Bearing Capacity Characteristics of Deep Foundations in Homogeneous Soil under Lateral Loads

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The deflection and bearing capacity characteristics of model piles (deep foundations) under lateral loads in homogeneous clay and sand have been investigated theoretically and experimentally.Both two-dimensional and three-dimensional model piles which have various flexural rigidity EP (E: elasticity of pile, I: inertia of sectional area of pile) were used for lateral loading tests to obtain the load (P)-horizontal deflection at the free top of piles (y) relationship and the strain distribution on the pile shafts, and to observe the deflection behavior of pile axis under lateral loads.According to the experiment, the Broms's plastic hinges were observed and the places of them approached to the ground surface with decreasing in the value of EI. In the case of clay, when Vesic's dimensionless length betaL which indicated the relative flexural rigidity was less than about 2, piles were considered rigid (short piles), while betaL being greater than about 2, piles were considered flexible (long piles). On the other hand, in the case of sand, when Rifaat's dimensionless length etaL which indicated the relative flexural rigidity as in clay was less than about 2, piles were considered rigid (short piles), while etaL being greater than about 4, piles were considered flexible (long piles).In the region of the plastic deformation, P/D (D:breadth of pile)-y relationships were expressed as straight lines on the double logarithmic plots as expected by the FEM analysis in which the soil was considered elastic. The experimental values of ultimate lateral bearing capacity for both short and long piles in clay and sand were in good agreement with the calculated values by the Broms's theory.