沿海地区复杂地质条件下三角形深大基坑变形实测分析与数值模拟研究

Deformation analysis of a deep and large triangular foundation pit in coastal area based on field measurements and numerical simulations

以上海软土地区三角形深大基坑为背景,采用有限元软件,分析了基坑开挖过程中围护结构和周围土体的变形规律。同时结合三角形基坑的特殊结构形式,分析了不同边长、角点对于基坑变形的影响。研究表明:建立的有限元数值模型可以很好地预测基坑开挖引起的结构和地层变形;地下连续墙侧向位移呈现"鼓肚型"模式,墙后地表沉降在一定距离处出现沉降槽,且地下连续墙侧向位移和墙后地表沉降均随开挖深度的增加而增加;地下连续墙侧向位移和墙后地表沉降表现出显著的空间特性,在三角形长边中点处变形达到最大值,而在基坑角点附近,变形相对较小;角点角度越小,测点离角点越近,则变形越小。所得结论对于基坑工程的设计和优化具有一定的指导意义。

The deformation of the retaining structure and surrounding soil during the excavation of a deep and large triangular foundation pit in Shanghai soft soil was analyzed using finite element software.Meanwhile,the influence of the side length and the corner location of the triangular foundation pit on its deformation were studied based on its special triangular structure.The results show that the numerical model established in this paper can very well predict the deformation of the retaining structure and the surrounding soil caused by the excavation.The lateral displacement of diaphragm wall presented a "bulging"mode,and a surface settlement groove occurred behind the wall at a certain distance.Both the lateral displacement and the surface settlement increased with the continuous excavation,and showed significant spatial characteristics.The deformation reached the maximum at the middle point of the long side of the triangular pit,whereas the deformation was relatively small near the corners.The smaller the angle of the corner and the closer the measuring point to the corner point was,the smaller the deformation was.This study can provide some practical value for the design and optimization of the foundation pit in soft soil.