A Design Approach for Determination of Concrete Support Thickness in Vertical Mine Shafts

Stability in underground shafts is very important. Shaft lining can supply it. In this study, the concrete support thicknesses of a vertical shaft of 9 m diameter and reaching a depth of 900 m were determined by 2D numerical analysis. In numerical analysis different depths (Z), uniaxial compressive strength (σci), rock mass classification system (M-RMR) and also the surrounding rocks situation based on blasting (D) parameters were used. In each of the nine-meter-diameter shafts has 100, 300, 500, 700 and 900 meters where the M-RMR value is 10, 20, 30, 40, 50, 60, 70, 80, 90, 100 and the uniaxial compressive strength 50MPa and also situation formed in shafts surrounding rocks based on blasting (D = 0 and D = 0.5) the numerical analysis were made by Phase2 software. As a result, in this parametric study, a total of 100 scenarios were analysis. The optimum thickness (tc) of concrete support with C20 class concrete have been identified for each scenario. The maximum principal stresses (σ1), total displacement (U), the number of yielded elements formed in the surrounding rocks, strength factor (SF) and thickness of yielded region (ht) respectively were determined. Using Phase2 software 10 integrated charts were prepared. By data base to determine of concrete support thickness If the rock mass classification value (M-RMR) is known the thickness of yielded surrounding rocks (ht), concrete support thickness (tc) the total of displacement (U) to be formed in the shaft can be determined.