The design and behaviour of cement column in soft Bangkok clay

This thesis involves a general review of deep soil treatment methods, which leads to a detailed review of cement columns as cost effective medium depth foundations. A field study involving, the improvement of soft Bangkok clay by cement jet grouting was undertaken using cement columns in the range of 5m to 15m. The columns were loaded to ultimate to obtain data for verification of the design process. Subsequent to testing the columns were cored to allow correlation between mix design and in situ column behaviour. It was found that the existing design process was inadequate due to high variation between laboratory mix design and installed column strength. The high variation resulted in piles crushing before ultimate bearing capacity could be achieved. A new design process has been developed that will help reduce the likelihood of poor field behaviour. Finally a parametric study using a Finite Element Method was undertaken and the results compared with the data from the field testing. The computer model for the cement columns was then calibrated to allow its use to predict the ultimate load of the cement column without the need for further expensive full scale tests.