Abstract This paper presents results of meticu- lous laboratory testing and numerical simulations on the effect of reinforcement on the low-strain stiffness and bearing capacity of shallow founda- tions on dry sand. The effect of the location and the number of reinforcement layers is studied in the laboratory, whereas numerical simulations are used to study the reinforcement-foundation inter- action. Laboratory tests show an increase of 100, 200, and 275% not only in bearing capacity but also in low-strain stiffness (linear load–displace- ment behaviour) of a square foundation when one, two, and three layers of reinforcement are used, respectively. The specimen preparation technique is found to be crucial for the repeat- ability and reliability of the laboratory results (less than 5% variability). Numerical simulations demonstrate that if reinforcements are placed up to a depth of one footing width (B) below the foundation, better re-distribution of the load to deeper layers is achieved, thus reducing the stresses and strains underneath the foundation. Numerical simulations and experimental results clearly identify a critical zone between 0.3 and 0.5B, where maximum benefits not only on the bearing capacity but also on the low-strain stiff- ness of the foundation are obtained. Therefore, soil reinforcement can also be used to reduce low- strain vibrations of foundations. Keywords Soil reinforcement Bearing capacity Low-strain stiffness of foundations Numerical simulations Notation B Footing width b/B Ratio of reinforcement width to footing width C u Coefficient of uniformity C c Coefficient of curvature D 10 Soil particle size such that 10% of the particles are smaller than that size D 50 Soil particle size such that 50% of the particles are smaller than that size d/B Ratio of reinforced depth to footing width (multiple reinforcement layers) EA Elastic normal (axial) stiffness of reinforcement e max Maximum void ratio e min Minimum void ratio N Number of reinforcement layers SIF Stiffness improvement factor u/B Ratio of depth to first layer of reinforcement to footing width W. Chung Golder Associates Ltd., Whitby, ON, Canada L1N 8Y6 G. Cascante (&) Department of Civil Engineering, University of Waterloo, Waterloo, ON, Canada N2L 3G1 e-mail: gcascant@civmail.uwaterloo.ca Geotech Geol Eng (2007) 25:265–281 DOI 10.1007/s10706-006-9109-0 123 ORIGINAL PAPER Experimental and numerical study of soil-reinforcement effects on the low-strain stiffness and bearing capacity of shallow foundations Wilson Chung Giovanni Cascante Received: 23 January 2006 / Accepted: 20 September 2006 / Published online: 27 October 2006 Ó Springer Science+Business Media B.V. 2006