University of Khartoum

Experimental Study of Bearing Capacity of Circular Footing on Stiff Clay Overlying Loose Sand

Experimental Study of Bearing Capacity of Circular Footing on Stiff Clay Overlying Loose Sand

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Title: Experimental Study of Bearing Capacity of Circular Footing on Stiff Clay Overlying Loose Sand
Author: Al Jaki, Mohammed Abdulrahman Hussein
Abstract: The soil profile in Khartoum city is formed of upper stiff silty clay underlain with loose to medium dense silty sand. Foundations are often placed on the upper clay. The objective of this research was to study the effect of the top layer thickness on the bearing capacity of stiff clay overlying loose sand. In this study an experimental model was constructed. It consisted of a circular tank, frame, and loading system. The tank was 60cm in diameter and has two parts, the upper part in which the stiff clay was prepared was 15cm high whereas the bottom part in which the sand was pulverized was 60cm high. Plate load tests were conducted on the stiff clay layer of fixed thickness overlying the loose sand. Steel plates ranging in diameters from 75mm to 300mm were used as foundations. Hydraulic jack was used to apply loads to the circular steel plates resting on the surface of the stiff clay for each test. The load – settlement curves were plotted and the ultimate bearing capacity was obtained using the tangent method. Meyerhof and Hanna (1978) equation was used to determine the theoretical ultimate bearing capacity. The results showed that the bearing capacity decreases with the increase of the plate diameter or the decrease of thickness of the clay layer over footing diameter ratio (H/D). Ultimate bearing capacity decreased linearly with H/D for Meyerhof and Hanna whereas it decreased in non-linear manner for the experimental results. The same behavior was obtained for the bearing capacity factor (N_c^*) when plotted against H/D. The value of N_c^* ranged from 6.56 to 2.61. The Meyerhof and Hanna equation gave results very close to experimental model results.
Description: 84 page
URI: http://khartoumspace.uofk.edu/123456789/16972
Date: 2015-11-11


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