Study On Bearing Capacity Of Expanded Pile In Changchun Mudstone Area

The middle pile foundation of the reverse work of Changchun comprehensive transportation transfer center is used for the middle pile foundation,which has large structure,strict deformation requirements and the possibility of floating.Therefore,strict requirements are put forward for the compression and uplift bearing performance of the enlarged base pile.The study on the differential bearing performance of the enlarged base pile under conditions.The Changchun area is a mudstone geology.Through the study of the bearing capacity of the enlarged base pile under the mudstone geological condition,it can provide reference and basis for the design and construction of the enlarged base pile under the similar geological conditions.In this paper,normative calculation,experimental analysis and numerical simulation are used to study.Through the standard calculation and comparing the calculation results with the experimental data,the original calculation formula is verified or the correction coefficient is introduced.On the basis of the field self balance test,the MIDAS-gts numerical simulation is used to complete the loading,and the parameters of the enlarged base pile in the mudstone geological area are calculated according to the standard and the corresponding parameters of the non mudstone area are compared and analyzed.In view of the conservative calculation results of the original codes,the correction coefficient is introduced to make the calculation results closer to the experimental results.Through numerical simulation,four test piles continue to be loaded,and its ultimate bearing capacity is higher than that of the field self balance test value of about 30%.The mean of the end resistance ratio of the mudstone area is 70.80%,which is obviously higher than that of the non mudstone area.It shows that the mudstone geology has made better use of the structure characteristics of the expanded pile.Bearing characteristics.The bearing capacity of the unit volume concrete in the mudstone area is 439.2kN/m3 far higher thanthat of the 298.7kN/m3 in the non mudstone area.The mudstone geology fully improves the use efficiency of the concrete,and has achieved the purpose of economic and efficient.In the mudstone area,the foundation of pile foundation can be expanded well.It can make good use of the good engineering properties of the mudstone formation,give full play to the bearing effect of the pile end enlargement,and improve the bearing capacity of about 35%.The change of the bottom expansion position will not affect the compressive bearing capacity of the enlarged base pile,but the bottom position of the pile is set at the bottom of the pile.Under three types of geological conditions,the same size pile is loaded separately.Under the operating conditions,the loading amount of significant changes is approximately the same,but the settlement deformation of the soil with better engineering properties is smaller,which is beneficial to the high carrying capacity of the soil and the high efficiency of the bearing capacity of the pile foundation.When the load level is low,the pile side friction resistance first plays the role when the load level is low,and the Q-s curve is basically coincided.With the increase of the load level,the longer the length of the pile length is,the smaller the load settlement curve is,the displacement increment is not obvious,the more the load is not easily destroyed,the bearing capacity is improved.In addition,with the change of pile length,the bearing capacity of pile is closely related to soil properties and burial depth.