Analysis And Calculation Of Rigid Pile Composite Foundation Settlement

The rigid pile composite foundation is composed of higher rigid concrete pile or the cement fly-ash grave (CFG) pile. Cushions are set between the piles and the bottom of the foundation, which can adjust the load distribution between the pile and the soil to ensure the combined action of the pile and the soil. Because the rigid pile composite foundation can improve the bearing capacity of foundation and effectively reduce foundation settlement. It has been used in many engineering projects, and show a great economic and social benefit. However, compared with the shallow foundation and the pile foundation, study on the rigid pile composite foundation is inadequate, especially the calculating method of its settlement. Therefore the settlement calculation of the rigid pile composite foundation has become the study hotspot in the foundation engineering with strong academic value and practical significance. This paper study the settlement calculation of the rigid pile composite foundation by using analytical method and numerical method, based on the 25 engineering examples of the rigid pile composite foundation.This paper firstly reviews and summaries the working mechanism of the rigid pile composite foundation and several theoretical calculation methods. Then a comparison and analysis on these calculation methods is made based on 25 practical projects. The comparison of the measured settlement data and theoretical calculating of the settlement data show that there are rather larger deviation between the measured and calculating value. Some suggestions and proposals are proved for the improve of settlement calculation method and a set of experimental parameters is suggested.Finally the numerical simulation is used towards the rigid pile composite foundation with the three-dimensional finite element proceduce of MIDAS-GTS. The influencing of the pile space, the pile modulus and the underlayer soil modules of the rigid pile composite foundation are studied and analysised. It is drawn out that the final settlement of the rigid pile composite foundation decreases with the increasing of pile and underlayer soil modulus, and the decrease of pile space can make the reduce of the final settlement of the rigid pile composite foundation, but the decrement is tend to unchanged when the pile space is less than three times of the pile diameter.