Stability control method of surrounding rock in deep roadway with large deformation

To investigate the surrounding rock control of deep roadway with large deformations,the theories,such as Kanstner theory,were applied to study the influence of supporting resistances on the surrounding rock deformation in roadways subjected to high in situ stress. The mechanical essences of the difficult control of these deformations were discovered,and the new supporting concepts of roadway stability were then proposed. The large roadway deformation mainly consists of discontinuous deformations that result from the shear dilation and dilation of shallow fractured sur- rounding rocks and the continuous deformations that mainly result from the stress-induced plastic deformations. Results indicate that the present supporting system exerts limited influences on the continuous deformation,a part of the de- formation cannot be successfully controlled,that means ‘given deformations’ are encountered. To successfully control the roadway deformation and significantly reduce support cost,the support concept should be transferred from deforma- tion control to stability control. This transfer will ensure the even distributions of in-situ stress,coordinated deforma- tions and the eliminations of roof falling and wall caving. Thus,the integrity and stability of surrounding rocks will be further enhanced. In the excavation process of roadways,the enlarged roadway sections that can tolerate the ‘given de- formations’ and the support system that can continuously deform will provide higher support resistances. Therefore,the integrity and stability of roadway are ensured. Even and coordinated deformations of roadway will be successfully ful- filled. The practice results show that the support mainly by the integrated control technology of reserved deformation and “addable lengthen bolts + stiffness thread steel lengthening bolts+bolting net+W steel belt+sprayed concrete” and supplemented by the scheme of addable lengthen bolts strengthen roadway roof can control the stability of roadway sur- rounding rock effectively,and ensure the safety of roadway during its service.