Pile Group Effect Analysis And Numerical Simulation Under Vertical Load

With the development of the chinese rapid economic,citie’s demand for the pile group increased year by year.In order to make the bearing capacity of both piles and soil between piles for full playing, it is necessary to study factors which influences group pile effect.Based on pile static load test which from Liaoning province meteorological bureau northeast regional meteorological center business building,Using FLAC3D Finite difference software to do the numerical simulation of single pile and group pile,analysising the influence of pile group effect factors under the vertical load to settlement, pile side resistance and pile tip resistance,to provide some reference for future pile group designed under similar geological conditions.First of all, according to the actual engineering background to simulating single pile static load test, through comparing the simulation data and the measured data, pile top settlement error is0.03mm which is6.3%times of measured value.And through the settlement of pile and soil to calculate relative displacement of contact surface,viscous soil’s limit displacement is6-12mm.Applied to the last level of the load the relative displacement of pile soil did not reach this value. So pile side resistance load sharing curve is on the rise. Secondly, for the same pressure and the same geological conditions of single pile and pile group foundation numerical simulation comparison research,that the group of pile foundation’s pile top settlement is the single pile settlement value of18times more.And all of the single pile settlement under the same cushion cap,the largest number is center pile and the second is side pile and angle pile is least.Finally, by changing the pile long、pile distance、cushion cap width and so on to do the numerical simulation for mechanical properties and deformation characteristics of the pile group foundation.The results show that under the same vertical load,the greater the pile length, the smaller the settlement; the larger pile distance, the smaller the settlement.The bigger the ratio of Cushion cap width and the pile length, the smaller the settlement.Under the same loads the pile body axial force with different pile distance is similar.Top axial force changes smally and the mid-lower changes greatly.The pile axial force along the pile shaft length direction first increases, then decreases gradually.And the maximum pile force is on a certain depth of pile body top down, and not in the pile top surface. Each pile side resistance of pile group is gradually development from top to bottom. And the mid-lower resistance of the pile body is big, the upper side resistance is obviously less than the lower side.At the same time pile bottom side resistance with the increase of pile distance increases. With the increase of the upper load, the load percentage shaded by pile of group pile foundation is a non-linear growth.