反复等向加卸载路径下粉质黏土变形特性研究

黏土的变形特性与应力路径密切相关,直接影响到相关工程的安全性。针对三峡库岸某路基边坡粉质黏土,采用应力路径控制试验系统,开展了两组等向固结应力状态下反复多次的加卸载试验,揭示了土体的体积变形发展规律,发现再固结过程呈现为一条先平缓后变陡的曲线,说明前期固结压力范围内的再加载也会产生不可恢复的塑性变形,且变形速率随加卸载循环次数逐渐减小。最后,结合试验曲线特点,建立了土体再固结系数与加卸载次数及应力状态相关的数学模型,能够较好的模拟反复等向加卸载条件下土样的体变特征,且可预测土体经历更多次加卸载循环中的次固结过程,为土体的持续塑性变形分析和预测提供参考。

Cyclic Response and Modeling of Saturated Silty Clay Due to Repeated Isotropic Loading and Unloading

The deformation characteristics of clay are closely related to the stress path, which affects the safety of related projects directly. Aiming at the silty clay from a embankment slope beside Three Gorges Reservoir, two groups of repeated isotropic loading-unloading tests are completed by stress path controlling equipment, which reveals the cyclic response of soil volumetric deformation. The reloading processes can be described as curves of first gentle and then steep, which induces unrecoverable plastic deformations even when the stresses are in the range of pre-consolidated pressure, and the deformation rate decreases gradually with the increase of loading-unloading cycles. Then, on the basis of the characteristics of test curves, a mathematical model is established to describe the relationship of re-consolidation coefficients with the cycle number and the stress state. The presented model can simulate the volumetric cyclic response due to repeated isotropic loading and unloading and predict the deformation developments due to more reloading cycle. Moreover, the calculation results can also provide references for analyzing and predicting the continuous plastic deformation well.