不同循环加载条件下岩石阻尼比和阻尼系数研究

发布时间：2018-03-25 19:20

本文选题：岩石力学　切入点：动荷载　出处：《岩土力学》2017年09期

【摘要】：为了合理地描述岩石的阻尼行为,提出了考虑轴向和环向阻尼振动的岩石阻尼参数计算方法;通过动循环荷载、分级循环荷载和常幅循环荷载试验,对比分析了这3种不同应力路径下砂岩、砾岩及砂砾岩的阻尼特性,得到了阻尼参数对应力幅值、应变幅值的响应特性,揭示了常幅循环加载过程中阻尼比和阻尼系数随循环次数的演化规律;从熵守恒和能量守恒定律出发,建立了岩石阻尼比随循环次数演化的经验模型。结果表明:(1)动荷载下岩石的阻尼比与轴向应变幅值成线性递增,而阻尼系数恰好相反;分级循环荷载下岩石的阻尼参数都随应力幅值成线性递增。(2)疲劳破坏门槛值是岩石耗散能和阻尼比演化规律发生变化的分界点,在应力上限高于疲劳破坏门槛值时,耗散能、阻尼比及阻尼系数随循环次数都呈3阶段的变化规律,演化曲线呈半U型;在应力上限低于疲劳破坏门槛值时,呈现2阶段的发展规律,演化曲线呈L型;(3)通过砂岩的阻尼比试验,验证了所建模型能够描述砂岩在常幅循环荷载过程中阻尼行为。
[Abstract]:In order to describe the damping behavior of rock reasonably, a method for calculating the damping parameters of rock considering axial and toroidal damping vibration is put forward, and the dynamic cyclic load, graded cyclic load and constant cyclic load are tested. The damping characteristics of sandstone, conglomerate and sandy gravel under these three different stress paths are compared and analyzed, and the response characteristics of damping parameters to stress amplitude and strain amplitude are obtained. The evolution law of damping ratio and damping coefficient with the number of cycles in constant amplitude cyclic loading is revealed, and the conservation of entropy and energy is considered. An empirical model for the evolution of rock damping ratio with cyclic times is established. The results show that the damping ratio of rock increases linearly with the amplitude of axial strain under dynamic loading, but the damping coefficient is exactly the opposite. Under graded cyclic loading, the damping parameters of rock increase linearly with the stress amplitude. 2) the fatigue failure threshold is the boundary point of the evolution law of dissipation energy and damping ratio of rock. When the upper stress limit is higher than the fatigue failure threshold, the dissipative energy can be obtained. The damping ratio and damping coefficient change in three stages with the cycle number, and the evolution curve is half U, and when the upper limit of stress is lower than the fatigue failure threshold, it shows the development law of two stages. The model is proved to be able to describe the damping behavior of sandstone under constant cyclic loading.
【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(No.11572246,No.51678484) 陕西省自然科学基础研究计划(No.2015JM5175)~~
【分类号】：TU45

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