北京市某深基坑支护工程实录

 以开挖深度为19.55 m的北京市某深基坑支护工程为例，对其所在区域的场地条件、周边环境及工程地质条件进行了具体的分析，提出土钉墙与桩锚相结合的复合支护方案，充分发挥两种支护形式相应的优势。方案设计紧密结合施工工艺的适用性，针对卵石地层采用人工挖孔法成孔技术，有效解决机械成孔所带来的诸多不利因素，并制定合理的施工过程。支护效果表明，方案设计合理，边坡变形得到有效控制，水平位移最大值仅为12.1 mm，各支护单元的受力性能发挥正常。同时，合理的施工过程使得支护工程先于预定工期11 d完成，为整个项目的后续施工赢得了宝贵的时间，为类似工程提供一定的借鉴经验。

ENGINEERING CASE OF A DEEP FOUNDATION PIT SUPPORTING IN BEIJING

Based on a deep foundation pit supporting engineering with excavation depth 19.55 m，the ground situation and surroundings as well as engineering geology are analyzed；and a composite support plan combining the soil-nailed wall with pile-anchor system is proposed to make use of their respective advantages. The technique of artificially excavated piles is adopted for the cobble stratum to solve the problems that power drilling brings about. The maximum value of horizontal displacement is only 12.1 mm and the mechanical properties of each support element are all in working consequence. The support result illustrates that the design is reasonable and the displacement of the pit is controlled effectively. Meanwhile，the work is completed 11 days ahead of the construction arrangement，which leaves much time for the following work. The experience is valuable for the similar projects.