不同含水状态下基床级配碎石填料变形特性研究

Deformation characteristics of subgrade graded gravel with different water contents

基床级配碎石在外界雨水侵入时含水状态发生改变对其变形特性不利,从而影响行车安全,但目前研究含水率对基床级配碎石变形特性的成果甚少,为进一步揭示不同含水状态下基床级配碎石的变形特性,对不同含水率的级配碎石试样开展了多组大型静动三轴试验。首先,通过静三轴试验探讨了含水率对级配碎石应力-应变关系和强度特性的影响;然后,基于动三轴试验,重点研究了含水率、动应力水平对累积应变随荷载作用次数发展规律的影响;在此基础上,建立了综合考虑含水率、荷载作用次数、动应力水平相互耦合作用的累积应变预测模型。基于含水率为5.0%和7.3%的累积应变试验结果,确定了模型中的待定参数,通过含水率为8.6%的试验结果验证了其正确性和合理性,此模型不仅克服了不同动应力水平下累积应变计算模型的分散性,而且能够直观地体现出含水率对累积应变的影响。

The deformation characteristics of subgrade graded gravel can be impaired by the variation of water content due to rainwater infiltration so that the traffic safety is adversely affected. However, there is a paucity of the research that addresses the influence of the water content on the deformation characteristics of subgrade graded gravel. To investigate its deformation characteristics at different water contents, a series of large-scale static and dynamic triaxial tests is carried out. The effect of the water content on the stress-strain relationship and shear strength of graded gravel is explored, and the influence of dynamic stress level on the accumulative strain of the soil is studied based on the results of dynamic triaxial tests. Also, an analytical model which accounts for the influences of water content, dynamic stress level, and cyclic number is proposed. Using parameters obtained by firing the tests for water contents of 5% and 7.3%, the proposed model is validated by calibrating the tests for water content of 8.6%. Comparison of the proposed model and Gidel model shows that the proposed calculation approach yields better results for various dynamic stress levels and loading cycles. The proposed model can not only avoid the scattering of calculated accumulative strain, but also directly reflect the influence of water content on the accumulative strain.