海积淤泥质软土地层深基坑降水设计与成果分析

Dewatering design and analysis of precipitation results of deep foundation pit in soft soil layer of marine debris

以分布深厚海积淤泥质黏土层的深圳地铁5号线前海湾车站基坑为例,通过建立三维有限元数值计算模型,详细分析海积淤泥质软土地层项目降水对基坑性状与周围环境的响应,结果表明:为保证达到降水效果,在海积淤泥质软土地区进行基坑降水时,需要尽量延长降水时间;随着降水深度的增大,使得开挖和降水引起的地表总沉降及不均匀沉降均明显增大,其主要影响范围在50 m左右;地下连续墙等止水措施能降低坑外有效应力的增加和减弱渗流,减弱降水造成坑外土体压缩和固结而产生的沉降。

Taking the foundation pit of Qianhaiwan Station,Shenzhen Metro Line 5,which is distributed in deep marine sediment and clay layers,as an example,this paper established a three-dimensional finite element numerical calculation model to study the impact of marine sediment and soft soil layers on the characteristics of the foundation pit and the surrounding environment during engineering precipitation in detail.The study shows that when the foundation pit precipitation project is carried out in marine sediment areas,it is necessary to extend the precipitation time as much as possible to ensure the precipitation effect is achieved.The total and uneven surface settlement caused by excavation and precipitation both increase significantly with the increase of precipitation depth,and their main impact range is around 50 m.Underground continuous walls and other waterproofing measures can reduce the increase of effective stress and seepage outside the pit,and reduce surface settlement caused by compression or consolidation of the soil outside the pit due to precipitation.