不同加载方式下真空加固吹填软土的现场试验与数值模拟

In-situ tests and numerical simulation of soft soil consolidation using vacuum preloading method under various loading

吹填软土在真空负压作用下发生排水固结时,其强度和变形特性与真空负压的加载方式关系密切。首先对吹填软土进行了真空预压现场加固试验,通过对地表沉降、真空度跟踪监测,研究并比较不同负压加载方式下地基沉降规律及加固效果;然后采用FLAC3D建立三维弹塑性数值模型,对软土地基采用不同加载方式进行数值模拟,并与现场试验的实测数据进行对比,深入探讨加载方式对软土地基固结影响的细观机理。研究结果表明:采用真空预压法加固吹填软土地基时,慢速加载方式比瞬时加载方式更有利于土体的加固,建议在实际工程中采用分级加载方式施加真空荷载。

Under vacuum negative pressure,the deformation and strength characteristics of soft soil have a close relationship with the loading mode.Firstly,we carry out the vacuum consolidation test to the filled soft soil.Based on the monitoring of foundation settlement and vacuum degree,we compare the foundation settlement law and consolidation effect under different loading modes.Adopting FLAC3D,we establish elastic-plastic 3D numerical simulation model to simulate the soft soil by different loading modes,the result of which is compared with the real-measured data of field test to probe into the mechanism of the effect of the loading mode on consolidation of soft soil.The research indicates that taking multi-stage loading is more advantageous than that of the instantaneous loading to the consolidation of soil when vacuum preloading is adopted to consolidate soft soil foundation.So it is recommended to use the multi-stage loading pattern for the vacuum loading in the project.