软岩巷道围岩微观结构与三轴变形性能试验研究

Experimental Study on Microstructure and Triaxial Deformation Performance of Surrounding Rock in Soft Rock Roadway

辽宁铁法能源有限公司小康矿S_(2)S_(2)巷道开挖后发生较大的围岩变形,为了深入探究围岩变形机制,通过XRD、SEM和三轴试验等方法对顶板围岩的矿物成分、微观结构以及宏观力学特性进行了较为深入的研究,试验结果表明:(1)微观实验表明:围岩中砾岩和粉质砂岩晶体结构致密,胶结方式主要为钙质胶结和泥质胶结;对于砂质泥岩微观晶体结构呈片状结构,晶簇边界弯曲,结构致密,孔隙不发育。泥岩微观结构呈粒状分布,其结构松散,晶体结构单元间呈面-面接触、点-面接触等形态;(2)三轴试验结果表明:围岩岩样的主要破裂形式是剪切破坏,破坏形式相对单一。同时,三轴试验所得全应力应变曲线显示围岩试样具有较强的蠕变特性,岩体的变形呈现剪胀形态,在轴压作用下,试件内部沿着剪应力最大面发生剪切滑移。上述结论为揭示S_(2)S_(2)巷道顶板围岩变形失稳提供了一定的理论支持,为选择合适锚固结构提供了较好的理论支撑。

Large deformation of surrounding rock occurred after the excavation of S_(2)S_(2) roadway in Xiaokang Mine of Liaoning Tiefa Energy Co.,Ltd.In order to further explore the deformation mechanism of surrounding rock,the mineral composition,microstructure and macroscopic mechanical properties of roof surrounding rock were studied by means of XRD,SEM and triaxial test.The results show that:(1)Microscopic experiments show that the crystal structure of conglomerate and silty sandstone in surrounding rock is compact,and the cementation mode is mainly calcareous cementation and argillaceous cementation.The microscopic crystal structure of sandy mudstone is distributed in flakes,the boundary of crystal clusters is curved,the structure is dense,and the pores are not developed.The microstructure of mudstone is granular distribution,the structure is loose,and the crystal structure units are in the form of surface-surface contact and point-surface contact.(2)The results of triaxial test show that the main failure mode of surrounding rock samples is shear failure,and the failure mode is relatively single.At the same time,the full stress-strain curve obtained from the triaxial test shows that the surrounding rock sample has strong creep characteristics,and the deformation of the rock mass presents a dilatancy pattern.Under the action of axial compression,the shear slip occurs inside the specimen along the surface with the maximum shear stress.The above conclusions provide some theoretical support for revealing the deformation and instability of surrounding rock of S_(2)S_(2) roadway roof,and provide a good theoretical support for selecting appropriate anchorage structure.