Parameters Affecting the Shield Support Efficiency in Longwall Mining

The orientation and location of the hydraulic legs are two very important parameters for the design of shield supports in longwall mining. Studies have shown that leg orientations and locations of a support determine the magnitude, orientation and location of the resultant support resistance which in turn affects the efficiency of the support and the ability to prevent premature roof falls in the face area. Therefore, there is a need to determine the best combination of orientation and location of the hydraulic legs for each type of shield support under various geological conditions. This paper attempts to evaluate, first, the individual role of each parameter (orientation or location) and then to determine their integrating functions in terms of ground control employing finite element analysis. Three types of shield support (2-leg and 4-leg shields and 4-leg chock shield) with various combination of the parameters are simulated and their effects are discussed. The optimum design for each parameter for each support type under various geological conditions is also discussed and recommended.