近海淤泥地层基坑工程变形研究

Study on Deformation of Offshore Silt Formation

为研究近海淤泥土层基坑开挖过程中周围地层以及基坑辅助结构的变形特征,以沿海某地区新建地铁基坑为工程背景,利用岩土工程软件geostudio的sigma/w模块,分析基坑开挖过程中周围土体的应力场、渗流场、周围地层的沉降规律、基坑表面的变形特征以及灌注桩支护结构的侧向变形。计算结果表明:基坑开挖过程中,坑外地下水不断涌入坑内,灌注桩周围土体的孔隙水压力不断减小,最底部监测点较初始孔压力减小30%。基坑开挖过程中,周围地表土层呈U型沉降。灌注桩的侧向位移总体呈“弓”字型分布。基坑底部表面竖向位移随着开挖的进行不断增大,呈倒U型分布。

In order to study the deformation characteristics of the surrounding stratum and the auxiliary structure of the foundation pit during the excavation of the offshore silt soil layer,a new subway foundation pit in a coastal area was used as the engineering background,and the sigma/w module of geostudio was used to analyze the foundation pit.During the excavation process,the stress field and seepage field of the surrounding soil,the settlement law of the surrounding stratum,the deformation characteristics of the surface of the foundation pit,and the lateral deformation of the supporting structure of the cast-in-place pile.The calculation results show that during the excavation of the foundation pit,the groundwater outside the pit continuously floods into the pit,the pore water pressure of the soil around the cast-in-place pile continues to decrease,and the lowest monitoring point decreases by 30%compared with the initial pore pressure.During the excavation of the foundation pit,the surrounding surface soil showed a U-shaped settlement.The lateral displacement of the cast-in-place piles is generally distributed in a“bow”shape.The vertical displacement of the bottom surface of the foundation pit continues to increase with the progress of the excavation,showing an inverted u-shaped distribution.