Research On The Stress Behavior Of Surrounding Rock During Construction Adopting CD Method Of Large Cross-section Tunnel

With the development of traffic construction of our country, the large-section tunnel and underground projects increases gradually, and the construction technology of the large-section tunnels has been greatly developed. Compare with tunnels which were built before, new request for the construction of the large-section tunnels appears in the form of cross sections, lining structures, construction technology, primary support structure models and parameters, etc. Although at the current time there is a lot of computation cases of the large-section tunnels, most of them lack of general and systemic research especially in the analysis of influence of construction technology to tunnel stress by the simplification of parameters and simulation.Currently in construction stage of the large-section tunnels, the excavation was mostly separate into some cross sections. By the influence of excavation orders the surrounding rock stress distribution will be unbalanced after the excavation of the tunnel cross. Aims at the problem of unbalanced surrounding rock stress distribution after excavation, this thesis used the ANSYS software to research the main contents shown as below:1. Four normal forms of the tunnel cross section were selected as the research subjects by the comparison of cross section forms of large-section in China, and the design principles were promoted to direct the cross section design from the mechanics aspect;2. The influence of geology parameters to tunnel steadiness were summarized based on the analysis of steadiness of different symmetry sites of surrounding rock after the excavation of the large-section tunnels which used the CD method.3. During the construction stage of the large-section tunnels, the condition of different geology parameters at the site of same cross section will always exist. Combined with the construction process of CD method, the stability coefficient K values were compared to research and summarize the stress regulation of different site of surrounding rocks during the excavation and after-excavation stages.4. Aim at the problem of unbalanced surrounding rock stress distribution during the construction of large-section tunnels, the surrounding rock parameters were raised to balance the stress by establishing the anchor strengthening area. The influence regulation of the anchor strengthening area parameters to the stability of tunnels was summarized as result.