DEVELOPMENT OF INNOVATIVE PILE FOUNDATION DESIGNS ON SUBSIDENCE SOILS

Abstract

New technical solutions for the elimination of negative friction forces in the construction of pile foundations on subsidence soils are considered. The friction forces arising between the subsidence soil and the side surface of the pile, according to the Amonton-Coulomb law and the theoretical justifications of B.V. Deryagin, are presented as the sum of a term depending on adhesion and the product of the coefficient of friction by normal pressure. There is some function approximating the total friction force along the side surface of the pile. Differentiating this function, we obtain a formula that determines the change in soil pressure on the side surface of the pile, which varies with the depth of the pile location in the subsidence soil. To sharply reduce the forces of negative friction, the author has developed the design of a pile foundation made of asbestos cement pipes. Studies have shown that in these piles, the forces of negative friction are reduced by 20-30 %, compared with concrete piles manufactured in factory conditions. The author has developed two variants of the method of building a pile foundation on subsident soils, in which the role of antifriction lubricant is performed by a layer of humbrine. Humbrin is a waste of the technology of purification of technical oils. This waste accumulates in large quantities in the landfills of oil refineries. The author has proposed a new design of a pile foundation, in which recycled tires are used as an outer shell to remove the forces of negative friction. Experimental studies have shown that even with vertical deformations of the tire screen of more than 0.04 m, the amount of pile precipitation turned out to be negligible, only 0.02 mm. The author also developed a pile foundation erected on subsident soils. This pile foundation has an external cylindrical shell. In the gap between the cylindrical shell and the side surface of the pile there is a spiral-wound elastic rubber rolling harness. When the surrounding soil subsides, the outer cylindrical shell moves vertically down the rolling spiral bundle, removing negative friction from the side surface of the pile. In addition, the rolling spiral elastic harness also performs the function of a seismic isolator.