Relationship between pore structural characteristics and physical-mechanical properties of sandstone in Shendong mining area

LI Huamin; LIANG Yafei; CHEN Jiangfeng; LI Huigui; CHEN Xiangqi

Abstract：In order to study the effect of pore structure on the mechanical properties of sandstone in Shendong mining area,the rock composition,microstructure and pore characteristics were obtained by polarizing micro-scope,scanning electron microscope,and nuclear magnetic resonance.Based on uniaxial compressive tests of sandstone with different types,the relationship between microstructure characteristics of sandstone and its uni- axial compressive strength,elastic modulus and poisson’s ratio was analyzed emphatically.The results showed that the main components of sandstone are quartz and feldspar,in which the content of quartz is above 15% , the content of feldspar is more than 40% ,and there is a small amount of mica.Siltstone is calcareous cementa-tion,fine grained sandstone and medium grained sandstone are argillaceous cementation;The pore diameter and particle diameter of sandstone basically obey normal distribution;The surface of siltstone is smooth and dense, with nebulous grain boundary,while small pores are distributed on the surface of fine-grained sandstone.The pore structure of middle grained sandstone is developed with cluster shape,and the degree of cementation is poor.The relationship between compressive strength and porosity of sandstone shows a negative exponential re-lationship.There is a critical point on the curves of compressive strength and porosity of sandstone,and the critical porosity increases with the increase of particle size and pore diameter;The elastic modulus of sandstone is negatively correlated with its porosity,in which the elastic modulus of siltstone and fine sandstone decreases exponentially,while the elastic modulus of the middle grained sandstone varies linearly; Poisson’s ratio of sandstone is not significantly associated with its porosity.