循环荷载下红层泥岩的动力特性及路用性能研究

DYNAMIC CHARACTERISTICS AND PAVEMENT PERFORMANCE OF RED MUDSTONE SUBJECTED TO CYCLIC LOADING

为验证达成(达州——成都)线红层泥岩能否满足高速铁路路基填料的要求,对其进行室内动三轴试验和红层泥岩路基的现场循环加载试验。由动三轴试验研究红层泥岩在循环荷载下的动强度和变形特性,引入动应力水平的概念,得到达成线红层泥岩的临界动应力水平约为30%;通过分析动剪应力比SRd与土体累积变形之间的关系,提出一个红层泥岩循环累积变形的计算模型,并明确模型参数的物理意义及确定方法。现场循环加载试验表明,用红层泥岩填筑路基基床底层,路基的沉降量和沉降速率均能满足高速铁路的要求;应用所提出的预测模型来计算红层泥岩路基层的累积变形,其达到稳定时的计算值和实测值很接近,但由于现场和室内试验条件的不同及加载频率的影响,在变形稳定以前,模型计算值和实测结果之间存在一定的差异。

In order to verify the applicability of red mudstone as subgrade filling in Dazhou--Chengdu railway, laboratory dynamic triaxial tests and field cyclic loading tests were performed. The dynamic strength and deformation properties of red mudstone were investigated by the dynamic triaxial tests. After introducing the concept of dynamic stress level, the test results indicate that the critical level of dynamic stress is about 30%. By analyzing the correlation between dynamic shear stress ratio and accumulative deformation, this paper proposes a calculation model of accumulative deformation of red mudstone subjected to cyclic loads, and presents the physical meaning and determining method of model parameters. The results of field cyclic loading tests demonstrate that settlement and rate of subsidence of subgrade can meet the requirements of high-speed railway construction when using red mudstone to fill the base layer of subgrade bed. Employing the proposed prediction model to calculate the accumulative deformation of red mudstone layer, the calculated and measured values match well as the deformation is stable： but some differences are observed before deformation stability due to different conditions and loading frequencies between laboratory and field tests.