Study On The Effect Of Lateral Surcharge On The Deformation Of Pile Group Foundation Of High-Speed Railway Viaduct

The high-speed railway has been greatly developed in China in recent years because of its advantages of fast speed,large capacity,low energy consumption,high safety and environmental friendliness etc.And it has played a vital role in China's comprehensive transportation system.Because of the vast territory and complex terrain of our country,it is often necessary to erect viaducts while building high-speed railway.And in soft soil areas,pile foundations need to be designed to support viaducts.Various engineering cases show that surcharge near railway will lead to track deviation and cause serious potential safety hazards.Therefore,it is necessary to study the influence of adjacent surcharge on pile foundations.In the first part of this study,a centrifuge model test is carried out.Four pile foundation models with different pile length are made to study the effect of surcharge.In the centrifuge test,the real stress level of the soil is created by adding high gravity acceleration field.The key data are monitored by arranging pore pressure transducers,laser displacement meters and strain gauges on the piles.The stress and deformation of piles adjacent to surcharge are analyzed from the distribution of excess pore pressure,displacement of pile top and bending moment.Based on the centrifuge test presented in the fisrt part of this study,a 3D finite element model is established in the second part of this study.The results of the finite element calculation are compared well with those of the centrifuge test.By analyzing these results,the different deformation mechanism of soil and pile foundations adjacent to surcharge is analyzed more clearly and deeply.The internal force changes of different pile foundations can be analyzed more completely.Based on a case where the lateral deformation of piers was caused due to adjacent surcharge,a finite element model is established by using PLAXIS 3D.The feasibility of this model is verified by comparing the measured field data.The behaviour of piles and the influence of the inclination of pile caps on the upper structure are studied according to different connection modes between pile and pile cap and different pile end support conditions.Finally,the safe distances between pier and surcharge with different surcharge height are suggested.