Analysis on Spatial-Temporal Change of Construction Mechanics of Long-Span Disaster-Proof Half-Tunnel Structure System

Abstract

Largely-rolling hills are widely distributed in China. In these areas, high-cut slope is common in road construction. Such form of construction usually causes excessive disturbance to hills and serious damage to vegetation, which is easy to induce natural disasters and affect traffic safety in the operation period. In order to protect the natural environment and prevent natural disasters, a new type of tunnel structure - long-span disaster-proof half-tunnel structure system -is increasingly used in highway tunnels. This type of structure involves a variety of constructions, necessitating a process of structural system conversion. For this reason, construction mechanics is unknown. In the context of the half-tunnel structure system of an expressway, this paper establishes 11 spatial-temporal conditions using the Load Release Coefficient of Slope, performs the coupled simulation of the half-tunnel combined system with the most unfavorable section through numerical calculation, analyzes the changes in the construction mechanics of the combined system under different working conditions, and proposes the good timing for construction of half-tunnel structure system according to the monitoring and measurement data obtained from the construction site. The result shows that the half-tunnel structure system is a system combining side slopes, backfilled masses and half-arch inclined-column structure, which interact with each other. The half-tunnel construction should allow for the coordination of the three combination factors. With an eye to assuring the safety and stability of structure system and making the structure solution economically feasible, it is supposed to be a good time to start the construction of half-tunnel structure system when about 70% of the stress inside slopes is released.