The Influence of Room and Pillar Method Geometry on the Deposit Utilization Rate and Rock Bolt Load

Abstract

In this article, a model of ore deposit in form of a lense carried out in the MineScape program, is presented. The lense had a thickness of 30 m, length along the strike 200 m, and the depth buried was for 80 m to 110 m below the surface. In the first layer, counting from the lowest level, a room and pillar method with variable geometry was designed. The width and length dimensions for rooms and pillars were: 4 m, 5 m and 6 m, respectively. For the selected part of the deposit, three variants of the system with variable geometry of rooms and pillars were designed, for which the deposit utilization coefficient was determined. The next stage of the research was to determine the influence of the geometry of the pillars and rooms on the range of the rock destruction zone around room excavations. For this purpose, numerical calculations using the three-dimensional Examine 3D program, based on the boundary element method, were made. The results of numerical tests were used to calculate the load of the rock bolt support, which is currently used in the zinc and lead underground mine "Olkusz-Pomorzany" in Poland. Currently in the mine, the bolt spacing is 1 m × 1 m, and the technology for fixing the bolt rod is based on resin cartridges that completely fill the bolt hole. In order to spread the spacing of the rock bolt support and to apply segmental fixing of the bolt rod, in the laboratory tests, rock bolt supports with increased strength were tested. Based on the results obtained, it was found that the rock bolt can be installed segmentally, using a cement grout, and its spacing can be increased to 2 m.

Evaluation of the Total Quality of Tunnel Contour Using Projection Pursuit Dynamic Cluster Method

“…In this work, we define the utilization rate to represent the frequency of the index used in quality rating. Following the definition in literature [33], the utilization rate is defined as the ratio of the utilization times of the index to the total number of existing methods. e adoption rate of the index utilized in traditional quality rating is statistically analyzed, as shown in Figures 2-4.…”

Adjustment of the Yielding System of Mechanical Rock Bolts for Room and Pillar Mining Method in Stratified Rock Mass

“…The rock bolt with a sleeve mechanical head was subjected to tensile tests on a testing machine in the bolting laboratory, which was specially designed for testing rock bolt support in a geometric scale 1:1 [43,44]. In the tests, a bolt hole diameter of 25.5 mm was used; the choice of this diameter corresponded to the technology of bolting in industrial conditions.…”

“…The test results are presented in Figure 12a-e and in a Table 1. 43.55 In all cases, the rod material was broken in the thread.…”

Modified Rock Bolt Support for Mining Method with Controlled Roof Bending

“…If there are minor rock deformations, bolts of greater stiffness, e.g., bolts installed with resin or cement grout, should be used [6][7][8]. For resin bolts, laboratory tests are carried out to determine the influence of the embedded length on the load capacity of the bolt [9][10][11]. Li et al [12] determined the minimum embedded length for a 20 mm diameter rock bolt that was installed with a cement binder with three different water-to-cement ratios.…”