中文摘要：

利用SEM电镜扫描技术和X衍射晶体鉴定技术，对经0．01mol／L，pH值为12的NaOH溶液作用前后的φ50mm×100mm大小砂岩试件的表面和矿物成分进行分析，探讨砂岩试件腐蚀表面的微区形貌和矿物组成的变化特征。通过一系列室内试验，对0．01mol／L，pH值为12的NaOH溶液作用下不同时刻砂岩试件的孔隙率、溶液pH值进行测定，并对其变化规律进行分析，得出砂岩孔隙率变化受溶液酸碱度影响和制约的结论。基于化学动力学理论和溶质迁移理论，建立水岩系统的对流-扩散-反应模型，运用孔隙率的变化来定量描述由于水岩作用引起的岩石细观结构的变化。采用有限元法对0．01mol／L，pH值为12的NaOH溶液的作用下砂岩孔隙率的动态演化过程进行数值计算，结果表明，数值解与试验结果吻合较好。该研究为定量研究化学腐蚀作用对岩石物理力学特性的影响提供了重要依据，为更准确地评估和计算坝基、边坡、核废料处置库、隧道等众多与水化学相关的岩石工程的安全性和稳定性提供了有效的解决手段和分析方法。

英文摘要：

In the underground repositories, the microstructure change of surrounding rock under the action of the chemical corrosion will cause the increase of porosity in medium and the accelerative diffusion of chemical contaminator. Aiming to analyze the chemical corrosion effect on the environment medium, micro-local pattern and composition of sandstone specimens with size φ50 mm× 100 mm under chemical corrosion of NaOH solution with pH value of 12 and concentration of 0.01mol/L are tested using SEM and X-ray technology firstly. After a series of laboratory tests on evolution of porosity of sandstone specimens and pH value of solution at different periods under chemical corrosion of NaOH solution（0.01 mol/L, pH value is 12） are conducted： the microstructure change of sandstone under chemical corrosion is analyzed from the view of porosity change. On the basis of the results of tests and the theory of chemical thermodynamics, the corrosion mechanism is concluded for the dissolution of quartz matrix mineral and siliceous cement. Then, based on the theory of chemical kinetics,chemical thermodynamics, and solute transportation, a reactive-transport model for describing porosity change under chemical corrosion is established. Finally, a simplified mathematic model is derived to describe microstructure change of rock under chemical corrosion. And the numerical simulation is performed. The simulation result indicates that, with the corrosion time increasing, the porosity increases firstly and then is driven to stabilization in the end. The study results can be used as a valuable reference to understand the mechanism of the chemical corrosion effect on the microstructure change of rock damage evolution, to set up the corresponding damage constitutive model, and to offer an effective parameter for exactly estimating the safety and stability of many rock engineering projects such as dam foundation, radioactive waste repositories, slope and tunnel which are related to hydrochemistry.