Abstract: The disintegration characteristics of saturated red clay from Guilin were examined under the action of (NH₄)₂CO₃ solution of different concentrations through a self-made disintegration device. The microscopic mechanism of disintegration was analyzed from aspects including the pH value of solution, the content of elements C and N in the soil, as well as the micromorphology of soil before and after the action of (NH₄)₂CO₃. Meanwhile, the macroscopic effect of disintegration was discussed in terms of shear strength and permeability. Test results manifested that the disintegration of saturated red clay intensified with the increase of solution concentration, and the disintegration process was divided into rapid, constant and stable stages. The first stage, which lasted a short time, was mainly caused by disturbance of the ring cutter; and the second stage, as the main stage of disintegration and lasting long, was closely related with the thickness of water film, the intergranular forces, the cementation force, the strength and the permeability of soil.

Key words: saturated red clay, disintegration, (NH₄)₂CO₃ solution, shear strength, permeability coefficient, micromorphology