摘要
研究了澜沧老厂铅矿遇水快速膨胀垮塌型凝灰岩的微观结构,通过扫描电镜观察,对比分析了干凝灰岩、缓慢吸水凝灰岩和浸水处理凝灰岩的SEM图像,在观察凝灰岩的裂缝孔隙特征基础上,分析了凝灰岩膨胀过程中裂缝孔隙的变化、水的流动过程和分解垮塌速度较快的原因,进而讨论了凝灰岩的膨胀机理.研究表明,仅在湿润环境长时间放置后,凝灰岩中才有疏松的水合结晶物,快速浸水凝灰岩中无明显的水合结晶现象,由水合结晶导致的凝灰岩膨胀不具有普遍性,不是凝灰岩快速膨胀分解的主要原因.凝灰岩中普遍存在微片状结构的高岭土,由计算毛细管力的平行板模型可知,微小的片间距使得片间毛细管力较大,导致普遍和强烈的毛细吸水,吸水后微片发生卷曲,片间距剧增并产生大量微孔隙和微裂缝,以致凝灰岩快速膨胀和在水中快速分解垮塌.因此,广泛存在的亲水的片状结构强烈吸水并卷曲,是凝灰岩遇水膨胀垮塌的主要原因.
In this paper,the microstructure of quickly collapse type tuff of Lancang Laochang Lead Mine is researched.Scanning electron microscopic observation is adopted to compare and analyze the SEM images of the dry tuff,the slowly water wetted tuff and the quickly water immersed tuff.Based the crack and pore characteristics of the tuff,the changes of the crack and pore,the water flow process and reasons for the quick collapse are then studied to discuss the expansion mechanism.It is shown through the researches that,the crystalline hydrate only appear after the tuff has been placed in moist environment for a long time,and that the tuff expansion caused by the crystalline hydrate is not universal,therefore,the growth of crystalline hydrate is not the main reason of the tuff＇s expansion.It is also shown that the kaolin which has micro lamellar structure exist in tuff widely.Through the computation of the capillary force by the parallel plate model,it is found that the very small distance between the lamellar leads to the large capillary force,and that the widely existence of hydrophilic lamellar structure causes the wide and strong capillary absorption.After the water absorption,the slice become curly,the distance between the lamellar grows and lots of pore and crack come into being,which causes the tuff collapse in the water quickly.The strong water absorbent and curl of the wide existence of hydrophilic lamellar structure is the main structure reason of the expansion and collapse of the tuff.
出处
《昆明理工大学学报（自然科学版）》
CAS
北大核心
2012年第5期5-10,共6页
Journal of Kunming University of Science and Technology(Natural Science)
基金
国家危机矿山接替资源找矿项目(20089943)
关键词
凝灰岩
膨胀机理
微观结构
毛细管力
tuff
expansion mechanism
microstructure
capillary force
