Investigation on rational width of coal pillar and roadway support in isolated panel of extra-thick coal seam

Abstract

The methods of numerical simulation and on-site measurement is used to analysis reasonable coal pillar width (CPW) and roadway support in isolated panel of extra-thick coal seam. Numerical modeling shows that a maximum vertical stress in isolated panel is 32.9 MPa, and stress concentration factor reaches 2.99, which is more affected by the mining of adjacent panel, and the peak stress on both sides is higher. By comparing the failure and deformation characteristics of different pillar widths, it is shown that a 6 m pillar can reach the load requirements of overlying strata and ensure that the roadway is in an undamaged and controllable environment. According to the asymmetry of surrounding rock deformation, the final joint control technology of asymmetric anchor cables, high intensity anchor cables, and coal pillar grouting is proposed and get good control effect on site. The research results provide guidance value for surrounding rock control under similar geological condition.

Stability control of goaf‐driven roadway surrounding rock under interchange remaining coal pillar in close distance coal seams

“…To explore the influence of various factors on the lower coal seam vertical stress distribution under the remaining coal pillar, the control variable method is used to calculate the changes of the vertical stress distribution characteristics under the influence of a single factor, as shown in Figures 7–9. The range of variation of relevant parameters is as follows: coal seam depth is 300–1500 m, stress concentration coefficients K 1 , K 2 , and K 3 are 1.5–3.5, 1–2.5, and 1.5–3.5, respectively, and widths x 1 – x 5 are 0–40, 30–60, 49–61, 55–95, and 85–125 m, respectively 30–33 . In single factor analysis, except for the factors that need to be analyzed, the values of each factor are taken as the median.…”

“…The range of variation of relevant parameters is as follows: coal seam depth is 300-1500 m, stress concentration coefficients K 1 , K 2 , and K 3 are 1.5-3.5, 1-2.5, and 1.5-3.5, respectively, and widths x 1 -x 5 are 0-40, 30-60, 49-61, 55-95, and 85-125 m, respectively. [30][31][32][33] In single factor analysis, except for the factors that need to be analyzed, the values of each factor are taken as the median. In addition, considering the actual,K 2 is not greater than K 1 , then K 2 is taken as 1.…”

Optimal Layout Methods for Deep Chamber to Separate Coal and Gangue Based on the Weak Stratum Horizon

“…The engineering community generally defines rocks with uniaxial compressive strength of less than 25 MPa as weak rocks [28]. The physical and mechanical parameters of rock masses in the geological model are selected concerning relevant references (Table 2) [29,30]. The bulk density of the weak rocks is 2.46 × 10 4 N/m 3 .…”

Failure properties of roadway with extra-thick coal seams and its control techniques

“…In order to research the surrounding rock stress evolution laws and deformation features of the roadway with thick top coal, the similarity models [ 2 ], the Hoek-Brown failure criterion [ 3 ], the field measurement and the numerical simulation methods have been applied by many scholars. Based on the relevant research results, it is well known that the superimposed mining stress which induced by the large mining thickness of the coal seams and the intense movement of the overlying strata could aggravate the deformation and instability failure of the roadway with thick coal roof [ 4 ], the supporting system and its efficiency will gradually decrease [ 5 , 6 ] during this process, and the asymmetric floor heave and significant deformation was more easily appear for gob side roadway in extra-thick Coal Seams [ [7] , [8] , [9] ]. In order to control the surrounding rock deformation of the roadway with extra-thick coal seam, the dense combined supports have to be applied in roadway construction on site, which significantly reducing the driving efficiency and leading to the technical problem of mining proportion imbalance in the mine [ 10 ].…”