张掖某深基坑在降水条件下支护结构的性能分析

Performance Analysis of Supporting Structure under Dewatering Conditions for a Deep Foundation Pit in Zhangye City

在基坑工程中地下水对基坑支护结构性能的影响不能忽视。本文以张掖市某深基坑工程为背景,论述了复合支护土钉墙(上部土钉墙支护,下部排桩预应力锚杆支护)设计要点,同时对降水设计进行了详细的论述,并且利用岩土分析软件PLAXIS,采用HSS土体高级本构模型对此工程进行了数值分析计算,分析结果表明:降水作用对基坑坑底的隆起量影响较小,但对基坑壁的侧向变形影响较大,同时设计软件计算的排桩桩身弯矩值比考虑降水条件下和未考虑降水条件下的弯矩值都大,因此设计结果偏于保守。最后在降水条件下基坑地表的沉降量比一般条件都大,这与地下水的源汇项和土体参数有关。

The impact of groundwater on the performance analysis of supporting structure of foundation can not be ignored in the foundation pit engineering. Taking a deep foundation pit in Zhangye City as an example in the article,the design highlights of composite soil nail wall（ the soil nailing wall on the upper part,the pile-prestressed anchor on the lower part） are discussed,while dewatering design is discussed in detail,and by using the geotechnical analysis software PLAXIS,and the HSS soil constitutive model is adopted for numerical calculation in the project,the analysis results show that： dewatering conditions have no impact on pit bottom uplift,but have an greater impact on the lateral deformation of the pit wall,the pile bending moment by design software is greater than that with and without considering dewatering,therefore,the design is a little conservative. The last pit surface subsidence in dewatering conditions is greater than that in general conditions,which is related to the source and sink terms of groundwater and soil parameters.