Abstract:

The soil-cement deep mixing column with different cross-sections is a kind of newly soft soil foundation treatment methods. Since special modifications have been made towards those drawbacks which exist in traditional deep mixing columns, the the soil-cement deep mixing column with different cross-sections exhibits good foundation treatment effect and thus has been gradually popularized in China recently. Based on in-situ static load tests in subsoil of Huzhou, the bearing capacity and load transfer mechanism of long soil-cement deep mixing columns with different cross-sections are studied. The result shows that load transfer is limited to a certain range due to soil-cement strength of column body. Stress concentration appears at the position of cross-section variation. Axial force decreases with depth. The maximum lateral friction resistance occurs at the top of column. The lateral friction resistance below varied cross-section decreases sharply due to the end resistance effect of the varied cross-section. But the lateral friction resistance of the lower part of the column is improved. The base resistance below varied cross-section increases with total load. Compared with the value of lateral friction, base resistance is less. So this column is a type of friction column with base resistance below varied cross-section. Based on three failure models of single column, the ultimate bearing capacity calculation of long soil-cement deep mixing columns with different cross-sections parts is proposed.

Key words: different cross-sections, deep soft soil, soil-cement deep mixing column, bearing capacity, load transfer rule