In this work, effective thermal conductivity (λ_Eff) of fractured rock masses was numerically investigated. A two-dimensional Discrete Fracture Network (DFN) model of the fractured rock masses was established based on the statistic results of natural fracture development in a potential area for high level radioactive waste disposal in China. Steady state heat transfer processes in the fractured granite rock masses were numerically simulated using finite element method (FEM). The calculated λ_Eff values of the fractured granite rock masses in dry and saturated conditions are 1.99 W/(m K) and 2.31 W/(m K), respectively. Compared with the thermal conductivity of intact granite [λ_Intact, 2.5 W/(m K)], the drop rates are 20.4% and 7.6%, respectively. Sensitivity analysis was conducted on the main model parameters including fracture density (F_Density), trace length (F_Length), thermal contact resistance (F_TCR), and λ_Intact. The results indicate the relation between λ_Eff and three fracture parameters (F_Density, F_length and F_TCR) can be fitted using power law or negative exponent functions with good consistency. When fracture network parameters remain unchanged, λ_Eff is in linear positive correlation to λ_Intact. The slop of the fitted line is determined by the fracture network parameters. Due to the fact that distribution of generated fractures in different directions are quite uniform, λ_Eff did not show significant difference in different directions. On the basis of the above-mentioned results, an estimation model was proposed for the determination of λ_Eff of fractured rock masses using P₂₁ (total length of fracture traces per unit area), F_TCR, and λ_Intact. The proposed estimation model shows good consistency to the calculated results of FEM model.

在这项工作中，对裂隙岩体的有效热导率 ( λ _Eff ) 进行了数值研究。根据我国高放废物处置潜力区天然裂缝发育统计结果，建立了裂缝岩体二维离散裂缝网络（DFN）模型。使用有限元方法 (FEM) 对破裂的花岗岩岩体中的稳态传热过程进行了数值模拟。在干燥和饱和条件下，断裂花岗岩岩体的计算λ _Eff值分别为 1.99 W/(m K) 和 2.31 W/(m K)。与完整花岗岩的导热系数相比 [ λ _Intact, 2.5 W/(m K)]，下降率分别为 20.4% 和 7.6%。对主要模型参数进行了敏感性分析，包括断裂密度（F _Density）、迹线长度（F _Length）、接触热阻（F _TCR）和λ _Intact。结果表明λ _Eff与三个裂缝参数（F _Density、F _length和F _TCR）之间的关系可以使用幂律或负指数函数拟合，具有良好的一致性。当裂缝网络参数保持不变时，λ _Eff与λ _Intact呈线性正相关。拟合线的斜率由裂缝网络参数决定。由于生成的裂缝在不同方向上的分布比较均匀，λ _Eff在不同方向上没有表现出显着差异。在上述结果的基础上，提出了利用P ₂₁（单位面积裂缝轨迹总长度）、F _TCR和λ _Intact确定裂隙岩体λ _Eff的估计模型。所提出的估计模型与有限元模型的计算结果具有良好的一致性。