Study On Settlement Calculation Of Differential Pile Group Foundations And Its Engineering Application

With the further progress of West Development, the mountainous highway andrailway gain a rapid development. To protect the existing ecosystem, the excavating tothe mountain should be avoid when the highway and railway cross the mountains.Therefore the pier and pile foundation has been widely used in the mountainousbridges. Since there are much uncertainty for the engineering geological conditions,the geotechnical parameters, and the loading, it is necessary to conduct the study onthe reliability of the pier and pile foundation of the mountainous bridges. There aremany researches on the reliability of the load-carrying capacity of the pile foundation,however, the studies on the reliability of the pile deformation, including the verticaland horizontal deformation, are rare. In the present paper, based on Daba bridge2inthe section K82+965of the Longyong highway, the study on the reliability of thevertical and horizontal deformation of the pile foundation of the pier1to6wasconducted.Firstly, the existing researches on the calculation method of the pile foundationdeformation under the vertical and horizontal loading, and the reliability of the pilefoundation were summarized. Secondly, the calculation model and method of thevertical deformation of the mountains pile foundation were established based on theshear displacement method, and the calculation method of the reliability index of themountainous pile foundation settlement was present based on the improvedRosenblueth method. Thirdly, the load-carrying behavior and the failure mode of thepier and pile foundation of the mountainous bridges were analyzed, and the differentialequation of deflection curve of each characteristics segment was obtained through thesimplified calculation model of the pier and pile foundation of the mountainousbridges under the horizontal loading. Furthermore, based on the power series methodthe semi-analytical result of the internal forces and the deformation of the pier and pilefoundation of the mountainous bridges under the horizontal loading were obtained, andthe reliability index of the horizontal deformation of the mountainous pile foundationwas present based on the design point method. Finally, the reliability index and thefailure probability about the settlement and the horizontal deformation of the pilefoundation of the pier1to6of the Daba bridge2were analyzed and the influence ofthe variability of parameters on the reliability index of the settlement and the horizontal deformation of the pile foundation was discussed.The calculation results of the Daba bridge2not only verify the method present inthis paper, but also provide a technical guidance for the design, the construction andthe operations management of the actual bridge.