Design and optimization of bolt and wire mesh support for a tunnel based on the grey-fuzzy theory

In order to solve the mechanical problems during tunnel-supporting design under the mined gob with a thin roof coal seam, orthogonal experiments with 7 factors and 3 levels including 27 numerical simulations were carried out. The influence of the key factors on the tunnel stability was analyzed and corresponding optimized schemes were chosen according to 3 evaluation standards. The grey-fuzzy theory was utilized to make comprehensive evaluation and overall optimizing design. Cost factors such as supporting expense and construction time were considered during the study. The stress transformation, displacement character and failure mechanism of wall rock after support were analyzed, and a feasible construction plan was established. After utilizing the introduced supporting technique formally in Tianzhu Mining Zone of Yaojie Coal-electricity Inc. in China, favorable economical benefit is brought.