Deformational Assessment of Shallow Footings Founded on Carbonate Sand

Abstract

Carbonate (calcareous) sandy soils are well known to be prone to crushability and to have higher compressibility compared to siliceous sands. This study assess the deformational behavior of carbonate (calcareous) sand under shallow footings by carrying out back analyses load tests of twelve full-scale footings founded on improved carbonate (calcareous) sand fill and uniformly loaded up to the allowable bearing pressure. The footings are reinforced concrete isolated pads ranging from 1.5×1.5 m up to 3×3 m in size. These full-scale loading tests are combined with extensive in-situ static cone penetration tests carried out under the location of each footing to test the foundation soil. The recoded measurements of these full-scale load tests are utilized to measure the immediate settlements of the sand fill under variable stresses and to extrapolate long-term (creep) settlement as wells. Based on the analyzed results, comprehensive back analyses were carried out to validate several commonly-used settlement prediction formulae, including Schmertmann’s method (Schmertmann et al., 1978) and Meyerhof (1965 and 1974) for utilization validation with carbonate (calcareous) coarse-grained materials.