Pile Group Bearing Capacity Of The Long Auger Bored Piles Under Vertical Load

Long auger bored pile has been widely used since its inception by the virtue ofsimple equipment, easy operation and faster construction. Long auger bored pileare often used in engineering in the form of pile group, however, the bearingmechanism and bearing capacity of pile group are not identical with the singlepile’s. So choose long auger bored pile as the research object to study theperformance and bearing capacity in the form of pile group under vertical load.Long auger bored pile is dry-construction, the pile strength and the lateralfriction are large, the study need to base on these characteristics of the long augerbored pile. This is significant to analysis and obtain the analytical results.This paper is divided into three parts to analysis the pile group effect of longauger bored pile, respectively, theoretical analysis, FLAC3D numerical simulationand optimization design.(1) Comparing to the single pile bearing mechanism, detailed analysis thebearing mechanism and failure modes of pile group, base on this analysis, derived aformula for calculating the bearing capacity of pile group.(2) Using the FLAC3D (Fast Lagrangian Analysis of Continua in3Dimensions)to establish a numerical model of the single pile according to the static compressionloading test data and determine reasonable model parameters. And then, establishthree group model, of which the pile length, number of piles and pile spacing arevariable respectively: four piles group with the pile length is10m,15m,20m,25m;four piles group, six piles group, nine piles group with the pile length is20m; fourpiles group with pile spacing is3d,4d,5d,6d. Through these comparative models,to study the effect of pile group bearing capacity by the different pile length, pilenumber, pile spacing.(3)According to the second and third chapters, which are study the bearingcapacity performance of the long auger bored pile group under certical load. Evenunder uniformly distributed load, the pile group is uneven settlement, in order tosolve this problem, give some theory to optimize the design of pile group,Elaborate the design theory of variable stiffness, and set some engineer for exampleto give specific instructions.