Soil Improvement with Quicklime and Filter Fabric

The multiple strip-sandwich method is a specially devised method using quicklime and filter fabric for embankments with difficult cohesive soils. A quicklime layer of 5 cm (2 in.) thick, sandwiched between two sheets of filter fabric of 30 cm (12 in.) wide, is placed in a triangular configuration with a horizontal pitch of about 2 m (6.6 ft) at each stage of piling the cohesive soil. Owing to combined actions resulted from the hydration of quicklime, particularly the absorption of water, the cohesive soil is effectively dewatered resulting in consolidation in success, to be able to achieve a high embankment efficiently due to an adequate increase in the shear strength of the cohesive soil by a certain depth both on and beneath the respective sandwich layers. This paper describes a case history for the construction of a high embankment, 32 m (105 ft) high, using the method with cohesive soil of a strongly weathered tuff. The work was successful and the multiple strip-sandwich method proved to be useful for constructing high embankments with difficult cohesive soils.