Sandwich形加筋土筋土界面的循环剪切特性

发布时间：2018-05-10 06:00

  本文选题：道路工程 + 加筋土　； 参考：《中国公路学报》2017年05期

【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。
[Abstract]:In view of the insufficient research on the effect of cyclic shear on the interfacial shear characteristics of Sandwich reinforced soil, a series of circular direct shear tests on Sandwich reinforced soil were carried out by using a large direct shear apparatus in the laboratory. The steel bar used in the test is geogrid, the sand is Fujian standard sand, and the clay is remolded clay with moisture content of 28%. The shear rate is studied when the vertical stress is 30 ~ 600 ~ 90kPa, the shear displacement amplitude is 3 ~ 6 ~ 6mm, the shear rate is 1 ~ 2 ~ 2 ~ 10 mm / min ~ (-1), and the thickness of thin sand layer is 4 ~ 6 ~ 8 ~ 10 ~ 1 ~ 12 ~ (14 mm), respectively. The influence of thickness of thin sand layer, cyclic shear amplitude and vertical stress on cyclic shear characteristics of Sandwich reinforced soil interface. The experimental results show that the peak shear stress of the interface increases first and then decreases when the thickness of the thin sand layer increases from 2mm to 14mm. The peak shear stress increases from 54.3kPa to 67.9 KPA and then decreases to 59.4 KPA. When the thickness of the thin sand layer is 8mm, the peak shear stress of the interface reaches the maximum value of 67.9 KPA, and when the shear rate is 1 mm / min ~ (-1), the shear hardening is mainly observed at the interface of the reinforced soil. In the first few cycles, the increase of peak shear stress is larger, and with the increase of cycle, the increase decreases gradually, and when the shear rate is more than 1 mm / min ~ (-1), the shear softening occurs at the interface of the reinforced soil, and the shear rate increases with the increase of the cycle. In the process of increasing shear amplitude from 3mm to 9mm, the shear dilatation and shear-shrinkage alternations of the reinforced soil interface become more and more obvious during cyclic shear, and the larger the shear amplitude, the greater the final shear shrinkage of the interface, and when the vertical stress is 30 ~ 60,90,120kPa, The peak shear stress corresponding to the reinforced soil interface is 32. 6 脳 43.2 / 60.4 / 82.9 KPA, respectively, indicating that the peak shear stress of the interface increases with the increase of vertical stress.
【作者单位】： 上海大学土木工程系;
【基金】：国家自然科学基金项目(51478255,51678352) 上海市自然科学基金项目(14ZR1416100)
【分类号】：U416
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本文编号：1868085