Study On The Properties Of Rigid-flexible And Long-short-Piles-Net Composite Foundation With Flexible Load

Pile-net composite foundation, which are with the characteristics of horizontal and vertical reinforcement, While piles, net and soil coordinate with each other, shows significant effect on settlement controls and stability improvements. Thus, it domains more and more fields in the engineering practice.In addition, rigid-flexible and long-short piles composite foundation is generally composed by rigid-long pile and flexible-short pile. The rigid-long piles are mainly used for controlling the settlement of composite foundation, while the flexible-short piles improving the stability and enhancing the capacity, correspondingly, the construction period is shortened and the cost is reduced.Based on the advantages of piles-net composite foundation and Rigid-flexible and long-short piles composite foundation, rigid-flexible and long-short piles-net composite foundation is composed by adding horizontal reinforcement in the cushions of rigid-flexible and long-short piles composite foundation. It's thought that this kind of foundation could further improve stability and capacity of composite foundation and reduce the differential settlement between piles and soil based on the engineering practice. Mechanism of this composite foundation is more complex because combined action of rigid-flexible and long-short piles, soil among piles and net is involved. As study on the characteristics of this composite foundation is almost a blank at present, it's of great academic and engineering significance to explore its characteristics.Characteristics of rigid-flexible and long-short piles-net composite foundation was studied by laboratory model test in this thesis, effect on the law of load-settlement, pile-soil stress ratio, variation of bending moment by some factors including replacement ratio, cushion thickness and grating layers was analyzed, and deformation of flexible pile was recorded, A comparison between this kind of composite foundation and rigid pile-net composite foundation was made. Some reference was got for engineering design and further research. At last, with model test results and numerical analysis, a treatment plan of an engineering project with rigid-flexible and long-short piles composite foundation was compared to that with rigid-flexible and long-short piles-net composite foundation, and the latter was found to have more advantages from the results.