Investigation of performance with model experiments for polyester based composite piles

Pile foundation systems are used in cases where criteria such as bearing capacity, settling, stability and liquefaction are not met with surface foundation systems. Piled foundations are difficult to manufacture and have high application costs. Today; In order to improve the behavior characteristics and performance of the pile foundations in the structure-foundation-soil interaction and to minimize the costs, studies are being carried out on composite pile manufacturing by bringing together different chemical materials. In this study; L16 design table was used for the preparation of the samples and the results were evaluated by SN and variance analysis according to Taguchi optimization method. Polyester has used as 10%, 20%, 30%, 50% of dry sand weight. Different binder admixtures (cement, fly ash and silica fume) used as 0%, 5%,10%, 20% of dry sand weight. For all mixture desings water has used in ratio of 0%, 3%, 6%, 9%. Sixteen model pile has been produced according to explained ratios. As a result of the study; The effects of the parameters on the splitting tensile strength and unconfined compressive strength were determined. It was determined that the most effective parameter was 75% polyester on unconfined compressive strength and the second most effective parameter was water content with ratio of 10%. It was determined that the unconfined compressive strength would be maximum in 50% polyester, 5% cement, 0% fly ash and 20% silica fume ratios. As a result of the study, full section pile and hollow section polyester based composite piles with 7 cm diameter and 40 cm height were produced by using optimum mixing ratios. Pile loading tests were performed by placing these model piles in test tanks filled with dense sand. In the model experiments, it was observed that it performed close to the concrete pile behavior. In particular, its ability to absorb energy and to exhibit elastic behavior compared to concrete indicates that such polyester-based piles can be used in cases exposed to horizontal and seismic load effects. Key Words: Composite pile, Pile foundation, Pile loading test, Polyester, Taguchi method, Single pile