深井基坑分段开挖方法数值模拟分析

Numerical Simulation Analysis of Segmental Excavation Method for Deep Well Pit

为研究大“长宽比”深井基坑使用分段依次开挖的方式修建深基坑的剪应变和塑性区变化,文章依托江心洲中间风井基坑工程,利用FLAC3D软件对基坑开挖过程进行模拟,分析采用分段依次开挖对大“长宽比”深井基坑的施工过程产生的影响。研究结果表明:基坑最大剪应变主要发生在基坑内部的“临空”边缘面;基坑开挖过程的模拟结束后基坑内现存的剪切破坏区主要存在于开挖基坑与地连墙边缘接缝处,而现存的拉伸破坏区主要存在于开挖基坑的临空边缘处;地下连续墙周围塑性区较少。在使用分段依次开挖方法进行基坑施工时,应尤其注意基坑内部的临空边缘面,避免发生垮塌危害;同时地下连续墙可以有效避免了基坑以外土层的坍塌陷落,在控制成本的情况下应尽量使用。

In order to study the change of shear stress and plastic zone in the construction of deep foundation pit with large"aspect ratio"using segmental sequential excavation,the article relies on the Jiangxinzhou intermediate air shaft foundation pit project,and simulates the excavation process of the foundation pit by using FLAC3D software to analyze the effect of segmental sequential excavation on the construction process of the large"aspect ratio"deep well foundation pit.aspect ratio"deep well pit construction process.The results show that:the maximum shear strain of the foundation pit mainly occurs in the"proximity"edge surface inside the foundation pit;after the simulation of the foundation pit excavation process is finished,the existing shear damage zone inside the foundation pit mainly exists at the joints between the edge of the excavation pit and the ground wall,and the existing tensile damage zone mainly exists at the proximity edge of the excavation pit;there are fewer plastic zones around the diaphragm wall.The plastic zone is less.When using segmental sequential excavation method for foundation pit construction,special attention should be paid to the critical edge surface inside the foundation pit to avoid collapse hazards;at the same time,diaphragm wall can effectively avoid the collapse of the soil layer outside the foundation pit,and it should be used as much as possible under the circumstance of controlling the cost.