中文摘要：

为分析胶结砂岩的力学响应和破坏机理，基于试验建立不同刚度比的三维颗粒流数值模型，验证数值模型的可行性，并分析不同胶结性状的砂岩力学响应，进一步说明胶结物质的重要作用及模型的适用性。分析颗粒接触刚度比和平行黏结刚度与颗粒接触刚度的比值变化时，砂岩的应力比、体应变、配位数和平行黏结破坏数的变化规律以及对模型的泊松比、初始刚度和延性的影响。结果表明：不同的颗粒刚度比对岩样宏观力学响应的影响不同，颗粒接触刚度比越小，且切向刚度越大时，胶结砂岩的脆性越强；平行黏结刚度与颗粒接触刚度的比值越大，脆性越强，黏结破坏越容易，剪切破坏越明显。颗粒刚度对胶结砂岩的力学响应和变形能力有重要的影响，是实际储层砂岩力学模拟选择有效细观参数和构建本构关系的关键。

英文摘要：

For determining the mechanical parameters and failure mechanism of cemented sandstone, based on experiments, a mi-cromechanical method based on 3-D particle flow code （PFC3D） was proposed to simulate the gradual failure process considering dif-ferent particle stiffness ratios to verify the feasibility of the numerical model. The mechanical response of sandstone with different ce-mented materials was analyzed to further indicate the significance of cemented materials and the applicability of the numerical model. Considering changes in the particle stiffness ratio and the ratio of parallel bond stiffness to particle stiffness, the stress ratio, volume strain, coordination number and number of broken parallel bonds changing with axial strain were discussed and their influences on the Poisson’s ratio, initial stiffness and ductility were deeply investigated for the cemented sandstone. Simulation results show that different stiffness ratios have different influences on the micromechanical response of the cemented sandstone. Especially with the decrease in particle stiffness, when the tangential stiffness is larger, the cemented sandstone is more brittle. The larger the ratio of parallel bond stiffness to particle stiffness, the greater the brittleness is, and shear failure is more prone to appear in the cemented sandstone. It is concluded that particle stiffness plays a significant role on the mechanical behavior and deformation ability of the cemented sandstone, and especially is very important to choose micro-parameters and construct a constitutive relation in 3-D numerical modeling for practical reservoir sandstone.