Gravel Pile Composite Foundation, Theoretical Analysis And Experimental Research

In recent years, the foundation treatment technology unceasingly was popularizing, enhancing and developing. Each kind of composite foundation had application in the more and more construction projects, and the composite foundation's type got more and more. Gravel pile-composite foundation is one kind of new foundation treatment technology which had widespread developed in application to highway foundation treatment.On the basis of the predecessor studies, taking the accounted for the some characteristics of the grave pile, a further study is conducted on the lateral deformability of gravel pile under the longitudinal load. The thesis analyzed the interaction rules between pile and soil surrounding piles, and derived new formula which compute the pile-soil stress ratio and modifying the bearing capacity of the gravel piles.The thesis analyzes the bearing capacity of the gravel piles which had different displacement rate and was filled in different graded aggregate macadam, when in the pile fills the different graded aggregate macadam, the bearing capacity characteristics of one pile is no visible improvement. The area displacement rate is the most main factor, which influence the bearing capacity of the gravel piles.The thesis analyzed the data of the static load test. The thesis drew a comparison among the observation of "the surrounding soil", "gravel pile" and "gravel pile-composite foundation". The author discovered that standard value of the bearing capacity is higher than the bearing capacity of the surrounding soil, and lower than the bearing capacity of gravel pile, when the bearing capacity of the composite foundation achieves allowed value. So, the thesis modified the current formula of the bearing capacity of the composite foundation, and proposed the reasonable determination method of modification factor.The thesis analyzed the load transfer rules and destruction mechanism of the gravel piles. The author proposed reducing pile length, raising replacement rate, changing uniform-section pile into variable -section pile, in order to raise the bearing capacity of foundation, reduce the volume of work and save the cost. The thesis studied the construction technology and machinery of the variable cross-section pile.