| Redundancy is the principal of designing important and complicated loading structure. In the Civil Engineering, redundancy was thought as the ability of the structure system to resist progressive collapse. If one element fails, adjacent elements can take over the function of the failed element. The redundancy theory now has been widely used in superstructure design. It is a common sense that important buildings must be designed according to the redundancy theory to restraint progressive collapse, such as National Stadium of China (Bird's Nest) and Guangzhou Tower of China. But,the redundancy theory used in Excavation Engineering has not any research in China or other country. The safety of excavation in soft soil is increasingly challenging as the depth of the excavation is becoming larger and larger, especially when the excavation is conducted at the densely populated area or near various infrastructures. If the excavation collapses, it will lead to disastrous consequences. Such as the redundancy theory was take into the Excavation Engineering to resistance progressive collapse of the foundation pit.In this paper, the redundancy theory in deep excavation and its catalog had been introduced,in addition the redundancy of plan support structures and the convex location of foundation pit supported by soil-nail had been studied. The report of the research said that the method of removal member bar and the Frangopo Formula can be used to evaluating redundancy of the plan support structures, and the plan support structures had been optimized to improving its bearing capacity redundancy and stiffness redundancy. The results of the research of the redundancy of pit convex location supported by soil-nail prove that consolidating the convex location of pit supported by soil-nails with breast beam can control the displacement of dangerous location effectively, transfer the redundant load and increase the transferring path. Hence, it can improve the redundancy of support system. |
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