Soft rock roadway buffering tapered double strong shell support system and construction method thereof

The invention discloses a soft rock roadway buffering tapered double strong shell support system. The soft rock roadway buffering tapered double strong shell support system comprises a first strong shell, a second strong shell and a telescopic U-shaped steel support, wherein the first strong shell is an internal grouting reinforcing ring formed after cement-water glass is injected in surrounding rocks of a loose damage area; the second strong shell is an external grouting reinforcing ring formed after high-pressure chemical grout is injected in surrounding rocks of an incomplete damage area, and the second strong shell is used for connecting complete surrounding rocks with the first strong shell; the telescopic U-shaped steel support is arranged on the surface of the first strong shell, a buffer pressure-relief layer is arranged between the back of the telescopic U-shaped steel support and the surface of the first strong shell, and an internal bearing structure of the support system is formed by the telescopic U-shaped steel support and the buffer pressure-relief layer together. According to a surrounding rock reinforcing method in different grouting manners regionally, the large rheological deformation of soft rock roadway surrounding rocks is controlled, the stress state of the support system can be improved, and the stability and non-deformability of the surrounding rocks are improved.