Optimization analysis of NPR cable support considering bearing structure in the NSF condition of deep shaft based on Daqiang coal mine.

The deep soft rock shaft with non-uniform stress is a technical challenge for the selection of support parameters. In order to obtain the stress distribution, failure mode, and control characteristics of shaft surrounding rock under non-uniform stress field (NSF), a shaft model under non-uniform stress field was established by numerical simulation software of FLAC3D. The characteristics of maximum stress-bearing circle and plastic zone were investigated using theoretical analysis and numerical simulation. The maximum stress-bearing circle and plastic zone increased with the increase of the NSF coefficient. The peak stress in the y-axis direction increased, while the peak stress in the x-axis direction decreased. However, the change of the plastic zone in the x-axis was not obvious. The negative Poisson's ratio (NPR) cable was proposed to control the stability of the shaft, and the optimal support schemes with space of 1000 mm and length of 8 m were obtained by comparing the plastic zone, maximum stress-bearing circle, and shaft failure. The results indicated that the optimal support scheme reduced the plastic zone and failure significantly, which indicated that NPR cable support could effectively improve the bearing capacity of the shaft. The optimal NPR cable support scheme was also applied to control the stability of the shaft in field test. According to 200 days of monitoring data, the deformation of the surrounding rock is very small, which provides guidance for shaft support. [ABSTRACT FROM AUTHOR]