稀疏裂隙岩体三维饱和水流—传热及热应力半解析计算方法研究与应用

发布时间：2018-04-26 18:33

本文选题：裂隙岩体 + 饱和水流　；参考：《北京交通大学》2014年博士论文

【摘要】：高放射性核废物地下深埋处置、石油和天然气及其它矿产资源的开采、地热能源的开发等众多工程领域,都涉及裂隙岩体中的水、热、力及化学等多场耦合问题。本文研究了饱和稀疏裂隙岩体三维水流-传热过程中温度场和应力场的半解析计算方法,并用该方法计算分析了高放核废物地质处置库近场裂隙岩体的温度与热应力分布特征。主要的研究内容和成果包括： (1)单裂隙岩体三维饱和水流-传热模型中温度场的半解析计算方法和影响因素分析：提出了由分布热源、饱和单裂隙和两侧无限大岩石构成的三维水流-传热简化模型,建立了单裂隙岩体三维饱和水流-传热问题中温度场的半解析计算方法,编写了相应的计算程序,与仅考虑岩石沿裂隙面法向一维热传导的解析解进行了对比；计算分析了分布热源作用下饱和单裂隙岩体的三维渗流-传热特征及其对裂隙水流速、岩石热传导系数和热源热流集度的敏感度。单裂隙岩体三维水流-传热半解析计算方法与解析法得到的结果基本一致,但由于半解析计算方法考虑了岩石的三维热传导,计算所得裂隙水上游温度相对较低,下游温度相对较高；在裂隙水的流动传热作用下,分布热源对裂隙水温度和岩石温度的影响在裂隙水流的下游区域比较显著。 (2)稀疏裂隙岩体三维饱和水流-传热模型中温度场的半解析计算方法和算例分析：提出了由分布热源、饱和稀疏裂隙和岩石构成的简化模型,建立了稀疏裂隙岩体三维饱和水流-传热问题中温度场的半解析计算方法,编写了相应的计算程序,并通过三个算例分析了不同条件下饱和稀疏裂隙岩体受分布热源作用影响的三维水流-传热特征。结果表明,裂隙几何分布对稀疏裂隙岩体中的温度分布和演变具有重要影响；在无内热源的单裂隙岩体模型中,裂隙附近岩石的热传导可由沿裂隙法向的一维热扩散方程来近似；在多裂隙岩体模型中,当受其它裂隙或热源的影响很小时,裂隙附近岩石中沿裂隙法向的一维热传导在传热过程中起主导作用。 (3)单裂隙岩体三维饱和水流-传热模型中热应力和位移的半解析计算方法和算例分析：针对单裂隙岩体三维水流-传热简化模型,建立了岩石的热弹性控制微分方程,根据Goodier提出的热弹性位移势法,将模型的热应力和位移分成两部分：由温度场变化引起的特解(温变应力和位移)和为满足边界条件得到的通解(约束应力和位移),并分别建立了相应的半解析计算方法。编制了计算程序,与仅考虑岩石沿裂隙面法向一维热传导的解析解做了对比,并研究了热应力与位移的分布特征。半解析解与解析解基本吻合,但半解析法考虑了岩石的三维热传导,因此两者的温度分布存在微小差异,热应力分布也存在微小差异；在距离分布热源较近的区域,岩石受热膨胀作用明显而产生较大的压应力,而离分布热源较远的区域,岩石需要满足变形协调条件,因此会产生拉应力。 (4)稀疏裂隙岩体三维饱和水流-传热模型中温变应力和位移的半解析计算方法和算例分析：建立了稀疏裂隙岩体三维水流-传热简化模型中温变应力的半解析计算方法,并编制了计算程序,分析了不同条件下饱和稀疏裂隙岩体受热源作用影响下的热应力分布特征。结果表明,裂隙网几何特征和热源分布是影响热应力分布的重要因素；分布热源在裂隙的垂直投影位置处裂隙面上的法向主应力出现峰值。 (5)核废料处置库近场裂隙岩体水-热-力半解析计算分析：利用上述稀疏裂隙岩体三维饱和水流-传热作用下温度和热应力的半解析计算程序,计算分析了核废物处置库近场裂隙岩体的温度、热应力和位移分布特征,研究了裂隙水流速和分布热源间距对温度、热应力和位移的影响。结果表明,在分布热源的影响下,处置库近场岩石中的温度、热应力和位移在前期急剧上升并达到峰值,之后,由于热源热流强度的降低,近场岩石中的温度、热应力和位移缓慢下降；裂隙水的流动传热作用将处置库近场岩石的热量向下游传递,从而降低了近场岩石的温度,减小了近场岩石中的热应力和位移,裂隙水流速越快,对近场岩石中温度、热应力和位移的影响越明显；热源间距越小时,处置库近场温度和裂隙-岩石交界面上法向主应力及法向位移值越高；当热源间距小于一定值时,不同热源间传热作用的叠加将使处置库近场的温度和裂隙-岩石交界面上法向主应力和位移峰值急剧增大。
[Abstract]:The deep underground disposal of high radioactive nuclear waste, the exploitation of petroleum and natural gas and other mineral resources, and the development of geothermal energy are all related to the multi field coupling problems of water, heat, force and chemistry in fractured rock mass. The semi solution of temperature field and stress field in the three dimensional flow and heat transfer process of saturated sparsely fractured rock mass is studied in this paper. This method is used to analyze the temperature and thermal stress distribution characteristics of the near field fractured rock mass in the geological disposal repository of high radioactive waste. The main research contents and results include:
(1) a semi analytical method for calculating the temperature field in a three-dimensional saturated flow and heat transfer model of a single fractured rock mass and analysis of the influence factors: a simplified three-dimensional flow and heat transfer model consisting of a distributed source, a saturated single fissure and an infinite rock on both sides is proposed, and a semi analytical calculation of the temperature field of the three dimensional saturation of a single fractured rock mass and the flow and heat transfer in a single fractured rock mass is established. The corresponding calculation program is written and compared with the analytical solution of the one dimensional heat conduction with only the rock along the crack surface method. The three-dimensional seepage and heat transfer characteristics of the saturated single fractured rock mass and the sensitivity to the flow velocity of the fractured water, the number of the rock heat conduction system and the heat flow set of the heat source are calculated and analyzed. The results of the three-dimensional flow and heat transfer semi analytical calculation are basically the same as those obtained by the analytical method. However, because of the three-dimensional heat conduction of the rock, the upper reaches of the fractured water are relatively low and the downstream temperature is relatively high because of the semi analytical calculation. The effect is more significant in the downstream area of fissure flow.
(2) a semi analytical calculation method and an example of the temperature field in the three-dimensional saturated flow and heat transfer model of a sparsely fractured rock mass: a simplified model composed of distributed heat source, saturated sparse fissure and rock is proposed. A semi analytical calculation method for the temperature field of three-dimensional saturated flow and heat transfer in a sparse fractured rock mass is established, and the corresponding calculation is written. The three-dimensional flow and heat transfer characteristics of the saturated sparsely fractured rock mass affected by distributed heat sources under different conditions are analyzed by three examples. The results show that the geometric distribution of the fissure has an important influence on the temperature distribution and evolution in the sparsely fractured rock mass; in the single fissure rock mass model without internal heat source, the heat of rock near the fissure is hot. The conduction can be approximated by the one-dimensional thermal diffusion equation along the fracture method. In the multi fractured rock mass model, the one dimensional heat conduction along the fracture method in the rock near the fissure plays the leading role in the heat transfer process when the influence of other cracks or heat sources is very small.
