冰水堆积体路基填料水泥改性试验研究

Experimental Study on Cement Modification of Fluvioglacial Deposit Subgrade Filler

采用成乐高速公路桩号K71+000处冰水堆积体土样,水泥掺量分别为3%、4%、5%、6%,开展土工击实、承载比、无侧限抗压强度、直剪试验等,得到改良前后颗粒级配、塑性指数、CBR值、无侧限抗压强度和抗剪强度等参数,探究冰水堆积体用作路基填料可行性。研究表明:改良后冰水堆积体最大干密度、CBR值、无侧限抗压强度(7、14、28天)、黏聚力和内摩擦角均随水泥掺量增加而增大;水泥掺量小于5%时,指标随水泥掺量近似呈线性增大;水泥掺量大于5%时,指标随水泥掺量增加,增大幅度有明显减弱。确定出最佳水泥掺量为5%,各项指标均符合路基填料规范要求,冰水堆积体经改良后可用作路基填料。

By adopting the soil samples of fluvioglacial deposits of Pile No.K71+000 of Chengdu—Leshan Expressway and by adding cement contents of 3%,4%,5%,6%respectively,the geotechnical compaction tests,bearing ratio tests,unconfined compressive strength tests and direct shear tests were carried out.The parameters such as particle gradation,plasticity index,CBR value,unconfined compressive strength and shear strength before and after the improvement were obtained.The feasibility of using fluvioglacial deposits as subgrade filler was explored.The research shows that the maximum dry density,CBR value,unconfined compressive strength(7 d,14 d and 28 d),cohesion and internal friction angle of the improved fluvioglacial deposits increase with the increase of cement content.When the cement content is less than 5%,the index increase linearly with the cement content.As the cement content more than 5%,the increase extent of the index decreases obviously with the increase of cement content.The optimal cement content is determined to be 5%.All indicators meet the specification requirements of subgrade filler,and the fluvioglacial deposit body can be used as subgrade filler after improvement.