A centrifugal model test study of lime-improved expansive soil under drying and wetting circles
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摘要: 为研究南宁石灰改良膨胀土高铁路堤在干湿循环作用下的工程特性，运用相似原理，以室内离心模型试验为主要手段,对路堤模型进行三次干湿循环试验，探究土压力、吸力、含水率、温度等随时间、深度及干湿循环次数变化的规律。研究表明：在离心模型试验中，自行推导建立的蒸发相似关系对蒸发时间和强度的控制适用可行，效果良好；路堤边坡变形与含水率变化密切相关，蒸发过程中产生少量裂缝，最大宽度不足2 mm，降雨过程裂缝消失；三次干湿循环后路堤整体变形不明显；土压力、吸力、含水率、温度随时间和深度等具有明显的变化规律，随深度增加大气影响减弱，试验测得其影响深度为8.0 m。研究结果可为现场石灰改良膨胀土高铁路堤施工提供一定参考，具有良好的工程应用价值。Abstract: In order to study the engineering properties of the expansive soil improved with lime of the Nanning high-speed railway embankment under drying and wetting circles, three times of centrifuge model tests under drying and wetting circles were carried out on the embankment model based on the similarity principle, and the effects of time, depth as well as drying and wetting circles on the variations of earth pressure, suction, moisture content and temperature were explored. The research results show that the established similarity relationship of evaporation is well feasible to the evaporation time and the intensity control during the centrifugal model test. The deformation of the embankment slope is closely related to the moisture content. A few cracks occurred in the process of evaporation with the maximal width of less than 2 mm, and the cracks disappeared during the rainfall process. After three times of drying and wetting circles, the entire deformation was not obvious. The earth pressure, suction, moisture content and temperature show obvious changes with time and depth. The influence of the atmosphere decreases with the increasing depth, and the effect depth is 8.0 m. The results of this study can provide some suggestions for high railway embankment construction with lime-improved expansive soil. It is of certain engineering application value.
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