By taking on standard cross section used for two-lane soft rock tunnel on high-speed passenger railway for 250 km/h

Muzhai Mountain soft rock tunnel is cited here. Meanwhile

energy accumulation

deformation

mechanical response and plastic zone are developed to study stability of tunnel in different characteristics of geostress field. When the horizontal maximum principal stress is parallel to the tunnel axis

high energy and plastic zones occur at wall of tunnel mostly. Energy density ahead of working face is smaller; and squeezing deformation of working face is larger. However

when the horizontal maximum principal stress is perpendicular to the axis

high energy and plastic zones distribute at crown and invert of tunnel

ahead of working face. The energy density is larger and the squeezing deformation is smaller ahead of working face. Consequently

the conclusions can be drawn as follows: there is mechanical behavior of deformation-energy orthogonality ahead of working face. Nowadays

squeezing deformation is adopted to evaluate stability ahead of working face simply

which is worth to further study. It is not suitable that tunnel axis should be parallel to horizontal maximum principal stress regulated by means of the relevant codes in different tectonic geostresses. Bolt has effect on formation of arch effect temporarily at initial stage of excavation. It can make the arch effect closer to tunnel and reduce effectively the peak value of tangential stress for surrounding rock at wall. With advance of working face

arch effect moves to deep rock. Therefore

staged arch effect is formed.