孟加拉滨海相复杂互层地基真空预压加固特性研究

Characteristics of vacuum preloading reinforcement for complex interlayered foundations in coastal area of Bangladesh

针对孟加拉国某港口工程真空预压加固中遇到的透水性较差的黏土层和透水性较好的砂土层反复交互出现,可能存在边界透水透气、地基固结规律复杂难以预测、地基加固效果难以预测等问题。依托工程的试验区块及典型施工区块,研究黏土搅拌桩的密封墙密封效果、透水层对固结速度理论计算的影响、复杂互层场地加固后的物理力学特性改变等。主要采用试验检测和试验实测数据与理论计算数据对比分析的方法,对表层沉降-时程曲线、孔隙水压力消散曲线、加固前后的SPT指标、压缩性指标等比较研究。结果表明:黏土密封墙在粉砂地层具有良好的适应性,透水性砂层的存在对于实际场地固结的影响远小于理论或者理想边界条件下的试验,真空预压对于复杂互层地基具有较好的加固效果等。对于在复杂互层地基上的真空预压法加固设计具有一定的参考意义。

To the repeated interaction between the clay layer with poor permeability and the sand layer with good permeability encountered in the vacuum preloading reinforcement of a port project in Bangladesh,there may be problems such as boundary permeability,complex and difficult to predict foundation consolidation laws,and difficult to predict foundation reinforcement effects.Based on the experimental and typical construction blocks of the project,this article focuses on the sealing effect of clay mixing piles on the sealing wall.The influence of permeable layers on the theoretical calculation of consolidation velocity,as well as the changes in physical and mechanical properties of complex interlayered sites after reinforcement are studied.This article mainly uses experimental detection and comparative analysis of experimental measured data and theoretical calculation data to compare and study the surface settlement time history curve,pore water pressure dissipation curve,SPT index before and after reinforcement,compressibility index,etc.The results show that clay sealing walls have good adaptability in silty sand formations,and the presence of permeable sand layers has a much smaller impact on actual site consolidation than experiments under theoretical or ideal boundary conditions.Vacuum preloading has a good reinforcement effect on complex interlayer foundations.It has certain reference significance for guiding the design of vacuum preloading reinforcement on complex interlayer foundations.