In this paper, field behaviors of two trial embankments in Australia are presented. The first case study has a trial embankment which is approximately 90m in length and 40m in width, and has two sections with vertical drain installed, and a no drains section. The second case study gives detail of a trial embankment with stone column, and incorporated 3 separate sections (2 sections with stone columns, and a section without stone column), and is constructed on soft estuarine clay with high sensitivity. The trial embankments were constructed to evaluate the effectiveness of ground improvement techniques on the soft clays in this region. This paper interprets the findings obtained from the field observations during the construction phase.
Soft clays are found in many projects in Australia, and they pose difficult problems in the design and construction of roads, expressways and motorways. By definition, soft clays are of low shear strength and high compressibility. Generally, they are sensitive and their strength is readily reduced by disturbance during sampling and testing. Such subsoil conditions can have considerable implications on the design of embankments and structural foundations. This is due to both low shear strength and a tendency to deform with time. The simplest solution to such unfavorable soil conditions is to find an alternate alignment, although this can be costly and impractical. As an economic alternative to structural foundations, ground improvement techniques are becoming more prevalent. Ground improvement in Australia primarily encompasses the use of stone columns, surcharge with vertical drains, and chemical stabilization. This paper presents the soil characteristics of a trial site located in Gold Coast (Southeast corner of Queensland). Included in this paper are the in-situ conditions before the embankment was constructed and the subsequent conditions after the embankment was built. The vertical settlement, horizontal settlement profile, and lateral displacement plots, determined from the in-situ field equipment, are provided.
