ANALYTICAL SOLUTION FOR CONSOLIDATION OF STONE COLUMN-REINFORCED FOUNDATIONS TAKING INTO ACCOUNT CONSOLIDA-TION DEFORMATION OF PILE UNDER PROGRESSIVE LOADING

For the sake of improvement of the composite foundations consolidation theory, an analytical solution is obtained for consolidation of stone column-reinforced foundations taking into account the consolidation deformation of pile under progressive loading. Column consolidation and deformation are considered with the following two assumptions:(1)the quantity of water flowing through the disturbed soil zone into the column is not equal to that flowing out from the column and (2)the difference between them is equal to the volume change of the column. In addition, the linear distribution pattern of the horizontal permeability of soil in the disturbed zone is also taken into account for the disturbance effect of columns construction on the surrounding soil. To prove the correctness of the solution, a discussion is performed in the article. If the loading time tends to zero, the obtained solution can be convert to the solution in the condition of constant load. Furthermore, if the loading time and the size of stone columns tend to zero at the same time, the obtained solution can be convert to the one-dimensional solution obtained by Terzaghi. In the end, the average degree of consolidation of a composite foundation is obtained and discussed. The results show that the influence of loading process on the consolidation is obvious. The consolidation rate under the linear distribution pattern of the horizontal permeability of soil in the disturbed zone is faster than the consolidation rate in the condition of constant permeability. The consolidation rate considering deformation of pile is slower than consolidation rate using traditional assumptions. So that it is unsafe to ignore deformation of pile. Furthermore, the differences increase gradually as the loading time, the radius ratio, the stress ratios and the permeability coefficient ratios decrease.