稀疏裂隙岩体水流-传热模拟与高放射核废处置温度预测研究

Processes involving water flow and heat transfer in sparsely fractured rocks are commonly encountered in several disciplines of engineering, such as geological disposal of nuclear wastes and geothermal development. For deep geological disposal of high level nuclear wastes,heat transfer in saturated sparsely fractured rocks is not only related to the physical properties and configurations of the rock blocks, but also influenced by the configuration, velocity and flux volume of water flow in the fractures,and it is necessary to carry out thermal loading design and temperature prediction based on water flow and heat transfer analyses. This research is to develop theoretical models and computational methods for water flow and heat transfer and for predition of disposal temperature of high level nuclear waste repository in sparsely fractured rocks,through the following aspects of studies:① Experiments of 3-D water flow and heat transfer in a meter-scale sparsely fractured rock model; ② Characteristics and theoretical model of heat exchange between fracture water and rock matrix, heat transport features of different configurations of water flow in the fractures, influence of water velocity and flux volume on the mode of heat transfer in rock mass,conditions for applicability of the instantaneous local thermal equilibrium assumption and various equivalent continuum heat transfer models; ③ Semi-analytical models and computational methods; ④ Rules of control for numerical discretizations of fracture planes,heat exchange between fracture water and rock matrix, and for artificial cut-off boundary selection; ⑤ Simulation theory for water flow and heat transfer processes at various (disposal hole,drift,zone,repository) scales of high level nuclear waste disposal.

核废地质处置、地热开发等工程领域都经常涉及稀疏裂隙岩体水流-传热过程。对于高放射核废地质处置而言，稀疏裂隙岩体中的传热过程既与岩块构形和热物理性质有关，又受到裂隙水流形态、速度和流量的影响，需要在水流-传热分析的基础上，进行处置荷载设计和处置温度预测。项目研究的目标是：建立饱和稀疏裂隙岩体水流-传热分析与高放射核废处置温度预测的理论模型和计算方法。内容主要包括：① 米尺稀疏裂隙岩体模型的三维水流-传热试验；② 裂隙水与岩石之间的热交换特征，不同裂隙水流构形的传热特征，裂隙水流速和流量对岩体传热模式的影响，裂隙水-岩石热交换模型和计算方法，瞬时局部热平衡假设的适用条件，等效连续介质传热模型的适用条件；③ 稀疏裂隙岩体三维水流-传热的半解析模型和计算方法；④ 裂隙面数值离散、裂隙水-岩石热交换数值离散、数值截断边界选择的控制原则；⑤高放射核废处置孔、巷道、区、库尺度水流-传热的模拟理论。

针对高放射核废处置库近场的水流-传热-应力问题，取得了以下研究成果：提出了壁面局部接触裂隙岩体水流-传热的理论模型，建立了稀疏裂隙岩体水流-传热、热应力、全应力-全位移的三维理论模型和半解析计算方法，进行了裂隙水流-传热对高放废物处置库近场温度影响的三维离散元分析，进行了稀疏不规则填充裂隙岩体水流-传热-应力模型试验与离散元模拟。这些研究成果揭示和解释了裂隙方位和水流速度对岩石温度、热应力、全应力-全位移的影响方式，发展了裂隙岩体水流-传热-应力耦合的理论模型和计算方法，可以为高放射核废地质处置库的行为分析提供参考。