神东侏罗纪砂岩微观结构对其力学性质及声波传播速度的影响

Influence of Jurassic sandstone microstructure on the mechanical properties and acoustic velocity in Shendong mining area

为了分析神东侏罗纪砂岩微观结构对其力学性质及声波传播速度的影响,利用偏光显微镜、岩石力学试验系统对砂岩进行研究,同步测定砂岩声波传播速度。结合数理统计方法建立宏观力学特性、声波速度与砂岩内部微观结构之间的定量关系。结果表明:随着碎屑颗粒粒径增加和不均匀系数增大,砂岩的单轴抗压强度、弹性模量和应变相应减小,其力学性质呈减弱的趋势,而泊松比变化趋势不明显;同时随着砂岩碎屑颗粒粒径增加和不均匀系数增大,声波速度也相应减小;对比发现,同一岩石类型侏罗纪煤系砂岩单轴抗压强度与碎屑颗粒平均粒径之间的关系和石炭-二叠纪煤系砂岩相反。

In order to analyze the influence of Jurassic sandstone microstructure on its mechanical propertiesand acoustic velocity, the sandstones from Shendong mining area were studied by using polarizing microscopeand rock mechanics test system. Acoustic velocity of sandstones was tested simultaneously. The quantitative correlations between macroscopic mechanical properties,acoustic velocity and sandstone microstructure were established on the basis of the mathematical statistics method. The results showthat the mechanical propertiesbecome weak witli the increase of clastic particle size and non-uniform coefficient of sandstones, i. e. , uniaxialcompressive strength,elastic modulus and strain decrease accordingly. The alteration of Poisson’s ratio is notsignificant and the acoustic velocity decreases correspondingly. By contrast, the correlation between uniaxial compressive strengtii and clastic particle size of sandstones in Jurassic coal measures is found be opposite to Carboniferous-Permian sandstones in the same type of rocks.