湿陷性黄土–砾石集料流态固化土工程特性试验研究

Experimental Study on Engineering Characteristics of Fluidized Solidified Soil Containing Collapsible Loess and Gravel

针对传统回填方法与回填材料存在的缺陷,结合湿陷性黄土地区特点,提出了一种基于湿陷性黄土–砾石集料的预拌流态固化土。通过开展流动性试验与无侧限抗压强度试验,对比分析了不同土石比、水固比和胶集比对该预拌流态固化土工作性和力学性能的影响;同时借助渗透性试验与黄土湿陷试验讨论了所提出材料固化后遇水的性能变化情况。主要得出以下结论:(1)胶凝材料用量固定时,拌合物为满足流动性要求所需用水量随着湿陷性黄土用量的增加而增大,但试样强度整体呈下降趋势;(2)胶凝材料用量的增大提高了试样强度,但降低了拌合物的流动性,且对土石比较大和水固比相对较低的配合比的流动性影响显著;(3)满足流动性和强度要求的湿陷性黄土–砾石集料预拌流态固化土,其抗渗性和湿陷性也均满足相关规范要求;(4)调整水固比满足基本流动性要求后,土石质量比取1.50~1.86,胶集质量比不小于0.06的湿陷性黄土–砾石集料流态固化土具有良好的工作性能和力学性能。

To eliminate the defects of traditional backfilling methods and materials,combined with the characteristics of collapsible loess area,the premixed fluidized solidified soil with collapsible loess and gravel as aggregate was prepared.The influence of different loess-to-gravel(L/G),water-to-solid(W/S)and binder-to-aggregate(B/A)ratios on the workability and mechanical properties of the premixed fluid solidified soil was analyzed by carrying out flowability and unconfined compressive strength tests.The permeability test and collapsibility test were conducted to discuss the performance change of the proposed material after solidification and water exposure.The main conclusions are as follows:(1)For certain fixed cementitious material content,with the increase of collapsible loess content,the amount of water required to meet the flowability requirements of the mixture also increases,but the strength of the sample decreases as a whole.(2)The increase of the content of cementitious materials improves the strength of the sample,but reduces the flowability of the mixture,especially for the mixture with large L/G ratio and relatively low W/S ratio.(3)Premixed fluidized solidified soil made with collapsible loess and gravel which meets the requirements of flowability and minimum strength also meets the requirements of impermeability and collapsibility in the relevant specifications.(4)According to the test results,after W/S ratio is adjusted to meet the flowability requirement,the fluidized premixed solidified soil with L/G ratio between 1.50 and 1.86 and B/A ratio not less than 0.06 has good workability and mechanical properties.