中文摘要：

针对循环剪切作用对Sandwich形加筋土界面剪切特性影响研究不足的状况,采用室内大型直剪仪对Sandwich形加筋土进行了一系列循环直剪试验。试验所用的筋材为土工格栅,砂为福建标准砂,黏土为含水率为28%的重塑黏土,分别在竖向应力为30,60,90kPa,剪切位移幅值为3,6,9mm,剪切速率为1,2,5,10mm·min（-1）,薄砂层厚度分别为4,6,8,10,12,14mm时,研究了剪切速率、薄砂层厚度、循环剪切幅值和竖向应力等因素对Sandwich形加筋土筋土界面循环剪切特性的影响。试验结果表明：在薄砂层厚度由2mm增加到14mm的过程中,界面的峰值剪应力呈现出先增大后减小的现象,峰值剪应力先由54.3kPa增加到67.9kPa,然后又减小到59.4kPa,薄砂层厚度为8mm时筋土界面峰值剪应力达到最大值67.9kPa;当剪切速率为1 mm·min（-1）时,筋土界面主要表现出剪切硬化现象,且在前几个循环周次,峰值剪应力增幅较大,随着循环周次的增加,增幅逐渐减小;当剪切速率大于1 mm·min（-1）时,筋土界面表现出剪切软化现象,且剪切速率越大,软化现象越明显;在剪切幅值从3mm增加到9mm的过程中,循环剪切时筋土界面的剪胀、剪缩交替现象越来越明显,并且剪切幅值越大,界面最终剪缩量也越大;竖向应力为30,60,90,120kPa时,筋土界面对应的峰值剪应力分别为32.6,43.2,60.4,82.9kPa,表明随着竖向应力的增加,筋土界面的峰值剪应力也随之增加。

英文摘要：

Aiming at the paucity of research on the effect of cyclic shear on shear behavior of reinforced soil interface, a series of cyclic direct shear tests of Sandwich reinforced soil were performed by a large-scale direct shear device. The effect of shear rate, thickness of thin sand layer, cyclic shear amplitude and vertical stress on the cyclic shear behavior of Sandwich reinforced soil was investigated by Geogrid, Fujian standard sand and remolded clay with 28% water ratio, when the vertical stresses were 30, 60 and 90 kPa respectively and the shear displacement amplitudes were 3, 6 and 9 mm respectively with shear rates of 1, 2, 5 and 10 mm · min -1 respectively as well as the thickness of thin sand layer being 4, 6 ,8, 10, 12 and 14 mm respectively. The results show that when the thickness of thin sand layer increases from 2 mm to 14 mm, the peak shear stress on soil geogrid interface increases from 54.3 kPa to 67.9 kPa and then decreases to 59.4 kPa. When the thickness of thin sand layer is 8mm, the peak shear stress on soil-geogrid interface reaches a maximum value, namely, 67.9 kPa. When the shear rate is 1 mm · min -1 soil-geogrid interface mainly shows the shear hardening. The increase amplitude of the peak shear stress is large in the first few cycle numbers and gradually decreases with the increase of cycle number. When the shear rate is more than 1 mm · min-1 , the shear softening phenomena begin to appear on soil-geogrid interface and the more obvious the phenomena become, the higher the shear rate is. With shear amplitude increasing from 3 mm to 9 mm, the alternation of shear dilatation and contraction becomes more and more obvious and the final value of shear contraction increases with the increase of shear amplitude. When the vertical stresses are 30, 60, 90 and 120 kPa, the corresponding peak shear stresses on soil-geogrid interface are 32.6, 43.2, 60.4 and 82.9 kPa respectively, which show that the peak shear stress on soil-geogrid interface increases with the increase of vertical stress.