Foundations form the base of a structure and are designed to transfer loads through the upper weak layer of soil to a stronger layer of soil or bedrock below. The primary concerns for foundation design are bearing capacity and settlement beneath the foundations.
Bearing capacity is the ability of soil to support imposed loads. Ultimate bearing capacity is the theoretical maximum pressure which can be supported without shear failure. Allowable bearing capacity is a function of the characteristics of the ground, the depth and dimensions of the foundations and the degree of total and differential settlement which can be tolerated by the structure.
Sometimes, on soft soil sites, large settlements may occur under loaded foundations without shear failure occurring; in such cases, the allowable bearing capacity is based on the maximum allowable settlement.
Settlement will occur under all foundations. Structures with light loads or built on rock may experience negligible total settlement. For heavier structures or softer soils, both total and differential settlement are normally considered. Of particular concern is settlement which occurs post construction, as immediate settlement can usually be compensated for during the construction process.
Each geotechnical assessment or ground investigation is site-specific and must be tailored to meet the engineering requirements for the project. The scope of the investigation will depend upon the anticipated ground conditions and the design and construction proposals. Foundation engineering solutions may include normal shallow spread foundations, rafts, ground improvement, load bearing and settlement reducing piles.
RSA Geotechnics has experience providing structural foundation solutions for a wide range of buildings from single houses to multi-storey blocks with basements, and small factory extensions through to large commercial warehouses.