云贵高原地区高膨胀易垮塌凝灰岩的膨胀垮塌机理研究

Problems caused by high expantion and easy collapse tuff has been an obsession to production activities from long ago, it is necessary to study the expansion and collapse mechanism to solve these problems betterly . Based on the case of early stage fundamental research, to intensive study the high expansion and easy collapse tuff’s mechanism of the Yunnan Guizhou Plateau area’s deep mine. The main research contents, methods and key scientific problem are:(1) The basic researches to the tuff in the Yunnan Guizhou Plateau area , such as output characteristics , composition, physical and chemical properties ,etc. (2) With the sample’s chemical treatment, to design the contrast test, and with the microstructure characteristics and it’s changes during the expansion process obtained by microscopic observation, to reveal the relationship between the microstructure changes, micro mechanical process and the expansion and collapse. (3) The material and component causes of the tuff collapse and expansion will be studied by a variety of tests and chemical experiments, according to these causes , the material basis of the measures to prevent collapse could be provided. (4) Design series of chemical methods, to discuss the chemical characteristics and chemical principle of collapse and anti-collapse , to develop the anti collapse drilling fluid, and to discussed the anti sloughing mechanism by expansion and collapse mechanism.(5) Combined with the aforementioned methods and results, the key problem is to be discussed by electrochemical and micro mechanics: The mechanism of the tuff microlayer’s end part selectively blocking the hydrated ion. Finally ,the systematic results of the tuff expansion and collapse mechanism of the Yunnan-Guizhou Plateau region will be obtained.

高膨胀易垮塌凝灰岩问题长期困扰着生产活动，对膨胀垮塌机理做深入研究，方可更好地解决这些问题。拟基于前期的个例基础研究，对云贵高原地区高膨胀易垮塌凝灰岩的膨胀垮塌机理做深入研究。主要的研究内容、方法及关键科学问题为：（1）云贵高原地区凝灰岩的产出特征、成份组成、理化性质等基础研究；（2）通过样品化学处理设计对比试验，由显微观察研究微观结构特征及其在膨胀过程中的变化，揭示微观结构变化及微观力学过程与膨胀垮塌的关系；（3）由多种检测及化学试验设计研究膨胀垮塌的物质及成分原因，以之提供采取防塌措施的物质依据；（4）设计系列化学方法，讨论垮塌与防塌的化学特征、化学原理，研制防塌钻井液，并由防塌机理讨论膨胀垮塌机理；（5）结合前述方法和成果，由电化学及微观力学等综合讨论关键问题：凝灰岩微层片端部对水合离子团的选择性阻入机理。最终，获得云贵高原地区凝灰岩膨胀垮塌机理的系统化分类成果。

高膨胀易垮塌凝灰岩分布广泛，危害严重。项目以云贵高原地区软弱凝灰岩的膨胀垮塌机理为研究目标，采用了化学实验对比设计与多种检测手段相结合的方法，对多个地区凝灰岩样品的物质成分及演化、微观结构及孔隙变化、防塌钻井液的研制及原理等内容进行研究，做了大量工作，研究结论清楚，论据充分，理论与应用结合紧密，研究内容的完成度总体较好，具有良好的应用前景。研究表明：（1）高膨胀易分解凝灰岩中普遍含有大比例微片层状的强亲水性硅酸盐矿物，硅酸盐快速吸水是凝灰岩膨胀垮塌最重要的物质原因。硅酸盐矿物主要是粘土矿物和云母类矿物，占40%以上。（2）凝灰岩中普遍含有较大比例的黄铁矿，黄铁矿氧化后产生强酸，强酸不仅促使凝灰岩溶蚀风化，还使得凝灰岩内含有大量可溶盐，可溶盐在凝灰岩的骨架和胶结中有重要地位。盐快速溶解是凝灰岩分解的重要因素，阻止溶解可有效阻止分解。（3）硅酸盐微片吸水后微片卷曲、片间距增大，新孔隙大量产生，微片卷曲及水层插入微片间是膨胀的微观力学和结构因素。（4）凝灰岩的膨胀垮塌性与风化程度有关。除长石等易风化矿物的转化外，凝灰岩风化时云母类矿物向粘土矿物转化使得凝灰岩更易膨胀垮塌，黄铁矿氧化及强酸的溶蚀亦是风化演变中物质及结构变化的重要组成部分，由EDS分层测试及氧化模拟对比实验从微观和宏观上十分清楚地证实。（5）研制了防塌钻井液，并经接近实际应用的高压扰动实验证实非常有效。对防塌原理进行了研究，由此印证和反推膨胀垮塌机理。其中，成膜隔水防塌是对多个凝灰岩均有显著作用的首要防塌因素，阻溶防塌对部分凝灰岩具有重要作用但对已经高度水化强度极低的凝灰岩作用不明显，离子交换改性防塌对高粘土化凝灰岩有很好的效果。（6）静电场对带电盐离子防塌的影响有限，但可明显增强含带电离子隔水膜的防塌效果。凝灰岩对盐离子的选择性阻入机理为：除离子交换改性外，阻入本质上是阻止凝灰岩内的盐溶解而保持了凝灰岩的稳定性。