高含水率路基回填土改良试验研究

Experimental Study on the Improvement of Subgrade Backfill with High Water Content

为解决城市道路施工工期短、降雨多以及质量要求高的矛盾,结合长沙智能驾驶测试区公路,重点对高含水率路基回填土快速施工的改良方案进行了试验研究。采用不同配比的水泥和生石灰对高含水率路基回填土进行处置,并通过三轴剪切试验对处置后的改良土力学性质进行了对比研究。结果表明:通过在土体中加入水泥和石灰进行处理后,其无侧限抗压强度峰值增大63. 8 k Pa以上,最高可达201. 3 k Pa,且改良土的强度特征与固化剂的配比存在一定关系;生石灰和水泥配比分别为7%和0%,5%和2%,3%和4%的条件下均可使土样达到改良标准强度;水泥石灰混合改良的效果优于水泥单一改良效果,但其中一种固化剂效应的发挥依赖于另一种固化剂的相对含量;该项目改良标准强度为405. 6 k Pa,最优改良配比为3%石灰和4%水泥。

Combining with the road of Changsha intelligent driving test area,in order to solve the contradiction between short construction period,high precipitation and high requirement of construction quality of urban road,the improvement scheme for rapid construction of subgrade backfill with high water content was studied.Backfill was treated with different proportion of cement and quick lime and the mechanical property of the improved soil after treatment was compared and studied by triaxial shear test.The results show that:the peak value of unconfined compressive strength increased by more than 63.8 kPa,up to 201.3 kPa for the highest by adding cement and lime in the soil.Meanwhile,the strength characteristics of improved soil have a certain relationship with the proportion of curing agent.Different proportions of quick lime and cement could make the backfill achieve the standard strength,namely,7%and 0%,5%and 2%,3%and 4%.In addition,the improvement of backfill strength by adding cement and quick lime is better than that of cement,but the effect of one of curing agents depends on the relative content of another curing agent.In terms of intelligent drive highway project in Changsha,its standard strength was 405.6 kPa.Correspondingly,the optimum improvement proportion of curing agent was 3%quick lime and 4%cement respectively.