Theoretical Analysis On The Compaction Effect Of Static Sinking Pipe-pile With Holes

Static pressure pipe pile is widely used because of its reliable quality,noiseless and vibration-less characteristics,less construction stress and so on.But static pressure pipe pile belongs to partial squeezing soil pile,the squeezing effect produced during pile sinking will not only produce huge disturbance to the soil around the pile,but also produce huge excess pore water pressure in a short time.The pipe-pile with holes can make the free water flow into the inner cavity of the pipe to reduce the displacement of soil,thus reducing the maximum value of excess pore water pressure and accelerating the dissipation of excess pore water pressure.Based on the theory of cavity expansion,the squeezing effect in the sinking-pile is studied in the paper,deduced and then the stress increment and radial displacement of pipe-pile without holes and pipe-pile with holes is compared for the sinking piles in both the plane and space state.With the stress increment solution,the excess pore pressure of pipe-pile with holes while sinking is analyzed.Then the analysis formula between the excess pore water pressure and radial distance,pile settlement rate,depth,pore size,time is derived.Using the numerical simulation method,the penetration process of the pile is simulated to obtain the relationship between the excess pore water pressure and its factors,thus the rationality of theoretical analysis is verified.The specific research contents are as follows:(1)In this paper,the general analytic solution of the stress increment and radial displacement of the soil around the pile during the sinking of the pile are analyzed,the stress increment and radial displacement solution of pipe-pile with holes are deduced considering the change of the stress at the opening of the pile.The comparative conclusion shows that the stress increment and the radial displacement of the pipe-pile with holes are less than that of the non-holes pile.(2)Considering the influence of depth,analytic solution of the stress and displacement of the pipe-pile with holes while pile sinking is derived.By comparing the two kinds of pile,shows that,under space state,the stress increment and the radial displacement of the pipe-pile with holes is less than the pipe-pile without holes.On this basis,the radial displacement of the soil in plastic stage is deduced which based on the plugging effect.(3)The analytic formulas for excess pore water pressure with the radial distance,velocity,depth,opening aperture and piling time are deduced.Combined with an engineering project,shows that the excess pore water pressure decreases with the increase of radial distance;increases with the increase of the velocity;increases with depth deepening;decreases with the increase of pore size.(4)Using the finite element analysis software ABAQUS,a numerical simulation is used for pipe sinking of static pressure pipe-pile with holes,we can obtain that the excess pore water pressure decreases with the increase of radial distance;at the same radial distance,the excess pore water pressure increases with depth deepening,and the pore water pressure increases with the increase of the velocity of the pile while at the same depth and radial distance.