孔隙数量及空间分布对砂岩三轴抗压强度影响分析

Analysis of the impact of quantity and distribution of pores on the three-axis strength of sandstone

为了弥补三轴压缩状态下孔隙岩石三维建模的缺陷,以砂岩为研究对象,通过对取样砂岩加工的标准圆柱试样进行试验,得到砂岩的力学参数及孔隙率,使用FLAC3D软件及自带的FISH语言建立与实际砂岩孔隙率相等的砂岩标准圆柱试样随机孔隙模型。以此模型为基础,应用数值模拟试验方法,通过三轴模拟试验进行孔隙数量和孔隙空间分布对孔隙砂岩强度影响的研究。结果表明:随着孔隙数量增加,孔隙率增大,砂岩三轴抗压强度降低,同一围压下的三轴抗压强度呈现指数递减趋势,并得出了拟合公式;孔隙率不变时,不同孔隙空间分布模型的三轴抗压强度误差在5%以内,即可认为孔隙空间分布对砂岩三轴抗压强度没有明显影响。研究结果可为孔隙岩石三轴抗压强度评价提供参考。

In order to make up for the defects in the establishment of three-dimensional pore rock model under a three-axis compressed state.The sandstone was served as the research subject,and the mechanical parameters and porosity were obtained through the triaxial test of standard cylinder specimen.Then FLAC3D and FISH language were used to model the standard cylinder specmen with random pores,and its porosity was equal to that of the actual sandstone.Based on this model,the impact of quantity and distribution of pores on the strength of sandstone was studied by three-axis numerical simulation.The results showed that with the increase of pore quantity,the porosity increased,while the triaxial compressive strength of sandstone decreased on an exponential decline trend under the same confining pressure,and the fitting formula was given;As the porosity was constant,the triaxial compressive strength error of the model with different pore space position distribution was within 5%,it could be considered that pore distribution effected the strength of sandstone slightly.The achieved results supplied references for the influence of porous rock on triaxial compressive strength.