A Comparison Study of the Radial and Non-Radial Support Schemes in the Deep Coal Mine Roadways under TBM Excavation by the 3-D Equivalent Continuum Approach

In recent years, TBM has been widely applied in deep coal mining to lift the TBM tunneling efficiency and avoid accidents, and more flexible support schemes are expected and required. This research aims to evaluate the performance of the two different support schemes and to study the law of the support effect. A three-dimensional continuum model was established based on the available geological information, and the support effect at the three-dimensional level was studied by changing the support spacing and was assessed in term of the stress, displacement, failure zone, bolt force distributions, and axial deformation behavior of the tunnel. The results show that no matter what the geological condition was, the support of the non-radial support was a little lower than that of the radial support, and with a worse geological condition, the non-radial support had a better performance in the stabilizing tunnel. Additionally, the law of the support effect was found. The interlapping of the support influence domain was the essence of the increase in the support effect. Finally, according to the support law, the appropriate support spacing is found, which is smaller than 50% of the support influence domain length.