复杂条件下超深基坑支护方案比选及优化设计

Comparison and optimization of supporting schemes for Super Deep Foundation Pit under complex conditions

针对某一建筑超深基坑工程,结合其工程地质及水文地质条件、场地周边环境,并考虑基坑自身及周围建(构)筑物的安全及造价等因素,综合确定采用混凝土地连墙落底+三道内支撑的支护方式。通过数值模拟的方式对不同地连墙长度条件下基坑降水及开挖引起的基坑变形进行了分析。结果表明,不同的地连墙长度对坑外土体变形的影响范围及程度不同,是否封闭地下水是影响土体变形的重要因素。由此确定了合理的地连墙长度,同时验证了支护方案的合理性。

For an ultra deep foundation pit project of a building,combined with its geological and hydrological conditions,the surrounding environment of the site,and considering the safety and cost of the foundation pit itself and the surrounding buildings(structures)and other factors,the support mode of concrete diaphragm wall bottom dropping plus three internal supports is comprehensively determined.By means of numerical simulation,the dewatering of foundation pit and the deformation of foundation pit caused by excavation under different length of diaphragm wall are analyzed.The results show that the influence range and degree of soil deformation outside the pit vary with the length of the diaphragm wall,and whether to seal the groundwater is an important factor affecting the soil deformation.Therefore,the reasonable length of the diaphragm wall is determined,and the rationality of the support scheme is verified.