Study on the time effect of shear strength of alfalfa-loess composite

The alfalfa-loess composite, obtained by artificial planting in PVC tubes, was selected as the research object. Through triaxial compression tests, the time effect of shear strength change of alfalfa-loess composite was analyzed, and the effects of confining stress and water content on the shear strength of alfalfa-loess composite were compared. The results shown that the shear strength of alfalfa-loess complex was significantly enhanced compared to the plain loess. The cohesion of the alfalfa-loess composite significantly increased with increasing growth period of alfalfa (60 days, 90 days, 120 days and 150 days). Under a lower confining stress, the cohesion of alfalfa-loess composite with different growth periods in unconsolidated and undrained (UU) test increased by 7.02%, 18.81%, 26.09% and 36.41%, respectively, compared with that of plain loess, while that in the unconsolidated and undrained (CU) test increased by 27.62%, 50.87%, 77.62% and 158.11%, respectively. Under a higher confining stress, the cohe