Abstract
A quantitative evaluation of confining or restraint effects which are recognized as one of the fundamental mechanism of earth reinforcement is made in this paper. Firstly a confining stress increment caused by friction between soil and geosynthetic reinforcement material is analyzed phenomenologically. Secondly a uniaxial compression test is carried out for a sand specimen (air-dry Toyoura sand) confined by a geotextile cylinder. A radial normal stress component in the specimen induced by the application of axial compression load is calculated and a hoop tensile stress of geotextile is measured using a pi-meter.
Confining effects equivalent to the frictional effects between soil and geotextile are estimated based on the equilibrium of force. A fair coincidence was obtained between the analytical result and the measured one. In addition the increase in the safety factor was demonstrated based on the reinforcement by confining effects.
