PREDICTION OF VERTICAL-BAND-DRAIN PERFORMANCE BY THE FINITE-ELEMENT METHOD

This paper presents the predictions of the performances of vertical-band drains (i.e. Alidrains) on soft Bangkok clay underfull-scale embankment loading in the field and during large-scale consolidation with a drain by using a reconstituted sample in the laboratory. A finite-element model of transient- and axisymmetric-flow problems considering equal strain was used. The numerical model also included the smear effects. The predicted data were compared with the laboratory- and field-test results. Laboratory consolidation tests using a Rowe cell and an oedometer apparatus were performed to obtain the compressibility parameters. By using a value of k(h)/k(s) of 10 together with d(s) = 2d(m), the predicted results agreed with the field performance of the vertical drains. In the laboratory, by using a reconstituted clay specimen, better predictions were obtained with k(h)/k(s) = 2 and d(s) = 2d(m). Thus the prediction by means of an equal-strain finite-element model was found to be satisfactory for the performance of vertical-band drains on soft Bangkok clay provided that the disturbance due to its installation was taken into account.