土工基础

›› 2018, Vol. 32 ›› Issue (6): 602-604.

• 工程实录 • 上一篇    下一篇

浅析基坑开挖对单桩竖向抗拔承载力的影响

张 文1,2，汤飞翔2，徐 梅2，陆春明1   

  1. （1.如皋市勘测院，江苏南通 226500；2.如皋市岩土工程勘测有限公司，江苏南通 226500）
  • 收稿日期:2018-07-25 修回日期:2018-08-07 出版日期:2018-12-20 发布日期:2018-12-21
  • 作者简介:张 文（1984-），男，工程师，注册土木工程师（岩土），研究方向为桩基检测与岩土工程勘察。

Influence of Foundation Excavation on the Uplift Resistance of Single Piles

ZHANG Wen1,2, TANG Feixiang2, XU Mei2, LU Chunming1   

  1. (1.Rugao Reconnaissance and Surveying Institute, Nantong 226500；
    2.Rugao Geotechnical Engineering Reconnaissance and Surveying Co., Ltd., Nantong 226500)
  • Received:2018-07-25 Revised:2018-08-07 Online:2018-12-20 Published:2018-12-21

摘要： 通过江苏如皋市区一基坑工程试验桩及工程桩单桩竖向抗拔静载试验的比对，得到试验桩和工程桩单桩竖向抗拔极限承载力相差较大，用单桩竖向抗拔极限承载力标准值计算公式得出的工程桩抗拔极限承载力远大于工程桩抗拔静载试验所得到的试验值，偏离了岩土工程的合理范围。导致这一现象的原因，初步分析认为是大面积基坑开挖后桩土界面法向应力减少，坑底土体卸载引起坑底土体隆起，而坑底土体的隆起带动基桩回弹，产生向上的摩阻力（类似于抗压桩的负摩阻力），从而进一步减少了工程桩的竖向抗拔极限承载力。

关键词: 基坑开挖, 单桩竖向抗拔承载力, 土体卸载回弹

Abstract: The uplift resistances of test piles and production pile for a deep excavation project in Rugao, Jiangsu Province, were compared throughout the static uplift loading tests and large uplift difference were identified between two piles. The uplift resistance value from the code suggested formula was much greater than that of the production pile inside the excavated area and this difference was exceed from the reasonable range due to the soil strata variation. The further evaluation concludes that the deep excavation reduces the normal pressures on the pile and unloading of the soil at the bottom of the excavation induces the rebound of the soil. As results from the soil rebound, an upward friction (similar to the negative friction) developed in the production pile was the major reason for the uplift resistance reduction.

Key words: Deep Excavation, Uplift Resistance of Single Piles, Unloading Rebound