李连祥+刘兵+李先军

摘要：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。

关键词：基坑；桩锚支护结构；永久支护结构；耐久性

中图分类号：TU443 文献标志码：A

文章编号：1673-2049（2017）02-0119-08

Abstract：In order to study the application value of foundation pit support piles under permanent working conditions， a permanent design was made for a pile-anchor retaining structure in Jinan. The permanent supporting structure system was formed by the connection of supporting piles and the underground structure through the supporting members， which resisted the lateral pressure of foundation pit. Finite element simulation software PLAXIS-3D was carried out for each working condition of the structure. The results show that the permanent supporting structure can effectively reduce the stress on the basement exterior wall. Most of the soil pressure is born by the supporting piles. The basement walls only burden earth lateral pressure produced by backfill soil， so its design just needs to meet the construction requirement. After changing the support， the bending moment of the piles and the ground settlement around foundation pit are largely increased， thus the supporting piles and surrounding are adversely affected and supporting piles design needs to meet higher requirements. Crack calculation results show that the permanent supporting structure meets the existing specifications for durability of concrete structure， and affords the foundation of the extension of permanent supporting structure.

Key words：foundation pit； pile-anchor retaining structure； permanent supporting structure； durability

0引 言

基坑支護工程是为保证地下结构顺利施工和保证周边环境安全而建造，随着城市的发展，地下结构层数不断增加，与之相对应的基坑深度也不断增大，挡墙式基坑支护结构得到大量应用。现阶段基坑支护结构一般视为临时性施工措施，包括地下室、地下车库在内的主体结构地下部分为永久结构，在主体施工完毕基坑回填后，基坑临时支护结构被遗弃地下，造成资源浪费和环境污染，不利于城市地下空间的可持续发展[1-3]。

将基坑支护结构应用于建筑地下主体结……