含砂量对砂−细粒混合土一维蠕变行为的影响

Influence of sand content on one-dimensional creep behavior of sand-fines mixtures

利用一维固结蠕变试验研究了宁夏中部黄土高原淤地坝前砂−细粒混合土的蠕变特性,结合压汞试验结果探讨了含砂量对其蠕变特性的影响作用机制。借鉴Yin-Graham一维等效时间线弹黏塑模型的理论框架,同时考虑一维条件下蠕变的有限性和蠕变系数的衰减性,建立了适用于描述淤地坝前砂−细粒混合土应力−应变−时间关系的经验蠕变模型。研究结果表明:含砂量小于28.57%时,次固结系数和次固结变形与含砂量呈负相关,细颗粒决定着砂−细粒混合土的蠕变性;含砂量超过28.57%后,次固结系数和次固结变形随含砂量增加逐步增大,砂−细粒混合土的蠕变性和砂性土相似。所建模型的预测曲线和一维蠕变试验曲线吻合良好,说明该模型适用于一维条件下砂−细粒混合土蠕变特性的描述。

In this study,one-dimensional consolidation creep tests were conducted to study the influence of sand content on the consolidation creep behavior of sand-fines mixtures in front of the check dams in the Loess Plateau of central Ningxia,and the influence mechanism of sand content on its creep properties was investigated according to the mercury intrusion tests.Drawing on the theoretical framework of the Yin-Graham isochronic elastic-viscoplastic model,an empirical creep model,which took into account the finiteness of creep under one-dimensional conditions and the attenuation of the creep coefficient,was developed to capture the stress-strain-time relationship of sand-fines mixtures.The results show that when sand content is less than 28.57%,there is a negative correlation between sand content and secondary consolidation coefficient and secondary consolidation deformation,and the creep behaviors of sand-fines mixtures are controlled by fine particles;when sand content is greater than 28.57%,the secondary consolidation coefficient and secondary consolidation deformation gradually increase with the increase in sand content,and the creep properties of sand-fines mixtures are similar to that of sandy soil.The predicted curves of the proposed model are in good agreement with the strain-time curves of one-dimensional creep tests,indicating that it is suitable for characterizing the creep characteristics of sand-fines mixtures under one-dimensional conditions.