摘要
白垩系砂岩沉积时间短,胶结程度差,在水化作用下极易发生崩解。选用湖北宜昌地区白垩系五龙组砂岩开展室内静态与动态崩解试验,分析了静动态崩解方式下白垩系砂岩的耐崩解指数的变化规律。通过测定崩解循环后不同粒径范围内崩解物颗粒质量百分含量的变化分析白垩系砂岩的崩解过程,采用电镜扫描试验观察崩解前后白垩系砂岩的镜下微观特征,根据崩解后崩解残留物的形态特征分析白垩系砂岩的崩解破坏模式,研究白垩系砂岩的崩解机理;从能量耗散的角度入手,引用表面能增量定量描述白垩系砂岩崩解过程中的破碎程度。结果表明:静态崩解下白垩系砂岩的耐崩解指数整体上低于动态崩解,随着崩解次数变大,小粒径颗粒(0.25~0.075 mm)的质量百分含量逐渐增加,最终趋于稳定;白垩系砂岩的崩解破坏主要是沿着节理裂隙面、颗粒胶结面以及微裂隙逐渐展开,随着崩解物粒径由大变小,与水的接触机会增多,且相应的裂隙扩展路径变短,崩解物破碎程度加大。采用表面能累计增量可以较好地反映白垩系砂岩在崩解过程中的破碎程度,表面能累计增量越大,崩解残留物越破碎,崩解程度越高。研究成果可为易崩解软岩地区岩土体工程性质评价提供理论参考。
The Cretaceous sandstone has a short sedimentation time and a poor degree of cementation. It is easy to disintegrate under hydration. The Cretaceous Wulong Formation sandstone in Yichang, Hubei is selected to carry out laboratory static and dynamic disintegration tests. The variation law of the Cretaceous sandstone’s disintegration resistance index under static and dynamic disintegration methods is analyzed. The disintegration process of Cretaceous sandstone is analyzed by measuring the change in the mass percentage of disintegrated particles in different particle size ranges after the disintegration cycle. The microscopic characteristics of the Cretaceous sandstone before and after the disintegration is observed by scanning electron microscope tests. The morphological characteristics of post-disintegration residues is analyzed for the disintegration failure mode of Cretaceous sandstone. The disintegration mechanism of Cretaceous sandstone is examined. Starting from the perspective of energy dis sipation, the surface energy increment is used to quantitatively describe the process of Cretaceous sandstone disintegration degree of fragmentation. The results show that the Cretaceous sandstone under static disintegration has a lower disintegration resistance index than that of dynamic disintegration. As the number of disintegration in creases, the mass percentage of small particles(0.25~0.075 mm) gradually increases, and eventually stabilizes. The disintegration of Cretaceous sandstone mainly spreads along the joint fracture surface, particle cementation surface and micro-cracks. As the particle size of the disintegrated material becomes smaller, the chance of contact with water increases, and the corresponding crack propagation path becomes shorter. The degree of disintegration is increased. The cumulative increase in surface energy can better reflect the degree of fragmentation of the Cretaceous sandstone during the disintegration process. The greater the cumulative increase in surface energy, the more broken the disintegration residue and the higher the degree of disintegration. The research results can provide a theoretical reference for the evaluation of the engineering properties of the rock and soil mass in the soft rock area.
作者
左清军
朱盛
张中君
赵先强
李朝铭
童权
罗忠权
ZUO Qingjun;ZHU Sheng;ZHANG Zhongjun;ZHAO Xianqiang;LI Chaoming;TONG Quan;LUO Zhongquan(National Field Observation and Research Station of Landslides in Three Gorges Reservoir Area of Yangtze River,China Three Gorges University,Yichang 443002,China)
出处
《工程地质学报》
CSCD
北大核心
2022年第1期187-196,共10页
Journal of Engineering Geology
基金
国家自然科学基金(资助号:41402259)。
关键词
白垩系砂岩
崩解
能量耗散
干湿循环
Cretaceous sandstone
Disintegration
Energy dissipation
Dry-wet cycle