مهندسی عمران شریف (Sep 2015)
ANALYTICAL INVESTIGATION OF PRESSURE-SETTLEMENT RESPONSE OF FOOTING SUPPORTED BY A GEOCELL REINFORCED BED
Abstract
Geosynthetic materials, such as geotextile, geogride and geocell (as 3D-inclusion reinforcements), have been widely used in geotechnical engineering applications for, e.g., road construction layers, stable embankments over soft soil, longer-lasting road construction layers and expedient access over soft ground. An additional, possible, use would be to improve the bearing capacity of footings. Although analytical solutions on the bearing capacity of planar reinforcements have often been studied, there is a major lack of study into the bearing capacity of footings when supported on geocell-reinforced soil. Thus, according to the widespread use of geocell-reinforced beds, providing an analytical approach to the design of shallow foundations and to explain their stress-settlement behavior could be very useful. Due to the three-dimensional mechanism of a geocell, the cell walls of geocell reinforcement keep the encapsulated soil from being displaced from the applied load by confining the material through the hoop action of a cell, thereby increasing the shear strength of the composite system. This paper presents a new analytical method, based on the theory of pavement layers and the theory of multi-layered soils, for estimating the pressure-settlement response of circular footings resting on a reinforced sand bed with a single layer of geocell. The elastic modulus of the unreinforced layers and geocell reinforced soil layer (geocell and soil inside the geocell pockets) as a composite material, was evaluated by an equivalent composite material, which was developed from triaxial compression tests on unreinforced and geocell-reinforced soil samples. Comparisons of the present analytical results with plate load test results show favorable agreement, and thus, indicate the accuracy and appropriate performance of this method. Also, parametric studies are carried out to investigate the influence of the dimensionless soil stiffness modulus, stiffness geotextile used in constructing the geocell, the height of the geocell layer and diameter plate loading, on the pressure settlement variations of the footing.
