循环荷载下软岩阻尼行为的试验研究

发布时间：2019-08-01 20:59

【摘要】：动剪切模量和阻尼比是岩体重要的动力特性参数,其取值的合理性对场地地震响应分析的结果有重要影响.利用WDT-1500多功能材料试验机,对砂岩、砾岩和砂砾岩等软岩试样进行了循环荷载试验,研究了软岩的动剪切模量和阻尼参数对应力、应变幅值和应力水平的响应特性,得到了动剪切模量和阻尼参数随应力幅值、应力水平及含水率的变化规律,讨论了其变化机理.结果表明,在不同应力水平和不同应力幅值下阻尼参数随着应力幅值的增大而增大,与应力幅值成线性拟合关系.当应力幅值较小时,含水率对岩石动剪切模量的影响较小,而对阻尼比和阻尼系数的影响较大;当应力幅值较大时,恰好相反.含水率,应力水平和应力幅值都相同时,应力水平逐级增大的应力路径下测得的阻尼参数大于应力幅值逐级增大的应力路径下测得的阻尼参数.建立的不同应力水平和不同应力幅值条件下软岩的动剪切模量与阻尼比关系模型能够描述分级循环荷载过程中阻尼行为.研究成果对抗震工程的地震反应分析和场地安全性评价有着重要参考价值.
[Abstract]:Dynamic shear modulus and damping ratio are important dynamic characteristic parameters of rock mass, and the rationality of their values has an important influence on the results of site seismic response analysis. The cyclic load tests of soft rock samples such as sandstone, gravel and gravel were carried out by using WDT-1500 multifunctional material testing machine. The response characteristics of dynamic shear modulus and damping parameters of soft rock to stress, strain amplitude and stress level were studied. The variation of dynamic shear modulus and damping parameters with stress amplitude, stress level and water content was obtained, and the change mechanism was discussed. The results show that the damping parameters increase with the increase of stress amplitude under different stress levels and different stress amplitudes, and there is a linear fitting relationship between damping parameters and stress amplitude. When the stress amplitude is small, the effect of moisture content on the dynamic shear modulus of rock is small, but the effect on damping ratio and damping coefficient is greater, but when the stress amplitude is large, it is just the opposite. When the moisture content, stress level and stress amplitude are the same, the damping parameters measured under the stress path with the gradual increase of stress level are larger than those measured under the stress path with the increase of stress amplitude step by step. The relationship between dynamic shear modulus and damping ratio of soft rock under different stress levels and different stress amplitudes can be used to describe the damping behavior during graded cyclic loading. The research results have important reference value for seismic response analysis and site safety evaluation of seismic engineering.
【作者单位】：西安理工大学岩土工程研究所;
【基金】：国家自然科学基金资助项目(51179153;51308456) 陕西省自然科学基础研究计划(2015JM5175)资助
【分类号】：TU45

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