Experimental Study on Shear Strength of Saturated Remolded Loess

Abstract Loess has the characteristic of macropore, loose structure, homogeneous composition and collapsibility. It is easy to saturate when it encounters heavy rainfall and irrigation, resulting in landslides, roadbed subsidence and dam instability in the loess area. To study the influence of dry density and shear rate on shear strength of saturated remolded loess, an SLB-6A stress-strain controlled triaxial shear penetration tester was used to conduct Consolidated Undrained(CU) test in the Yan'an area. During the test, three variables of shear rate, confining pressure and dry density were controlled. The dry densities of the samples were 1.5g/cm3, 1.6g/cm3 and 1.7g/cm3 respectively. The CU test of the saturated remolded loess at a confining pressure of 100kPa, 150kPa, and 200kPa was performed at a shear rate of 0.04mm/min, 0.08mm/min, 0.16 mm/min, and 0.4mm/min respectively. It is found that the stress-strain curve of saturated remolded loess gradually moves up with the increase of dry density. When the dry density is equal to ρd = 1.5g/cm3, the deviatoric stress under different confining pressures there is a tendency to increase first and then decrease with increases of shear rate. When the dry density is equal to ρd = 1.6g/cm3 and ρd = 1.7g/cm3, the deviational stress under different confining pressures shows the trend of increasing first, decreasing and then increasing with the increase of shear rate, which is different from that at the dry density ρd = 1.5g/cm3 at a shear rate v = 0.4mm/min. When the dry density ρd = 1.5g/cm3, the cohesive force decreases first and then increases with the increase of shear rate. When the dry density ρd = 1.6g/cm3 and ρd = 1.7g/cm3, the cohesive force first increases at 0.08 mm/min, and then decreases with the increase of shear rate. The cohesion and internal friction angles tend to increase as the dry density increases.