软土超深基坑失稳破坏的离心模型试验研究-《郑州大学学报(工学版)》

文章信息/Info

Title:: Research onCentrifhge Model Testof Soft Clay Ultra-deep ExcaVation Instabi Utyand Failure

Author(s):: FENGHul; GAO Dan．yin91; LIUGuo-bin2; MA Xian—fen92; 1.School of CivilEngineering zhengzhou university，zhengzhou 45000l，China；2．Depanment of Gegtechnical Engineering，Tongji University，Shanghai 200092，China

Keywords:: softclay excavation; geotechnicalcentrifbge; stability failure; insertion depthratio; slip suIface

摘要:: 通过土工离心机对三组挖深24 m软土超深基坑的开挖施工过程及失稳破坏进行模拟,研究了软土超深基坑稳定影响因素、破坏特征与征兆等.结果显示,墙趾进入硬土层后的嵌固作用对“踢脚”变形控制非常有利,也显著提高了基坑稳定性.嵌固作用在墙趾插入到硬土层中一定深度以后不再随插入深度增加而增强.挡墙位于上海典型软黏土中且不进入硬土层时,其临界插入深度比为0.78.软土深基坑失稳破坏征兆:(1)挡墙“踢脚”明显,量值约为墙体最大水平位移1/3；(2)坑外地表沉降达到1.38％H(开挖深度),地面出现大量横裂缝；(3)坑底靠近挡墙的土体隆起大于基坑中部,最大量值达到3.1％～3.8％H；(4)坑内土体处于被动土压力极限状态.可用于综合评判基坑的稳定性,指导类似超深基坑的设计、施工和安全监控.

Abstract:: Though simulating the excaVation process and stability fhilure of soft clay excavation whose depth was24m bycomplex geotechnical centrifuge，the stability factors，failure characteristics and symptoms were researched．Resultsdisplayedthat the embedded role on controlling the”skining”defb瑚ationwasvery favorable，also the case fbr excaVation stabilitywhen thewaUtoeinserted in hardpan，but whenwall toe reacheda cenain depth，the innuence wasunapparent as the insert depthincreasing．Forthe typical soft clay in Shanghai，critical insertion depthratio of retaining wall is 0．7．The failure symptomswere as follows：(1)The skirting deformation ofretaining wallwasobVious and its quantity valueis about 1／3 ofthemaximumhorizontal displacement ofthe wall．(2)Themasstransversal cracks arise whenthe surfacesubsidenceoutsideof excavation reached 1．38％日(日一excaVation depth)．(3)The upheaval of bottom increases rapidly，the value reached 3．1～3．8％日，and near the retaining wall greater than the central．(4)Pit soilwasin the passive earth pres— sure limit state．The destruction slip surface characteristics were obtained byanalyzing failure phenomena．