FOOTING WITH INVERTED PYRAMIDAL PROTRUSIONS FOR SETTLEMENT CONTROL IN SANDY DEPOSITS

Abstract

This paper examines the feasibility of using an innovative footing with a corrugated base to
enhance the load-bearing capacity of shallow foundation, and to reduce the substructure’s subsidence as a
whole or differentially. The corrugated base consists of inverted pyramidal protrusions which give a 3-fold
advantages: (1) the pointed tips help smoothen the process of installation on site, (2) the protrusions provide
additional contact surface between the foundation and the soil for better load-bearing, (3) the corrugated base
entraps soil between the individual protrusions, improving the foundation’s stability against settlement and
sliding. Scaled models of the 8 cm x 8 cm footing were produced using 3D printing: CONTROL- smooth base,
Design A corrugated base with16 inverted pyramidal protrusions of 2 cm x 2 cm x 2 cm each, and Design B-
corrugated base with 64 inverted pyramidal protrusions of 1 cm x 1 cm x 1 cm each. Both designs had the same
contact surface area with the soil, though the penetration depth of the pyramids and the space between the
protrusions varied. Maintained load tests were carried out in simulated soil beds to determine the improved
performance of the foundation. It was shown that the corrugated slabs reduced settlement up to over 85 %
compared with the conventional smooth-base footing, with Design B giving slightly better results. It was also
observed that the larger pyramidal protrusions (Design A) tended to entrap air between them, forming air
cushions which resisted further penetration of the corrugated base into the soil, i.e. inhibiting mobilization of
the maximum load-bearing capacity.