土工袋抗土体静态液化机制探讨

On the Static Liquefaction of Soilbag-Reinforced Soils

土体在特定的应力路径条件下会发生静态液化问题,将易液化土体放入土工袋内,可以增加土体的抗液化稳定性.现有的文献对土工袋如何增强土体的强度已经提出了较为系统的阐述,但对其抗静态液化的机制却鲜有报道.为此,基于Hill二阶功失稳判据,在弹塑性本构理论框架内讨论了土体静态液化的模式与土体屈服、硬化以及剪胀性的关系;并分别在等周和等张力假设条件下,探讨了土工袋的抗静态液化的机制.研究结果表明:土体的静态液化触发条件可以通过Hill二阶功失稳判据识别,但液化后为暂态液化或完全液化与土体的剪胀特性有关;土工袋通过限制土体的应变路径,约束了袋内土体静态液化的发展,从Hill二阶功准则看,土工袋对袋内土体提供的附加二阶功恒为正,有助于降低土体的静态液化风险;土工袋抗静态液化的效果与袋体的模量正相关、与袋子尺寸呈反比.

Soils may exhibit static liquefaction under certain stress paths.The stability of liquefiable soils can be increased by enveloping soilbags.The existing studies have well revealed the mechanism of how soilbags increase the shearing strength of soils,whereas the mechanism for the static liquefaction of soilbags was barely reported.To this end,the static liquefaction of soils was discussed within the framework of elasto-plasticity using Hill's second order work criterion.Its relationship with the yielding,hardening and plastic potential of soils was analyzed.Furthermore,the static liquefaction of soilbag-reinforced soils was discussed by using both the hypotheses of iso-circumstance and homogenous fabric tension of the bag.It was found that:the initiation of the static liquefaction could be identified by Hill's second order work criterion,but whether the liquefaction was complete or temporary was governed by the shearing dilatation of the soil.The development of the static liquefaction of soilbag-reinforced soils was constrained by limiting the allowable strain paths.From the point of view of Hill's second order work criterion,soilbag provided addition positive second order work to the system,which could help reduce the risk of static liquefaction.The effect of the reinforcement by the soilbag against the liquefaction is proportional to the tensile modulus of the bag and is inversely proportional to the size of the bag.