Deformation behaviour and bearing capacity of sand under two adjacent foundations

Deformation of sand due to both single and adjacent surface foundations was observed by means of a newly developed method of image analysis to measure displacement field in model soil. Development of deformed area and propagation of slip lines were illustrated and effectiveness of two adjacent foundations were discussed. The results showed that an additive 50% of ultimate bearing capacity is available if spacing of two adjacent foundations equals the width of each foundation. Otherwise the effect begins to vanish when the spacing exceeds 2.5 times of the width of each foundation, and works as if two individual foundations when the spacing exceeds four times of the foundation width.