反压土作用下超大圆形基坑灌注桩变形响应  

Deformation Characteristics of Bored Pile for Super-Large Circular Bermed excavation

作　　者：单联君 倪芃芃 杨宇哲 王锐松 董宏源 Shan Lianjun;Ni Pengpeng;Yang Yuzhe;Wang Ruisong;Dong Hongyuan(Guangzhou Municipal Engineering Design&Research Institute Co.,Ltd.,Guangzhou 510060,P.R.China;School of Civil Engineering,Sun Yat-sen University,Zhuhai 519082,P.R.China;Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai),Zhuhai 519082,P.R.China)

机构地区：[1]广州市市政工程设计研究总院有限公司,广州510060 [2]中山大学土木学院,广东珠海519082 [3]南方海洋科学与工程广东省实验室(珠海),广东珠海519082

出　　处：《地下空间与工程学报》2023年第4期1299-1307,共9页Chinese Journal of Underground Space and Engineering

基　　金：国家自然科学基金(52078506);广东省自然科学基金(2023A1515012159)。

摘　　要：由于矩形和不规则多边形基坑开挖时容易产生坑角效应,通常采用具有明显空间拱效应的圆形支护形式进行超大基坑开挖。为了提升反压土计算方法在基坑支护体系的应用,本文提出了适用于深厚软土地区超大圆形基坑灌注桩变形分析的反压土简化理论,并采用数值分析及现场实测对理论分析进行了验证。结果表明:(1)推导得出的折减系数α在反压土平台及支护结构深度范围内均保持连续,仅为深度z的函数;(2)简化理论与土层结构法在计算结果上趋势一致,且在现场实测数据范围内,证明了简化理论具有实用性和可操作性;(3)在基坑反压土预留时,土体对称平衡布置更有利于控制基坑变形。简化理论促进了反压土在基坑工程中的应用,提高了基坑开挖的效率。Rectangular and/or irregular polygonal excavation can easily cause the detrimental corner effect,whilst circular excavation has the obvious beneficial spatial arching effect,being suitable for use as a normal excavation scheme for super-large foundation pit.In this paper,a simplified calculation method for bermed excavation is derived to analyze the deformation characteristics of bored pile for super-large circular foundation pit in thick soft soil regions.The results obtained from numerical analyses and field measurements are used to evaluate the effectiveness of the proposed theoretical approach for bermed excavation.It is found that the reduction coefficient of earth pressureαhas a continuous profile with depth within the range of earth berm and supporting structure,and it is a function of depth z only.The simplified theory is practical and operable by comparing with the results of conventional finite layer method,and the theoretical results are consistent with the field measured data.In addition,for bermed excavation,a balanced layout of earth berms in a symmetrical manner is more beneficial to control the deformation of foundation pit.Essentially,the simplified theory can enhance the application of bermed excavation in foundation pit engineering,and improve the excavation efficiency.

关 键 词：圆形基坑 反压土 土弹簧 简化理论 变形响应 

分 类 号：TU753[建筑科学—建筑技术科学]