随着西部大开发战略的快速实施,地下工程越来越多,为保护生态环境、降低工程造价,将开挖出的强风化岩进行破碎后,掺入一定比例的黄土、水泥、膨润土和泵送剂进行固化改良作为流态填筑材料。以西北地区某基坑回填工程为依托,通过正交设计,对不同配比的流态固化土进行压缩特性试验研究,得到各因素的最优配比,分析了强风化岩流态固化土压缩模量的影响因素及其显著性大小,并对强风化岩流态固化土的微观变化机理和水稳定性进行研究。结果表明:对压缩模量影响最显著的因素是泵送剂,其次是强风化岩粗骨料掺量;各因素掺量对压缩模量影响的主次顺序为:泵送剂→强风化岩粗骨料→膨润土→水泥→黄土→强风化岩细骨料;改良试样浸水后压缩模量随龄期增长,下降幅值逐渐减小,表明其水稳定性和整体性能显著提高;通过微观分析得到泵送剂掺量为0.4%时,试样胶结性能较好。研究结果对评价强风化岩作为流态填筑材料可行性具有一定的参考价值。
Abstract
The implementation of the western development strategy has led to a surge in underground engineering projects. To protect ecological environment and reduce engineering costs, crushed strongly weathered rock is utilized in combination with loess, cement, bentonite, and pumping agent to create solidified and improved fluid filling materials. Based on a foundation pit backfilling project in northwest China, compression tests were conducted on fluid-solidified soil with varying proportions using orthogonal design. The optimal proportions of different factors were determined. The influencing factors and their significance on the compressive modulus of fluid-solidified soil made from strongly weathered rock were analyzed. Additionally, the microstructural changes and water stability of fluid-solidified soil were also investigated. Results demonstrate that the pumping agent is the most significant factor affecting the compressive modulus, followed by the dosage of coarse aggregate of strongly weathered rock. The influence of various factors on the compressive modulus can be ranked in the following order from large to small: pumping agent dosage, coarse aggregate content, bentonite dosage, cement dosage, loess dosage, and fine aggregate content. Moreover, the reduction rate of compressive modulus of improved samples decreases with age after being immersed in water. This indicates significant improvements in water stability and overall performance. Microscopic analysis reveals that a pumping agent dosage of 0.4% yields better sample cementation. The research findings hold valuable reference for evaluating the feasibility of using strongly weathered rock as fluid filling material.
关键词
强风化岩 /
流态固化土 /
正交试验 /
压缩特性 /
水稳定性 /
微观结构 /
显著性分析
Key words
strongly weathered rock /
fluid-solidified soil /
orthogonal test /
compression characteristics /
water stability /
microstructure /
significance analysis
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基金
国家自然科学基金面上项目(51978321);国家重点研发计划项目(2019YFD1101004);教育部长江学者和创新团队支持计划项目(IRT_17R51)
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