煤岩微观力学特性与宏观力学特性关系密切,是剖析宏观力学性质机理的关键指标,也是 影响煤层气压裂开采的重要因素。 现阶段煤岩微观力学特性研究局限于力学参数表征与现象描 述,演化机制及影响机理方面的研究较为缺乏。 以我国不同变质程度煤岩为研究对象,通过以纳米 压痕实验为主,低温液氮与原位激光拉曼测试为辅的手段,实现了纳米压痕实验关键参数优选,并 明确了煤岩镜质组与惰质组微观力学特性及其主控因素。 研究结果表明:1 预实验结果显示,低 载荷、小量程下,最大压入深度在 1 000 nm 左右(对应峰值载荷约为 9 mN)的参数设定较为适合煤 岩镜质组和惰质组的纳米压痕实验;2 煤岩惰质组的弹性模量和硬度均普遍高于镜质组,且同一 煤样中不同位置显微组分的弹性模量和硬度相近,说明在局部范围内煤基质显微组分的微观力学 性质分布具有一定相似性;3 煤岩显微组分和成熟度通过控制孔隙结构与化学结构以“一主一辅” 形式共同影响其微观力学性质,即镜质组微观力学强度随煤化程度加深先升后降再升,下降段主要 受因气孔增多导致的孔隙结构变化影响,上升段化学组分和结构为主控因素;惰质组的微观力学性 质随煤岩成熟度升高持续增加,始终以受化学组分和结构控制为主。 煤岩微观力学性质研究可广 泛运用于微观尺度下的煤基质变形机制分析、水力压裂过程中微裂缝的产生与拓展探究以及开发 有利区优选。

The microscopic mechanical properties of coal are closely related to its macroscopic mechanical properties. They are key indexes for analyzing the mechanism of macroscopic mechanical properties and important factors affect- ing the fracturing of coalbed methane(CBM). At present,the research on the micromechanical properties of coal is limited to mechanical parameter characterization and phenomenon description,and the evolution mechanism and influ- ence mechanism is lack of research. Taking the coals with different metamorphic degrees in China as research objects,the key parameters of nanoindentation experiment are optimized,the microscopic mechanical properties and main controlling factors of vitrinite and inertinite of coal are clarified by means of nanoindentation experiment,liq- uid nitrogen adsorprtion and in-situ laser Raman test. The research shows that: 1 The pre-experimental result shows that the parameter setting of the maximum indentation depth of about 1 000 nm(corresponding to the peak load of about 9 mN) is more suitable for the nanoindentation experiment of coal vitrinite and inertinite under low load and small range. 2 The elastic modulus and hardness of inertinite are generally higher than vitrinite,and the elastic modu- lus and hardness of macerals at different positions in the same coal are similar,indicating that the distribution of me- chanical properties of coal matrix macerals in the local range has certain similarity. 3 The macerals and maturity of coal affect its micro-mechanical properties by controlling the pore structure and chemical structure in the form of “one main and one auxiliary”,that is,the micro-mechanical strength of vitrinite increases first,then decreases and then increases with the deepening of coalification degree. The descending section is mainly affected by the change of pore structure caused by the increase of gas pores,and the chemical composition and structure of the ascending sec- tion are the main controlling factors. The micro-mechanical properties of inertinite increase with the increase of coal maturity,and are always controlled by chemical composition and structure. The study of micro-mechanical proper- ties of coal can be widely used in the analysis of deformation mechanism of coal matrix at micro-scale,the generation and expansion of micro-cracks during hydraulic fracturing,and the optimization of favorable development areas.