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Geobelt, made of polymeric materials, is one of the reinforcement materials. In the present study, a large site loading test program was performed on a square footing supported by the geobelt-reinforced crushed stone layer on the soft soil. The reinforced soil layer is thin, in which the ratio of the reinforced soil layer depth and the footing width is only 0.2. The various parameters studied in this testing program include the number of geobelt layers, the depth of first geobelt layer beneath the footing, the vertical spacing between two geobelt layers, and the linear density of reinforcement. The results show that the performance of the geobelt-reinforced crushed stone cushion was obviously improved compared with unreinforced crushed stone cushion. For one layer of geobelt reinforcement, the effect of the geobelt reinforcement is mainly controlled by the depth of first geobelt layer beneath the footing and linear density of reinforcement. With a shallow depth of the geobelt layer of reinforcement, it works efficiently at a small settlement of the footing. The beneficial effect of a double layer of geobelt is greater than that of a single layer, especially when the settlements are concerned.

Geogrids, made of polymeric materials, have been used as a construction material for many applications, such as walls, slopes, roads, building foundations, etc. In the past, geogrids were manufactured with apertures in a rectangular or square shape. Recently, geogrids with a triangular aperture shape have been introduced into the market. The new geogrids are manufactured with ribs oriented in three equilateral directions and expected to have a more stable grid structure, which can provide more uniform resistance in all directions. In this study, the numerical software – FLAC was adopted to investigate the responses of geogrids with rectangular and triangular apertures when subjected to a uniaxial tensile load at different directions relative to the orientations of ribs in air. The geogrid ribs were modeled using beam elements jointed rigidly at nodes (i.e., the angle between two adjacent ribs did not change) and subjected to tension in one direction. The numerical results showed that the stress–strain responses of the geogrids were different at different loading directions relative to the orientations of ribs. The effects of aperture shape of geogrid, and elastic modulus and cross-section area of geogrid ribs on the tensile stiffness of the geogrid were also evaluated. The geogrid with triangular apertures had more uniform tensile stiffness and strength distributions than the geogrid with rectangular apertures. An increase of the elastic modulus and cross-section area of the geogrid ribs could increase the stiffness of the geogrid with triangular apertures. The numerical results were verified by experimental data for geogrids with rectangular and triangular apertures.