聚丙烯纤维加筋水泥搅拌土拉压性能试验研究

为研究纤维掺量、水泥掺量及养护龄期对聚丙烯纤维加筋水泥搅拌土无侧限抗压强度及劈裂抗拉强度影响,进行纤维掺量为0~5%,增量0.5%,水泥掺量为10%,15%,20%和25%,养护龄期为7,14,28,60和90 d的抗压性能试验。研究结果表明:聚丙烯纤维加筋水泥搅拌土的无侧限抗压强度、劈裂抗拉强度及拉压比随着纤维掺量的增大而增大,延性随之增强。与未掺纤维的水泥搅拌土相比,纤维掺量5%,水泥掺量15%和养护龄期28 d的纤维水泥搅拌土的无侧限抗压强度提高了0.29倍,对应的峰值应变增大0.71倍;劈裂抗拉强度提高1.58倍,对应的峰值应变增大1.7倍,拉压比提高1.1倍。聚丙烯纤维对水泥搅拌土劈裂抗拉强度影响更显著。聚丙烯纤维加筋水泥搅拌土的无侧限抗压强度与劈裂抗拉强度随着水泥掺量和养护龄期的增大而增大,而峰值应变及延性则随之降低。研究结果对基坑工程纤维水泥搅拌桩设计、施工具有参考价值。

Experimental study on unconfined compressive strength and splitting tensile strength of polypropylene fiber reinforced cement mixing soil

The effects of fiber content, cement content and curing age on the unconfined compressive strength(UCS) and splitting tensile strength(STS) of cement mixing soil reinforced by polypropylene fiber were studied. In these tests, the fiber content is 0~5%, increased by 0.5%, the cement content is 10%, 15%, 20%, 25%, and the curing time is 7, 14, 28, 60 and 90 d. The results show that the UCS, STS and tension compression ratio of cement mixing soil reinforced by polypropylene fiber increase with fiber content, and the ductility increases with the increase of fiber content. Compared with the cement mixing soil without fiber, the UCS and peak strain of cement mixing soil with 5% polypropylene fiber, 15% cement and 28 d curing age increased by 0.29 times and 0.71 times respectively. And the STS increased by 1.58 times, the corresponding peak strain increased to 1.7 times, and the tension compression ratio increased by 1.1 times. Therefore, polypropylene fiber has more significant effect on the STS of fiber reinforced cement mixing soil. The UCS and STS of polypropylene fiber reinforced cement mixing soil increase with cement content and curing age, while the peak strain and ductility are opposite. This research is of conference value to the construction and design of fiber reinforced cement mixing pile in foundation pit engineering projects.