低幅值高循环荷载作用下土体的应变累积模型

高速铁路路基上的轨道以及附近区域的结构物承受低幅值、高循环振动荷载的反复作用。在此低幅值、高循环荷载作用下土体会产生不可恢复的应变累积，导致轨道及附近区域结构物发生附加沉降。当前，描述土体的循环变形特征的理论分为两类：一类是基于经典塑性理论的应力-应变滞回模型（例如边界面模型），另一类是基于循环三轴试验经验规律的应变累积模型（例如Bochum累积模型）。为了能够预测土体在低幅值、高循环荷载作用下的应变累积行为，在前人对土体在低幅值、高循环荷载作用下大量试验研究的基础上，在经典弹塑性理论的框架下，提出一个土体在低幅值、高循环荷载作用下的应变累积模型。该模型通过用对数律来描述塑性体应变的累积规律，并以此作为应变累积的大小度量，然后通过修正Cam-clay模型的流动准则来描述应变累积的发展方向。最后，通过多组试验结果的模拟，表明所提出的应变累积模型能够较好地预测土体在低幅值、高循环荷载作用下的应变累积行为，具有广泛的应用前景。

Strain accumulation model of soils under low-amplitude high-cycle loading

High-speed railway track and nearby structures are subjected to low-amplitude and high-cycle loading. Additional settlements of track and structures may be caused by irreversible strain accumulation of soils under the low-amplitude and high-cycle loading. At present, the theories described the deformation characteristics of soils have two kinds, stress-strain hysteretic model based on classical plastic theory, e.g. bounding surface model, and strain accumulation model based on empirical law obtained from the cyclic triaxial tests, e.g. Bochum accumulation model. Based on the existing test studies and classical elastoplastic theory, a strain accumulation model is proposed to predict strain accumulation behavior of soils subjected to low-amplitude and high-cycle loading. The model describes the accumulation law of plastic volume strain via a logarithmic law; and it can measure the strain accumulation. The direction of strain accumulation is determined using the flow rule of the modified Cam-clay model. Finally, with the simulation of test data, it is shown that the proposed model can predict strain accumulation behavior of soils subjected to low-amplitude and high-cycle loading. It has widely application prospect.