Axial Performance of ACIP Piles in Texas Coastal Soils

Methods were evaluated for assessing axial compressive capacities of augered, cast-in-place (ACIP) piles in the Pleistocene terrace deposits of the Texas Gulf Coast and Recent to Modern alluvial soils. The study involved a combination of data base analyses and the performance of new loading tests on instrumented piles. The results in sand deposits mirrored earlier studies that indicated that common methods used for designing drilled shafts are also appropriate for ACIP piles, although the patterns of load transfer in the tested piles suggested zones of both lower load transfer (running sands below the water table) and higher load transfer (compacted surface soils) than would be expected in drilled shafts. The action of drilling and grouting resulted in net increases in lateral effective stresses in the soil around the tested piles, near the ground surface, where such measurements were made. In overconsolidated clays, slightly higher unit side resistances were inferred for ACIP piles than are predicted by common drilled shaft design methods. However, common drilled shaft design methods, notably the FHWA method, produced generally accurate capacities for mixed soil profiles.