Analysis of Bolt Support Characteristics in Soft Rock Roadway

To ensure the stability of surrounding rock in soft rock roadway and determine the reasonable parameters of bolt support, the supporting effect of local anchoring bolt is equivalent to the supporting force acting on the surface of the cave wall and the body force acting on the surrounding rock of anchorage zone. Then, based on the theory of strength enhancement, the roadway mechanics calculation model is established. Finally, the theoretical calculation results are compared with those of FLAC^3D, and the influence of each bolt parameter on the displacement of tunnel wall and the area of plastic zone is studied. The results show that the tunnel cave wall displacement and the plastic zone calculated by the theoretical calculation are respectively 28.4 mm and 6.995 m, and the tunnel wall displacement and plastic deformation range obtained by FLAC^3D numerical simulation are respectively 30.1 mm and 7.097 m. Moreover, the difference between theoretical calculated value and FLAC^3D under different support strength is less than 10%, which verifies the correctness of the theory. Compared with other bolt parameters, the spacing and pre-tightening force of bolt have great influence on the deformation of surrounding rock, so it is necessary to adjust bolt spacing and use pre-stressed bolt reasonably in engineering.