Engineering properties of old alluvium for Changi extension line project in Singapore

Abstract

Old Alluvium is one of the main geological formations in Singapore. Three types of soils strata: Fill, Kallang Formation and Old Alluvium were encountered along the Changi Extension Line (CEL) project in Singapore. The Old Alluvium Formation comprises a sequence of very weak to weak quartzo-feldspathic sandstones with conglometric and mudstone horizons in which the upper parts have been weathered to form a silty clay and geavelly sand. A site investigation programme was carried to characterize the geotechnical properties of the three types of soil strata, in particular the Old Alluvium. The laboratory and in-situ test results are presented in this project. The in-situ tests include the Standard Penetration Tests (SPT), Field Vane Shear Tests (FVT), Piezocone Penetration Tests (CPTU), Pressuremeter Tests (PMT) and Cone Pressuremeter (CPM) tests. The index properties, soil classification, compressibility, consolidation parameter and shear strength parameters for each type of strata are analyzed and presented in this report. Correlations between laboratory and in-situ data were made. The suitability of the some of existing interpretation methods and correlation relationships are examined.