Abstract:

The structural mode of land section of Xiamen Second West Passage varies and it is highly risky. In this paper, the construction technologies for shallow mined doublearch tunnel, large and deep opencut foundation pit and tunnel crossing above existing Metro tunnel are discussed. Some conclusions are drawn as follows: 1) The shallow mined doublearch tunnel has many disadvantages, such as shallow cover, large span, weak rock and complex conditions on ground; and the settlement control is the key. The design supporting and construction method are feasible according to theoretical calculation results. A series of technologies, i.e. supporting parameter optimization, paying attention to stress system conversion, monitoring strengthening and informatized construction, should be adopted. 2) The keys to large and deep foundation pits are deformation control of supporting structure, structural safety, waterproofing, safety of surrounding buildings and stability of combined retaining system of complex strata. 3) The uplifting of existing Metro tunnel induced by abovecrossing tunnel construction can not be avoided. It has any influence on existing tunnel structure, but it has influence on tunnel tracks. As a result, antiuplifting technology, monitoring and prepared countermeasures should be adopted.

Key words: Xiamen Second West Passage, land section, mined doublearch tunnel, opencut foundation pit, three pilot adit, long pipe roof, bored pile, jet grouting pile