不同剪切速率和孔径下立体格栅筋土界面剪切特性

Direct Shear Behavior of Three-dimensional Geogrids-soil Interface with Different Square Apertures under Various Shear Rates

为研究横肋加厚的三维立体土工格栅孔径对筋土界面直剪特性的影响,利用3D打印技术制作出不同规格的三维立体土工格栅,将格栅孔径(25 mm×25 mm、35 mm×35 mm、45 mm×45 mm)、竖向应力(30 kPa、60 kPa、90 kPa)、剪切速率(0.5 mm/min、1 mm/min、2 mm/min)作为试验参数,通过室内大型直剪仪进行单调直剪试验,对以上三种因素影响下的筋土界面剪切特性进行研究。结果表明:3种孔径格栅中,35 mm×35 mm孔径格栅的筋土界面峰值剪应力、内摩擦角最大;随着剪切速率倍增,峰值剪应力变化幅度较小,3种不同剪切速率对应的峰值剪应力之间的相对变化率处于-4%~11%;竖向应力越大,峰值剪应力越大,筋土界面峰值剪应力相对变化率大于20%,表明竖向应力对筋土界面剪切特性影响明显。

For reaching the influence of the aperture of the three-dimensional geogrids with enhanced transverse ribs on the interface behavior,three geogrids with different square apertures were made by 3D printing technology.Effect of the square apertures(25 mm×25 mm,35 mm×35 mm,45 mm×45 mm),vertical stresses(20,40,60 kPa),shear rates(0.5,1,2 mm/min)were investigated by large scale direct shear test.The results show that the peak shear stress and friction angle of the interface between the geogrid with aperture of size 35 mm×35 mm and soil are greater than others;as the shear rate increases doubly,the peak shear stress changes less,and the rate of peak shear stress change at different shear rates is between−4%and 11%;the greater the vertical stress,the greater the peak shear stress,and the rate of peak shear stress change is greater than 20%,indicating that the vertical stress has obvious effect on the shear character of the interface of reinforced soil.