How can you predict soil bearing capacity? (2024)

Estimating soil bearing capacity can be done through field tests that measure the soil's reaction to applied loads. Standard penetration test (SPT) involves driving a steel rod into the soil at a constant rate and recording the number of blows required to penetrate a certain depth. Cone penetration test (CPT) uses a cone-shaped probe pushed into the soil at a constant rate and measuring the resistance and pore pressure. Plate load test (PLT) entails placing a steel plate on the soil surface and loading it incrementally until the soil settles or fails. While field tests provide direct and reliable data, they are also costly, time-consuming, and invasive.

Estimating soil bearing capacity can be achieved by performing laboratory tests on soil samples collected from the site. The Triaxial test involves subjecting a cylindrical soil sample to a confining pressure and an axial load until failure. Alternatively, the Unconfined compression test (UCT) involves loading a cylindrical soil sample axially without any lateral support until failure. Lastly, the Direct shear test (DST) requires a rectangular soil sample to be placed between two horizontal plates and sheared until failure. Although laboratory tests provide more controlled and accurate data, they are also prone to sample disturbance, scaling effects, and variability.

A third way to estimate soil bearing capacity is to use empirical formulas that relate soil properties and parameters to bearing capacity. Terzaghi's formula considers the soil's cohesion, friction angle, and unit weight, as well as the foundation's width and depth. Meyerhof's formula is a modification of Terzaghi's that accounts for the shape, inclination, and eccentricity of the foundation and the load. Vesic's formula is a generalization of Meyerhof's that takes into account the soil's dilatancy and anisotropy. Although empirical formulas provide simple and convenient estimates, they are based on assumptions, approximations, and correlations that may not apply to all cases.

Estimating soil bearing capacity can be done through numerical models such as the finite element method (FEM), finite difference method (FDM), and discrete element method (DEM). These models provide more realistic and comprehensive estimates, however, they are complex and computationally intensive. Additionally, they are sensitive to input parameters and boundary conditions.

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Civil Engineering

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