Soil distrubance associated with mandrel-driven prefabricated vertical drains: field experience

It has been widely known that load-settlement behaviors of cast-in placed bored piles are determined not only by the soil properties alone but also by the construction methods. This paper discusses the performances of (6) instrumented test piles of various diameters (80; 100 and 120 cm) and constructed using different techniques i.e. mud-water, polymer slurry and full-casing under relatively uniform subsurface condition that consisting of very stiff silty clay in West Jakarta. Each test pile was instrumented by vibrating wire strain gauge (VWSGs) and loaded to near ultimate load ( 2.5 times design load) with objective to obtain the loadtransfer characteristics of the test pile. Variation in pile diameters and construction methods that may affect the concrete modulus, load-settlement and load transfer behaviors are observed and discussed.