基于正交设计的红层软岩改良土压缩模量试验研究

Experimental study on the compression modulus of red-bed soft rock improved soil based on orthogonal design

摘要:

西部地区大型基础性工程项目日益增多,为处理工程开挖出的大量土方,减少工程造价和实现绿色发展的目标,通过对红层软岩改良土进行试验研究,评价其作为路基回填料的可行性。以西北某地铁深基坑项目为依托,首先通过对不同黄土和水泥掺比下红层软岩改良土进行正交试验研究,其次对该改良土压缩模量的影响因素进行分析,并给出最佳配合比,最后对最佳配合比下的改良土进行浸水前后试验,评价其水稳定性。结果表明:黄土和水泥均对压缩模量影响显著,推荐的红层软岩改良土的最佳配合比为黄土20%,水泥7%;浸水前改良试样压缩模量随养护时间的增加而逐渐增大,浸水后的试样压缩模量随龄期增长其下降幅度逐渐降低;黄土在提高了压缩模量和压实效果的同时并未对水稳定性造成影响。以上结论对评价改良后的红层软岩作为路基填料的可行性具有一定参考价值。

Abstract:

There are more and more large-scale basic engineering projects in the western region of China. To deal with the earthwork excavated from the projects, reduce the project cost and achieve the goal of green development, the feasibility of red-bed soft rock improved soil as subgrade backfill was evaluated through experimental research. Based on the deep foundation pit project of a subway in Northwest China, the red-bed soft rock improved soil with different loess and cement mixing ratio were first studied by orthogonal test. Then, the influencing factors of the improved soil's compression modulus were analyzed, and the best mix proportion was given. Finally, the improved soil with the best mix proportion was tested before and after soaking to evaluate its water stability. The results showed that both loess and cement have significant effects on the compression modulus. The recommended optimum mix proportion of red-bed soft rock improved soil is 20% loess and 7% cement. The compression modulus of the improved sample increases gradually with the increase of curing time before soaking, and decreases with the increase of age after soaking. Loess not only improves the compression modulus and compaction effect, but also has no impact on the water stability. The above conclusions have a certain reference value for evaluating the feasibility of the improved red-bed soft rock as subgrade filler.