Vol16 No.5: 1184-1197
【Title】Influences of soil moisture and salt content on loess shear strength in the Xining Basin, northeastern Qinghai-Tibet Plateau
【Author】FU Jiang-tao1,2,3; HU Xia-song1,4*; LI Xi-lai5; YU Dong-mei1,2; LIU Ya-bin1,2,3; YANG You-Qing1,2,3; QI Zhao-xin1,2,3; LI Shu-xia1,2,3
【Addresses】1 Key Laboratory of Comprehensive and Highly Efficient Utilization of Salt Lake Resources, Qinghai Institute of Salt Lakes, Chinese Academy of Sciences, Xining 810008, China; 2 Qinghai Provincial Key Laboratory of Geology and Environment of Salt Lakes, Xining 810008, China; 3 University of Chinese Academy of Sciences, Beijing 100049, China; 4 Department of Geological Engineering, Qinghai University, Xining 810016, China; 5 College of Agriculture and Animal Husbandry, Qinghai University, Xining 810016, China
【Corresponding author】HU Xia-song
【Citation】Fu JT, Hu XS, Li XL, et al. (2019) Influences of soil moisture and salt content on loess shear strength in the Xining Basin, northeastern Qinghai-Tibet Plateau. Journal of Mountain Science 16(5). https://doi.org/10.1007/s11629-018-5206-9
【Abstract】Moisture and salt content of soil are the two predominant factors influencing its shear strength. This study aims to investigate the effects of these two factors on shear strength behavior of loess in the Xining Basin of Northeast Qinghai-Tibet Plateau, where such geological hazards as soil erosion, landslides and debris flows are widespread due to the highly erodible loess. Salinized loess soil collected from the test site was desalinized through salt-leaching in the laboratory. The desalinized and oven-dried loess samples were also artificially moisturized and salinized in order to examine how soil salinity affects its shear strength at different moisture levels. Soil samples prepared in different ways (moisturizing, salt-leaching, and salinized) were measured to determine soil cohesion and internal friction angle. The results show that salt-leaching up to 18 rounds almost completely removed the salt content and considerably changed the physical components of loess, but the soil type remained unchanged. As salt content increases from 0.00% to 12.00%, both the cohesion and internal friction angle exhibit an initial decrease and then increase with salt content. As moisture content is 12.00%, the salt content threshold value for both cohesion and internal friction angle is identified as 3.00%. As the moisture content rises to 16.0% and 20.00%, the salt content threshold value for cohesion is still 6.00%, but 3.00% for internal friction angle. At these thresholds soil shear strength is the lowest, below which it is inversely related to soil salinity. Beyond the thresholds, however, the relationship is positive. Dissimilar to salinity, soil moisture content exerts an adverse effect on shear strength of loess. The findings of this study can provide a valuable guidance on stabilizing the engineering properties of salinized loess to prevent slope failures during heavy rainfall events.
【Keywords】Salinized loess; Desalinized loess; Salt-leaching; Shear strength indices; Moisture content; Salt content