Hydraulic Fills to Support Structural Loads

Data are compiled based upon a review of the literature, concerning the relative density, penetration resistance, compressibility and rate of consolidation. Only hydraulic fills placed by sluicing through pipes are considered, and emphasis is upon performance under ordinary dead and live loads. Fills are classified according to the nature of the borrow materials: (1) fairly clean sand, resulting in a reasonably uniform fill of moderate density; (2) silty or clayey sand, for inhomogeneous fill of large void ratio; (3) stiff cohesive soil, resulting in a skeleton of clay balls with a matrix of sand and clay; and (4) soft cohesive soil, resulting in a laminated normally consolidated clay. The characteristics of each type of fill are illustrated by a case study. The placement and engineering properties of the most desirable type of fill—that derived from a fairly clean sand—are considered in detail.