Abstract
With the increase in mining depth, the problem of the floor heave of a roadway is becoming increasingly prominent. Solving this problem for a deep high-stress roadway is the key to ensure safe supply and utilization of coal resources in China. This study investigates the floor heave of a horizontal transportation rock roadway at the depth of 960 m at the Xieyi Mine. A four-way loading simulation test frame similar to the Xieyi Mine was used to reproduce the high-stress environment of a deep roadway by loading different pressures on the roof, floor, and two sides of the roadway. The experimental results show that after the tunnel had been excavated, the surrounding rock failure could be divided into three stages: the initial deformation stage, fissure development stage, and mild deformation stage. The destruction time periods of these stages were 0–0.5 h, 0.5–2 h, and 2–6 h, and the destruction ranges were 0.4 m, 1 m, and 1.5 m, respectively. The amount of roof subsidence, the displacement of the two sides, and the floor heave influence each other, and the range of the bearing ring (5.6 m) of the floor is larger than that of the roof (3.4 m) after the surrounding rock has been damaged. The findings suggest that the floor should be supported first, before the two sides and the roof; then, the support of the key parts (roof and floor corners) should be strengthened. The roof, floor, and two sides are considered for controlling the deformation of the surrounding rock in a coupled trinity support mode. Because of the unfavorable conditions in the area, overexcavation backfill technology was used. The new support was successfully applied during the subsequent construction of the rock tunnel. Based on the long-term monitoring results of the surrounding rock deformation, the floor heave control yielded satisfactory results and maintained the long-term stability of the roadway. Therefore, this study can serve as a reference for preventing floor heave in similar high-stress roadways in the future.
Highlights
Socioeconomic development is inseparable from the exploitation and utilization of energy
The increase in mining depth is accompanied by many problems, such as the complex conditions of three “high” and one “disturbance.” Among them, high in situ stress can cause issues such as rock bursts, high temperature, floor heave, a large deformation of the two sides, and roof collapse
By loading different pressures on the roof, two sides, and floor to replicate the high-stress environment of the site, the roadway damage could be closer to the site to better analyze the failure mechanism of surrounding rock
Summary
Socioeconomic development is inseparable from the exploitation and utilization of energy. Deep roadway floor heave is more common and severe, which has become an urgent problem for deep mining This effect causes great difficulty in controlling the rock surrounding the roadway and seriously threatens the safety of the coal mine. Kulatilake et al used 3DEC software to simulate high-stress roadways and proposed the use of 3 m bolts and inverted arch roadways to control the surrounding rock [24]. Based on a similar simulation experiment of the model frame, the stress distribution, deformation, and failure characteristics of the surrounding rock of the original support scheme of a transportation roadway were replicated. A new floor heave treatment was proposed and applied on site for verification
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