Cyclic Direct Simple Shear Test to Measure Strain-Dependent Dynamic Properties of Unsaturated Sand
Cyclic Direct Simple Shear Test to Measure Strain-Dependent Dynamic Properties of Unsaturated Sand
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DOI：
10.1520/gtj20160128
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发表时间：
2017-05-01
影响因子：
1.6
通讯作者：
Ghayoomi, M.
中科院分区：
文献类型：
--
作者：
Le, K. N.;Ghayoomi, M.
利用新罕布什尔州大学的直接简单剪切（DSS）试验装置，研究了不同饱和度下纯砂的动力特性。介绍了该决策支持系统的具体特点，并讨论了测试过程。该装置采用轴平移和张力测量技术来控制土样中的基质吸力。对F75渥太华砂的研究表明，在不同饱和度（干燥、饱和和部分饱和）的应变测试范围内，通过增加剪切应变，剪切模量降低，阻尼增加。无论饱和度如何，在中等剪切应变的应用范围内的模量降低证明了DSS始终捕获动态特性变化的能力。试验结果表明，基质吸力对土体的刚度有很大的影响。然而，这种影响的程度可能取决于在非饱和土中的有效应力的诱导应变水平。此外，部分饱和的标本导致较低的动态压缩。
The dynamic properties of a clean sand under different degrees of saturation were investigated using a modified custom built Direct Simple Shear (DSS) apparatus at the University of New Hampshire. The specific characteristics of the DSS were presented, and the testing procedures were discussed. The device used the axis translation and tensiometric techniques to control the matric suction in the soil specimen. The investigation on F75 Ottawa Sand showed a decrease in shear modulus and an increase in damping by increasing the shear strain over the tested range of strains for various degrees of saturation: dry, saturated, and partially saturated. The modulus reduction in the applied range of medium shear strains regardless of the degree of saturation demonstrated the capability of the DSS in consistently capturing the changes of dynamic properties. Experimental results indicated that the matric suction can have a substantial effect on the stiffness of the soil. However, the extent of this effect may depend on the induced strain level of the effective stress in unsaturated soil. In addition, partially saturated specimens resulted in lower dynamic compression.