Geotechnical behaviour of soft soil in East Java, Indonesia

Abstract

Currently, the construction of road infrastructure in all regions of Indonesia is highly encouraged, including free roads that connect between provinces. In some parts of the area in East Java, the free roads pass through regions with soft clay so that special treatment is needed. A geological and geotechnical analysis of the nature of the soft soil needs to be conducted to determine the methodology of reducing the compressibility of the soft soil. Based on geological analysis, soft soil is a sedimentation product of the Pliocene - Holocene era. This soil is generally fine-grained, with a high natural water content, and a large amount of organic matter. Several laboratory experiments determined that the soft soil was classified as high plasticity silt with SPT value less than 10 and reached down to a depth of 15.5 m. The value of the undrained cohesion of the soil is around 24.7 kN/m2 dependent on the conditions of water content. Estimation of primary consolidation settlement is 2.24m in 18 years. In the soaked-un-soaked CBR experiment, the water content of 37.7% is the residual water content, which is the lowest CBR.