Research On Behaviour Of Barrettes By Theoretical Analysis And Model Tests

Recently, barrettes have been used widely all over the world. However there are few researches carried out on their vertically-loaded behaviour, especially in influence of their non-axisymmetrical cross-section on it. So in order to improve the understanding of barrette behaviour further, preliminary researches on barrettes are carried out in this paper.Firstly unified load-settlement solution of single barrette pile based on bilinear load transfer function is developed in this paper. With the aid of the solution, the barrette behaviour is analyzed preliminarily. In consideration of limitations of load transfer method, which cannot take into account its non-axisymmetrical cross-section, the approximate three-dimensional method is proposed based on elastic theory method which was proposed by Poulos(1968). The proposed method can consider its non-axisymmetrical cross-section. At the same time, the program corresponding to the proposed method is compiled in FORTRAN90, which is used to analyze the influence of several factors on behaviour of barrettes, including ratio of length to width, ratio of depth to equivalent diameter, ratio of modulus of pile to soil, Possion's ratio, the finite layer etc. Many useful conclusions are obtained from the above analyse. In addition, some comparisons can be made between load transfer method and elastic theory method in this paper.In order to study the behaviour of barrette pile group interaction and barrette pile group-soil-cap interaction, the proposed approximate three dimensional method of single pile is extended in this paper. The respective governing load-settlement equations corresponding to barrette pile group interaction and barrette pile group-soil-cap interaction have been derived. At the same time, the corresponding programs on the above two methods can be compiled in FROTRAN90 respectively, which are used to analyze the influence of several factors on behaviour of barrette pile group and barrette pile group-soil-cap interaction, including collocation of pile, ratio of length to width, pile spacing, ratio of depth to equivalent diameter, ratio of modulus of pile to soil, Possion's ratio, the finite layer, the number of piles etc.Lastly a series of model tests on vertically- loaded bahaviour of single pile are made, tests results are analyzed, and the causes of tests failure are preliminarily discussed in this paper.