软土超深基坑失稳破坏的离心模型试验研究  

Research on Centrifuge Model Test of Soft Clay Ultra-deep Excavation Instability and Failure

作　　者：冯虎[1] 高丹盈[1] 刘国彬[2] 马险峰[2] 

机构地区：[1]郑州大学土木工程学院,河南郑州450001 [2]同济大学地下建筑工程系,上海200092

出　　处：《郑州大学学报（工学版）》2013年第5期1-6,共6页Journal of Zhengzhou University（Engineering Science）

基　　金：教育部高等学校博士学科点专项科研基金资助项目(20124101120013);河南省教育厅科学技术研究重点资助项目(13A560679)

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.Though simulating the excavation process and stability failure of soft clay excavation whose depth was 24m by complex geotechnical centrifuge, the stability factors, failure characteristics and symptoms were researched. Results displayed that the embedded role on controlling the ＂ skirting＂ deformation was very favor- able, also the case for excavation stability when the wall toe inserted in hardpan, but when wall toe reached a certain depth, the influence was unapparent as the insert depth increasing. For the typical soft clay in Shang- hai, critical insertion depth ratio of retaining wall is 0.7. The failure symptoms were as follows ： （ 1 ） The skirt- ing deformation of retaining wall was obvious and its quantity value is about 1/3 of the maximum horizontal dis- placement of the wall. （2）The mass transversal cracks arise when the surface subsidence outside of excavation reached 1.38% H （H-excavation depth）. （3） The upheaval of bottom increases rapidly, the value reached 3.1 - 3.8% H, and near the retaining wall greater than the central. （4） Pit soil was in the passive earth pres- sure limit state. The destruction slip surface characteristics were obtained by analyzing failure phenomena.

关 键 词：软土基坑 离心机 失稳 插入深度比 滑裂面 

分 类 号：TU473.2[建筑科学—结构工程]