EFFECTS ON THE STRENGTH OF SOFT SOILS SURROUNDING PILES IN DRAIN AND DRY JET MIXING COLUMN METHODS

The drain and dry jet mixing column method is a new method for soft soil improvement.This method was used to treat the soft soil encountered in the Huaiyan highway.The results after the treatment show that this new method is effective.However,the change in properties of surrounding soils was not well understood.In this project,a number of field testing method including CPT and vane shear tests were used to evaluate the strength changes due to the installations of cement-mixed columns.The field test results have shown that the strength of the soft soils surrounding the piles reduced at the initial stage and then increased with the elapsed time.