碳酸盐岩裂隙溶蚀扩展试验与模拟研究  

Experiment and simulation study on dissolution widening of carbonate rock fracture

作　　者：武亚遵[1] 于江浩 林云[1] 金毅[1] 刘源 王雪奇 WU Yazun;YU Jianghao;LIN Yun;JIN Yi;LIU Yuan;WANG Xueqi(School of Resources and Environment,Henan Polytechnic University,Jiaozuo,Henan 454003,China)

机构地区：[1]河南理工大学资源环境学院,河南焦作454003

出　　处：《水文地质工程地质》2024年第1期41-46,共6页Hydrogeology & Engineering Geology

基　　金：国家自然科学基金项目(41502224,42271041);河南省高等学校青年骨干教师培养计划(2019GGJS055);河南省高等学校重点科研项目(21A170011)。

摘　　要：研究表明碳酸盐岩的溶蚀过程可用溶解速率方程进行表征,但表征的形式存在较大差别,主要体现在远离平衡的欠饱和态下。为进一步确定碳酸盐岩在欠饱和态下的溶解特征及溶蚀速率的表征形式,首先开展了碳酸盐岩裂隙溶蚀试验研究,探讨了CO_(2)及溶液初始Ca^(2+)浓度对溶蚀过程的影响,并基于试验结果构建了欠饱和态下的溶解速率方程;而后采用碳酸盐岩裂隙渗流-溶解耦合模型,通过数值模拟对量化模型的参数进行率定和检验。结果表明:(1)CO_(2)的参与加快了碳酸盐岩的溶蚀扩展,溶液初始Ca^(2+)浓度越高,对碳酸盐岩的溶解抑制程度就越高;(2)CO_(2)作用下碳酸盐岩裂隙溶蚀扩展的平均溶蚀速率增加了1.82~2.29倍;(3)溶液不同初始Ca^(2+)浓度在同等区间流量条件下,蒸馏水为溶蚀溶液的样品中Ca^(2+)浓度差值下降了0.0915mmol/L,溶液初始Ca^(2+)浓度为0.352,0.476,0.581mmol/L的溶蚀溶液中,Ca^(2+)浓度差值分别下降了0.0742,0.0536,0.0474mmol/L;(4)在高度欠饱和状态下溶解动力学由线性速率定律控制,随着溶液中Ca^(2+)浓度的升高,溶解动力学将变为非线性关系,此时Ca^(2+)浓度为0.4倍的平衡时Ca^(2+)浓度。研究结果可为定量评价岩溶发育演化提供数据支撑。Previous researches show that the dissolution of carbonate rocks can be characterized by dissolution rate equation,but the form of characterization is quite different,which is mainly reflected in the undersaturated state far from equilibrium.In order to further determine the dissolution characteristics of carbonate rocks in the undersaturated state and the characterization form of dissolution rate,first of all,the fracture dissolution test of carbonate rocks was carried out,and the influence of CO_(2) partial pressure and initial concentrations of Ca^(2+)on dissolution was discussed.Based on the test results,the dissolution rate equation in the undersaturated state was constructed.Then,the carbonate rock fracture seepage dissolution coupling model was used,calibrating and verifying the parameters of the quantitative model through numerical simulation.The results indicate that:(1)The participation of CO_(2) accelerates the dissolution expansion of carbonate rocks,and the higher the initial Ca^(2+)concentration of the solution,the higher the degree of dissolution inhibition of carbonate rocks.(2)The average dissolution rate of carbonate rock fractures under the action of CO_(2) increased by 1.82-2.29 times.(3)Under the same interval flow rate conditions for different initial Ca^(2+)solutions,the difference of Ca^(2+)concentration in distilled water decreased by 0.0915 mmol/L,and the initial Ca^(2+)concentration of 0.352,0.476,0.581 mmol/L decreased by 0.0742,0.0536,0.0474 mmol/L,respectively.(4)The dissolution kinetics is controlled by the linear rate law under the highly undersaturated state.With the increase of the concentration of Ca^(2+)in the solution,the dissolution kinetics becomes nonlinear,and the threshold of Ca^(2+)concentration between the two is 0.4 times the saturated of Ca^(2+)concentration.The study provides a reference for quantitative evaluation of karst development and evolution.

关 键 词：溶蚀扩展 溶解速率 欠饱和 碳酸盐岩 溶解动力学 

分 类 号：P642.25[天文地球—工程地质学]