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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。
After the freeze-thaw cycle, the strength of coarse saline soil will directly affect the stability of embankment in saline soil area. However, the conventional shearing test will result in the particle effect of coarse saline soil. Based on the coarse saline soil Freeze-thaw characteristics and shear test principle, a large-scale coarse-grained soil freeze-thaw cycle shear test device combining the freeze-thaw cycle test and the shear test was designed and developed, which can effectively test the strength characteristics of materials under different temperature conditions. Relying on a highway saline soil test section project, the natural coarse saline soil is used to simulate the embankment, and its strength variation after freezing and thawing cycles is tested. The actual working conditions are calculated by the test data. The results show that with the increase of the number of freeze-thaw cycles, the cohesion of the soil near the cold end gradually increases, the internal friction angle first decreases and then increases, and the strength of the soil near the warm end gradually decreases. Nine freeze-thaw cycles The friction angle of the soil adjacent to the warm end increases to a certain extent. The change of the strength of the embankment filled with the natural coarse-grained saline soil is small, and the embankment strength is basically stable.