ADEN 30% Foundation and structure Part 6

Bridge Foundations & Substructures Settlement & Bearing Capacity: Actual soil settlement usually occurs three to five times faster than theoretical models predict due to three-dimensional consolidation and higher horizontal permeability . When building on rock, allowable bearing pressures use a safety factor of 3 for sound rock, and a safety factor of 6 to 8 for non-homogeneous or unsound rocks . Design & Stability: Foundations must maintain strict safety factors against overturning (up to 2.0) and sliding (up to 1.5) depending on the load combination . For deep foundations, the bottom must extend adequately below the deepest anticipated scour level to provide grip . Construction Details: Abutments and piers require bed blocks (like reinforced concrete) to properly distribute superimposed loads . They must also include drainage systems, utilizing weep holes and a backfill of at least 600 mm of hand-packed boulders/cobbles backed by granular materials . Application of Load: Once concrete or masonry is completed, structural loads must be applied incrementally (50%, 75%, and full design load) over a timeframe of 7 to 28 days, depending on the type of cement used and air temperature .