为了研究纤维加筋花岗岩残积土的循环剪切特性,将聚丙烯纤维掺入到残积土中,通过动单剪仪对纤维加筋的残积土进行水平循环单剪试验,分析了不同纤维掺量(0、0.3%、0.6%、0.9%)、循环应力比(0.15、0.20、0.25、0.30)对花岗岩残积土动力特性的影响。试验结果表明:随着循环应力比增大,动剪应变越大,纤维的加入有效抑制了残积土的动剪应变的发展,且纤维掺量越高,动剪应变越小；纤维提高了残积土的临界循环应力比,在临界循环应力比下,加筋的试样破坏时的循环次数远大于未加筋试样,这表明纤维的加入增加了土体的韧性,大大延缓了土样达到破坏的时间；动剪切模量和阻尼比均随水平循环次数的增加先减小后保持稳定不变,在同一循环应力比下,纤维掺量越大,动剪切模量和阻尼比越大；对于动剪切模量而言,循环应力比越小,纤维加筋的优势越明显。对H-D模型进行了改进,改进后的模型可用来分析不同循环应力比、不同纤维掺量下花岗岩残积土的动力响应。

In order to study the cyclic shear characteristics of fiber reinforced granite residual soil, polypropylene fiber was incorporated into the residual soil. The horizontal cyclic simple shear test of fiber reinforced residual soil was carried out by dynamic simple shear apparatus. The effects of different fiber content ( 0,0.3%, 0.6%, 0.9% ) and cyclic stress ratio ( 0.15,0.20,0.25,0.30 ) on the dynamic characteristics of granite residual soil were analyzed. The test results show that with the increase of cyclic stress ratio, the dynamic shear strain increases. The addition of fiber effectively inhibits the development of dynamic shear strain of residual soil, and the higher the fiber content, the smaller the dynamic shear strain. The fiber increases the critical cyclic stress ratio of the residual soil. Under the critical cyclic stress ratio, the number of cycles when the reinforced sample is destroyed is much larger than that of the unreinforced sample, which indicates that the addition of the fiber increases the toughness of the soil and greatly delays the failure time of the soil sample. The dynamic shear modulus and damping ratio decrease first and then remain stable with the increase of the number of horizontal cycles. Under the same cyclic stress ratio, the larger the fiber content, the greater the dynamic shear modulus and damping ratio. For the dynamic shear modulus, the smaller the cyclic stress ratio, the more obvious the advantage of fiber reinforcement. The improved H-D model can be used to analyze the dynamic response of granite residual soil under different cyclic stress ratios and different fiber contents.

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