| Squeezed branch pile, called DX pile, is a new kind of variable section piles, which is designed basing on uniform section concrete pile. There are differences on construction technology and mechanical characteristics between DX piles and some other kinds of piles. DX piles consist of several branches or plates and uniform section piles. The soil mass around the pile have an extruding effect. So the bearing capacity of DX piles includes several parts of end resistance and several parts side friction resistance.At the present time, the research on uplift piles is in its infancy and growing phase around the world. There are limited researches on the uplift ultimate bearing capacity of single pile and the failure model of soil round the piles. Experimental formulas just obtain the ultimate bearing capacity by superimposing plate resistance, friction resistance and end resistance simply. However, when DX piles with single plate are pulled and reaches ultimate state, the results of such an analysis shows that when it is a short distance between the plate and the top of pile, the soil mass is lead to punching shear failures and when it is a Song distance between the plate and the top of pile, the soil mass is lead to slip failures. So two kinds of calculating formulas should be obtained for punching shear failures and slipping failures. For addition, When DX piles with several plates are pulled and reach ultimate state, not all the plates reach the ultimate bearing capacity. When it is a short distance between different plates, all the plates reach the ultimate bearing capacity at the same time and when it is a long distance between different plates, the plates reach the ultimate bearing capacity relying on the positions of the plates from the bottom to the top. Therefore the coefficience η, which need further research, should be introduced to consider the interaction of plates and the end resistance. Some impact factors to the bearing capacity should be considered, such as numbers of plates, pile technology, size effect, plate spacing and so on.This project study the uplift ultimate bearing capacity of single pile and the failure model of soil round the pile, which covers the shortage of the research. Consequently the paper analyzes the failure model by numerical simulation and experimental results. |
