Horizontal coefficient of consolidation of soft Bangkok clay

This paper presents the results of the coefficient of consolidation in the horizontal direction determined from the laboratory and the field through testing, along with back analysis from settlement measurement of embankment constructed with prefabricated vertical drains at the Suvarnabhumi Airport site in Bangkok. Constant rate of strain consolidation tests with radial drainage and standard oedometer tests were conducted to provide the consolidation characteristics of soft Bangkok clay. A 20-mm piezoprobe was used to measure the pore water pressure dissipation characteristics of the soft clay in the field, and the corresponding horizontal coefficients of consolidation were estimated based on established theory. The test results, such as the horizontal coefficients of consolidation and permeability, were compared with back analysis of the constructed runway embankment based on Asaoka method. The results show very good agreement in both horizontal coefficients of consolidation and permeability obtained from different testing methods and back analysis, implying the reliability of the testing methods adopted.