层理方向对砂岩力学性质和渗透性的影响研究

Influence of Bedding Direction on Mechanical Properties and Permeability of Sandstone

层理方向对砂岩力学性质和渗透性具有显著影响。本文通过制备不同层理方向的砂岩试样,开展了力学性质和渗透率测试试验,探明了不同层理方向岩石的力学性质和渗透率的演化规律和演化机理。研究表明:不同α夹角的试样在受载-变形-破坏过程中均呈现显著的压密阶段、弹性阶段、屈服阶段和破坏阶段,α夹角越大,应力应变曲线越陡,压密阶段越不容易被辨别。砂岩的峰值强度随α夹角增大呈“先减小后增大”的倒U型关系,而砂岩弹性模量随α夹角增大呈近似线性关系;受载-变形-破坏过程中试样渗透率均随着α夹角的增大而逐渐减小,符合指数函数关系;数值模拟显示层理方向对流体压力和流线分布具有显著的影响,层理面上易形成优势流,进而影响不同层理方向试样的渗透率。

The bedding direction has a significant impact on the mechanical properties and permeability of the sandstone.Sandstone samples with bedding planes in different directions were prepared,mechanical property and permeability tests were carried out,and the evolution law and mechanism of mechanical properties and permeability of rocks in different bedding directions were clarified.The result shows that the samples with different α angles show significant compaction stage,elastic stage,yield stage and failure stage during the loading-deformation-failure process.With the greaterαangle,the stress-strain curve is steeper,and the compaction stage is harder to be identified.With the increase of α,the peak strength of sandstone shows an inverted U-shaped relationship of"first decrease and then increase",while the elastic modulus appears an approximate linear relationship with the increase of α angle.The permeability of decreases with the increase of α angle during the loading-deformation-failure process,which conforms to the exponential function relationship.The numerical simulation shows that the bedding direction has a significant influence on the fluid pressure and streamline distribution.The dominant flow is easy to form on the bedding surface,which is the main cause to affect the permeability of rocks with bedding planes in different directions.