The action of geotextiles in providing combined drainage and reinforcement to cohesive soil

Abstract

This thesis describes a study into the action of geotextiles in providing combined drainage and reinforcement to cohesive soil and the identification of the interaction of different geotextiles with a cohesive soil. The study involved both experimental and analytical investigations. Fine grained cohesive soil is a complex material. The introduction of geosynthetics providing both drainage and a reinforcement function produce a marked increase in the shear strength characteristics of the clay material. A number of consolidated undrained and consolidated drained triaxial compression tests and Rowe cell consolidation tests were conducted. The objective of the tests was to identify the separate effects (improvement) on the shear strength properties of the cohesive soil (kaolin) provided by the drainage function and separately that provided by the reinforcing function of a number of geotextiles. An Electron Scanning Microscope study was used to investigate the interaction between the cohesive soil and the geosynthetic materials. The study provided qualitative information concerning the relative improvement of the physical properties of a fine grained cohesive soil when used in construction with range of geosynthetic materials. Analysis of the results of the research suggest that geotextile products could offer significant technical, practical and economic advantages when constructed with poor quality soils. The combined function of drainage and reinforcement which could be developed by some geosynthetic materials could be substantial. Combining the functions of drainage and reinforcement in a single material requires the resulting geosynthetic to have special properties. The form of a geocomposite drainage and reinforcement material with these properties is proposed