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为探讨水化状态对饱和压实膨胀土应力-应变-强度特征的影响,以压实度为95%的荆门弱膨胀土为研究对象,开展了2种典型水化状态下的固结与三轴试验,其中第1种水化状态采用常规饱和方法,第2种水化状态为试样自由膨胀至稳定状态。结果表明:(1)受变形约束条件与渗径的影响,不同水化状态下体膨胀率有较大差别;(2)第2种水化状态下的饱和压实膨胀土具有更大的硬化指数λ与膨胀指数κ、较小的弹性剪切模量,其有效内摩擦角为第1种水化状态下的77.2%,体现出膨胀土饱和强度的变动性;(3)2种水化状态下的固结曲线均呈现出明显的屈服现象,其屈服应力分别为123.2 kPa与94.5 kPa;(4)第1种水化状态下,低围压下试样应变软化与剪胀,高围压下应变强化与剪缩;第2种水化状态下试验围压范围内均发生剪缩和轻微的应变软化;(5)2种水化状态下试样在固结与剪切过程中均表现出超固结性,这种超固结性并非完全由先期固结压力所致,而是试样受荷过程中膨胀受到约束造成的;(6)不同水化饱和状态下初始孔隙比不同,膨胀势也不同,膨胀势与外部约束条件、排水条件、应力状态相互作用,造成其应力-应变-强度特征的差异性。
In order to investigate the influence of hydration state on the stress-strain-strength characteristics of saturated compacted expansive soils, Jingmen weak expansive soil with compaction degree of 95% was used as the research object to carry out two kinds of typical hydration consolidation and three Shaft test, where the first state of hydration using conventional saturation method, the second state of hydration for the sample free expansion to a steady state. The results show that: (1) the body expansion rate under different hydration conditions is greatly affected by the deformation constraints and the osmosis diameter; (2) the saturated compaction expansive soil under the second hydration condition has a larger hardening index λ and expansibility index κ, the effective internal friction angle is 77.2% under the first hydration state, which shows the variation of the saturation strength of expansive soil; (3) Two kinds of hydration state Under the confining curve under the confining pressure shows obvious yield phenomenon, the yield stress is 123.2 kPa and 94.5 kPa respectively; (4) In the first hydration state, the specimens under low confining pressure strain soften and dilatancy, high confining pressure Under the second hydration state, shear shrinkage and slight strain softening occurred in the confining pressure range; (5) The samples under the two kinds of hydration state all showed consolidation and shearing Out of overconsolidation, this overconsolidation is not entirely caused by the preconsolidation pressure, but due to the expansion of the specimen under load is constrained; (6) under different hydration saturation initial porosity ratio is different, The swelling potential is also different. The interaction between the swelling potential and external constraints, drainage conditions and stress states leads to the stress-strain-strength characteristics The difference.