砾类土在循环荷载作用下的变形影响因素试验研究

Study on influence factors of gravel soil accumulative deformation under cyclic loading

砾类土是新疆铁路和公路常用的路基填料,为了控制和减小砾类土路基的沉降,首先需要明确各因素对该类路基在循环荷载作用下的变形影响规律。通过动三轴试验研究围压、初始静偏应力、循环荷载作用频率、循环荷载大小和固结比对砾类土累计塑性变形的影响规律,得出其累计塑性应变随着初始静偏应力、循环荷载大小的增加而增大,随着围压、荷载作用频率和固结比增加而减小。同时计算各影响因素对累计塑形应变的极差,得出影响因素对累计塑形应变影响的大小。在路基施工时,可以通过提高路基的围压,同时使路基充分固结来减小路基的营运沉降。提出一种针对砾类土应变较小时的塑性累计变形模型,并验证模型的正确性,可为新疆砾类土路基的设计和施工提供参考。

Gravel soil is the commonly used railway and highway subgrade filling in Xinjiang. In order to control and reduce settlement of embankment,it should be firstly confirmed that the change law of influencing factors on the gravel soil roadbed accumulative deformation under cyclic loading. The effect of confining pressure,the initial static deviatoric stress,cyclic loading frequency,cyclic loading value and consolidation ratio on cumulative plastic strain of gravel soil was investigated through the dynamic triaxial tests. The accumulative deformation increases with the increasing value of initial static deviatoric stress and the cyclic loading; however,it shows an opposite trend with the increase of confining pressure,cyclic loading frequency and consolidation ratio. At the same time,the cumulative plastic strain range under different influencing factors was calculated and their impact on the cumulative plastic strain were obtained. Thus in the subgrade construction,increasing confining pressure and consolidation ratio of gravel soil subgrade can be adopted to reduce operation settlement. A new model of gravel soil cumulative plastic strain arming at small plastic deformation was put forward and the correctness of the model was validated. The research results can provide reference for the design and construction of gravel soil subgrade in Xinjiang.