鄂西北页岩饱水软化微观机制与力学特性研究

发布时间：2018-06-15 11:56

本文选题：鄂西北页岩 + 饱水软化　；参考：《岩土力学》2017年07期

【摘要】：针对鄂西北页岩隧道施工中存在的地下水加剧软岩隧道大变形问题,进行页岩饱水软化的微观机制与力学特性研究。通过开展X射线衍射、自然吸水试验和SEM电镜扫描,探索不同饱水时间条件下页岩吸水率和微观结构的变化;进而通过开展单轴压缩试验,分析页岩强度和变形参数随其饱水时间的演化规律。试验结果显示,页岩吸水率随着饱水时间的增加呈对数规律增长,页岩饱水后峰值抗压强度和弹性模量均随着饱水时间的增加呈负对数规律降低;页岩力学性质在饱水20 d内变化迅速,50 d后趋于稳定。同时,随着饱水时间的增加,页岩中绿泥石和白云母矿物遇水产生膨胀,使片层状结构分散剥离出细小矿物颗粒,并产生大量松散多孔的絮状物;由于水化作用的影响,页岩原有的致密层状结构变得松散破碎,矿物颗粒之间的胶结逐步破坏,孔隙、裂隙增多,宏观上表现为页岩强度降低,抵抗变形能力减弱,破裂面更为密集,且贯通性增强。
[Abstract]:Aiming at the large deformation of soft rock tunnel caused by groundwater in the construction of shale tunnel in northwest Hubei Province, the microscopic mechanism and mechanical characteristics of shale saturated softening were studied. By means of X-ray diffraction, natural water absorption test and SEM scanning electron microscope, the changes of shale water absorption rate and microstructure under different saturated time were explored, and the uniaxial compression test was carried out. The evolution of shale strength and deformation parameters with saturated time is analyzed. The results show that the shale water absorption increases logarithmically with the increase of saturated time, and the peak compressive strength and elastic modulus decrease with the increase of saturated time. The mechanical properties of shale tend to be stable within 20 days of saturated water. At the same time, with the increase of saturated time, chlorite and Muscovite minerals in shale expand when they meet with water, which makes the lamellar structure disperse and peel off fine mineral particles and produce a large number of loose porous flocculants; due to the effect of hydration, The original dense layered structure of shale becomes loose and broken, the cementation between mineral particles is destroyed gradually, the porosity and fissure increase, the macroscopic performance is that the strength of shale decreases, the ability of resisting deformation weakens, the fracture surface is denser, and the penetration is enhanced.
【作者单位】：中国科学院武汉岩土力学研究所岩土力学与工程国家重点实验室;中国科学院大学;
【基金】：国家重点研发计划项目(No.2016YFC0401802) 国家自然科学基金重点项目(No.51539002);国家自然科学基金项目(No.51209198,No.51204158)~~
【分类号】：U452.11

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