粗糙裂隙水、气两相流相对渗透系数模型与数值分析

粗糙裂隙水、气两相流相对渗透系数是岩体工程多相渗流以及水力耦合分析的重要参数。从粗糙裂隙的细观结构出发,基于毛细吸持理论和立方定理,提出了粗糙裂隙水、气两相流相对渗透系数模型。通过与具有不同空间分布的粗糙裂隙水、气两相流试验数据对比分析,验证了模型的准确性。为进一步验证理论模型对不同粗糙程度裂隙的适用性,基于SRAM与Invasion Percolation模型,提出了粗糙裂隙的开度分布生成以及水、气两相流数值分析方法,计算结果表明理论模型与数值数据基本吻合一致,且优于X模型、V-C模型以及Corey模型。

Relative permeability model for water-air two-phase flow in rough-walled fractures and numerical analysis

The relative permeabilities for water-air two-phase flow in rough-walled fractures of rock are significant parameters on multiphase flow and hydro-coupling analysis in fractured rock engineering. According to the capillary theory and cubic law, the rough-walled fractures are conceptualized as a large number of parallel plates of different apertures, and a relative permeability model for water-air two-phase flow in rough-walled fractures is proposed on the basis of micro structure of rough-walled fractures. The theoretical model is validated by the comparison with experimental data from two different rough-walled fractures with distinguished spatial distributions. No matter for water phase or air phase, the proposed model can satisfy the experimental data better than X model, V-C model and Corey model. In order to evaluate the feasibility of the proposed model on rough-walled fractures with different spatial distributions, a numerical approach is developed to generate the aperture distribution based on random successive addition method, and to perform water-air two-phase flow process based on the invasion percolation model, respectively. On the basis of a large number of numerical results, predictions of the proposed model are consistent with the calculated data and presents better goodness of fit than X model, V-C model and Corey model. This more reliable analytical model can be used for better understanding the multiphase flow and hydro-coupling analysis in fractured rock.