ONE DIMENSIONAL ANALYTICAL SOLUTION FOR CONSOLIDATION OF A COMPOSITE GROUND WITH T-SHAPED DEEP CEMENT MIXING COLUMNS

T-shaped deep cement mixing (DCM) column is a new type of DCM column with an enlarged column cap. Based on the equal vertical strain assumption, the equations governing consolidation of the surrounding soil around a fully penetrated T-shaped DCM column was derived under instantaneous load. The corresponding analytical solutions were developed by using the one dimensional consolidation theory of a double-layer ground. Then, the accuracy of the proposed analytical solution was evaluated through the comparison of the consolidation rates of the composite ground from the proposed analytical solution with the FEA. Finally, the main influence factors were analyzed to investigate the consolidation behavior of the composite ground. The results showed that the consolidation rate of the composite ground increased with an increase in the constrained modulus of T-shaped DCM column, the area replacement ratio of the DCM column with small diameter under the enlarged cap and the constrained modulus of the subsoil around it. It decreased slightly with the increase of the diameter of the column cap. The length of the column cap had little influence on the consolidation rate when it was less than half of the length of a T-shaped DCM column. However, it increased rapidly with the increase of the column cap length when the column cap length is larger than half of that of a T-shaped DCM column.