20 Civic Center Plaza - Soils Report

Home Browse Search

Griffin Realm SA, inc.-Geotechnical Investigation Law/Crandal! Project 70131-7-0261.0001 July 8, 1997 .. 6.1 FOUNDATIONS Drilled Pile Capacities The downward and upward capacities 6f 18-, 24-, and 30-inch-diameter drilled piles are presented as a function of penetration below pile caps in Figure 2, Drilled Pile Capacities. Dead plus live load capacities are shown; a one-third increase may be used for wind or seismic loads. The capacities presented are based on the strength of the soils; the compressive and tensile strength of the pile sections should be checked to verify the structural capacity of the piles. Piles in groups should be spaced at least 20 diameters on centers. If the piles are so spaced, no reduction in the downward capacities need be considered due to group action. Settlement Although foundation load information is not available, we estimate the settlement of the proposed building, supported on drilled piling in the manner recommended, will be less than 'h inch. Differential settlement between adjacent columns is expected: to be about 'A inch or less. Lateral Loads Lateral loads can be resisted by the piles, by soil friction on the floor slab, and by the passive resistance of the soils. The soils adjacent to a 24-inch-diameter pile, at least 20 feet long, can resist horizontal loads imposed at the top of the pile of up to 20,000 pounds. The lateral resistance of other sizes of piles may be assumed to be proportional to the diameter. In calculating the bending moment in a pile, the lateral load imposed at the top of the pile may be multiplied by a moment arm of 5 feet. For design, it may be assumed that the maximum bending moment will occur near the top of the pile and that the moment will decrease to zero at a depth of 20 feet below the pile cap. The lateral capacity and reduction in the bending moment are based in part on the assumption that any required backfill adjacent to the pile caps and grade beams will be properly compacted. 5