Soil Stabilization Techniques for Roads on Expansive Soils and Loose Sand

Abstract

There are various techniques to stabilize soil which changes in volume due to vibration. Structural foundation in regions with expansive soil or loosely filled soil have to be laid after stabilizing such soils or by adopting the depth of foundation below the zone of movement. The tunneling induced vibration or alternative swelling and shrinking of soil due to seasonal change or change in ground water table level, causes movement of soil. This movement of soil result in additional stresses on the foundation, if the foundation depth is within this zone of movement. Normally, this zone of movement will be 1.5 to 2m below ground level. In some cases, this zone of movement may extend up to 5 to 6m. In this paper we have reviewed the various methods of stabilizing the expansive soil and loosely filled soil, especially the soil subgrade below the roads. Moreover, tunneling induced vibration due to underground metro rail construction also affects the soil behavior which in turn affects roads and nearby structures. Hence we have studied the effect of vibration on sandy soil by conducting laboratory experiments in the vibration table . The experimental result showed that the sandy soil settled more due to vibration when compared to the soil stabilized with gravel column. Addition of geomaterials such as gravel/stone in the form of column reduced the settlement level of loosely packed sand. Hence installing stone columns in soil is a better method to reduce settlement due to vibration that are produced during tunneling operations. Stone columns also prevents pore water pressure that builds up during earthquake vibration.