Research On Shape And Construction Of Four-Lane Highway Tunnel

With the development of traffic construction of our country, the large-section tunnel and underground project increases gradually, and the construction technology of the large-section tunnel has been greatly developed. Compared to the post-constructed tunnel, large-section tunnel have lot of problems to solve, and we haven't mastered the basic principle of rock mechanics and geology particularly, so on the design ang construction of large-section tunnel ,we're still on the phase of exploration and attemption. Strictly speaking, the current code can only guide the design and construction of the tunnel under 15m-span and underground project, while can't do those for four-lane road highway tunnel and the important factor-the surrounding rock is structure is neglected. In a word, it is important to carry on the systematic advanced research on the design and construction of the four-lane highway tunnel.Under the guidance of the basic principle of rock mechanics and NATM, this thesis analyze surrounding rock stress distribute characteristic of different span-ratio three-center tabular cavern. Therefore the surrounding rock steady basic criterion of large-section highway tunnel can be established. This thesis closely is according to construction of national large-scale key engineering, construction process of some common construction methods at different surrounding rock terms is analyzed by ANSYS .And the results shows that it has well settled the stability problems of the constructions excavate and support structure. During calculating and analyzing of numerical simulation, the model is based on the rockness-structure mode which is better and more reasonable than the controversive mode in tunnel design. The thesis pays attention to interaction of surrounding rock and structure considering the surrounding rock is not only loads but also is structure and it reflects the soul of the NATM. The results ofcalculation of the thesis are relatively identical with result of construction and design of real model. The relevant conclusions of the thesis can be referred by adopting elastoplastic finite element to analyze construction mechanics effect of large-section tunnel and construction method optimum seeking and highway tunnel (large-span) construction revision of the technical specification.