Research and application on new high pre-stressed anchor cable with bolt-grouting comprehensive support technology

The existing supporting materials and technology are difficult to support the deep soft rock with large de- formation. In order to overcome this support problem,in this study,a new type of high pre-stressed anchor cable and its supporting technology are developed based on theoretical analysis and laboratory tests. Initial pre-stress applied on the new type of anchor cable can reach 70-100 kN,and the elongation of the rod body can reach 10% -12% ,which can effectively prevent the rapid deformation of the surrounding rock after excavation and maintain the integrity and stabili- ty of the surrounding rock. The new type of anchor cable has the advantages of low cost,high strength,and not easy to loose,etc. According to the deformation characteristics and mechanism of the surrounding rock in typical deep soft rock roadways,the combined control techniques with the core of new high pre-stressed anchor cable and grouting bolt are proposed. The new high pre-stressed anchor cable,metal mesh,concrete spray layer are used during primary support. Full-sectional grouting is adopted in a later period,which improves the support strength fundamentally by combining with interior and exterior. The research results show that this new technology can effectively improve the bolt stress,reduce the deformation rate of the surrounding rock and shorten the deformation time of the surrounding rock based on field tests. The finally deformation of the surrounding rock accounts for only 30% of the original supporting scheme, and the anchor cable force increases by nearly 4. 7 times on average. This study achieves a good supporting effect and has an important application value.