斜坡非饱和带低渗透岩石中水气分子的扩散机理

张修硕,徐则民*,杨继清,申林方,王志良,张 瑞,王洪波

斜坡非饱和带低渗透岩石中水气分子的扩散机理

张修硕1,徐则民1*,杨继清12,申林方1,王志良1,张瑞2,王洪波3

(1. 昆明理工大学建筑工程学院,云南 昆明650500;2. 云南农业大学建筑工程学院,云南 昆明650201;3. 中国矿业大学(北京)力学与建筑工程学院,北京100083)

 

摘  要  根据分子运动论,对水气分子在低渗透岩石中的扩散模式进行研究,得出水气分子中的主要气体H2O、CO2以及O2在新鲜二长岩和玄武岩中的扩散为过渡型扩散。通过计算得到三者的有效扩散系数。以微砂质细粒长石石英砂岩为研究对象,在电子显微镜下获得砂岩的铸体薄片图像,并对其进行处理,建立砂岩的二维孔隙扩散模型,模拟岩石风化过程中水气分子在砂岩孔隙内的扩散过程,得到砂岩模型内部的速度分布图、压力分布图和雷诺数图。结果表明,天然状态下,水气分子的流动主要出现在胶结物受腐蚀的风化区域。胶结物溶蚀产生的贯通孔隙是水气分子的主要扩散通道和贮存场所。水气分子在砂岩内部孔隙中的流动符合流体流动的基本规律,雷诺数的量级为10-3,流动状态为层流。同时对风化岩石的剖面进行分带,分析了水气分子扩散对岩石风化产生的影响。

关键词  滑坡;岩体演化;岩石风化;水气分子扩散

中图分类号:TU 452     文献标识码:A       doi:10.3969/j.issn.1000-6281.2017.03.007

 

Diffusion mechanism of water vapor in the unsaturated zone of slope with low permeability

ZHANG Xiu-shuo 1,XU Ze-min1*,YANG Ji-qing12,SHEN Lin-fang1

WANG Zhi-liang1,ZHANG Rui2,WANG Hong-bo3

(1.Faculty of Civil Engineering and Mechanics, Kunming University of Science and Technology, Kunming Yunnan 650500, China;2.College of Architectural Engineering, Yunnan Agricultural University, Kunming Yunnan 650201, China;3.School of Mechanics & Civil Engineering, China University of Mining & Technology(Beijing),  Beijing 100083, China)

 

Abstract   According to the theory of molecular motion, the diffusion mode of water vapor in the low-permeability rocks was studied in this paper and found that diffusion patterns of the main components in water vapor, such as H2O, CO2 and O2, were defined as transitional forms in the fresh monzonite and basalt. The effective diffusion coefficients of these three kinds of gas in the monzonite and basalt were acquired by calculation. Micro sandy fine feldspathic quartz sandstone was analyzed by the sandstone casting thin-section image processingunder an electron microscope, and therefore two-dimensional sandstone pore diffusion model was established in order to simulate the diffusion process of water vapor in the weathering process of sandstone. The velocity distribution, pressure distribution and Reynolds number of the internal model of sandstone were obtained. The results show that the flow of water vapor in the natural state mainly occurrs in the weathered corrosion area of the cements. The through-pores formed by dissolution of cements in the low-permeability rocks are the main diffusion channels and storage sites of water vapor in weathering process. The flow of water vapor in the pores of the sandstone complys with the basic rules of fluid flow, and the Reynolds number is 10-3. The flow state is laminar. At the same time, the section of weathered rock was divided into different zones and the influence of diffusion of water vapor on the weathered rock mass was analyzed.

Keywords   landslide;evolution of rock mass;rock weathering;water vapor diffusion 

 


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