Foundations for light structures

Abstract

Due to developments in soil mechanics, the price of foundations for ordinary structures has decreased to 5 to 10 per cent of the overall price of the building, but it still remains relatively high, sometimes exceeding 30 %. In Estonia, this issue has been relevant for the past years. The first solution was to use wedged piles under agricultural buildings (barns, storage units etc). As a result, the concrete content of foundations decreased 30 to 60 %, and the rate of steel use went up by 50 %. Currently the cooperation between wedged piles and grillage is being researched, with the objective of lowering the price of foundations. ln weak soils, 2-8 m injection piles have been used under private houses, holiday homes and storage structures, but one can save in the cost of foundations that way. Light structures and storage units have often been erected on screw piles (the steel pipe of the pile 100x100x6 filled with concrete, the pile end a steel sheet 15-20 mm thick and (depending on load bearing capacity) 25-60 cm in diameter. These piles can receive pressure as tension and if designed with the cooperation of piles and grillage in mind, the cost of foundations will decrease 50-60%. All of these solutions have been in use in Estonian silt and sands, the screw piles also in weak soils, where they stand on the dense intermediary layers alternating in weak soils.