(3) a semi analytical method and example analysis of thermal stress and displacement in a three-dimensional saturated flow and heat transfer model of a single fractured rock mass: a differential equation of thermoelastic control for a rock is established for a simplified three-dimensional flow and heat transfer model of a single fractured rock mass. The thermal stress and displacement of the model are divided into two parts according to the thermo elastic displacement potential method proposed by Goodier. The special solution (the temperature variation stress and displacement) caused by the change of temperature field and the general solution (constrained stress and displacement) obtained to satisfy the boundary conditions, and the corresponding semi analytical calculation method is established respectively. The calculation program is compiled, which is compared with the analytical solution that only considers the rock along the fracture surface to the one-dimensional heat conduction, and studies the thermal stress and the position. The semi analytic solution basically coincides with the analytical solution, but the semi analytical method considers the three-dimensional heat conduction of the rock, so there is a small difference in the temperature distribution and the distribution of the thermal stress. In the far area of the heat source, the rock needs to meet the deformation coordination condition, so the tensile stress will be generated.
(4) a semi analytical calculation method and example analysis of the temperature variable stress and displacement in the three-dimensional saturated flow and heat transfer model of a sparsely fractured rock mass: a semi analytical calculation method for the temperature variable stress in the simplified three-dimensional flow and heat transfer model of a sparse fractured rock mass is established, and a calculation program is developed to analyze the heat source of the saturated sparsely fractured rock mass under different conditions. The results show that the geometric characteristics of the fractured network and the distribution of the heat source are the important factors affecting the distribution of thermal stress, and the normal stress of the distributed heat source has a peak stress on the crack surface at the vertical projection position of the fissure.
(5) semi analytical calculation and analysis of water thermal force in the near field fractured rock mass of nuclear waste disposal reservoir: the temperature, thermal stress and displacement distribution characteristics of the near field fissure rock mass in the nuclear waste disposal reservoir are calculated and analyzed by the semi analytical calculation program of the three-dimensional saturated flow and heat transfer in the sparse fractured rock mass, and the flow velocity of the fissure water is studied. The results show that the temperature, thermal stress and displacement in the near field rock of the repository rise sharply and reach the peak in the early stage under the influence of distributed heat source, and then the temperature, thermal stress and displacement in the rocks in the near field decrease slowly because of the heat flow intensity of the heat source. The heat transfer of the near field rock is transferred to the downstream of the near field rock, thus reducing the temperature of the near field rock, reducing the thermal stress and displacement in the near field rock, the faster the velocity of the crack flow, the more obvious the influence on the temperature, the thermal stress and the displacement in the near field rock; the nearer the heat source space, the near-field temperature of the repository and the fissure rock. The higher the normal stress and the normal displacement on the interface, the superposition of the heat transfer between the different heat sources will increase the temperature of the near field and the peak stress and the peak displacement at the fissure rock interface when the distance of the heat source is less than a certain value.

【学位授予单位】：北京交通大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：TU452

【参考文献】