Torsional Properties Of Single Piles Subjected To Torsion Based On The Vlasov Foundation Model

As a most practical deep foundation,piles are wildly used in high rise buildings,large factories,bridges,railway,and offshore oil production platforms for their high bearing capacity,excellent stability,high strength and stable settlement.piles are usually destroyed by the torsional load in the building projects such as high rise buildings,seaside architecture and offshore platforms.Therefore,study on the piles subjected to torsion is very essential and meaningful for the engineering practice.The existing research on the piles subjected to torsion all focused on the stiffness and displacement of pile.Meanwhile,the solution derived by traditional energy needed an iterative an iterative procedure and can-not obtain an explicit answer.Based on the two-parameter foundation model,the study on the end-bearing pile and infinite pile subjected to static or dynamic torsional load is conducted.First of all,under the assumption that vertical and radial displacement are ignored,the function form of torsional displacement is proposed.Then the separate variable method is used to solve the equilibrium equation for the soil-pile system and the attenuation function of the soil-pile system.The torsional resistance around the shaft can be obtained by the analysis of surrounding soil with the principle of minimum potential energy and Hamilton principle.Meanwhile,a physical model is proposed to explain the composition of torsional shaft resistance around the shaft.At last,a parametric study of the torsional resistance is performed.Referring to the static condition,the torsional resistance produced by Winkler spring around the shaft plays a major role.With increase of shear modulus ratio of soil and pile,the torsional resistance decrease.Referring to the dynamic condition,the torsional resistance produced by Winkler spring and participating mass are major parts.With increase of soil-pile shear wave velocity ratio,the torsional resistance decrease.The major contribution of this study is:(1)the torsional resistance under static and dynamic torsional load is obtained explicitly.(2)a physical model is introduced to explain the composition of the torsional resistance.The physical model is consisted of Winkler springs and the membrane produced by continuity and participating mass of soil.