Deformation and strength properties of unsaturated remolded loess under K₀ pre-consolidation condition

In order to discuss the influence of K₀ pre-consolidation on the strength and deformation properties of loess, the experiments on a total of 36 remolded Q₃ loess samples in two groups are carried out using the improvement of unsaturated soil triaxial apparatus. The first group includes 24 tests, and each test includes three stages, namely, the samples are consolidated under the constant vertical pressure, and then, they are consolidated through the constant control suction and net confining pressure, and the drainage shear tests with constant control suction and net confining pressure are carried out in the end. The second group includes 12 tests, but each test only includes the last two stages of the first group. The results show that the initial tangent slope of stress-strain curves of the tests in the first group is greater than that of the second group, and the difference becomes more and more obvious with the increase of the suction and net confining pressure. The failure stress of the test samples in the first group is significantly greater than that of the second group. Except the tests on the saturated samples with no suction, the volumetric strain of two groups is similar. Unlike the shear shrinkage state of the test samples in the second group, the test samples of the first group exhibit slightly shear dilatancy at the initial stage, but it is not obvious and they become shear shrinkage insantly. Although the effective internal friction angle and destruction ratioare almost the same under the two kinds of experimental conditions, n is fairly different. Besides, the curves of total cohesion-suction and the relation curves of the index k in the initial modulus expression of Duncan-Chang model and suction (k-s) are rather different. Based on the test results, the modified formulas of apparent cohesion and tangent Young's modulus are put forward considering the comprehensive effects of