（1 兰州理工大学土木工程学院， 兰州 730050； 2 后勤工程学院建筑工程系， 重庆 400041）

［摘要］通过对西宁火车站深基坑桩锚支护结构桩身内力进行现场实测，分析了不同工况下桩锚式支护桩的受力特性及其变化规律。结果表明：冠梁不仅能使桩顶部分受力特性不同于上端自由的直立杆件，而且可以有效减小桩身内力；桩锚式支护桩桩身钢筋应力实测值远小于钢筋强度设计值；悬臂支护阶段桩身最大弯矩位于基坑底面附近，桩锚支护阶段桩身最大弯矩位于基坑底面以上至1/3基坑深度的区域内；支护桩嵌固深度过长并不能改善支护桩的受力特性；对于桩锚支护结构，用极限平衡法与弹性支点法进行计算都是偏于安全的，在基坑底面以上，设计时采用极限平衡法比弹性支点法更为经济，而在基坑底面以下采用弹性支点法得出的结果与实测值更加吻合；支护桩桩顶侧向位移随基坑开挖深度的增大而增大，设置预应力锚杆能有效控制基坑顶部侧向位移的发展。

［关键词］深基坑; 支护桩; 内力; 弯矩

中图分类号：TU473      文献标识码：A      文章编号：1002-848X(2014)17-0063-06

Experimental study on internal force of retaining piles in pile-anchor supporting structure

Huang Xuefeng1,2, Chen Shuaiqiang1, Ma Long1, Kong Yang1

 (1 Department of Civil Engineering, Lanzhou University of Technology, Lanzhou 730050, China; 2 Department of Civil Engineering, Logistic Engineering University, Chongqing 400041, China)

Abstract: Through the field measurement of the internal force of retaining piles in pile-anchor supporting structure of the deep foundation pit in Xining railway station, mechanical performance and changing laws of the internal force were studied under different working conditions. The  results show that the capping beam can make the mechanical performance of the pile top quite different from that of the upright free head shaft and effectively reduce the internal force. The measured reinforcement stress value of retaining piles in pile-anchor supporting structure is far less than its design value. The maximum bending moment of retaining piles in cantilever supporting phase lies near the bottom of foundation pit, and that of retaining piles in pile-anchor supporting phase lies at the position from one-third depth to the bottom of foundation pit. The mechanical performance of retaining piles can not be improved though deepening the embedded depth of the retaining piles. The limit equilibrium method and elastic fulcrum method are conservative for pile-anchor supporting structure, the limit equibrium method is more economic above the bottom of the foundation pit, while the elastic fulcrum method has good agreement with the measurement under the bottom. The displacement of retaining piles increases with the increase of foundation pit depth, and the lateral displacement of foundation pit is controlled by setting prestressed anchors remarkably.

Keywords: deep foundation pit; retaining pile; internal force; bending moment

作者简介：黄雪峰，博士，教授，Email：hxfen60@163.com。

参考文献

［1］刘建航，侯学渊．基坑工程手册［M］. 2版. 北京：中国建筑工业出版社，2009.

［2］朱彦鹏，王秀丽，于劲，等．悬臂式支护桩内力的试验研究［J］．岩土工程学报，1999，21(2)：236-239．

［3］肖武权，冷伍明，律文田. 某深基坑支护结构内力与变形研究［J］. 岩土力学，2004, 25(8): 1271-1274.

［4］黄雪峰，杨校辉，朱彦鹏，等．西宁地区常用基坑支护结构对比分析［J］．岩土工程学报，2012，34(12)：2-8.

［5］武崇福，李长洪．深基坑桩锚支护结构桩身内力及土压力试验研究［J］．施工技术，2012，41(24)：4-7.

［6］夏永承，董道洋，胡敏云，等．深基坑护壁桩的受力特性和土压力［J］. 岩土工程学报，1999，21（2）:222-226.

［7］王建军，黄强．深基坑工程支护桩内力试验研究［J］．建筑结构，2006，36(10)：5-11.

［8］JGJ 120—2012建筑基坑支护技术规程［S］.北京：中国建筑工业出版社，2012.