Strength and structure of Q₃paleosol

Paleosol is an important part of loess stratum, but there are few researches on its mechanical properties.In order to study the strength and structure of paleosol, Q₃paleosol in Xi'an is taken as the research object.Through the way of soil mechanics, the unconfined compressive strength test is carried out for undisturbed, remolded and saturated paleosol.The unconfined compressive strength values of the paleosol in the corresponding states are obtained, and the initial structure index is calculated.Based on the composite power exponent model, the expressions for unconfined compressive strength of the undisturbed and remolded paleosol with the water content are obtained, and the rules of the unconfined compressive strength, the disturbance sensitivity, the immersion sensitivity and the structure index of the undisturbed and remolded paleosol are analyzed.The results show that the structure of paleosol is strong, and its failure mode is still brittle when it is saturated.Under the same density, humidity and particle size, the strength of undisturbed paleosol is less than that of remolded paleosol, and its disturbance sensitivity is less than 1, which is contrary to the law of general loess.The immersion sensitivity and structure index of the paleosol decrease with the increase of water content, but when the water content is small or large, the change of structure with water content is not large, and the structure index can be less than 1, which shows that the paleosol has different structure characteristics from loess.