Effects of high pressure on cooling process of clays in deep alluvium

Considering that large earth pressure will influence the strength and the stability of frozen wall by means of changing soil frozen temperature and its cryo-structure, a series of cooling process tests on clays from the deep stratum with different water contents and applied pressures prior to freezing are performed to study their cooling process characteristics. The aim of the tested samples subjected to a certain pressure is to simulate the earth pressure of the freezing ground. In order to reduce the error of the testing system, the initial temperatures of the tested samples prior to being frozen are 5°C, and the ultimate temperatures after being frozen are -10℃. The results show that the frozen temperature, initial frozen temperature and super-cooling degree closely relate to the suffered applied pressure of the tested soils. No matter the soils are saturated the frozen temperature decreases with the increase of the applied pressure, while the initial frozen temperature shows a fluctuation with the change of the applied pressure. Applying the crystallization theory of materials, it is concluded that the freezing process of soils mainly relates to the phase-change process of void free water. The applied pressure will change the adsorption capacity of soil particles to water molecules to influence the amount of free water in soils, and further change their latent heat releasing during crystallization. As a result, the applied pressure in freezing process of soils influences their cryo-structure.