Bearing capacity of soft clay improved by heating through different spacing cased boreholes

Abstract EN

This paper presents the effect of heat treatment on ultimate bearing capacity and total settlement of soft clay.

The soft clay that was used in this study was prepared by mixing Baghdad’s clay with sufficient water content which gives a shear strength of 7 kPa.Seven model tests were carried out on soft clay inside a cubic steel box of 750 mm side length after heat treatment, two of which were used as a reference without treatment for comparison.

A special heating system was designed and manufactured for this purpose by using the gas as a source of heating through boreholes.

Four square patterns casing boreholes having 3.5 cm in diameter and 30cm in length with spacing 3d, 4d, 5d, 6d and 7d (were d is the diameter of the borehole) and the time of heating was six hours for each model.

A monotonic load was applied on an aluminum square model footing of 150 mm length and 20 mm thick placed on the center of surface area of the soft clay until the settlement exceeds 10% of the width footing.

The results showed that the bearing capacity increases and the settlement decreases with spacing increasing until some limiting value (5d) then the bearing capacity decreases and the settlement increases.

The 5d spacing is the best one where the bearing capacity increases nine times and the settlement decreases to one tenth compared with that without heating.