ISSN 1003-8035 CN 11-2852/P

    基于室内试验的四川峨眉—汉源高速廖山隧道碳酸盐岩溶蚀特征分析

    Experimental analysis on dissolution characteristics of carbonate rocks in Liaoshan tunnel of Emei−Hanyuan expressway in Sichuan Province

    • 摘要: 廖山隧道是峨汉高速的控制性工程之一,隧址区岩溶地质条件复杂,为了深入研究隧址区碳酸盐岩的溶蚀特征,文章以隧址区中生界三叠系中统雷口坡组典型白云质灰岩、灰岩及钙质泥岩试样为研究对象,开展静态溶蚀试验,定量分析了碳酸盐岩溶蚀速率特征及相关影响因素,最后定性探讨了扫描电镜下试样溶蚀过程的微观结构变化。结果表明:(1)试验条件下(20 ℃、1 atm、乙酸溶液、pH=5.30、静态溶蚀),隧址区雷口坡组灰岩溶蚀速率约3.48 mm/a,白云质灰岩溶蚀速率约1.57 mm/a,钙质泥岩溶蚀速率约0.90 mm/a;(2)碳酸盐岩的溶蚀受矿物组分及溶蚀环境控制,相同溶蚀环境下,溶蚀速率与方解石含量呈正相关,与白云石含量及溶蚀介质PH值呈负相关,总体上具有灰岩>白云质灰岩>钙质泥岩的特征;(3)有机酸与无机酸环境下灰岩溶蚀速率差异不大,总体趋势相同,而中性盐溶液与碱性环境则对灰岩溶蚀起到不同程度的抑制作用;(4)碳酸盐岩具有优先沿矿物成分、岩石微结构选择性溶蚀的特征,主要矿物含量的不同也使得碳酸盐岩的微观溶蚀过程存在一定差异。

       

      Abstract: The Liaoshan tunnel is one of the controlling projects of the E-han expressway, the karst geological conditions in the tunnel site area are complex. In order to deeply study the characteristics of carbonate dissolution in the field, this paper takes the typical dolomitic limestone, limestone and calcareous mudstone samples of the Mesozoic Triassic Middle Leikoupo Formation in the tunnel site area as the research object to carry out the static corrosion simulation experiment. The characteristics of dissolution rate of carbonate rock and related factors are analyzed quantitatively, and the changes of microstructure in the process of sample dissolution under SEM are discussed qualitatively. The results show that: (1) Under the experimental conditions (20 ℃, 1 atm, acetic acid solution, pH≈5.30, static dissolution), the dissolution rate of limestone in Leikoupo Formation is about 3.48 mm/a, that of dolomitic limestone is about 1.57 mm/a, and that of calcareous mudstone is about 0.90 mm/a. (2) The dissolution of carbonate rocks is controlled by the mineral composition and dissolution environment. Under the same dissolution environment, the dissolution rate of carbonate rocks is positively correlated with the content of calcite, and negatively correlated with the content of dolomite and the pH value of the dissolution medium, and generally characterized by limestone>dolomitic limestone>calcareous mudstone. (3) Under the environment of organic acid and inorganic acid, the dissolution rate of limestone has little difference and the general trend is the same, while the neutral salt solution and alkaline environment have different degrees of inhibition on the dissolution of limestone. (4) Carbonate rock has the characteristic of preferential selective dissolution along mineral composition and rock microstructure. The difference of the main mineral content also makes the micro dissolution process of the carbonate rock different.

       

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