Loading tests on compacted soil, bottom-ash and lime layers

This paper addresses the interpretation of loading tests bearing on a layered system formed by a compacted soil, coal bottom-ash and carbide lime top-layer overlying a compressible residual soil stratum. Load-settlement behaviour is observed from tests carried out using circular steel plates ranging from 0.30 to 0.60 m diameter on the top of a 0.15-0.60 m thick artificially cemented layer. Field data demonstrate the effectiveness of compacted soil-ash-lime layers in increasing bearing capacity and reducing foundation settlements where shallow foundations are used on weak residual soils. The paper also stresses the need to express test results in terms of dimensionless variables in plots of normalised applied pressure against settlement-to-diameter ratio. The efficiency of existing analytical solutions for layered cohesive-frictional soils in determining the bearing capacity of footings on processed cemented soil overlying a weakly bonded residual soil with high void ratio is evaluated.