Creep and Sliding in Clays Slopes: Mutual Effects of Interlayer Swelling and Ice Jacking

摘要

In swelling clays, the frost heave results not only from ice lens formation but includes swell heave as well. During the growth of the lenses, the clay desiccates gradually and promotes further water adsorption through the unfrozen hygroscopic water layers. This forces the clay phases to expand and the excess water to form ice lenses, finally resulting in a maximum heave, composed of a freeze and a clay swell part. Measurements of the volumetric expansion of clays subjected to freezing temperature show that the amount of volume increase is greater than the expected 10-11% increase in pore volume due to the freezing of the water in the soil. The increase in volume is the result not only of frost heave, as well tested and calculated phenomenon, but also of water uptake around clay flakes and within their crystal interlayer spaces. Therefore heave calculations in case of swelling clay soils have to consider swell heave in addition to pure frost heave. One thawing, swelling clays not only rearrange their microfabric but remain expanded for a much longer time than coarser grained soils or clays without swelling phases.