| 不同水化状态下的压实膨胀土应力-应变-强度特征 |
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| 引用本文： | 周葆春,孔令伟,郭爱国.不同水化状态下的压实膨胀土应力-应变-强度特征[J].岩土力学,2012,33(3):641-651. |
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| 作者姓名： | 周葆春 孔令伟 郭爱国 |
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| 作者单位： | 1. 中国科学院武汉岩土力学研究所 岩土力学与工程国家重点实验室，武汉 430071；2. 信阳师范学院 土木工程学院，河南 信阳 464000 |
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| 基金项目： | 国家自然科学基金资助项目(No.51009118);中国博士后科学基金资助项目(No.20100470058);河南省基础与前沿技术研究计划项目(No.082300410180);河南省高等学校青年骨干教师资助计划项目(No.2008083) |
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| 摘 要： | 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。
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| 关 键 词： | 膨胀土 应力-应变-强度特征 水化状态 超固结性 剑桥模型参数 |
| 收稿时间： | 2011-09-06 |
Stress-strain-strength behaviour of compacted expansive soil under different hydration states |
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| ZHOU Bao-chun
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KONG Ling-wei
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GUO Ai-guo.Stress-strain-strength behaviour of compacted expansive soil under different hydration states[J].Rock and Soil Mechanics,2012,33(3):641-651. |
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| Authors: | ZHOU Bao-chun KONG Ling-wei GUO Ai-guo |
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| Institution: | 1. State Key Laboratory of Geomechanics and Geotechnical Engineering, Institute of Rock and Soil Mechanics, Chinese Academy of Sciences, Wuhan 430071, China; 2. College of Civil Engineering, Xinyang Normal University, Xinyang, Henan 464000, China |
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| Abstract: | In order to investigate the effects of hydration state on the stress-strain-strength behaviour of compacted expansive soil,a series of mechanical property tests under one-dimensional consolidation and triaxial compression are carried out under two typical hydration states which are both saturated.The conventional saturation method is adopted for the first hydration state,while the second state permits samples swelling to steady state.The results show that there is a significant difference of volume expansion between the two hydration states;and the volume expansion rate is influenced by both the deformation constraint condition and the length of seepage.Compared with the first hydration state,the soil sample under the second hydration state has greater compression index λ,swelling index κ,and lower elastic shear modulus.The effective internal friction angle is 77.2% of the corresponding value of the first hydration state,which reflects the variability of saturated shear strength of the compacted expansive soil.The yield phenomena of consolidation curves can be observed with the yield stresses 123.2 kPa for the first hydration state and 94.5 kPa for the second hydration state.Under the first hydration state,the samples present strain softening and shear dilatancy at lower confining pressures,while they present strain hardening and shear contraction at higher confining pressures.Under the second hydration state,the samples present shear contraction and weak strain softening.The samples under the two hydration states show overconsolidation in the process of consolidation and shear loading.The overconsolidation is not due to preconsolidation pressure only;however,it is partially caused by that swelling of the soil is constrained in the process of loading.Under the different hydration states,the expansive soil has both different initial void ratios and different swelling potentials,while the interaction of the swelling potentials with external constraint conditions,drainage conditions and stress states leads to the complex stress-strain-strength behaviour. |
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| Keywords: | expansive soil stress-strain-strength behaviour hydration state over consolidation Cam-clay model parameters |
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