泥质软岩锚固孔钻渣泥化黏附特征及影响因素

Characteristics of argillization and adhesion and influencing factors of drilling cuttings in borehole of roadway in soft argillaceous surrounding rock

  • 摘要: 锚固孔钻进是煤矿巷道围岩锚固控制的必经环节,成孔质量直接影响锚固施工效率以及锚固剂与围岩界面的锚固黏结作用。泥质软岩锚固孔钻进时存在抱钻、卡钻现象,钻渣遇水泥化难以排出是制约其快速高质量成孔的瓶颈。因此,笔者利用理论分析及实验室试验方法,对含高岭石泥质软岩锚固孔钻渣泥化黏附机理及影响因素展开了研究。结果表明:高岭石晶层表面电负性较强的氧原子会吸附水分子中的氢原子形成氢键,并不断吸水扩层,最终形成多层水分子的“水膜”。钻渣表面高岭石黏粒对水的吸附作用,使钻渣同样被“水膜”包覆,同时随着非泥质矿物的不断溶解以及钻渣颗粒的吸水膨胀,钻渣颗粒间距缩小,极易被彼此“水膜”间范德华力捕获,使彼此聚集形成黏聚体。钻渣自身“水膜”与钻头表面产生的静电力以及与钻头表面“水膜”形成整体结构的界面张力作用是造成钻渣黏附的主要原因,其中静电力在钻渣泥化黏附过程中发挥了重要作用。钻渣泥化程度随钻渣粒径、液渣比、钻具搅拌转速及时长、K+离子浓度的增加而降低,酸性溶液也会对钻渣泥化产生抑制作用。试验范围内各因素对钻渣泥化抑制的显著程度按照由大到小的顺序依次为:液渣比、钻渣粒径、搅拌时长、搅拌转速、pH值及K+离子浓度。提出了钻渣泥化抑制对策,调整钻头结构,提高进液压力,增加钻具成孔转速,调整钻进液组分,可削弱泥质钻渣与水的泥化反应程度,降低其对钻具的黏附作用。研究成果可为提高泥质软岩锚固孔成孔质量、成孔效率及锚固支护效果提供一定理论参考。

     

    Abstract: Borehole drilling is an essential step for the anchoring control of roadway surrounding rock of coal mines. The efficiency of bolt installation and bonding effect between resin-rock interface are closely related to the quality of borehole formation. When borehole drilling in argillaceous surrounding rock, the phenomenon of drill sticking and drill jamming exists, and it is difficult to discharge the drilling cuttings when occurring argillization, which is the bottleneck restricting rapid and high-quality formation of borehole. Therefore, by using theoretical analysis and laboratory test methods, this paper studied the mechanism of argillization and adhesion and influencing factors of the drilling cuttings in the borehole of soft argillaceous surrounding rock containing kaolinite. The results show that the oxygen atoms with strong electronegativity on the surface of kaolinite crystal layer adsorb hydrogen atoms in water molecules to form hydrogen bonds, and constantly absorb water molecules to expand the water layer, and finally form a "water film" of multi-layer water molecules. The adsorption of water by kaolinite clay on the surface of drilling cuttings makes the drilling cuttings also coated by "water film". At the same time, with the continuous dissolution of non- argillaceous minerals and the swelling of drilling cuttings particles, the spacing between drilling cuttings particles is reduced, which is easily captured by van der Waals forces between each other 's water films, so that they aggregate to form aggregates. The main reason for the adhesion of drilling cuttings is that the drilling cuttings is subjected to the electrostatic force generated by its own "water film" and the surface of the drill bit and the interfacial tension of the overall structure formed by the "water film" on the surface of the drill bit. The electrostatic force plays an important role in the process of argillization and adhesion of drilling cuttings. The degree of argillization of drilling cuttings decreases with the increase of particle size of drilling cuttings, solid-liquid ratio, stirring speed and time of drilling tool, and K ion concentration. Acidic solution will also inhibit the mudding of drilling cuttings. The significant degree of each factor on the inhibition of drilling cuttings argillization in the test range is in the order: solid-liquid ratio, particle size of drilling cuttings, stirring time, stirring speed, pH value and K ion concentration. The countermeasures to suppress the argillization of drilling cuttings are put forward. such as adjusting the structure of the drill bit, increasing the liquid inlet pressure, increasing the rotation speed of the drilling tool, and adjusting the composition of drilling fluid can weaken the degree of argillization of argillaceous drilling cuttings and water, and reduce the adhesion to the drilling tool. The research results can provide a theoretical reference for improving the quality, efficiency and anchoring support effect of the boreholes in soft argillaceous surrounding rock.

     

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