The Supporting Technology Research in Large Section Inclined Shaft with Fracture and Soft Surrounding Rock

This paper is based on the large section inclined shaft crossing goaf of Pingdingshan No.6 Mine as engineering background, and aimed at solving the difficult supporting problem of fractured surrounding rock. After establishing and calculating the mechanical models of U-steel and inverted arch, the support's vertical reaction force (N1) and horizontal counterforce (X1) are determined as 180.96 KN and 48.12 KN, while the maximum bending stress (σmax) and ultimate bearing capacity of the inverted arch are obtained as 375.59 Mpa and 0.27 Mpa. It shows that the deformation of surrounding rock is well controlled by the supporting structure. The numerical simulation model is built by using the software FLAC3D to analyze the stability of surrounding rock after supporting. The results suggest that the deformation of roof, floor and sides is reduced by 17%, 23% and 71% respectively after supporting with U-steel in the inclined shaft, and the accuracy of results has been verified by a field experiment. Therefore, the "U-steel+ pouring concrete + inverted arch + backwall grouting" technology can effectively control the damage of surrounding rock and improve the stability of surrounding rock.