Experimental Study on Microstructure and Triaxial Deformation Performance of Surrounding Rock in Soft Rock Roadway
Large deformation of surrounding rock occurred after the excavation of S2S2 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 S2S2 roadway roof,and provide a good theoretical support for selecting appropriate anchorage structure.
Rock mechanicsMicrostructureMechanical propertiesTriaxial test
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