-channel arrangement and analyzed the width of the plastic zone of the coal pillar.…”

A Study on the Calculation Method of Support Pressure in the Structure of Typical Upper Cladding Rock Formations

“…Coal mining destroys the balance of original rock stress field and causes the concentration of abutment pressure of overlying strata near the coal wall. When the stress concentration exceeds the overall bearing capacity of working face, rock burst accident will occur [15,16].…”

Study on Coal Pillar Size Design Based on Non-integral Contact Structure of Coal and Rock Under Static and Dynamic Loads

“…The maximum mining depth in Germany has reached 1713 m (Pan et al, 2020), and there are more than 50 mines with a mining depth exceeding 1000 m in China (Huang et al, 2020). With the increase of mining depth, the instability of the roadway is widespread, so the coal pillar for roadway protection is an effective guarantee for roadway stability (Li et al, 2019). In the complex geological environment of deep mines, coal pillars are not only subjected to long-term effects of high static loads, but also frequently subjected to impact dynamic loads.…”