SOIL GEOTEXTILE INTERACTION - EVALUATION OF MEMBRANE SUPPORT

A general expression for evaluating the increase of bearing,capacity d ue to membrane action based on strict equilibrium conditions is presen ted. In order to provide closed form solutions for design purposes, an average membrane action is also defined. Particular expressions of th e average membrane action are obtained assuming constant - as most mod els do - and variable strain deformation of the membrane. The general expression derived herein provides a valuable framework to compare the most commonly used expressions. This comparison is made in terms of d imensionless parameters. The most commonly used design procedures to q uantify the membrane action provided by the inclusion of geotextiles o n soft soils underlying granular fills are reviewed. Circular and para bolic shapes are used to simulate the geotextile deformation. It is sh own that independently of the model used and geotextile deformation sh ape assumed, comparable values for membrane support for relatively sma ll rutting ratios are obtained. On the contrary, for large rutting rat ios, the choice of membrane support model and geotextile deformation s hape has significant influence on the results, the latter being the mo st influential one.