Abstract：
It is a challenge for tunnel builders to keep a tunnel portal stable in a shallow buried section with bias pressure, which directly relates to construction and operation safety. In order to address this issue, a new composite arching structure with an umbrella and piles was adopted. This utilized the supporting property of the piles to reduce the cutting height of the side slope. It also improved the bearing capacity of the arching structure in order to prevent the portal and portal slope from subsiding and slipping, ensuring safe construction and operation of the tunnel in the section of bias pressure and fractured soft rock. This paper introduces the new composite arching structure and its construction method, and a mechanical analysis is carried out.
2013, Vol. 50 