Digging length optimization analysis of shallow bias highway tunnel

In the process of construction of the shallow bias highway tunnel, it is crucial to rationally delimit the size of digging length. If the size of digging length is too small, the construction time will be prolonged and temporary protection will increase. If the size is too large, the rocks on the top of the tunnel will be instability. This thesis take some shallow bias highway tunnel as the engineering background, obtained the reasonable digging length of shallow bias tunnel is 2.0 m by analyzing the “space effect law” diagram, which basing on the spatial effect theory of excavation face and introducing the displacement release coefficient. The research results provided a guiding role for shallow bias highway tunnel construction.