Stability of Deep Underground Openings through Large Fault Zones in Argillaceous Rock

Abstract

Abstract:The stability of underground openings is pivotal to sustainable safe mining in underground coal mines. To determine the stability and tunneling safety issues in 800-m-deep underground openings through large fault zones in argillaceous rocks in the Guqiao Coal Mine in East China, the pilot industrial test, laboratory experimentation, and field measurements were used to analyze the large deformations and failure characteristics of the surrounding rock, the influence factors of safe excavation and stability of underground openings, and to study the stability control countermeasures. The main factors influencing the stability and tunneling safety include large fault zones, high in situ stress, poor mechanical properties and engineering performance of the argillaceous rock mass, groundwater inrush and gas outburst. According to the field study, the anchor-ability of cables and the groutability of cement-matrix materials in the argillaceous rock in the large fault zones were extremely poor, and deformations and failure of the surrounding rock were characterized by dramatic initial deformation, high long-term creep rate, obviously asymmetric deformations and failure, rebound of roof displacements, overall loosened deformations of deep surrounding rock on a large scale, and high sensitivity to engineering disturbance and water immersion. Various geo-hazards occurred during the pilot excavation, including roof collapse, groundwater inrush, and debris flow. Control techniques are proposed and should be adopted to ensure tunneling safety and to control the stability of deep underground openings through large fault zones, including regional strata reinforcement technique such as ground surface pre-grouting, primary enhanced control measures, floor grouting reinforcement technique, and secondary enclosed support measures for long-term stability, which are critical for ensuring the sustainable development of the coal mine.

Numerical investigation of failure evolution for the surrounding rock of a super‐large section chamber group in a deep coal mine

“…Li et al used numerical simulation and field measurement to analyze the instability mechanism of the surrounding rock in a soft rock roadway under high‐stress conditions and proposed the surrounding rock stability control method. Qian et al determined the influence of creep and time‐dependent behavior on the stability of deep underground chamber through large fault zones in argillaceous rocks by in‐site monitoring. Wang et al deduced the critical load of initial buckling and continuous buckling failure of a thick and hard floor by using thin plate theory and revealed the floor failure mechanism of a deep large chamber.…”

Failure Characteristics and Stability Control of Bolt Support in Thick‐Coal‐Seam Roadway of Three Typical Coal Mines in China

“…Roadway VR 4203 has a burial depth of 810 m, which presents a control problem that is typical for deep high-stress roadways. is depth exposes the roadway to rock deformation across the brittle-plastic transformation, associated rheology, and long-term expansion characteristics [22]. e VR 4203 roadway is separated from the #4201 goaf by 15 m of coal pillars (Figure 2(a)), which strongly affects the residual bearing pressure.…”

Rapid Excavation and Stability Control of Deep Roadways for an Underground Coal Mine with High Production in Inner Mongolia

“…The shallow coal resources in eastern China are being exhausted, while the development of high-quality coal resources in western China has become a major element of the national energy strategy [1][2][3]. With the development of China's supply-side structural reform, the large-scale restructuring of coal enterprises further promotes the optimization and integration of coal resources development, especially in Inner Mongolia.…”