Stability of Close Chambers Surrounding Rock in Deep and Comprehensive Control Technology

Abstract

The purpose of this paper is to solve the problem that deep and close-distance cavern and roadway group were easily affected by the adjacent chamber or roadway excavation disturbance and low stability and significant deformation of surrounding rock occurred. The stability and control technology of surrounding rock in the main shaft and auxiliary shaft system has been analyzed by the adjacent chamber and roadway group of −850 m level in Qujiang Mine, China, as an engineering background. Firstly, the numerical calculation of the excavation chamber was, respectively, carried out in different ways with the propagation theory of the excavation disturbance wave. The results show that the interaction of adjacent chamber excavation was more intense. When excavated at the same time, there is a large increase in the movement of the sides and the roof-floor of the chamber and roadway. Then, the mechanism of interaction between low-high stress and excavation disturbance was considered, the corresponding control principles were provided, and a set of critical technologies and equipment were designed according to the deformation characteristics of the large deformation soft surrounding rock. Finally, the comprehensive control method was put forward with the water pump house as an example, that is, anchor, metal net, grouting, combined anchor cable and large-diameter anchor cable. And the related support parameters were determined by the internal damage of the surrounding rock chamber. The numerical simulation results show that the surrounding rock deformation of the chamber and roadway reduced with the revised support program, which the expansion of the rock mass loose circle prevented effectively. The site test shows that the convergence rate of surrounding rock with the improved support was less than 0.2 mm/d, and the rock deformation of chamber and roadway suppressed significantly.

A new theoretical method for calculating front abutment stress during coal mining

“…The above parameters are substituted into Equations (3), (7), and (9) so that the disturbance stresses −P 3 (x) and −P 2 (x), and incremental loads f 3 (x) and f 2 (z) can be depicted by MATLAB software, as shown in Figure 9. As shown in Figure 9, the peak value of the disturbance stress −P 3 (x) produced by the interaction of M 3 and Q 3 in KS3 is 3.1 MPa, and its influence range is from O 3 to 110 m (O 3 is the initial breaking point of KS3, which is a marker point in Figure 1); after transferring to KS2, the influence range of the load increment f 3 (x) is basically unchanged, but the peak stress value decreases to 1.6 MPa, and the peak position moves forward 8 m. However, the peak value of the disturbance stress −P 2 (x) produced by the interaction of M 2 , Q 2 and f 3 (x) in KS2 is 6.5 MPa, and its influence range is from O 2 to 180 m (O 2 is the initial breaking point of KS2, which is a marker point in Figure 1); after transferring to KS1, the influence range of the load increment f 2 ( z ) changes to O 1 -180 m (herein, O 1 is 0), but the peak stress value drops to 2.6 MPa, and the peak position moves forward 9 m. Hence, when the disturbance stress is transmitted downward, the influence on the stress range of the underlying strata is not significant, but the stress will gradually attenuate, and the peak stress will shift forward.…”

“…The mining disturbance of the working face causes abutment stress in the surrounding rocks of the stope and roadway [1][2][3][4][5][6][7] and induces deformation and destruction of the surrounding rocks, even inducing dynamic disasters such as coal burst and rock burst. [8][9][10] This has an impact on underground equipment and production systems and poses a threat to the safety of underground personnel.…”

Numerical Simulation of the Supporting Effect of Anchor Rods on Layered and Nonlayered Roof Rocks

“…Yang et al conducted theoretical calculations, numerical simulations, and field tests and determined that increasing the support strength and support density under the current support level was not an effective means of controlling the roadway-surrounding rock [20]. Overall, therefore, the problem of roadway roof fall accidents has not been adequately solved, the roadway maintenance remains challenging, the repair rate is high, and the maintenance and repair costs are considerable [21][22][23][24].…”

Analyzing dynamic disturbance fragmentation mechanism of surrounding rock in roadway roof

“…In literatures [14][15][16], the mechanics and seepage characteristics of rock under confining pressure are studied experimentally. In literatures [17,18], a U-shaped steel support scheme was proposed to handle the issue of the roadway surrounding rock support, which was based on the displacement, plastic zone and principal stress difference distribution under different support schemes.…”