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目的:探索核废料地质处置库近场岩体在热源(核素衰变产生热量)和裂隙水流动影响下的应力和变形规律,为处置库的安全评估提供理论基础。创新点:针对包含内热源和饱和裂隙水流动的岩体,提出一种稀疏裂隙岩体水流传热过程中热应力及位移的半解析计算方法,并将该方法应用于核废物处置库近场裂隙岩体温度、热应力和位移的分布特征分析。方法:首先根据热弹性位移势法建立拉普拉斯变换域内的基本积分方程,然后将裂隙离散化,利用数值积分方法计算不含奇点的裂隙单元积分,采用解析法计算包含奇点的单元积分,再根据拉普拉斯数值逆变换将热弹性位移势转换到时间域中,最后利用中心差分法计算热应力和位移。结论:1.在处置库运营早期,岩石受分布热源影响而产生热膨胀区域的范围(即受压区域)较为有限;2.核素在经过长期的衰变过程后,热流强度大幅降低,使得处置库近场岩石中仅有热源附近的极小部分岩石为受压区域;3.裂隙水的流动传热作用使得处置库下游的温度峰值更高,且裂隙水流速越大,流动传热作用越明显,裂隙水流速对热应力和位移的影响与温度类似;4.过小的热源间距会使不同热源间传热作用叠加,从而导致处置库近场的温度、热应力和位移峰值急剧增大。
Objective: To explore the stress and deformation rules of near-field rock mass in nuclear waste geological repository under the influence of heat source (heat generated by decay of nuclide) and fissure water flow, and provide a theoretical basis for the safety assessment of repository. Innovative point: Aiming at the rock mass containing internal heat source and saturated fissure water flow, a semi-analytical method to calculate thermal stress and displacement in the process of water flow in sparse fissured rock mass is proposed. The method is applied to near field of nuclear waste repository Distribution Characteristics of Temperature, Thermal Stress and Displacement of Fractured Rock Mass. Methods: Firstly, the basic integral equation in Laplace transform domain was established according to the thermoelastic displacement potential method. Then the fractures were discretized, the integrals of fractured cells without singular points were calculated by numerical integral method, and the singular points Integral, and then according to Laplace inverse numerical transform the thermo-elastic displacement potential into the time domain, and finally calculate the thermal stress and displacement using the center difference method. In the early stage of the operation of the repository, the range of the thermal expansion zone affected by the distributed heat source is limited (that is, the area under pressure) is limited; 2. The radionuclide intensity is greatly reduced after the radionuclide decay process for a long time, Only a small part of the rocks near the heat source in the near-field rock are the pressure-bearing areas; 3) the heat transfer of fissure water makes the temperature peak downstream of the reservoir higher, and the greater the fissure water flow rate, the more obvious the heat transfer is The effect of fissure water flow velocity on thermal stress and displacement is similar to that of temperature. 4. Too small heat source spacing will add heat transfer between different heat sources, resulting in a dramatic increase in temperature, thermal stress and displacement peaks in the near field of the repository.