关键词: 颗粒粒径, 剪胀性, 合理网孔尺寸, 剪切速率, 密实度

Abstract: In order to study the effect of the ratio of geogrid aperture size to the average sand particle size on direct shear characteristics of geogrid-coarse soil interface, a series of direct shear tests are performed using a large-scale direct shear device. Four kinds of sand with different particle diameters, and a type of geogrids with square aperture, are tested under the condition of different vertical loads and different shear rates and different soil densities. The vertical loads are 30, 60, 90 kPa, respectively; the shear rates are 0.25, 1, 2, 5 mm/min, respectively; and the soil densities are 22%, 55%, 75%, respectively. The test results show that the peak shear stress and residual shear stress of geogrid-coarse soil interface both increase with the ratio of geogrid aperture size to the average sand particle size increases. When the ratio of geogrid aperture size to the average sand particle size increases from 0.04 to 0.20, the adhesion from peak stress of geogrid-coarse soil interface increases from 13.79 kPa to 64.23 kPa; and the adhesion from residual stress of geogrid-coarse soil interface increases from 16.11 kPa to 51.56 kPa. When soil density is 22%, the soil exhibits contraction throughout the tests. When soil density is 55% and 75%, respectively, the soil tends to be dilatant. Shear rate has little effect on shear behavior of geogrid-coarse soil interface in direct shear tests.

Key words: particle size, shear dilatancy, reasonable mesh size, shear rate, soil density