Construction Practice of Seven-ring Internal Support Demolition in Super-large Deep Foundation Excavation
The foundation excavation project of Kunming comprehensive transportation international hub construction project is faced with the problems of huge amount of support demolition,complex coupling force conversion of seven-ring support,high control requirements of surrounding environmental deformation,and multi-layer peaty soil in excavation range.In order to ensure the rapid and safe demolition of the internal support of the foundation excavation,the"two vertical and two horizontal"is taken as the main force transfer skeleton,and the principle of"secondary and then primary"internal support demolition is proposed.The demolition sequence of"original road retreat and symmetrical demolition"is adopted.The"wire saw cutting"demolition process was adopted.The 2nd and 3rd supports were dismantled in different blocks,and the first support was dismantled by"removing branches and leaves and retaining backbone".Three kinds of auxiliary construction technologies are adopted,including steel brace replacement technology in displacement sensitive area,floor cooperative bearing technology of horizontal transfer of cutting block,and BIM auxiliary wire saw cutting point arrangement technology.Through the above technology,the millimeter-scale deformation control of the influence of the super-large-scale deep foundation excavation of soft peat soil on the adjacent subway is realized.
foundation excavationinternal supportdemolitioncoupling forceconstruction
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