宁波地铁窄基坑抗隆起稳定性及变形特性研究
姚任行1邱豪磊2安然2成怡冲2龚迪快2
Study on Anti-Heave Stability and Deformation Characteristics of Narrow Foundation Pits in Ningbo Metro
YAO Renxing1QIU Haolei2AN Ran2CHENG Yichong2GONG Dikuai2
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作者信息:1.宁波市轨道交通集团有限公司建设分公司， 315100， 宁波
2.浙江华展研究设计院股份有限公司， 315012， 宁波
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Affiliation:1.Ningbo Rail Transit Group Co., Ltd., Construction Branch, 315100, Ningbo, China
2.Zhejiang Huazhan Research and Design Institute Co., Ltd., 315012, Ningbo, China
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关键词:
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Key words:
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DOI:10.16037/j.1007-869x.2025.04.038
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中图分类号/CLCN:TU433
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栏目/Col:研究报告
摘要:
［目的］与宽基坑相比，窄基坑开挖引起的基坑坑底和坑外土体的应力场和位移场变化更小。现行规范规定的相关计算方法鲜有考虑基坑宽度的影响，易导致围护墙设计偏于保守，造成浪费。有必要对窄基坑抗隆起稳定性及变形特性进行研究。［方法］针对宁波地区3类典型地铁基坑，采用上海市《基坑工程技术规范》规定的方法及改进方法分别计算坑底抗隆起稳定性。基于计算结果的对比给出了围护墙深优化建议。基于宁波地铁车站基坑信息，系统性地分析了基坑变形与坑底抗隆起安全稳定系数的关系及基坑宽度对基坑变形的影响。［结果及结论］坑底抗隆起稳定性系数随嵌固深度的变化曲线呈多线段形式，转折点在软硬土层分界处；墙深优化空间与嵌固比、土体抗剪强度指标及是否考虑地基加固有关；围护墙平均侧移和坑外地面平均沉降的离散性较大；随坑底抗隆起系数的增大，基坑变形上界有逼近下界的趋势，这主要和工程地质条件有关；土体变形值及影响范围随基坑宽度的减小而减小，与嵌固深度的关系不大。
Abstracts:
［Objective］ Compared with wide foundation pits, the stress and displacement field changes of the soil at pit bottom and outside caused by narrow foundation pit excavation are smaller. The relevant calculation methods specified in current specifications rarely consider the influence of the foundation pit width, easily leading to conservative design of the retaining wall, causing waste. It is necessary to study the basal anti-heave stability and deformation characteristics of narrow foundation pits. ［Method］ Aiming at three kinds of typical subway foundation pits in Ningbo, the method specified in Shanghai′s Technical Codes for Foundation Pit Engineering and the improved method are used to calculate the basal anti-heave stability. Based on a comparison of the calculation results, optimization suggestions for the retaining wall depth are given. According to the foundation pit information of Ningbo Metro stations, the relationship between the foundation pit deformation and the basal anti-heave safety stability coefficient, and the influence of the foundation pit width on the foundation pit deformation are systematically analyzed. ［Result & Conclusion］ The curve of the basal anti-heave stability coefficient varies with the embedded depth in a segmented manner, with the turning point at the boundary between soft and hard soil layers; the wall depth optimization space is related to the embedded ratio, soil shear strength index and whether considering the foundation reinforcement; the average lateral displacement of the retaining wall and the average land subsidence outside the pit are relatively discrete; with the increase of the basal anti-heave stability coefficient, the upper limit of the foundation pit deformation tends to approach the lower limit, which is mainly related to the engineering geological conditions; the soil deformation value and the influence range decrease with the narrowing of foundation pit width, while showing little correlation with the embedded depth.
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