Dissertation > Transportation > Road transport > Road works > Roadbed, pavement engineering > Subgrade

Study of Settlement Computation Method of Composite Foundation under Embankment

Author LiHaiFang
Tutor GongXiaoNan
School Zhejiang University
Course Geotechnical Engineering
Keywords Embankment load Settlement of Composite Foundation Pile interaction Pile friction The amount of compression reinforcement area Typical segment method Dimensional finite element analysis Low strength piles composite foundation Pile-soil stress ratio Stratified settlement Lateral displacement Pore ??water pressure
CLC U416.1
Type PhD thesis
Year 2004
Downloads 1419
Quotes 55
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Composite foundation in engineering continued to develop its settlement calculation method is not yet ripe. The most recent research is rigid base composite ground under test and calculation results, only a small amount of embankment and flexible load composite ground under study. High-grade highway construction in soft ground, deck and bridge segment subsidence caused by the poor \Embankment reinforced composite foundation is different from the cushion composite foundation under rigid foundation, embankment piercing pile up enough space, the embankment load close to the flexible load, pile-soil stress ratio will be different. There is no flexible load field test method, to strengthen on-site testing and computational analysis is a way to explore the embankment under the composite foundation traits. In this paper, assuming the displacement mode, consider the pile-soil interaction, obtained by mechanical derivation of composite foundation under embankment load side friction, the analytical expression of the amount of soil compression reinforcement of pile and pile-soil stress ratio. According to the analytical solution of the pile friction, a simplified algorithm for the amount of compression reinforcement area; typical segment method factors affecting the three-dimensional finite element analysis of composite foundation settlement to avoid the plane strain analysis method of composite foundation pile in the unreasonable rates, so that the calculation model is more reasonable mechanical concepts. Based on finite element analysis, based on the natural foundation settlement calculation of composite foundation settlement calculation method and the corresponding chart. During the calculation of composite foundation settlement, usually natural foundation under embankment load corresponding reinforcement area and the amount of compression of the underlying layer. Then, determine the seven correction factor, recommended method to calculate the amount of compression of the corresponding region of the composite foundation and the total settlement. Field experimental study on the low strength piles composite foundation at Bridge section of soft soil foundation, on-site observations were analyzed, including the load plate and the embankment under the top of the pile and pile soil earth pressure and settlement, layered settlement side to the analysis of the observations of the displacement and pore water pressure. The field prototype observation showed that the soil between piles settlement settlement amount is greater than the top of the pile, fill in the arch effect, to fill load Q transfer of soil to the top of the pile, the pile-soil stress ratio gradually increased gradually from the pile. Filling load of pile-soil stress ratio change process is different from the process of change in the rigid loading plate, its value is far less than the soil stress ratio under the rigid loading plate. As a result of low strength concrete pile composite foundation, subgrade settlement is greatly reduced. The field measurement results show that the composite foundation settlement is about 1/3 of the natural ground subsidence. More importantly, with a variable length of pile coordination Bridge station and the road uneven settlement success, the road the Tiding surface settlement is basically uniform. Stratified settlement observations and surface measurements are consistent. Stratified settlement observation results also showed that the composite foundation compression deformation occurs within a certain range of the bottom and the top of the underlying layer of reinforcement area.

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