应力历史对黄土增湿变形影响

Influence of stress history on humidification deformation of loess

黄土由于其特殊的工程性质,即由它的水敏性、大孔性、结构性所造成的强烈湿陷性,常会在黄土地区的工程建设中出现与水的作用密切相关的多种工程病害.长期以来,对于黄土增湿变形的研究大多针对增湿速率、增湿路径及应力条件等因素展开.然而,在黄土地区需进行挖填方处理的建设场区颇为常见,大面积的挖填方工程改变了土体的应力状态,因此对于应力历史对黄土增湿变形的影响研究尤为重要.通过室内GDS三轴试验,对黄土试样进行应力历史的模拟之后,对试样进行偏压固结不排水试验和恒载增孔压试验.分析结果表明:不同应力历史条件下的黄土试样承载力无明显变化,高先期固结压力的试样发生变形的时间稍晚,但土体的破坏过程更为迅速,受剪初期出现剪胀的特性.

Due to its special engineering properties,namely the strong collapsibility caused by its water sensitivity,macroporosity and structure,loess often presents a variety of engineering diseases closely related to the role of water in the construction of loess areas.For a long time,most of the research on the humidification deformation of loess has been carried out for factors such as humidification rate,humidification path and stress conditions.However,the construction site that needs to be excavated and filled in the loess area is quite common.The large-scale excavation and filling works have changed the stress state of the soil.Therefore,it is important to study the influence of stress history on the humidification deformation of loess.Through the indoor GDS triaxial test,the stress history of the loess sample is simulated,and the sample is subjected to the bias consolidation undrained test and the dead load diafiltration test.The results show that there is no significant change in the bearing capacity of loess samples under different historical stress conditions,and the samples with high pre-consolidation pressure deform a little later,but the failure process of soil is more rapid,and dilatancy occurs at the early stage of shear.