No abstract

The stability of slope is critical important topic in rock mass engineering. In Panzhihua #7 Coal Mine, the coal mining is occurred under the slope, to obtain the optimal mining width, 125 numerical simulations were conducted, and the corresponding FOS was calculated. From the analysis of the numerical simulation results, it can be found that FOS decrease and then increase with increasing of filling length, meanwhile, the FOS is minimum value when the filling length is within the ranges of 10m and 20m, which is under the toe of slope. Furthermore, the minimum FOS decrease with increasing of mining width. Considered the stability of the slope and mining economy, the mining width is set to 6m, and the numerical simulation results is applied to the engineering practice. To guarantee the safety of the slope, some monitoring points were distributed on the slope, the displacement from numerical simulation and engineering practice is quite close, indicating the numerical simulation results is reliable, and the mining width is reasonable.

Drilling to relieve pressure is a simple and efficient solution to prevent impact ground pressure for the engineering problem of the high risk of impact on the surrounding rock of high stress roads, and choosing suitable drilling parameters is the key to it. The unloading law of borehole diameter, depth, and spacing was investigated using a combination of indoor tests, numerical simulations, and theoretical analysis. The characteristics of crack extension and plastic zone changes of the three were analyzed, and the relationship between boreholes and elastic strain energy was derived by developing a hole mechanics model. The findings indicate that as drilling radius and depth are increased, peak strength and the elastic strain energy stored in front of the peak decrease, the plastic zone around the hole and the main control crack on the surface of the block expand more obviously, and the vertical stress at the top and bottom of the hole decrease, and the peak stress increases with the depth of the hole. The plastic zone surrounding the hole is attached to one another more easily the closer the drilling spacing is. The test block is changed from independent damage to penetrating damage when the drilling spacing is less than or equal to 3.286 cm. However, the pressure release effect does not necessarily improve with narrower drilling spacing. The plastic zone radius and the elastic strain energy held in the rock body are linked to each other linearly and quadratically, respectively, by the drilling radius. The joint pressure relief of several holes should be prioritized when drilling pressure is relieved, and then the hole’s diameter should be increased, and, finally, the hole's depth should be increased. A reference for engineering applications is provided by this.