柳江盆地内赋存石炭二叠纪、侏罗纪两个煤田，盆地成煤后经历了多个期次的岩浆侵入、喷发活动，岩浆活动对煤层及其围岩产生了改造作用，为了探究盆地内岩浆活动对石炭二叠系主力煤田煤层顶板岩石力学特征的影响，进而为煤层顶底板稳定性评价、矿井设计以及采掘设备的选型等提供岩石力学参数，为具有相同或相似地质条件的煤田提供参考。首先，从盆地内岩浆侵入模式入手分析其对煤层顶板的影响;然后，根据古火山口的大概位置，结合盆地构造特征部署勘查工程，详细开展地面地质调查、岩芯地质钻探、岩芯精细地质编录和工程地质编录;之后选择4条主干剖面上的11个钻孔，对钻孔揭露3煤层及其顶板不同岩浆岩侵入位置的岩性、相同侵入位置不同岩性的岩石进行系统的岩石力学和煤岩分层采样和测试分析;最后，对比分析、综合评价盆地内岩浆岩侵入对煤层及其顶板岩石力学的影响，并根据评价结果指出矿井开采存在的工程地质问题和采掘设备选型应注意的问题。结果表明，盆地内侏罗纪多期岩浆的喷发、侵入对煤层顶板产生了不同程度的改造作用，形成了吞噬、侵入、复合和原生强化型以及原生型5种直接顶板岩性组合类型;3煤层的顶板岩性以闪长玢岩侵入-吞噬型为主，侵入型顶板次之、复合型及原生型顶板局部分布;岩浆侵入、烘烤、填充及挤压等综合效应强化了煤层顶板的工程地质特征，表现为密度增加，孔隙度、含水率的降低，抗压强度、抗剪强度、岩体的完整性等关键力学参数增强;根据钻孔和井巷道揭露在盆地内初步圈定了5个岩浆吞噬区，且均位于古火山口或岩浆喷出通道位置上，沿着吞噬区向外煤层顶板类型逐渐递变为侵入、复合、原生带，在平面上具有环带状分布的规律;在矿井设计中吞噬区可以作为矿井关键硐室的理想选择位置，在开采过程中吞噬区是决定矿井能否正常生产的关键因素，复合型顶板区域是顶板事故的多发区，侵入区域的顶板存在坚硬顶板长期悬顶，需要采用人工强制放顶措施，是矿井冲击地压管理的重点区域，也是盆地内矿井安全生产的关键问题;原生区域中等-易于冒落顶板;在矿井设备选型中一定要考虑岩浆侵入对煤及其顶板岩石力学特征的强化作用，为了保证矿井正常开采，在工作面回采前需要对工作面内火成岩夹矸、吞噬体及其改造后的坚硬煤体进行有效的探查和超前预处理。

There are two coalfields of CarboniferousPermian and Jurassic in Liujiang Basin.The basin experienced several periods of magmatic intrusion and eruption after coal formation,and the magmatic activities had transformed coal seams and their surrounding rocks.This study investigates the influence of magmatic activity on the mechanical characteristics of coal seam roof in the main carboniferous and Permian coalfields in order to provide rock mechanics parameters for the stability evaluation of coal seam roof and floor,mine design and equipment selection,and also provide reference for coalfields with the same or similar geological conditions.Firstly,the influence of magma intrusion and eruption mode on coal seam roof in the basin is analyzed.Then,according to the approximate location of the ancient crater and the structural characteristics of the basin,the exploration project will be deployed to carry out surface geological survey,core geological drilling,core fine geological logging and engineering geological logging in detail.Subsequently,11 boreholes on 4 main sections are selected,and the systematic rock mechanics and stratified sampling and test analysis of coal and rock are carried out on the rocks exposed by boreholes at different magmatic rock intrusion positions of coal seam 3 and its roof,and on the rocks of the same intrusion position and different lithology.Finally,the influence of magmatic rock intrusion on coal seam and roof rock mechanics in the basin is comparatively analyzed and comprehensively evaluated,and the engineering geological problems existing in mining and the problems that should be paid attention to in the selection of mining equipment are pointed out according to the evaluation results.The results show that the multiple eruption and intrusion of Jurassic multi-stage magma in the basin have altered the roof of coal seam to various degrees,forming five types of direct roof lithologic association:phagocytosis,invasion,recombination,primary strengthening and primary type.The roof lithology of coal seam 3 is dominated by diorite porphyrite intrusion-phagocytosis type,followed by intrusive roof,compound roof and primary roof.The comprehensive effects of magma intrusion,baking,filling and extrusion have strengthened the engineering geological characteristics of coal seam roof,which are shown as increasing density,decreasing porosity and water content,and enhancing key mechanical parameters such as compressive strength,shear strength and rock mass integrity.According to the drilling and mine roadway exposure,five magma phagocytosis zones have been preliminarily delineated in the basin,all of which are located in ancient volcanic vents or magma ejection channels.Along the phagocytosis zone,the roof type of coal seam gradually changes into intrusive,composite and primary zones,with a ringshaped distribution rule on the plane.In the mine design,the gobup area can be used as the ideal location for the key chamber of the mine.In the mining process,the gobup area is the key factor that determines whether the mine can normally be operated.The compound roof area is the area where roof accidents frequently occur.The roof in the intruded area has a hard roof hanging for a long time.It is necessary to adopt manual forced roof caving measures.It is the key area for the management of mine rock burst and the key problem for the safe production of the mine in the basin.The primary area is mediumprone to roof caving.In the selection of mine equipment,the strengthening effect of magma intrusion on the mechanical characteristics of coal and its roof rocks must be considered.In order to ensure the normal mining of the mine,the effective exploration and advanced pretreatment of igneous rock dirt bands,phagocytes and reformed hard coal in the working face must be carried out before mining.

1 地质概况

    1.1 地层及构造特征

    1.2 岩浆活动特征

2 煤层顶板岩石力学特征

    2.1 煤层直接顶板划分方法

    2.2 直接顶板组合类型

    2.3 直接顶板岩石力学特征

3 综合评价

    3.1 评价参数选择

    3.2 评价方法

    3.3 评价结果

4 结论与讨论