Experimental studies on use of bamboo mat as stone column encasement in clayey soils

Abstract

With the rapid urbanization and industrialization; scarcity of useful land is experienced for the infrastructure projects particularly in the urban areas. This has resulted in the use of sites with weak soil deposits such as soft clayey soils. Numerous problems are associated with these soils are high volumetric changes, heave, low bearing capacity, etc. So as to minimize the constructional difficulties associated with the soils; ground improvement techniques are practiced quite frequently on the sites. Stone column provision is one such approach used widely in the fields to enhance the properties of the weak soils. The stone column installation involves partial replacement of 10–35% of weak soils by gravelly materials to form stiffer composite mass.In the present study, an experimental program was undertaken to observe the improvement in strength properties of soft clayey soils collected from Nagpur area, Maharashtra State, India on insertion of stone column. Stone columns were placed single and in group with triangular arrangement. Effects of varying length (L) to diameter (D) ratios (i.e. L / D ratio) of stone columns on the strength properties were analyzed.As an attempt towards sustainable construction; demolition aggregates was used as partial replacement to the natural aggregate while preparing the stone columns. To increase the stiffness of stone column, cement was attempted in small quantity (4% by weight of aggregate) while preparing the specimen. Further, the use of bamboo mat as encasement was planned to study further improvement in load carrying capacity of stone column by increased lateral confinement.The experimental observations depict overall improvement in the load carrying capacity of clay beds on insertion of stone columns. Laboratory testing confirms the possibility of use of demolition waste in stone column construction, as the observed strength (uni-axial compressive strength) is 60–75% of the natural aggregate stone column. Use of bamboo as encasement is effective and shows noticeable improvement in the load carrying capacities (nearly 35–60%) and reduced settlement. Further, study illustrate that the use of single stone column is more effective.