Study On Punching Character Of Corner Column And Border Column On Raft Foundation

This paper deals with the punching failure of corner column and border column of high-rise building under vertical concentrated column load through large-scale model experiment in the laboratory. On the basis of crude soil, two identical raft foundations are experimented under the way of different adding-load, so the different punching failure cones of the vicinity area of corner column, border column can be received under vertical concentrated column load, and the rule of deformation and foundation soil pressure distribution also can be received. At the same time the paper compares the measure value and CRITERION calculation value of punching failure of raft foundation and receives some significative conclusion:1. Bending crack first appears on the surface of raft foundation under upper vertical concentrated column load, the crack diffuses outwards within different radiuses from the different columns.2. The punching failure cone of comer column is approximately 1/4 round estrade, that of border column is approximately 1/2 round estrade and that of center column is completely one round estrade. The punching failure angle of the same restriction raft section among corner column, border column and center column is between 53° and 60°, and that of outboard raft of corner column and border column is between 30° and 40°.3. After bending crack appears, the foundation soil pressure presents linear distribution in the area the distance on the diagonal axis is about 2h₀, on the side axis is about 2.5h₀, on the middle axis is about 2h₀, and within a radius of 2.5h₀ from the center column side.4. The relative displacement (discrepant settlement) is the need condition of raft foundation punching failure, so augmenting rigidity of foundation and upper structure can not only minish the relative flexibility value but also improve carrying capacity of the punching failure; And the punching failure load of raft and column's node of continuous foundation is greater than that of calculated according to CRITERION.