Abstract
Taking the fully mechanized mining face (FMMF) through the abandoned roadway (AR) in a coal mine in Shanxi Province, China as the engineering background, the field investigation, theoretical analysis, numerical simulation and field test were comprehensively used to study the instability mechanism of the trend AR. The deformation and failure evolution of the trend AR roof were deduced into four stages: initial deformation, bending and separation deformation, fracture failure, and collapse destruction. The high span ratio proved to be the key factor affecting the stability of the trend AR, and the control principle of timely support and reduction of roof span should be followed for controlling the roof of trend AR. Comparing the traditional method through the trend AR with the perspectives of technological and economic benefits, the technology of filling and controlling the trend AR with the high water material over in the FMMF was proposed, and the effect of the filling body on the roof of the trend AR was revealed. The key parameters of the filling body were identified: the strength of the filling body is 1.0 MPa, and the water-cement ratio corresponding to the high-water material is 8:1. Based on this information, the process of the trend AR filling was designed systematically. Industrial tests show that during the FMMF through the trend AR, the roof was effectively supported by the filling body and the normal coal mining was not significantly affected, so the safe mining of coal resources was guaranteed.
Highlights
Energy is the foundation and power of human civilization and progress [1]
The results show that the deformation of rock strata is basically perpendicular to the normal direction of the bedding plane, and the fissures of surrounding rock gradually develop into joint fissure group with the tunneling of abandoned roadway (AR); (2) Bending separation deformation
The support is strengthened by dense pillars or wooden stacks. 3301 fully mechanized mining face (FMMF) through the AR, each coal cutting cycle requires the removal of dense pillars or wooden stacks, the process needs to stop for 20 min, a total of 120 min a day, which is equivalent to cutting a knife less coal per shift
Summary
Energy is the foundation and power of human civilization and progress [1]. As one of the energy mineral resources, coal accounts for 25% of the world’s primary energy consumption. Based on the engineering and technical problems of a FMMF in Shanxi Province, the surrounding rock instability mechanism of the AR by theoretical calculation method was studied, and the technology of filling the AR with high water material by comprehensive technical and economic factors was proposed, and the action mechanism of the filling body on the roof of the AR by means of numerical simulation was revealed. On this basis, the key parameters of the filling body and the filling process scheme were determined, and the industrial test exploration was carried out successfully
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