冻融循环作用下纤维增强水泥改性黄土特性

Properties of Loess Modified Through Fiber Reinforced Cement Under Freeze-thaw Cycle

为了探究聚丙烯纤维和水泥共同改良黄土性能,通过无侧限抗压试验以及冻融循环试验,分析水泥掺量,聚丙烯纤维掺量与长度以及冻融循环次数对改性黄土无侧限抗压强度的影响.研究结果表明:改性黄土的无侧限抗压强度随着水泥掺量增多而提高,加入纤维则进一步提高其抗压强度.纤维的掺量和长度的增大会使改性黄土的无侧限抗压强度先提高后降低,聚丙烯纤维的最佳掺量为0.4%,最优长度为9 mm.水泥改性黄土经历15次冻融循环后,纤维增强水泥改性黄土经历10次冻融循环后强度损伤趋于平缓,变化幅度在3%左右.采用Lasso回归模型计算水泥-聚丙烯纤维改性黄土无侧限抗压强度回归预测模型,预测模型与试验结果吻合较好.

In order to explore the properties of modified loess with polypropylene fiber and cement,the effects of cement content,polypropylene fiber content and length,and freeze-thaw cycle times on the unconfined compressive strength of modified loess are analyzed through unconfined compression test and freeze-thaw cycle test.Results show that the unconfined compressive strength of modified loess increases with the increase of cement content,and the addition of fiber can further improve its compressive strength.The unconfined compressive strength of the modified loess increases first and then decreases with the increase of fiber content and length.The optimal content of polypropylene fiber is 0.4%and the optimal length is 9 mm.After 15 freeze-thaw cycles of cement modified loess,the strength damage of fiber reinforced cement modified loess tends to be gentle after 10 freeze-thaw cycles,with a change range of about 3%.Lasso regression model is used to calculate the unconfined compressive strength regression prediction model of cement polypropylene fiber modified loess.The prediction model is in good agreement with the test results.