Variations of suction and suction stress of unsaturated loess due to changes in lignin content and sample preparation method  

作　　者：LIU Wei WANG Qian LIN Gao-chao XU Xiang-tian 

机构地区：[1]Institute of Transportation,Inner Mongolia University,Hohhot,010070,China [2]Key Laboratory of Loess Earthquake Engineering China Earthquake Administration&Gansu Province,Lanzhou,730000,China [3]School of Civil and Environmental Engineering,University of New South Wales,Sydney,NSW,2052,Australia

出　　处：《Journal of Mountain Science》2021年第8期2168-2183,共16页山地科学学报（英文）

基　　金：funded by the Natural Science Foundation of the Inner Mongolia Autonomous Region(Grant No.2020BS04003);the Project of High-Level Talent Research in Inner Mongolia University(Grant No.12000-15031942);the National Natural Science Foundation of China(Grant No.51778590,51879131).

摘　　要：Unsaturated loess in natural sites loses stability as the overburden load continuously increases.Traditional soil modifiers such as cement and fly ash affect the surrounding environment.A new type of material,i.e.,lignin,is environmentally friendly and able to increase the strength of loess.However,the engineering characteristics of the improved loess under unsaturated conditions are not yet clear.In this study,the soil-water characteristic curves(SWCCs)of lignin-improved loess samples were determined from 0 kPa to 700 kPa using a pressure plate instrument,and then,they were fitted using the van Genuchten(VG)model and the Fredlund and Xing(FX)model.In addition,the effects of the lignin content and sample preparation methods on the SWCCs were investigated to determine the optimal lignin content and a suitable sample preparation method for loess foundations.As the lignin content increases,the matric suction and residual water content of the improved loess increase.The suction stress increases with the increasing lignin contents of 1%–2%.At lignin contents of 3%–4%,the suction stress begins to decrease and the samples prepared using the slurry method has a lower suction stress than that prepared using the wet mixing method.The air entry value(AEV)increases with increasing lignin content.In addition,scanning electron microscopy(SEM)was used to investigate the microstructural variations.It was found that after the addition of lignin,the entrapment of the loess particles by the lignin fibers created some larger particles and smaller pore diameters,which in turn led to poor connectivity of the loess pores.These changes cause the matric suction of the modified loess to increase.

关 键 词：Loess treated with lignin Sampling method Soil-water characteristic curve(SWCC) Suction stress characteristic curve(SSCC) Scanning electron microscopy(SEM) 

分 类 号：P642.131[天文地球—工程地质学]