A Study On Construction Mechanics For Four-lane Road Highway Tunnel

In recent years, with the development of material, technology, equipment and rockmechanics theory and the urgent demand for actual life, the large span tunnel andunderground project increases gradually. Although the construction technology of thelarge span tunnel has been greatly developed, it is still at initial stage. Strictly speaking,the current code can only guide the design and construction of the tunnel under15m-span and underground project, while can't do those for four-lane road highwaytunnel and the important factor-the surrounding rock is structure is neglected. In aword, it is important to carry on the systematic advanced research on the design andconstruction of the four-lane highway tunnel. This thesis closely combines construction of national large-scale key engineering.Under the guidance of the basic principle of rock mechanics and NATM, constructionmechanics effect of subsection excavate of large span highway tunnel will be analyzedby utilizing surrounding rock stress distribute characteristic of oval cavern. Thereforethe surrounding rock steady basic criterion of large span highway tunnel can beestablished. Construction process of some common construction methods at differentsurrounding rock terms is analyzed by ANSYS. And the results shows it has well settledthe stability problems of the constructions excavate and support structure. At the sametime, the load-structure mode based on experience is transformed into therockness-structure mode which is better and more reasonable than the former mode intunnel design. The thesis pays attention to interaction of surrounding rock and structureconsidering the surrounding rock is not only loads but also is structure and it reflects thesoul of the NATM. The results of calculation of the thesis are relatively identical withsimilar model experimental result. The relevant conclusions of the thesis can be referredby adopting elastoplastic finite element to analyze construction mechanics effect oflarge span tunnel and construction method optimum seeking and highway tunnel (largespan) constructionrevision of the technical specification.