颗粒形状对粗粒土-格栅界面剪切特性的影响

Effects of particle shape on shear behaviors of interface between coarse-grained soil and geogrid

为研究颗粒形状对粗粒土格栅界面剪切行为的影响,选择碎石和具有相同粒径分布的玻璃珠作为试验材料,利用动态直剪仪对碎石格栅和玻璃珠格栅界面进行一系列单调直剪试验、循环剪切试验和循环后单调直剪试验,分析竖向应力分别为30、60、90 kPa下加筋碎石和加筋玻璃珠界面的单调直剪特性;研究在位移幅值分别为1、3、6、9、12、15 mm的循环加载作用下两种加筋界面的循环剪切特性,并对比分析了循环剪切前、后两种加筋界面单调剪切特性的异同点。结果表明:单调直剪试验中,3种竖向应力下碎石格栅界面的抗剪强度和最大剪胀量均大于玻璃珠格栅界面的相应值。循环剪切试验中,在不同剪切幅值的循环加载作用下,碎石格栅和玻璃珠格栅界面的循环剪切行为存在差异。循环后单调直剪试验中,碎石格栅界面循环后的界面抗剪强度较未经受循环加载的界面有所提高,幅值为15 mm的界面除外;所有幅值下玻璃珠格栅界面循环后的抗剪强度均发生退化。

In order to study the effect of particle shape on shear behaviors of interface between coarse-grained soil and geogrid,the gravel and glass beads with the same particle size distribution were selected as test materials.A series of monotonic direct shear tests,cyclic shear tests and post-cyclic direct shear tests were carried out on the gravel-geogrid interface and glass bead-geogrid interface using a dynamic direct shear apparatus.The monotonic direct shear characteristics of the interface between reinforced gravel and reinforced glass beads under normal stresses of 30,60,90 kPa were analyzed.Then,the cyclic shear characteristics of two reinforced interfaces under cyclic loading with displacement amplitudes of 1,3,6,9,12,15 mm were studied.The similarities and differences of monotonic shear characteristics of the two reinforced interfaces before and after cyclic shear were compared and analyzed.The results show that in the monotonic shear tests,the shear strength and maximum dilation of gravel-geogrid interface under the three types of normal stresses are greater than the corresponding values of glass beads-geogrid interface.In the cyclic shear tests,the cyclic shear behaviors of gravel-geogrid and glass beads-geogrid interfaces under the cyclic loading with different shear amplitudes are not exactly the same.In the post-cyclic direct shear tests after cycling,the interface shear strength of gravel-geogrid interface after cycling is greater than that of the interface without cyclic loading,except for the interface with amplitude of 15 mm,while the corresponding value of glass beads-geogrid interface at all amplitudes is degraded.