深厚软土深基坑被动区土体加固机制  

Add to Favorite Reinforcement mechanism of deep foundation pits in deep soft soil ground with passive zone

作　　者：崔泽恒 胡科 阎波 何毓林 任兴伟 冯晓腊[1] CUI Zeheng;HU Ke;YAN Bo;HE Yulin;REN Xingwei;FENG Xiaola(Faculty of Engineering,China University of Geosciences(Wuhan),Wuhan 430074,China;Central&Southern China Municipal Engineering Design and Research Institute Co.,Ltd.,Wuhan 430010,China)

机构地区：[1]中国地质大学(武汉)工程学院,湖北武汉430074 [2]中国市政工程中南设计研究总院有限公司,湖北武汉430010

出　　处：《安全与环境工程》2024年第1期44-56,共13页Safety and Environmental Engineering

基　　金：国家自然科学基金项目(51708526);武汉市城乡建设局科技计划项目(202045);校企科研攻关项目(2020056378)。

摘　　要：周边环境复杂地区的软土深基坑对变形控制的要求极高,目前基坑支护主要遵循“强桩强撑”的设计思路,针对坑底以下存在深厚软土地层的情况,对基坑内侧被动区软土进行加固,能改善土体物理力学性能,有效约束基坑开挖变形。建立4种深厚软土地层基坑开挖模型,通过将离心模型试验的实际监测结果与Plaxis3D岩土有限元软件建立的等比例三维数值模型模拟结果相互验证,研究支护桩端在软土中的深基坑变形破坏模式和被动区加固效果。结果表明:在被动区软土未加固的情况下,支护桩端在软土中的基坑发生整体失稳破坏,支护桩进入硬土后的嵌固作用对基坑变形控制非常有利,在被动区设置裙边矩形加固,基坑变形显著减小;随着加固体深度、宽度的增加,基坑各项变形值均呈减小趋势,到一定值后变化不明显,加固深度、加固宽度的有效范围分别为0.4H~0.6H、0.6H~1.0H;加固体尺寸变化对地表沉降的影响最大,其次为支护桩水平位移、基底隆起。Deep foundation pits in soft soil in areas with complex surrounding environments have extremely high requirements for deformation control,and the current foundation pit support mainly follows the design idea of“strong pile and strong support”.For the case of deep soft soil layer below the bottom of the pit,the reinforcement of the soft soil in the passive zone of the inner side of the foundation pit can improve the physical and mechanical properties of the soil body,and effectively constrain the deformation of the excavation of foundation pits.Four types of deep soft soil layer foundation pit excavation models were established,and the deformation damage mode of deep foundation pit with supporting pile end in soft soil and the effect of passive zone reinforcemen twere studied through the mutual verification of the actual monitoring results of centrifugal model test and the equal scale numerical model established by Plaxis3D geotechnical finite element software.The results are as follows:in the case of unreinforced soft soil in the passive zone,the pit with supporting pile end in soft soil undergoes overall instability damage,and the embedded effect of supporting pile into hard soil is very favourable to pit deformation control,and the deformation of the pit is significantly reduced by setting up apron rectangle reinforcement in the passive zone;with the increase in the depth and width of reinforcement,the various values of deformation of the pit tend to decrease,and the change is not obvious after a certain value,and the depth of reinforcement.The effective range of reinforcement width is 0.4H~0.6H and 0.6H~1.0H,respectively;the change of reinforcement size has the greatest influence on surface settlement,followed by horizontal displacement of supporting piles,and the amount of foundation uplift.

关 键 词：软土深基坑 被动区裙边加固 离心模型试验 数值模拟 

分 类 号：X93[环境科学与工程—安全科学] TU47[建筑科学—结构工程]