Instability Mode and Control Technology of Surrounding Rock in Composite Roof Coal Roadway under Multiple Dynamic Pressure Disturbances

Abstract

In view of the problems of composite roof coal roadway under multiple dynamic pressure disturbances such as strong stratification, large deformation of the roadway surrounding rock, and poor safety and reliability, this paper analyzed the deformation and instability characteristics of composite roof coal roadway under different influencing factors using numerical simulation and expounded the stress distribution pattern of composite roof coal roadway under multiple dynamic pressure disturbances. The geological conditions of gas control roadway in the 22301 working face of Tunlan coal mine are taken as examples, and this study is carried out based on the analysis of roof instability conditions of composite roof coal roadway. The progressive crack development characteristics in composite roof coal roadway and the instability failure mode of surrounding rock under multiple dynamic pressure disturbances were revealed, and the control mechanism and support scheme were put forward. According to the result, it is difficult to form a stable bearing rock beam due to the occurrence characteristics of the weak interlayer of the composite roof. The deflection of the roadway roof and the extent of the plastic zone are negatively correlated with the distance from the soft rock layer to the roadway but positively correlated with the thickness of the soft rock layer. As the lateral pressure coefficient λ increases, the plastic zone of the roadway surrounding rock first decreases and then increases. With the increasing influence of dynamic pressure, the coal roadway with composite roof suffers from greater damage under the superposition of high ground stress, lateral abutment pressure, and advance abutment pressure, which is characterized by significant zonal failure of the roof and asymmetric failure of surrounding rock. The control method of high-strength thick anchorage + differential support can construct the thick layer stable rock beam of the roof and equivalent support of the side, realizing continuous stress transfer and geometrically coordinated deformation. The support scheme was finally applied to the on-site industrial test, and the mine pressure monitoring results showed that the deformation of the roadway surrounding rock was effectively controlled under the new support scheme.

Research on the Failure Mechanism of Surrounding Rock in a Dynamic Pressure Roadway and Active and Passive Coordinated Support Technology

“…Ma et al [11] investigated the mechanism of structural evolution in goaf roof roadways when subjected to dynamic pressure, computed the roof pressure for the short arm beam dynamic pressure model, formulated a calculation formula for identifying roof fractures, and derived a criterion for determining roof fracture occurrence. Wang et al [12] employed numerical simulation techniques to examine the instability properties of coal roadways with composite roofs. They uncovered the progressive evolution patterns of fractures, as well as the modes of instability and failure in roadways surrounding rock subjected to multiple dynamic pressures.…”

Deformation and Failure Laws of Surrounding Rocks of Coal Roadways under High Dynamic Load and Intelligent Prediction

“…Wang [26] established a model for major roof structures typical of fracture lines at different positions above the coal rib, based on which the structural conditions for dynamic load impacts on major roofs and the expression of impact force were obtained. In combination with an actual engineering case, Wang [27] expounded on the failure mode of surrounding rock instability of composite roofs of coal roadways under the influences of multiple dynamic load disturbances, leading to the conclusion that high dynamic load will significantly aggravate the damages of composite roof roadways in degree. By simulating the impact process of coal and rock roadways induced by disturbance waves, Chen [28] figured out the relationship between the deformation of roadway surrounding rocks and the loading level and strength of flexible waves, revealing that the damages associated with the risk of high dynamic load in the outer side of the roadway are minor compared with those in the inner side.…”

Mechanisms and Models of Attenuation of Shock Waves through Rock Formations

“…In the roadway support system, the roof support is always in the primary position. A strong roof can produce a barrier effect on the roadway under static or dynamic stresses, reducing or preventing damage to the roadway [30,31]. In this paper, the stress conditions and strength criterion for roof damage under the action of shock waves and high stresses are investigated, taking the Hujiahe mine as an example.…”