Study On Long Term Settlement Ofbridge Pile In Deep Soft Soil

There are many kinds of settlement calculation theories about pile foundations,but these calculation methods usually do not take into account the effect of time.Especially in recent decades,some projects have experienced serious accidents due to long-term settlement factors,which makes the calculation method for the long-term settlement of the pile foundation become an important part of the pile settlement calculation.At present,the commonly used method is to investigate the internal laws of the long-term settlement of the pile foundation through field tests and indoor tests,and then establish a mathematical model to derive the formula.It is expected that the long-term settlement can be accurately calculated to guide the actual project.With the development of time,the range of application of pile foundations has become wider and wider,not only in some places with good geological conditions,but also in more and more soft soil areas.Due to the characteristics of low intensity,high hydrophilicity,and high compressibility of soft soils,the result is that pile foundations in deep soft soil will take a long-term settlement owing to the load transmitted from the superstructure.The research on the settlement of pile foundation in deep soft soil should be studied from the characteristics of soft soil,the rheology of soft soil,the consolidation and settlement of soft soil foundation,and the frictional effect of pile-soil interface.(1)Several classical methods for calculating the settlement of traditional pile foundations are described.Although the results of the calculations can satisfy the design and construction of some areas with very good geological conditions,the calculation results are not taken into account because of the rheological effects under long-term influence.The error is larger than actual result.(2)Studying the characteristics of soft soil The method for calculating the consolidation settlement of soft soil is used to simulate the settlement of the pile foundation.The influence of time can be considered to some extent,but the mutual friction and dislocation between pile and soft soil are not considered.(3)Using the modified direct shear tester,perform direct shear creep test on soft soil to simulate soft soil shear in the soil around the pile;use concrete-soft soil interface friction rheology test to simulate the pile-soil interface.The shearing effect is simulated by the soft soil creep consolidation test to simulate the long-term consolidation deformation of the soil at the pile tip.Then use the power function,logarithmic empirical rheological model and several component rheological models to fit the test curve respectively,establish the creepcalculation formula under the corresponding conditions,and calculate the creep deformation as the long-term settlement of this point.(4)Taking the soft soil of Changshu City,Jiangsu Province as an example,considering the viscous properties of soft soil,the settlement is divided into three parts: Shear creep displacement between soft soil and pile-soil interface friction shear Shear displacement,vertical consolidation creep deformation of soft soil on the pile tip,and study of long-term settlement of pile foundation in soft soil layer.