Experimental Studies And Numerical Simulations Of The Effects Of Bottom Sediment On The Vertical Bearing Behaviour Of Bored Piles

Bored piles have many disadvantages, such as small settlement distortion, high bearing capacity and stable behavior, which are wildly applied in the modern foundation structure form. Affected by many factor, including construction technology, the level of team technical, the soil condition and so on, many defects are easy appeared, in which the bottom sediment is a common one.Presently the academic researches for bottom sediment pile mainly focus on causes, detection and the finite element analysis, what are incomprehensive and inaccurate understandings on the bearing behavior of bottom sediment pile, and not enough for engineering to choose treatment measures. In addition, it is highly blank on the research of model pile test and bottom sediment's simulation.This article studied the effects of bottom sediment on the vertical bearing behavior of bored piles by experimental studies and numerical simulations.In the experimental studies, a set of methods about make piles, loading, test and bottom sediment's simulation were put forward. Through some preparation work, such as designing and purchasing experimental equipment, perfecting laboratory'conditions, the model experiment of normal and defective piles in uniform sand were test to study the normal piles'bearing behavior and the bottom sediment'influence on the bearing behavior. The results of the study showed the bottom sediment would lower the model piles'ultimate bearing capacity, increase the model piles'settlement, and this influence would be more obvious with the increase of bottom sediment's thickness.In numerical simulations, the finite element analysis software PLAXIS were used to analyze the influence on the bearing behavior because of the variation of the bottom sediment's thickness and elastic modulus. The study of the curves, such as the load which the piles'settlement, the ultimate bearing capacity with the bottom sediment's parameters, the piles'settlement with the bottom sediment's parameters, the pile side friction with the depth, the pile side friction with the bottom sediment's parameters, showed that the sediment would lower the bored piles'ultimate bearing capacity, increase the bored piles'settlement, influence the pile side friction's play, and this influence was on a kind of rule with the change of the sediment's parameters.In this article, some preliminary conclusions of the effects of bottom sediment on the vertical bearing behavior of bored piles were given by experimental studies and numerical simulations, which accumulated a certain amount of research experience for further study and would have certain reference for engineering in dealing with bottom sediment defective piles.