“Anchoring-shed-shotcreting” collaborative control technology for limestone roof roadway with soft clay interlayer

Abstract

In view of the characteristics of low in-situ strength and poor integrity of surrounding rock of limestone roof roadway with soft clay interlayer, the internal causes of deformation and failure are discussed, and the reinforcement mechanism of “double-layer bearing arch” and the “anchor support spray” cooperative control technology are proposed. The rectangular section roadway is optimized to arch section, through improving the strength and stiffness of bolt (cable) and applying high preload, the “deep bearing arch” structure is formed in the surrounding rock body; at the same time, the U-shaped steel retractable support is erected in the roadway to form the “shallow bearing arch” structure on the roadway surface; finally, the concrete shotcrete layer is used to close the roadway surface to prevent the weathering of surrounding rock and the softening of water, so as to give full play to the bearing capacity of the “double-layer bearing arch” structure, so as to realize the long-term stability of the roadway. The field practice shows that the surrounding rock deformation of the roadway can be reduced by more than 90% by adopting the cooperative control technology based on “anchor support shotcreting”, and the stability of the roadway with limestone roof with soft clay interlayer can be significantly improved.

Keywords

• limestone with intercalated soft mud
• bolt mesh support
• u-shaped steel support
• concrete spraying layer
• roadway section optimization