Experimental Investigation of a Load-Transfer Material for Foundations Reinforced by Rigid Inclusions

Abstract

The rigid inclusion technique has been used worldwide to reinforce soft soil for road and railway embankments and deep building foundations. This technique is studied through field tests and physical and numerical models. Most studies focus on embankments or slabs on soils reinforced with rigid inclusions. Previous research based on numerical modeling demonstrated that the load-transfer mechanisms for a rigid slab differ from those for an embankment. Here, a simplified physical model was developed to assess the load-transfer mechanism between the inclusion head and the load-transfer platform (LTP) under a rigid slab. This research focused on the use of an alternative material for the LTP, which is a compacted soil with or without cement. When the reinforced soil contribution is neglected, the LTP weight and applied load are transmitted completely to the inclusion cap (load-transfer efficiency of 100%). As the LTP material stiffness increases, the settlement magnitude decreases considerably. The experiments demonstrated that the applied load was transferred to the inclusion head through an inverted truncated load-transfer cone (LTC) over the inclusion; the external angle depended on the LTP material strength in accordance with Coulomb’s theory. The principal stress state at the base of the LTC also was determined. Equations are proposed to determine LTP thickness and inclusion spacing.