交替式真空预压法加固吹填超软土试验及数值模拟研究

Experimental study and numerical simulation of an alternating vacuum preloading method for strengthening hydraulic fill super soft soils

常规真空预压法在加固吹填超软土地基时,常出现排水板淤堵等问题,导致加固效果不佳。为解决常规真空预压法中的淤堵问题,利用室内模型试验和数值模拟PFC2D,系统分析一种新型真空预压加固方法——交替式真空预压法处理吹填超软土的加固机制和加固效果。研究表明,交替式真空预压法中土颗粒的交替运移可有效地抑制淤堵泥层的形成及'土柱'现象的产生,使整体加固效果更加均匀有效。与常规真空预压法相比,交替式真空预压法的排水量增加14.92%,沉降量增大11.80%,加固后土体十字板剪切强度提升21.65%,含水率降低26.74%,所形成的淤堵泥层致密程度降低,淤堵泥层形成区域的孔隙率提升30%以上,破淤效果明显。

Drainage plate clogging often results in poor reinforcement effect of the conventional vacuum preloading technology applied to hydraulic fill super soft soil grounds.To solve the problem,a new type of vacuum preloading method,namely alternating vacuum preloading method,for treating hydraulic fill super soft soils,was proposed,and the reinforcement mechanism and effect were investigated based on the indoor model test and numerical simulation of PFC2 D.The study results show that the alternating movement of soil particles due to the alternating vacuum preloading can effectively prevent the formation of clogging mud layers and'soil columns'and hence,make the overall reinforcement more uniform and effective.It is also shown that,compared with the conventional vacuum preloading method,the water discharge and the settlement of the soil ground reinforced by the proposed method increase by 14.92%and 11.80%respectively,the vane shear strength of the reinforced soil rises by 21.65%and the water content reduces by 26.74%.The compaction degree of the clogging mud layer decreases while the porosity of the clogging mud layer increases by more than 30%,which indicates that the anti-clogging effect of the developed method is obvious.