聚丙烯纤维加筋水泥砂浆土三轴压缩试验研究

Experimental study on triaxial compression of polypropylene fiber reinforced cement mortar soil

为了研究纤维对水泥砂浆土的加筋效果,开展了聚丙烯纤维水泥砂浆土三轴压缩试验,研究纤维掺量、水泥掺量、掺砂量、养护龄期等因素对纤维水泥砂浆土的应力应变曲线、破坏偏应力、抗剪强度参数的影响。研究结果表明:纤维水泥砂浆土的应力应变曲线为应变硬化型,聚丙烯纤维能有效提升水泥砂浆土的韧性。纤维水泥砂浆土的破坏偏应力随纤维掺量的增大而增大。纤维水泥砂浆土的黏聚力随纤维掺量的增大而增大,未掺纤维的水泥砂浆土的黏聚力为0.06 MPa,4%掺量的纤维水泥砂浆土的黏聚力为0.24MPa,黏聚力增大了3倍,而纤维掺量对内摩擦角的影响不明显。纤维水泥砂浆土的黏聚力受掺砂量的影响不明显,而内摩擦角随掺砂量先增大后减小,最优掺砂量为0.3。本文成果对纤维水泥砂浆桩的设计和施工具有参考和借鉴意义。

In order to study the reinforcement effect of fibers on cement mortar soil,a series of triaxial compression tests were carried out.The effects of fiber content,cement content,sand content,and curing time on the stress-strain curve,deviatoric stress at failure and shear strength parameters of fiber reinforced cement mortar soil(FRCMS)were investigated.The results show that the stress-strain curve of FRCMS exhibits typical strain hardening behavior,and polypropylene fiber can effectively improve the toughness of cement mortar soil.The deviatoric stress at failure of FRCMS and the cohesion of FRCMS both increases with increasing fiber content.The cohesion values of cement mortar soil without fiber and cement mortar soil with 4%fiber are 0.06 MPa and 0.24 MPa,respectively.However,the influence of fiber on internal friction angle of FRCMS is not obvious.The influence of sand on the cohesion of FRCMS is inapparent,but the internal friction angle increases first and then decreases with sand content,and the optimal sand content is 0.3.The results of this research study can provide reference for the design and construction of fiber reinforced cement mortar mixing pile.