宜昌砂岩不同pH值酸性溶液浸泡下时间比尺及强度模型研究

结合试样切片检测、pH值变化精确测量、浸泡过程中岩石试样的腐蚀脱落深度量测等技术手段,对不同pH值酸性环境中宜昌地区钙质中～细砂岩的浸泡时间比尺及强度模型展开研究。以H+物质的量为基准量,提出时间比尺的概念。指出可以通过时间比尺的转化,用强酸的短时反应来模拟弱酸长时反应的效果,并分稳定酸根离子和没有稳定酸根离子补给2种情况给出算例,进一步论证该方法的可行性。提出并解释砂岩反应后的表面"多孔特性"和"多层状"现象,指出H+浓度降低速率随时间和腐蚀深度增长逐渐变缓,为强度模型建立提供基础,同时建立试样腐蚀脱落深度与浸泡时间的关系。基于岩石试样的腐蚀深度模型简图和相关假设,推导硫酸溶液作用下试样强度变化与时间关系式,并对比分析强度计算值及实测值,两者吻合较好。

STUDY OF TIME SCALE AND STRENGTH MODEL OF YICHANG SANDSTONE UNDER DIFFERENT PH VALUES OF ACIDIC SOLUTION IMMERSION

Time scale and strength model of calcareous medium-fine sandstone of Yichang in acid environment of different pH values are studied combining several technological means，such as rock sample test，pH value variation accurate measurement and corrosion depth measurement of rock sample in immersion and so on. The concept of time scale is proposed using the amount of substance of hydrogen ion as datum quantity. Through the transformation of time scale，the long time reaction of weak acid can be simulated by the short time reaction of strong acid. Then two examples with stable acid ion supply and unstable acid ion supply are developed to verify the feasibility of this method. The porosity characteristic and multilayer phenomenon of sandstone after reaction are proposed and explained；and the relationship between corrosion depth of samples and time is established. It is also proposed that the decreasing rate of hydrogen ion concentration gets slowly with time and the increase in corrosion depth，which provides a foundation for the development of strength model. Based on the sketch of corrosion depth model of rock sample and related assumption，the relational expression of intensity change of sample and time under the action of sulphuric acid solution is deduced；and the calculated values are well in agreement with the measured data.