Bearing Capacity of Footings Under Vertical and Inclined Loads on Layered Soils

Abstract

The bearing capacity of shallow foundations under axial vertical and inclined loads has been investigated for model strip and circular footings on layered soils. Two main cases have been considered, first, when the subsoil consists of a strong layer overlying a deep weak layer, and second, when a weak layer is overlying a deep strong layer.

Extensive theoretical and experimental studies have been found in the available literature on footings under vertical loads on a strong layer overlying a deep weak layer. Except for Meyerhof's theory - (1974) for the case of footings under vertical loads on a weak layer overlying a strong layer, no other attempts have been made to develop a rational solution. Further, there does not appear to be any theoretical analysis or experimental data reported on footings on layered soils subjected to inclined loads.

In this investigation, the case of a strong layer overlying a weak layer was simulated in the laboratory by testing footings on a dense and layer overlying loose sand, compact sand, and clay respectively. In the case of a weak layer overlying a strong layer, loose sand and compact sand overlying a dense sand were tested respectively. Homogeneous soils used in layer combinations were tested with the proposed footings under vertical and inclined loads. Results of these tests were verified according to established theories, and were used in the analyses of the test results of footings on layered systems. Further, these results provided an evaluation of the behaviour of the test materials.

The ultimate bearing capacity of footings on the mentioned soil layers was noted to vary between the ultimate bearing capacities of the homogeneous upper and lower layers, Increasing the load inclination resulted in a decrease in this ultimate bearing capacity. New approach.es for the analysis were developed by extending Meyerhof's theories (1974). The present test results, test results of other researchers, and the available data were found to be in reasonable agreement with proposed theories.

As a concluding part of the study, suitable design procedures are suggested for predicting the footing capacity in two layered soils and further research. points on the subject are recommended.