Soft Base Shallow Tunnel Construction Technology

This disseration combined with a shallow tunnel in soft foundation named Niulingjie Tunnel beneath the existing road. The construction schedule of double-side-wall drift, its stress characteristic and analyzed the feasibility of excavation in shallow-buried soft rock with benching technique are studied with the field measuring data, theoretical analyses and numerical simulation. The main content includes followings:Firstly, stress characteristic of Niulingjie Tunnel is analyzed; construction technology to establish correlative construction management and technology and emergency response plan when tunnel collapses during construction is optimized.Secondly, the feasibility of benching technique in the soft foundation is analyzed when the tunnel passes through the exiting road; surrounding rock pressure with different burial depth through creating a mechanic model is calculated; the affecting factors on settlement of early support is analyzed; the settlement regularities of early support with different bench length and rock resistant coefficient is studied, and reasonable dimension for early support is established. Results imply the plan is viable and economical.Thirdly, benching tunneling method and double-side-wall drift are simulated by FLAC-2D. Compared with the surrounding rock deformation of the two conditions, it is found that the second one is more reasonable.Finally, the principle of monitoring and measurement for Niulingjie Tunnel is put forward, some measurement results from two construction methods are analyzed by constrast to numerical results.Now Niulingjie Tunnel has been built and put into operatrion, it shows that the construction method and technology raised in this disseration is reasonable and make a remarkable economy value and social effect. It can also provide some reference value to other similar projects.