Settlement calculation for long-short composite piled raft foundation

Abstract

The mechanism of long-short composite piled raft foundation was discussed. Assuming the relationship between shear stress and shear strain of the surrounding soil was elasto-plastic, shear displacement method was employed to establish the different explicit relational equations between the load and the displacement at the top of pile in either elastic or elasto-plastic period. Then Mylonakis & Gazetas model was introduced to simulate the interaction between two piles or between piles and soil. Considering the effect of cushion, the flexible coefficients of interaction were provided. With the addition of a relevant program, the settlement calculation for long-short composite piled raft foundation was developed which could be used to account for the interaction of piles, soil and cushion. Finally, the calculation method was used to analyze an engineering example. The calculated value of settlement is 10.2 mm, which is close to the observed value 8.8 mm.

Keywords

long-short composite piled raft foundation / shear displacement method / settlement / Mylonakis & Gazetas model

References

[1] ShiF.. Analysis of bearing capacity and deformation of composite foundation[J]. Manufactured Building, 2002, 32(9): 41-45

[2] AvilkinV. L., AleksandrovV. M., KovalenkoE. V.. On using the more-accurate equations of thin coatings in the theory of axisymmetric contact problems for composite foundations[J]. Applied Mathematics and Mechanics, 1985, 49(6): 770-777

[3] UraoK., MasudaK.. Dynamic behaviors of a composite foundation[C]. Proceedings of the World Conference on Earthquake Engineering, Madrid, 1992, Spaim, A A Balkema Publishers: 1801

[4] DogrugluA. N., OmurtagM. H.. Stability analysis of composite-plate foundation interaction by mixed FEM[J]. Journal of Engineering Mechanics, 2000, 126(9): 928-936

[5] MaJ., ZhangD.-g., ZhangZ., et al.. Design of the composite foundation with long-short-pile[J]. Geotechnical Engineering Technique, 2001, 15(2): 86-91

[6] DengC., GongX.-nan.. Application of long-short-pile composite foundation to high-rise building[J]. Building Construction, 2003, 25(1): 18-20

[7] GeX.-s., GongX.-n., ZhangX.-ming.. Design of long-short-pile composite foundation[J]. Building Structures, 2002, 32(7): 3-7

[8] ZhuB.-l., ShenZ.-jiang.Calculation of soil mechanics[M], 1990, Shanghai, Shanghai Scientific Press

[9] ZhangJ.-h., DengA.-fu.. A new analytical method for piled raft foundation[J]. China Civil Engineering Journal, 2002, 35(4): 103-108

[10] The Compilation Committee of Pile Foundation Engineering Manual.Pile foundation engineering manual[M], 1995, Beijing, China Architecture and Building Press

[11] ChowY. K.. Analysis of vertically loaded pile groups[J]. International Journal for Numerical and Analytical Methods in Geomechanics, 1986, 10: 59-72

[12] MylonakisG., GazetasG.. Settlement and additional internal force of grouped piles in layered soil[J]. Geotechnique, 1998, 48(1): 55-72

[13] SongE.-x., ShenW., JinH., et al.. A practical method for the analysis of rigid pile composite foundation raft system [J]. Chinese Journal of Geotechnical Engineering, 2003, 25(3): 268-272

[14] ZhangD.. Settlement analysis and computation for composite foundation of friable material pile [J]. Journal of the China Railway Society, 1998, 20(6): 98-104

[15] GeX.-s., GongX.-n., ZhangX.-ming.. FEM analysis and design of long-short-pile composite foundation[J]. Journal of Building Structures, 2003, 24(4): 91-96

[16] GuX.-lu.Soil and foundation [M], 20033rd Edn.Beijing, China Architecture and Building Press