分级真空预压加固软土地基位移变化规律模拟

Displacement Variation Law of Soft Soil Foundation Strengthened by Step Vacuum Preloading

真空预压广泛应用于软土地基加固中。但在深厚软土地基处理中,常规加压方式易使加固区边界土体出现裂缝。而分级真空预压由于真空强度阶段性地分级增长,可有效控制边界区裂缝的出现。本研究采用FLAC3D软件建立分级真空预压的数值模型,并结合现场实测数据对模型的合理性进行验证。在此基础上,对比分析分级加载方式对地基变形的影响。结果表明:分级真空预压能有效减小坝基表层与软土层水平位移的差值,有利于控制裂隙的出现;在各分级加载方式中,方案四10-40-85kPa的加载方案更适用于该项目地基。上述研究成果可为分级真空预压的推广应用提供参考。

Vacuum preloading is widely used in soft soil foundation reinforcement because it is a mature technology.However,in the treatment of deep soft soil foundation,the conventional pressurization method tends to cause cracks in the soil at the boundary of the reinforcement area.As an alternative,the strategy with step vacuum preloading can effectively control the appearance of cracks in the boundary zone due to the graded growth of vacuum strength in stages.Therefore,FLAC3D software was used to establish the numerical models of the hierarchical vacuum preloading method,of which the rationality was verified by combining the field measured data.On this basis,the comparative analysis of initial vacuum strength and vacuum loading time on foundation deformation was carried out.The results show that the step vacuum preloading could effectively reduce the difference between the horizontal displacement of the dam foundation surface and the soft soil layer,which is conducive to controlling the occurrence of cracks.Among the step vacuum loading methods,Scheme IV with 10-40-85 kPa is more suitable for the foundation of this project.The above research results can provide reference for the popularization and application of the step vacuum preloading.