加卸载条件下红黏土强度变形与能量耗散规律研究

Study on the Strength and Deformation Properties and the Energy Dissipation Law of Red Clay Subjected to Loading and Unloading of Shearing

【目的】为掌握江西红黏土在直剪加卸载作用下的变形特性以及能量耗散规律。【方法】对江西红黏土进行了剪切加卸载条件下的直剪试验研究,并对其强度变形特性和能量耗散规律进行了分析。【结果】获取了红黏土在直剪加卸载条件下不同法向应力作用时的剪切应力、剪切位移、法向位移和能量耗散等力学行为的变化结果。【结论】红黏土在直剪加卸载作用下,低法向应力时耗散能增加的速率相较于高法向应力的工况要低。总体上来说,耗散能与法向应力呈正相关关系,法向应力越大,塑性变形消耗的能量越大。随着剪切加卸载次数的增加,耗散能也在逐渐增加。红黏土在加卸载直剪试验过程中整体呈现为剪缩变形,剪切卸载阶段法向位移增大,再加载阶段法向位移先增加后减少,产生剪胀变形,当剪切位移达到卸载前的值时剪胀结束。剪切加卸载会增加红黏土的法向位移,增大剪缩量,卸载作用对法向位移的影响随着法向应力的增加逐渐减少。

【Objective】To master the deformation characteristics and the law of energy dissipation of Jiangxi red clay under the condition of shear loading-unloading.【Methods】The direct shear loading-unloading tests are fin-ished,and the strength and deformation properties and the law of energy dissipation are studied.【Results】The mechanical behavior of red clay under various normal stresses,including shear stress,shear displacement,nor-mal displacement and energy dissipation,are obtained.【Conclusion】The dissipation energy increase rate under shear loading and unloading is comparatively lower for low normal stress as compared to high normal stress.On the whole,the dissipation of energy has positive correlation with the normal stress,and the greater the normal stress,the greater the energy consumed by the plastic deformation.The dissipated energy under the same unload-ing conditions increases with the increasing of numbers of unloading the red clay exhibits shear shrinkage during unloading and loading in a direct shear test.Normal displacement increases during the unloading stage,followed by an increase and then decrease during reloading,resulting in shear expansion deformation.Shear expansion ends when the shear displacement reaches its value before unloading.Shear unloading will increase the normal displacement and the shear shrinkage of red clay,and this effect of unloading on the normal displacement be-comes weaker with the increase of normal stress.