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为研究基坑支护桩在永久工况下的使用价值,对济南市某基坑桩锚支护结构进行永久化设计,通过设置支撑构件将支护桩与地下主体结构相连,形成共同抵抗坑外侧向土压力的永久支护结构体系,借助PLAXIS-3D有限元软件对该结构进行全工况模拟。结果表明:永久支护结构可有效减小地下室外墙土压力,基坑外侧土压力主要由支护桩承担,地下室外墙只承担少量回填土体的侧土压力,只需按构造要求设计;换撑之后,桩身弯矩和基坑外地表沉降均有明显增加,对支护桩受力和周边建筑环境均产生不利的影响,对支护桩设计提出更高要求;裂缝计算结果显示支护桩满足现有规范对混凝土结构耐久性的要求,为永久支护结构的推广奠定基础。
In order to study the use value of the foundation pit supporting pile under the permanent working condition, the pile-anchor supporting structure of a foundation pit in Ji’nan city is designed permanently. The supporting members are used to connect the supporting pile with the underground main body structure to form a common resistance pit External lateral earth pressure of the permanent support system, using PLAXIS-3D finite element software to simulate the structure of the whole working conditions. The results show that the permanent support structure can effectively reduce the earth pressure on the external wall of basement. The earth pressure outside the foundation pit is mainly borne by the support pile. The external wall of the basement only takes the side earth pressure of a small amount of backfill soil. After the replacement, the pile bending moment and the settlement of the foundation pit are obviously increased, which will adversely affect the force of supporting pile and the surrounding building environment, and put forward higher requirements for the design of supporting piles. The calculation results of cracks show that Pile to meet the existing requirements of the durability of concrete structures, laying the foundation for the promotion of permanent support structure.