CUR - The Council on Undergraduate Research

Quantifying the Improvement in the Ultimate Bearing Capacity of Strip Footings on Soft Clay Stabilized with a Granular Trench

Colton Corcoran and David Petersen, Mohammad Yamin, Department of Mechanical and Civil Engineering, Minnesota State University - Mankato, 228 Wiecking Ctr, Mankato MN, 56001

Research on foundational systems has brought increasing opportunity in the building construction sector for greater efficiency and accuracy in design. Available research development shows exploratory opportunity within a focus of quantifying the improvement offered by ground reinforcement through granular trench support in clay soils. Bearing capacity analyses were performed for a continuous strip footing placed on soft clay soil stabilized with a granular trench. The analysis software LimitState: Geo was used to develop models for evaluation and provide the ultimate bearing capacity for considered configurations. LimitState: Geo uses the Discontinuity Layout Optimization (DLO) approach which provides solutions using the upper-bound limit analysis (LA). Results from the theoretically developed model were compared with published research for physical modeling and numerical method results in the literature, showing positive agreement with available data. The results obtained from this study demonstrated significant improvements in the bearing capacity when considering the inclusion of a granular trench beneath the strip footing. Design parameters such as trench depth, trench width, footing width, and friction angle of the granular material in the trench were varied in the study to investigate contribution and impact in evaluation. The study concluded that these design parameters influence the bearing capacity significantly. Moreover, the results show that the bearing capacity of strip footings on soft clay with a granular trench can reach up to six times the bearing capacity when constructed purely on soft clay. The improvement in bearing capacity when using a granular trench was quantified for considered design configurations. The resulting improvement factors are then able to be provided for use in design to estimate the improvement available through granular trench reinforcement. As an available resource, the results provide progression in ability to accurately design reinforced foundational supports in building projects. 

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