Effect of Shaft Pillar Extraction on Stability of Main Shaft: A Case Study at Xincheng Gold Mine, China

Abstract

Mining of ore body in the vicinity of a shaft has a significant influence on its stability. The in situ monitoring and numerical simulation are employed to analyze the effect of shaft pillar extraction at Xincheng Gold Mine. The XI# ore body is recently found around and beneath the shaft, and mining in this area may be detrimental to the shaft. Firstly, on the base of geological survey and in situ displacement monitoring, mechanical parameters of rock mass are obtained and the displacement around the shaft is measured. Secondly, the sensitivities of five main factors that may affect the shaft displacement are analyzed by means of orthogonal experiment according to the numerical simulation with FLAC3D. Finally, a numerical model is established according to the in situ condition; in order to forecast the shaft displacement induced by mining activities of XI# orebody, the Mining Priority Index (MPI) is put forward and used to select the optimal mining sequence. Based on the comparison between the numerical results with the monitoring data, it is determined that the ore within 100 m from the shaft is not suggested to be extracted until the last period of the shaft life.

Prediction and Analysis of Vertical Additional Force of Shaft Wall in Topsoil Containing Multiple Aquifers during Drainage

“…The depth of the shaft continues to increase with the demand of coal resources, and the fracture disasters in vertical shafts, induced by the complex stress, are becoming increasingly frequent, which affect the operation of the entire mine and threaten the safety of personnel [1][2][3][4]. The stresses mainly consist of the vertical stress and the horizontal stress.…”

Analysis on the Vertical Additional Force of Shaft and Drainage Settlement Characteristics of Topsoil Containing Multiaquifers

“…As the strategic passage of a coal mine, the security of vertical shaft is of great significance in protecting the safety of personnel and normal production [1][2][3][4]. The additional force induced by drainage settlement of the topsoil has been proven to play an important role in the breakage of shafts [5,6].…”

“…In addition, the effect laws of drainage velocity, central aquifer thickness, location, and numbers on the additional force were obtained and analysed. 4 Geofluids 2(b) [23][24][25][26][27][28][29][30]. The basic assumptions are as follows: (1) the single-layer shaft model is used as representative of actual shaft wall, and the shaft wall, the depth and thickness of the strata, and the settlement deformation are all symmetric about the centerline of the shaft; (2) relative displacement between the shaft wall and surrounding strata will occur due to vertical additional forces; (3) the contact interface between the shaft wall and surrounding strata adopts a hyperbolic constitutive relationship (shown in Figure 3); (4) the strength criteria are taken on the shaft wall and each aquiclude and aquifer; (5) the interaction of the drainage effect between aquifers is ignored.…”