聚丙烯纤维加筋二灰土动强度试验研究
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摘要
为研究纤维掺量对加筋二灰土动强度特性影响,将长度为12 mm的聚丙烯纤维按照0. 12%、0. 24%和0. 36%的质量比掺入二灰土中。利用GDS三轴试验系统进行不同围压和动应力幅值条件下纤维加筋二灰土的动三轴试验。试验结果表明:随着聚丙烯纤维掺量的增加,二灰土动黏聚力先增大后减小,当纤维掺量达到0. 32%时,动黏聚力出现峰值,此时为最佳纤维掺量;而纤维加筋二灰土动内摩擦角与纤维掺量呈现正相关的关系。此外,纤维在土中形成三维网络框架,使土体嵌锁愈加紧密,并通过拉筋作用,减缓或阻止裂纹扩展,最终使土体破坏形式由具有明显贯通裂隙的脆性破坏逐渐转变为侧向鼓胀变形破坏。
In order to investigate the effect of different fiber content on the dynamic strength of the reinforced lime-fly ash soil (LFS),polypropylene fiber with length of 12 mm was added into the LFS in different weight proportions of 0. 12%,0. 24% and 0. 36%,respectively. The GDS Triaxial Testing System (GDSTTS) was employed to perform dynamic triaxial tests on fiber-reinforced LFS under different confining pressures and stress amplitudes. The experiment results show that with more polypropylene fiber added,dynamic cohesive force of the LFS is first increased and then decreased. When the fiber content is 0. 32%,the dynamic cohesive force reaches the peak,indicating that 0. 32% is the optimal fiber content. Besides,a positive correlation between the dynamic internal friction angle and fiber content is also observed. In addition,the fiber forms three-dimensional network in LFS,making the LFS more tightly integrated. Moreover,the fiber retards or prevents the expansion of cracks through reinforcement effects,which gradually transforms the collapse mode of the fiber-reinforced LFS from brittle failure with obvious transfixion cracks into lateral bulging deformation failure.
In order to investigate the effect of different fiber content on the dynamic strength of the reinforced lime-fly ash soil (LFS),polypropylene fiber with length of 12 mm was added into the LFS in different weight proportions of 0. 12%,0. 24% and 0. 36%,respectively. The GDS Triaxial Testing System (GDSTTS) was employed to perform dynamic triaxial tests on fiber-reinforced LFS under different confining pressures and stress amplitudes. The experiment results show that with more polypropylene fiber added,dynamic cohesive force of the LFS is first increased and then decreased. When the fiber content is 0. 32%,the dynamic cohesive force reaches the peak,indicating that 0. 32% is the optimal fiber content. Besides,a positive correlation between the dynamic internal friction angle and fiber content is also observed. In addition,the fiber forms three-dimensional network in LFS,making the LFS more tightly integrated. Moreover,the fiber retards or prevents the expansion of cracks through reinforcement effects,which gradually transforms the collapse mode of the fiber-reinforced LFS from brittle failure with obvious transfixion cracks into lateral bulging deformation failure.
引文
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[2]高磊,胡国辉,杨晨,等.玄武岩纤维加筋黏土的剪切强度特性[J].岩土工程学报,2016,38(增1):231-237.
[3]邓友生,吴鹏,赵明华,等.基于最优含水率的聚丙烯纤维增强膨胀土强度研究[J].岩土力学,2017,38(2):350-360.
[4]马晓杰,吴芳,李鹏,等.尼龙纤维增强水泥砂浆性能的试验研究[J].硅酸盐通报,2016,35(1):328-335.
[5]Butt W A,Mir B A,Jha J N.Strength behavior of clayey soil reinforced with human hair as a natural fibre[J].Geotechnical and Geological Engineering.2016,34(1):411-417.
[6]Welker A L,Josten N.Interface friction of a geomembrane with a fiber reinforced soil[C].Geo-Frontiers Congress,ASCE,Austin,Texas,United States,2005:1-7.
[7]牛建刚,李京军,尹亚柳,等.塑钢纤维轻骨料混凝土力学性能及最佳纤维掺量试验研究[J].硅酸盐通报,2016,35(1):87-91.
[8]沈金安主编.沥青及沥青混合料路用性能[M].北京:人民交通出版社,2001.
[9]张向东,曹启坤,潘宇.二灰改良土动力特性试验研究[J].岩土力学,2010,31(8):2560-2564.
[10]Mark E D,Seed H B.Undrained cyclic triaxial testing of gravels-the effect of membrane compliance[R].California:University of California,Berkeley.UCB/EERC,1987,87-08.
[11]孙舒,袁学锋.聚丙烯纤维土受力性能试验研究[J].长江科学院院报,2016,33(2):71-73.
[12]张克绪,谢君斐主编.土动力学[M].北京:地震出版社,1980.
[13]吴琪,陈国兴,周正龙.细粒掺量对细粒-砂粒-砾粒混合料动强度的影响[J].岩土工程学报,2017,39(6):1038-1047.