干燥蠕变与浸水湿化泥质岩粗粒土时效变形特性试验

Experimental study on time-dependent deformation characteristics of argillaceous coarse-grained soil under dry creep and wetting condition

由于环保及土地资源保护的迫切需要,泥质岩类软岩开挖粗粒土广泛应用于填方体工程,其蠕变及湿化变形是导致填筑体土工结构安全隐患的主要原因,已成为影响山区机场、土石坝及道路铁路路基等设施长期变形及稳定性问题的重要因素。为揭示粗粒土在干燥及浸水环境下的时效变形特性及其影响因素,以四川红层开挖土石料配置成不同缩尺的粗颗粒土,在模拟竖向加载及侧向约束下,对粗颗粒土干燥与浸水湿化蠕变特性进行了试验。结果表明:不同缩尺下的粗粒土具有不同的级配曲线,等量替代法缩尺模型粗颗粒质量占比最大,混合法缩尺模型粗颗粒质量占比居中,相似级配法缩尺模型粗颗粒质量占比最小;粗粒土干燥蠕变与浸水湿化蠕变特性差别较大,干燥蠕变主要因受力颗粒骨架时效变形引起,浸水湿化蠕变主要因颗粒软化破碎及结构重新排列引起;粗粒土干燥及浸水下时效变形特征与颗粒级配和细颗粒含量等密切相关;粗粒土干燥阶段的变形可采用分三部分的变形模型进行拟合,而浸水阶段的变形可采用广义凯尔文模型拟合,拟合效果良好。

The purpose of this paper is to study the time-dependent deformation law and influencing factors of coarse-grained soil under drying and wetting condition.To achieve this purpose,we designed and processed a special device to test the deformation of coarse-grained soil samples.Then,we prepared the excavated earth rockfill materials of red bed in Sichuan province into coarse-grained soil samples with different scales.The samples were 100 mm in diameter and 150 mm in height.At the beginning of the experiment,we executed the drying creep tests under vertical loading of 50 kPa and lateral constraints.After the drying creep information became steady,we poured water into the dipper well to carry out the wetting creep tests.Finally,we finished the test when the wetting creep information became steady.The experimental results showed that:(1) The grading curves of coarse-grained soils under different scales are different.Mass of coarse particles of equivalent substitution method in the scale model accounts for the largest proportion,that of mixing method accounts for the middle proportion,and that of similar grading method accounts for the smallest proportion.(2) There is a big difference between the drying creep characteristics of coarse soil and the wetting creep characteristics.The deformation of drying creep is mainly caused by the time-dependent deformation of the stressed grain skeleton while the deformation of wetting creep is mainly caused by the softening and crushing of particles and the rearrangement of the structure.(3) The characteristics of time-dependent deformation of coarse-grained soil under drying and wetting are closely related to grain composition and fine particle content.(4) The deformation law of coarse-grained soil in the drying stage can be fitted with a three-part deformation model.However,the deformation law in the immersion stage can be fitted by the generalized Kelvin model,and the fitting effect is good.