Cyclic Triaxial Test to Measure Strain-Dependent Shear Modulus of Unsaturated Sand
Cyclic Triaxial Test to Measure Strain-Dependent Shear Modulus of Unsaturated Sand
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DOI：
10.1061/(asce)gm.1943-5622.0000917
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发表时间：
2017-09-01
影响因子：
3.7
通讯作者：
Mirshekari, Morteza
中科院分区：
文献类型：
--
作者：
Ghayoomi, Majid;Suprunenko, Ganna;Mirshekari, Morteza
动态剪切模量在岩土系统的抗震评估中起着重要作用。由于基质吸力的存在，水饱和度的变化会影响土壤的动态特性。本文描述了吸力控制循环三轴装置的改进，以研究非饱和土的应变相关剪切模量。在不同饱和度的干净沙子上进行了几次应变和应力控制的循环三轴试验。对于不同的剪切应变水平，与干燥和饱和条件下的剪切模量相比，非饱和砂中的吸力增加了剪切模量，并且在较高吸力水平下具有峰值模量。此外，对于具有相似基质吸力的样品，剪切模量随着剪切应变的增加而降低。非饱和砂样本的归一化剪切模量遵循与可用经验剪切模量折减函数预测的趋势相似的趋势，但显示出较低的值。由于较高的有效应力和吸力引起的刚度，非饱和砂的模量减少率上升。这些趋势对于应变和应力控制测试都是一致的。 (C) 2017 年美国土木工程师学会。
Dynamic shear modulus plays an important role in the seismic assessment of geotechnical systems. Changes in the degree of water saturation influence dynamic soil properties because of the presence of matric suction. This paper describes the modification of a suction-controlled cyclic triaxial apparatus to investigate the strain-dependent shear modulus of unsaturated soils. Several strain-and stress-controlled cyclic triaxial tests were performed on a clean sand with various degrees of saturation. Suction in unsaturated sands increased the shear modulus in comparison with the ones in dry and saturated conditions for different shear strain levels, with a peak modulus in higher suction levels. Also, shear modulus decreased with an increase in the shear strain for specimens with similar matric suction. The normalized shear moduli of the unsaturated sand specimens followed a similar trend to the ones predicted by the available empirical shear modulus reduction functions but showed lower values. The modulus reduction ratios of unsaturated sands shifted up as a result of higher effective stress and suction-induced stiffness. These trends were consistent for both strain-and stress-controlled tests. (C) 2017 American Society of Civil Engineers.