Study On Penetrating Resistance Test And The Soil Compacting Effect By Numerical Analysis Of Jacked Pile

The jacked pile construction is noiseless,clean,vibrationless,able to connect to piles and possible to control pressure of the pile.However,it belongs to soil compaction piling which may damage adjacent buildings and underground pipelines.Thus,it is possible to reduce the damaging effect by estimating the soil compacting effect and taking preventive measures accordingly.In practice,the soil is layered and the compacting effect of jacked piling is more complicated.It is of great engineering significance to study the soil compacting effect by jacked piling in layered soil.In this thesis,we carried out field tests,qualitative and quantitative modeling of the soil compacting effect by finite element method.The expreiments followed the principle of single-factor variable.We analyzed the data from an actual jacked pile based ground reinforcement project and established 48 models.The work detail was as following:(1)The expansion of soil surrounding pile body can be treated as cylinder expansion while expasion of soil at the pile tip region can be regared as spherical expansion when the pile penetrates soil.Based onSpherical expansion theoryat pile tip region,we deducedthe stress field and displacement field based on the elastoplastic zone of Mohr-Coulomb and Tresca materials.(2)Using ABAQUS,a powerful general-purposed finite element software,with the displacement loading method,we established an axisymmetric model that accords with actual project.This approach solved several key technical problems in jacked piling: soil constitutive relations,large deformation problem,contact problem,the initial pressure balance of ground ground.We accomplished the stimulation of jacked piling process.(3)We carried out field test of jacked pile construction in foundation reinforcement project of Kunming Security Training Center of China Civil Aviation(the swimming pool of dianchi hotel in Yunnan).We then calculated by the theoretical formula of pile resistance and also carried out numerical simulation,considering the impacts of different soil types in on pile resistance.By comparing the depth curves of penetrating resistance derived from the three approaches,we verified that the finite element modeling and therical analysis was appropriate for jacked pile analysis.This work laid good foundations for further research.(4)we analyzed the effect of the soil compacting effect in jacked,under the homogeneous of soil layer soil.The displacement field of soil body is studied with different parameters(cohesion,friction angle,friction coefficient,Poisson's ratio and dilatancy angle).(5)Finally,we analyzed the soil compacting effect under the distribution of different soft and hard soil layer in jacked pileconstruction.For the soil types with hard interlayer or soft interlayer,we provide reasonable explanations for engineering phenomena encountered during the penetration of pile.