Experimental study of dynamic resilient modulus of subgrade soils under coupling of freeze-thaw cycles and dynamic load

Abstract

Although the dynamic properties of subgrade soils in seasonally frozen areas have already been studied, few researchers have considered the influence of shallow groundwater during the freeze-thaw (F-T) cycles. So a multifunctional F-T cycle system was developed to imitate the groundwater recharge in the subgrade during the freezing process and a large number of dynamic triaxial experiments were conducted after the F-T cycles. Some significant factors including the F-T cycle number, compaction degree, confining pressure, cyclic deviator stress, loading frequency, and water content were investigated for the resilient modulus of soils. The experimental results indicated that the dynamic resilient modulus of the subgrade was negatively correlated with the cyclic deviator stress, F-T cycle number, and initial water content, whereas the degree of compaction, confining pressure, and loading frequency could enhance the resilient modulus. Furthermore, a modified model considering the F-T cycle number and stress state was established to predict the dynamic resilient modulus. The calculated results of this modified model were very close to the experimental results. Consequently, calculation of the resilient modulus for F-T cycles considering the dynamic load was appropriate. This study provides reference for research focusing on F-T cycles with groundwater supply and the dynamic resilient moduli of subgrade soils in seasonally frozen areas.

摘要

为了考虑浅层地下水在路基土冻融循环过程中的影响,自主研发了多功能冻融循环试验系统,模 拟冻结过程中路基土存在地下水补给的工况,并对冻融循环后的试样进行大量动三轴试验。系统研究 了冻融循环次数、压实度、围压、循环偏应力、加载频率、初始含水率对土体动回弹模量的影响。结 果表明,路基土动回弹模量随着循环偏应力、冻融循环次数、初始含水率的增加而减小,相反,随着 压实度、围压、加载频率的增加而增加。此外,基于试验数据建立了考虑冻融循环和应力状态的动回 弹模量修正预估模型,模型计算结果表明,修正的预估模型具有较高的精度。本研究可为地下水补给 工况下的冻融循环研究和路基土动回弹模量研究提供相应参考。