Numerical Analysis Of Pit Jacked Pile Construction In Chen Jiahe General Office Building

In the reinforcement method of existing building foundation,pit-jacked pile is widely used in foundation reinforcement because of its advantages of less vibration,small noise also short construction time.Rescue and reinforcement of Chen Jiahe complex building project will be used as example.In this paper,the main strengthening construction technology in this project is introduced,the application of the pit-jacked pile in the construction is discussed,finically the key points of the construction of the pit-jacked pile are summarized.The finite element software LS-DYNA is used to analyze the construction process of pit-jacked pile,the distribution of stress,strain and displacement in the soil also the original independent foundation is obtained.After the calculation and analysis,conclusions are obtained as following.（1）Combining the existing formula for pressure pile resistance induced by domestic scholars,an empirical formula for estimating pile resistance by static cone penetration test data is proposed.Q_uk=Q_sk+Q_pk=u∑m_il_iβ_if_si+nαq_cA_p（2）Through the ALE algorithm,a pile pressing process model is established,and the Lagrange model is used to establish the jack Foundation’s action model.（3）Through numerical simulation,the distribution of stress and strain in the surrounding soil is analyzed,and the effect of pile sinking process on the surrounding soil is summarized.The stress concentration area of the"stress bubble"in the soil is3⁸D and the vertical depth is 2⁷D.The soil in the 5D area around the pile body of the steel pipe pile is extruded by the pile body to produce strain in the horizontal direction.（4）The internal stress and strain distribution of the original foundation under the action of Jack pressure is analyzed.During construction,the strain of the original foundation is around 2.3778×10^-5 and the stress is around 2.88MPa.（5）The displacement of the center point of the original jack is 1.06×10^-5m.It is proved that the construction of the pit jacked pile will not cause any damage to the original foundation.