The Mechanism And Application Of Supporting Structure For Deep Foundations In Unique Geotechnical Areas

As China features extensive territory, landform, terrain conditions and surrounding environment of construction projects are varied. Design and construction of excavation supporting structure is one of the engineering measures mostly connected to the above conditions. In recent years, with the rapid development of urban construction as well as railway and urban rail transit construction, scale expansion of construction project is observed, and deep and large foundation pit has become more and more ubiquitous.The complexity and uniqueness of excavation supporting structure are determined by special requirements of the project itself, landform and geological conditions of the project are a as well as complexity of the surrounding environment. In particular, design and construction of deep and large foundation pit in special rock & soil area such as expansive rock(soil) is one of the most complicated technical problems in engineering construction field.Except for foundation depth, geological conditions are crucial to scheme of deep exca vation supporting structure. Deep and large excavation supporting structure proposes new task for its design and construction, particularly how to coordinate between safety and cost-effe ctiveness with equal importance under the precondition of meeting safety requirements. Survey, design, construction(including dewatering, excavation and supporting), monitoring, asse ssment, feedback and adjustment of excavation supporting structure are closely related to each other, and every one of them are closely connected with safety. In recent years, with the rapid development of railway and urban rail transit construction, engineering practice under some special geological conditions and surrounding environment proves that the existing theory and technique can hardly ensure safety and efficiency of foundation pit works. There are good experiences as well as lessons learnt from failure. To this end, it is necessary and urgent to make comprehensive assessment and summary for the excavation supporting structure which is in thestage of half-experience and half-theory from the aspects of design theory and calculation method.Through discussion of real engineering cases, introduction of existing excavation supp orting structure types, and analysis of calculation theory and study on calculation method, whether deep and large excavation supporting structure is rational and scientific in special rock&soil area is discussed with certain railway project as study objective. Action mechanism, design scheme and construction control experience are summarized for deep and large excavation supporting structure in special rock & soil area combined with engineering practice, which provides theoretical and practical reference to similar engineering practice.