粗粒盐渍土大型冻融循环剪切试验

针对冻融循环后粗粒盐渍土的强度将直接影响盐渍土地区路堤的稳定性,而采用常规剪切试验将导致粗粒盐渍土的颗粒效应问题,基于西北地区粗粒盐渍土的冻融特点和剪切试验原理,设计研发了将冻融循环试验和剪切试验结合的大型粗粒土冻融循环剪切试验装置,可有效测试在不同温度条件下材料的强度特性。依托某公路盐渍土试验段项目,采用天然粗粒盐渍土模拟下路堤,测试其在经过冻融循环后的强度变化特点,并利用测试数据进行实际工况的数值计算。结果表明：随着冻融循环次数的增加,靠近冷端土体的粘聚力逐渐增大,内摩擦角先减小后增大;靠近暖端的土体强度逐渐减小,9次冻融循环后,靠近暖端的土体内摩擦角有一定增大;采用该天然粗粒盐渍土填筑的下路堤的强度变化量较小,路堤强度基本稳定。

Large shear test on coarse saline soil with freeze-thaw cycle

The shear strength characteristics of crude coarse grain saline soil under freeze-thaw cycles is directly related to the stability embankment on saline soil.The conventional shear test device will cause the particle-size effect of coarse grain saline soil.In order to make the test results more accurate,based on the features of coarse grain saline soil in northwest China after freezing and thawing and the principles of shear test,a large freeze-thaw cycle shear test device was developed to effectively test the strength properties of materials under different temperatures.Relying on the saline soil experimental section projects of a highway,the soil embankment was simulated with natural sulfate-chloride sand saline,the characteristics of strength change of natural sulfate-chloride sand saline soil was tested after freeze-thaw cycle test,the test datum were analyzed with numerical simulation under the actual working conditions.The results show that with the increase of freeze-thaw cycle times,the cohesion of the soil near the cold side gradually increases,the internal friction angle firstly decreases and then increases.The strength of the soil near the warm side gradually decreases,the internal friction angle has some increases after the 9 times freeze-thaw cycle test.The intensity of embankment with the natural sand saline soil filling is stable.