摘要
为研究多孔岩石在冻融过程中孔(裂)隙内部水分迁移导致的冻融损伤问题,对薄膜水压–吸平衡状态展开分析,发现液压的主要作用是抵消和平衡净吸力,给出压力变量和吸力变量之间的转换系数λ,认为表面吸附力来自于净吸力和抵消因子λPLy之差。基于毛细理论,推导出孔隙水冻结温度方程,给出冻结大孔薄膜水的受力状态。并针对抗冻性较差的"主干–旁枝型"孔隙结构,建立毛细–薄膜水分迁移单元模型,给出特征孔隙的应力分布、迁移方向和迁移路径。研究结果表明,冻结主干孔内部薄膜水受到的净吸力和液压均最大,净吸力驱使次级孔和微孔中的毛细水和薄膜水向主干孔迁移,而液压的增大导致主干孔启裂扩展以及结构破坏。最后,选取侏罗–白垩系粉砂质软岩为试验对象,开展颗粒分析、扫描电镜和低场核磁共振试验,分析粉砂岩的矿物成分、孔隙结构、以及孔隙分布,并根据冻融过程中T2谱的变化特征验证了毛细–薄膜水分迁移单元模型的正确性。
In order to study the freeze-thaw damage of porous rock caused by moisture migration inside the pores(cracks) during the freeze-thaw process,the pressure-suction equilibrium state of the film water was analyzed,and it was found that the main role of the liquid pressure is to offset and balance the net suction. The conversion coefficient λ between the pressure variable and the suction variable was given,and it was pointed out that the surface adsorption force comes from the difference between the net suction force and the offset factor λPLy. Based on the capillary theory,the freezing temperature equation of pore water was derived,and the stress state of film water in the frozen large pores was given. Besides,for the "main-side branch" pore structure with poor frost resistance,a capillary-film moisture migration unit model was established,and the stress distribution,migration direction and migration path of the characteristic pores were given. The research results show that the net suction and liquid pressure of the film water inside the frozen main pores are the largest. The net suction force drives the capillary water and film water in the secondary pores and micro-pores to migrate to the main pores,while the increase of the liquid pressure leads to the crack expansion and structural damage of the main pores. Finally,Taking the Jurassic-Cretaceous silty soft rock as the test object,particle analysis,scanning electron microscopy and low field-nuclear magnetic resonance tests were carried out to analyze the mineral composition,pore structure and pore distribution of siltstone,and the correctness of the capillary-film moisture migration unit model was verified according to the change characteristics of T2 spectrum during the freeze-thaw process.
作者
程桦
陈汉青
曹广勇
荣传新
姚直书
蔡海兵
CHENG Hua;CHEN Hanqing;CAO Guangyong;RONG Chuanxin;YAOZhishu;CAI Haibing(College of Civil and Hydraulic Engineering,Hefei University of Technology,Hefei,Anhui 230001,China;College of Civil Engineering and Architecture,Anhui University of Science and Technology,Huainan,Anhui 232001,China;College of Civil Engineering and Architecture,Anhui Jianzhu University y Hefei,Anhui 230601,China;Anhui Province Key Laboratory of Building Structure and Underground Engineering,Anhui Jianzhu University,Hefei,Anhui 230601,China)
出处
《岩石力学与工程学报》
EI
CAS
CSCD
北大核心
2020年第9期1739-1749,共11页
Chinese Journal of Rock Mechanics and Engineering
基金
国家自然科学基金资助项目(51874005,51878005,51778004)。
关键词
岩石力学
压–吸平衡
转换系数
水分迁移
冻融损伤
rock mechanics
pressure-suction equilibrium
conversion coefficient
water migration
freeze-thaw damage
