Use of dilatometer and dual dilatometer test for soft soils and peats

摘要

Measurement the properties of soft soils and peats in laboratory is very difficult task due to the difficulties in sampling and problems of disturbance. For these types of soils, in situ testing is preferable. This research uses the Marchetti dilatometer and dual dilatometer which was developed at UNPAR (Parahyangan Catholic University). Use of vane shear test is also common for soft soils, however not for peats, specially fibrous peats. Although the dilatometer is not a common tool in Indonesia, this device has been widely used in the world. The study area is located in Pelintung, Sumatera. In situ testing as well as laboratory tests were conducted and several correlations were established. The test result are promising especially new correlation are developed such as material index and the ratio of laboratory modulus and dilatometer modulus. The thrust of the blade during insertion is also measured and it is of interest that a correlation exists between the cone tip resistance and dilatometer thrust. The Dual Dilatometer Test which was developed at UNPAR (UNPAR DDMT) has 2 membranes where the second one is mounted in the upper part of the blade with twice thickness than the standard one. The results of dilatometer index of both membranes were compared and it was concluded that for test on peats, a thicker blade gives a more reasonable result than the standard blade. This is probably due to the fact that the thicker blade displace the soil in larger strain and hence the measurement is more sensitive. In general, the use of UNPAR DDMT enhance the more suitable technology for peats.