Study on the mechanism of loess landslide induced by chlorine salt in Heifangtai terran

抄録

It is well known that water content is the key factor affecting the loess strength. In arid and semi-arid regions, the salt content in pore solution of loess is relatively high. Rainfall or irrigation can change the water content of loess and induce geological disasters such as loess landslide and loess mud flow. In this paper, Heifangtai, Gansu Province, is chosen as the study site, where is the most typical place of loess landslides. The occurrence of loess landslides is closely related to water, salt. In order to investigate the interaction rules of these three factors, a series of pressure plate apparatus tests and undrained shear tests were conducted on saturated loess, to investigate the degradation mechanism of loess strength caused by the interaction between water and salt.The results showed that: NaCl concentration had a significant effect on the matrix suction, i.e. the water retention capacity of loess sample increased as the increase of NaCl concentration,especially in the boundary effect zone (low suction zone, soil almost saturated), concerning the remolded loess samples having a same dry density.The increase of NaCl concentration in pore water can also lead to the decrease of shear strength of saturated loess, especially for the cohesion. The results of Scanning Electron Microscopy (SEM) tests gave a microscopic explanation for the above results. In conclusion, the enrichment of salt leads to the increase of water holding capacity of approximately saturated loess, which is closely related to the decrease of undrained shear strength in saturated conditions. This will help us to understand the mechanism of loess landslide in this area.