Similar Physical Modeling of Roof Stress and Subsidence in Room and Pillar Mining of a Gently Inclined Medium‐Thick Phosphate Rock

Abstract

Gently inclined medium-thick orebodies are generally recognized as the most difficult type of orebody to mine, using current available strategies (i.e., the room and pillar method). In the present study, a similar physical model was used to investigate the roof stress and subsidence for mining gently inclined medium-thick phosphate rock from the Jinning Phosphate Mine, Yunnan Province, China. The stress field, displacement field, and roof failure evolution characteristics of the surrounding rock with stope structures of 3 m, 5 m, or 8 m ore pillars were considered. The results showed that, after mining stopped, obvious pressure relief areas formed above the three stope structures, and pressure-bearing areas formed at the front of the roof. With extending the mining in the working face, the stress relief boundary also gradually increased, and the top of the roof tended to sink with a maximum subsidence of –14.58 mm, –4.67 mm, and –3.48 mm. Due to the mining activity, the overlying strata bent and subsided from top to bottom, creating bending subsidence, fracture, and caving zones.

Study of the Stability of the Surface Perilous Rock in a Mining Area

“…The stability calculation and support design of the perilous rock mass do not consider the seismic action [27]. The stability calculation of the perilous rock mass in the working area during an earthquake mainly adopts the following two working conditions, and considers the reduction in the shear strength index of the rock mass structural plane under rainstorm conditions: Condition 1: dead weight + cleft water pressure (water filling height is calculated according to 1/3 fracture height).…”

Experimental Study on Strength and Permeability Characteristics of Cemented Rock-Tailings Backfill

“…According to a certain ratio, water was added to fully mix into an appropriate concentration of paste, which was sent into the mine through the pipeline. After solidification, it can be used as an artificial pillar to bear the ground stress in the stope; therefore, its mechanical stability was crucial to the safety of the stope (Zhang et al, 2011a;Zhang et al, 2011b;Lin et al, 2013;Hong et al, 2021;Li et al, 2021b;Li et al, 2021c). In addition, the backfill is a porous medium, and the permeation characteristic is also an important quality index of the backfill (Wang et al, 2009).…”

Research on Deformation and Fracture Characteristics of the Fractured Rock Mass Under Coupling of Heavy Rainfall Infiltration and Mining Unloading

“…The long-term stability of high and steep rock slopes under complex geological and external disturbance environments has become a major problem for large-scale mines to convert from open-pit to underground mining. In China, the geological structure of Jiangxi Province is complex, and the long-term strong tectonic movement has fully developed the primary faults, joints, and fractures in the rock mass (Pu et al, 2019;Ji et al, 2020;Shuai, 2021;Liu et al, 2020a;Song et al, 2020;Du et al, 2021;Li et al, 2021a, Li et al, 2021b. Affected by open blasting, mechanical excavation, and weathering, a large number of secondary fissures have been generated inside the high-steep rock slope, which further aggravates the fracture and instability of the rock mass.…”

“…Affected by open blasting, mechanical excavation, and weathering, a large number of secondary fissures have been generated inside the high-steep rock slope, which further aggravates the fracture and instability of the rock mass. In this area, the geological disasters induced by heavy rainfall are becoming more and more serious (Bai and Elsworth, 2020;Rutqvist and Stephansson, 2003;Lee and Cho, 2002;Li L. K et al, 2021;Li et al, 2019;Li et al, 2021a;Li et al, 2021b;Li et al, 2021c;Song et al, 2021;Zhong et al, 2021). The mine slope rock mass has undergone the two-stage compound mining unloading effect after open-pit and underground mining.…”