循环荷载作用下粉砂土路基累积变形试验研究

Experimental Study on Cumulative Deformation of Silty Sand Roadbed under Repeated Loading

为了对长期交通荷载作用下粉砂土路基累积不均匀沉降变形进行有效预测,必须合理描述其在不同应力及密实度状态下的变形规律。利用GDS动三轴仪,考虑不同初始密实度、不同初始围压及不同动应力水平,进行了一系列循环加载的三轴试验研究。动三轴试验表明,动应力水平越高、初始密实度越小、初始围压越低,则塑性应变增长率越高,但随着加载次数的增多,增长速率逐渐减缓。同时,粉砂土累积变形符合幂函数变化规律,在已有经验公式的基础上进行了改进,提出了粉砂土路基不均匀变形的预测公式及相应计算方法,可较好的反映上述4种因素的影响。

In order to effectively forecast the non-uniform cumulative settlement of silty sand roadbed under long term repeated traffic loading, it is important to reflect deformation patterns of silt sand reasonably under different stress levels and initial status. By adopting GDS triaxial apparatus, a series of cyclic loading tests were performed with consideration of different initial densities, different initial confining pressures and different cyclic stress levels. Test result shows that （1） the increment rate of plastic strain is lager with the higher dynamic stress level, the smaller density and the lower confining pressure; （2） the increment ratio of plastic strain reduces gradually with the increment of load cycles; （3） the relationship between cumulative deformation and load cycles accords with power law. Thereby, a new forecasting cumulative equation and calculating approach were proposed to reflect the effects of different influencing factors.