大直径高压旋喷桩+双排钻孔灌注桩复合式基坑支护结构工作性状

针对深厚软弱地层且特殊施工环境下的基坑围护,多采用大直径高压旋喷桩+双排钻孔灌注桩复合式支护结构,为研究该支护结构的工作性状,通过数值计算、现场监测等,分析不同的旋喷桩加固与灌注桩施作组合工况下,支护结构的变形、地表沉降以及桩间土的塑性区分布与塑性应变水平等变化特征。结果表明:大直径高压旋喷桩+双排钻孔灌注桩复合式支护结构能有效控制基坑变形,而仅施作双排灌注桩或仅采用旋喷桩加固,均不能满足基坑安全的要求;相比排桩数量而言,旋喷加固参数对支护结构的工作性状影响更为显著。该项研究可为今后类似支护结构的设计和应用提供参考。

Behavior of Combined Support Structure Consisting of ＂Large-diameter High-pressure Jet Grouting Piles ＋ Double-row Borehole Cast Piles＂

Combined structure of ＂large-diameter high pressure jet grouting piles ＋ double-row borehole cast piles＂ is used as the retaining structure of a foundation pit in deep soft strata under complex construction environment.In the paper,the deformation of the support structure,the ground surface settlement and the plasticized zone and plastic strain of soils between the piles under different combined working conditions of jet grouting piles and borehole cast piles are analyzed by means of numerical calculation and site monitoring,so as to study the behavior of the combined support structure.Conclusions drawn are as follows：1） The deformation of the foundation pit can be brought under effective control by adopting the combined support structure of ＂large-diameter high pressure jet grouting piles ＋ double-row borehole cast piles＂,however,the safety requirements of the foundation pit cannot be guaranteed by only adopting jet grouting piles or by only adopting double-row borehole cast piles; 2） Compared to the number of the double-row borehole cast piles,the parameters of the jet grouting piles have more impact on the behavior of the support structure.The paper can provide reference for the design and application of similar support structures in similar projects in the future.