Studies on support techniques for roadway bearing structure features under different geo-pressures

Abstract

This study investigates the timely support and multi-echelon support in relation to the structure partition of the surrounding rock. The instability behavior of the roadway bearing structure for different working depths and ground pressures is studied and the impact of the supports on the stability of the roadway is analyzed. Considering the distribution of the secondary stress field and the degree of deterioration of the surrounding rock strength resulting from the excavation, a new division method is proposed that involves “deep-shallow-critical” coupling bearing strata. In a similar simulation experiment, we used a stress-loading device fabricated in-house and a support airbag to simulate the impact of ground pressure and timely support force on the stability of the bearing structure and the development of fracture in the surrounding rocks. The results indicate that, with the increase in the ground pressure, the deep and critical bearing strata will move farther away from the roadway wall, the shallow bearing stratum would expand, and hence, the difficulty and expense of providing support will also increase. Timely support can control the movement of the bearing structure and the expansion of the affected range. With the increase in the ground pressure, the bearing structure will become unstable easily, and the stress in the arch foot of the roadway will be considerably concentrated. The instability will lead to more serious damage to the surrounding rocks, which is necessary to reinforce the support in advance. According to the bearing structure of the naked roadway, a multi-echelon support method is proposed. The effective support area is designed based on the outer boundaries of the deep, shallow, and critical bearing strata. The improved multi-echelon support can impose limits on the unfavorable impacts exercised by burial depths on the stability maintenance of the roadway bearing structure and eliminate the adverse effects on the integrity of the surrounding rock. Finally, the relationship between the area of failure and the bearing stratum is established theoretically, and the polynomial interaction equation is fitted according to the results of the simulation.