［摘要］组合支护体系由上部土钉墙和下部锚拉桩（墙）结构联合形成，北京城区超过15m深的基坑越来越多地采用这种支护体系。以开挖深度约22m的北京侨福花园广场深基坑工程为例，分析了上部土钉墙在基坑开挖各阶段的内力变化规律，在开挖至土钉墙底时，土钉内力增长速率最快，当基坑潜在滑裂面超过土钉墙末端时，进一步的开挖对土钉内力增长影响有限；由于预应力锚杆的存在，减小了基坑坡顶的位移，同时土钉内力比设计值要小很多，今后类似工程设计可以减小土钉杆体直径。
［关键词］组合支护体系； 基坑； 土钉墙； 锚拉桩（墙）； 土钉内力； 监测
中图分类号：TU753.1文献标识码：A文章编号：1002-848X(2011)10-0105-02
Stress monitoring and analysis on upper soil nailing  of super deep foundation pit with composite retaining system
 Zhang Zhiping， Cheng Xuejun(China State Construction International Co., Beijing 100125, China)
Abstract:The composite retaining system is composed by soil nailing wall on the upper side and piles (or diaphragm walls) supported by anchor on the lower side. Nowadays, such system has been applied more and more in project excavated deeper than 15m in Beijing. Taking Qiaofu Plaza project with its excavation depth about 22m as an example, the soil nailing force on the upper side of this system was monitored and analyzed. The results show that the force grows fastest when excavated to the bottom of soil nailing wall. When the potential slide line is over the end of soil nailing wall, the force grows slowly to stable. Anchor with pre-stress reduces the horizontal displacement of the foundation pit, meanwhile, the force of soil nailing is little, so the diameter of steel bar in soil nailing wall can be reduced in similar engineering.
Keywords:composite retaining system; foundation pit;  soil nailing wall; piles(or diaphragm wall) supported by anchor; soil nailing stress; monitoring
通讯作者简介：程学军，硕士，高级工程师，注册岩土工程师，Email：cheng_xuejun@126.com。
参考文献
［1］北京侨福花园广场深基坑工程施工组织设计［R］. 北京：中建国际建设有限公司，2006