基于延迟效应的干湿-冻融条件下水泥改良粉细砂影响分析

Analysis of the impact of cement modified fine sand under dry-wet freeze-thaw conditions based on delay effect

季节性冻土区土体的物理力学性质受干湿交替与冻融循环两种风化作用综合影响,开展单一冻融循环与干湿-冻融耦合作用下水泥改良粉细砂的UCS试验与剪切试验,并分析水泥延迟时间对土体物理力学参数的影响。试验结果表明:随着延迟时间的增大,水泥改良粉细砂的最大干密度先增大后减小,最优含水率先增大后趋于平缓再增大,延迟时间3 h时约为0 h时的70%;冻融循环3次后,随着延迟时间的增加,UCS值分别减小了-5.23%、5.15%、6.0%及6.32%,试样的UCS值、黏聚力整体减小,内摩擦角呈增大趋势;干湿-冻融循环作用下试样的各项参数均减小,先脱湿后吸湿路径下各项参数均比先吸湿后脱湿路径下略高。在不同风化作用下,试样的UCS值、黏聚力、内摩擦角均随延迟时间的增大而减小。研究结果可对季节性冻土区水泥改良粉细砂在施工及设计中的应用提供一定的参考。

The physical and mechanical properties of soil in seasonally frozen soil areas are comprehensively affected by two weathering processes:dry wet alternation and freeze-thaw cycle.UCS and shear tests were conducted on cement modified fine sand under single freeze-thaw cycle and dry wet freeze-thaw coupling effect,and the influence of cement delay time on soil physical and mechanical parameters was analyzed.Comparative analysis of the test results showed that as the delay time increased,The maximum dry density of cement modified fine sand first increases and then decreases,and the optimal water content first increases,then tends to be flat and then increases again.The UCS value gradually decreases.Under the action of freeze-thaw cycles,as the number of freeze-thaw cycles increases,the UCS value and cohesion of the sample decrease,and the internal friction angle shows an increasing trend.Under the dry wet freeze-thaw cycle,all parameters of the sample decrease,and the parameters under the dehydration followed by water absorption path are slightly higher than those under the dehydration followed by water absorption path.Under different weathering conditions,the UCS value,cohesion,and internal friction angle of the sample all decrease with increasing delay time.The experiment can provide some reference for the application of cement modified fine sand in construction and design in seasonally frozen soil areas.