It is determined by roof property, buried depth, coal pillars between the working face and the mining area, and fault protection pillars.
Finally, a method to minimize the distance between the working face and the invert installation was proposed by optimizing the invert installation and adopting the micro bench method.
Due to a height difference of 2 4 m between the working face and the roadway (the working face cutting height was 7 8 m, and the roadway height was 4 4.5 m) in longwall mining working face with super height cutting, the traditional step-by-step matching manner leads to substantial triangle coal loss.
More importantly, it can increase the efficiency of tunneling in weak rock, provide a bigger space for consequent works, reduce the distance between the working face and the invert/lining to meet the specification requirement, and assure the safety and advance rate of the tunneling.
The relationship between stress distribution and permeability in the front of the working face and the surrounding goaf rock was analyzed.
The input parameters include surrounding rock masses (SRM) rating index, ground engineering conditions (GEC) rating index, tunnel overburden (H), rock density, distance between monitoring station and working face (D), and elapsed time (T).
After the connection, a 2BEC80 gas drainage pump was used to drain the gas, the gas concentrations were maintained between 1.5 % and 2.2 % in the high drainage roadway, between 0.2 % and 0.3 % at the upper corner of working face, between 0.2 % and 0.3 % at the tail of the rear scraper conveyor, and between 0.15 % and 0.25 % in the return air.
The displacement rate of the entry will be greatly increased and reaches a certain value within a certain distance between the heading face and the working face.
In this paper, the characteristics of deformation and failure of the entry were investigated in terms of the tempo-spatial relations between heading and working faces through field study and numerical modeling.
Besides, the working face played an important role in BSRS and 75% of the BSRS events were generated within the 50 m between the monitoring station and the working face.
