Experimental study on dynamic shear modulus and damping ratio of undisturbed loess in different regions

In China, loess has obvious regional distribution characteristics, and there is a certain practical significance to grasp the distribution laws of its dynamic characteristic parameters from the space plane. The dynamic torsional shear triaxial tests are carried out on undisturbed loess of Lanzhou, Luochuan and Yangling under different moisture contents and different stress states, and the variation laws of dynamic shear modulus and damping ratio of loess are obtained. The results show that the dynamic shear modulus of Lanzhou, Luochuan and Yangling loess decrease gradually with the increase of dynamic shear strain, and the decrease rate becomes smaller and smaller. The moisture content and consolidation stress have significant influences on the dynamic shear modulus and the initial dynamic shear modulus. Under the same moisture content and consolidation stress, the initial dynamic shear modulus of Lanzhou, Luochuan and Yangling loess conform to the law of increment from the northwest to the southeast in the geographical spatial distribution, the dynamic shear modulus of Lanzhou loess is the smallest, the following is that of Luochuan loess, and that of Yangling loess is the largest. As a whole, the damping ratios of Lanzhou, Luochuan and Yangling loess increase with the increase of dynamic shear strain. The increase rate of the damping ratios in the three regions conform to the law of decrement from the northwest to the southeast, the damping ratio of Lanzhou loess is the largest, the following is that of Luochuan loess, and that of Yangling loess is the smallest.