发泡颗粒混合轻量土三轴应力-应变-孔压特性试验

Experiment on Triaxial Pore Water Pressure-stress-strain Characteristics of Foamed Particle Light Weight Soil

通过三轴试验对淤泥发泡颗粒混合轻量土进行研究,揭示了不同配比、围压对轻量土应力-应变-孔压特性的影响本质,以及变形模量的变化规律;并结合前人成果,对应力-应变关系进行了模型概化与曲线拟合;基于发泡颗粒混合轻量土的物质结构组成特性,提出了一个反映其物理力学性质的广义本构模型。分析结果表明:配比决定试样的胶结结构强度,围压决定试样的应力状态,围压大于胶结结构强度时,试样剪缩,应变硬化,孔压不断上升,反之,试样剪胀,应变软化,孔压上升后下降,甚至出现负值;变形模量随水泥掺入比的增大而线性增大,随EPS颗粒掺入比的增大而非线性减小,与围压关系不大;概化模型有应变硬化型、应变软化型及理想弹塑型3种;Ducan-Chang双曲线模型与Prevost软化模型的拟合效果较好,但软化模型很难对应变大于15%的曲线进行拟合。

Influence essence of pore water pressure-stress-strain characteristics of foamed particle light weight soil with different mixed ratios under different confining pressures was revealed by triaxial compression test.Combining precursors＇ research production,stress-strain relation models were summarized and test curves were fitted.Based on matter structure composition property of foamed particle light weight soil,a generalized constitutive model which can reflect its physical mechanical characteristics was brought forward.The analytical results show that mixed ratio decides cementation structure strength of soil sample;confining pressure decides stress state.When confining pressure is bigger than cementation structure strength,the soil sample becomes shear contraction,stress-strain relation is strain hardening,pore water pressure increases slowly;on the contrary,the soil sample becomes shear dilatancy,stress-strain relation is strain softening,pore water pressure increases firstly and then decreases,even reaches negative.There are three types of constitutive models： strain hardening,strain softening,and ideal elastic-plastic type.Fitting effects of Duncan-Chang hyperbolic model and Prevost softening model are better,but the curves whose strain is more than 15% can＇t be fitted by Prevost softening model very well.