Dynamic stress accumulation model of granite residual soil under cyclic loading based on small-size creep tests

Abstract

The creep behaviors of granite residual soil with pre-stress of 100 kPa was investigated by a series of small size creep tests. Three different types of strain curves were obtained at different stress levels. Based on creep characteristics of the granite residual soil under different stress levels, a creep model of the granite residual soil was established by rheological theory, and related parameters of the model were determined according to the experimental data at the same time. Further on, based on the established creep model, a theoretical model of dynamic stress accumulation in the granite residual soil under cyclic loading was deduced. It is found that there is a threshold of dynamic stress accumulation in this theoretical model. The dynamic stress accumulation laws of the granite residual soil are different under different cyclic loading stress. Finally, with the dynamic stress accumulation laws in the small-size samples of granite residual soil under different cycle loading studied and the experimental results comparing with the theoretical results, it verifies the validity of the theoretical model.

摘要

通过一系列的小尺寸蠕变试验,首先研究了预压应力为100 kPa的花岗岩残积土的蠕变行 为,从而获得了其在不同应力水平下的三种不同类型的蠕变曲线。基于流变学理论与花岗岩残积土在 不同应力水平下的蠕变特性,建立了花岗岩残积土的蠕变理论模型,与此同时,根据小尺寸蠕变试验 也获得了模型中相关参数的实测数据。然后,基于已建立的蠕变模型,通过推导得到了花岗岩残积土 循环荷载条件下的动应力累积理论模型。该理论模型中存在一个动应力累积的阈值,同时模型显示花 岗岩残积土的动应力累积规律在不同的循环荷载条件下是不同的。最后,对花岗岩残积土小尺寸试样 在不同循环荷载条件下进行了动应力累积规律的试验研究,并将试验结果与理论计算结果进行对比, 从而验证了理论模型的有效性。