Simulation analysis on half-open and half-hidden entrance way of half hollow-out form in Keshutu tunnel

The construction of highway tunnel entrance is always difficult, the good and bad entrance ways of tunnel directly influence the construction schedule and exterior environment quality. Based on Keshutu tunnel entrance engineering, the half-open and half-hidden entrance way of half hollow-out form was simulated by considering topography, geology and environmental conditions in the paper. The results have shown that the half-open and half-hidden entrance way of half hollow-out form is security and effective for the Keshutu tunnel, and the retaining wall structure has obvious effect on the support of half-open and half-hidden entrance, which can not only protect natural environment but also make the construction security and stabile. Under unsymmetrical pressure loads, the deformation values are bigger at the tunnel vault, the floor midpoint and the central part of the arch wall than at other points. But the deformation values are in security and stabile states. The rock bolts at the vault and the side wall are in tensile state, and the maximum axial tensile stress is 162.9kPa. The tensile stress appears in the vault of the lining structure, and the maximum value is 96.89kPa. The maximum tensile stress values of the anchor and the lining structure during the construction are both far below their tensile strength. The conclusions obtained have certain reference value for similar projects.