CC-SS - coupled crack-seal simulation

合性裂缝封闭脉是深部热液和反应性（THMC）环境中的一级构造，在这些环境中流体产生中等渗透率，并与变形相互作用。在最近的工作中，我们使用两种不同的方法成功地模拟了这些矿脉：我们使用相场法（PFM）来模拟石英在水溶液中的外延生长，基于热力学和动力学原理，但简化了对裂纹几何形状的假设；在另一项研究中，我们使用离散元法（DEM）基于力学原理，简化了晶体生长的假设，对裂纹密封脉的生长进行了三维建模。在此，我们提出将这两种方法结合起来，在双向耦合的PFM和DEM模型中研究复合裂纹密封脉的热、水力、力学和化学耦合演化。为此，我们将开发交换例程，将DEM的空间域转换为PFM，反之亦然，用DEM模拟压裂过程，用PFM模拟密封过程。对合成静脉微观结构的观察将提供微观结构、静脉晶体形态和面晶体学的数据，并将我们的结果与自然原型进行比较。耦合模型将有助于更好地理解压裂和密封过程之间的反馈机制，量化机械和输送过程的演变，帮助定义天然矿脉中的新诊断微观结构，并为模型的升级奠定基础。对合成石英和方解石脉的参数化研究将检验以下假设：(1)脉微观结构的演化，(2)打开速率与晶体生长速率的对比，(3)脉胶结物与寄主岩石的相对强度，以及(4)热液合成裂隙封闭脉孔隙度的连通性和渗透率演化。

Syntaxial crack-seal veins are first order structures in deep, hydrothermal and reactive (THMC) environments where fluids create and moderate permeability and reactions interact with deformation. In recent work, we successfully modelled these veins using two different approaches: we used the Phase Field Method (PFM) to model epitaxial growth of Quartz from an aqueous solution, based on thermodynamic and kinetic principles but with simplified assumptions on crack geometry; in another study we used the Discrete Element Method (DEM) to model the growth of crack-seal veins in 3D, based on mechanical principles but with simplified assumptions on crystal growth. Here we propose to couple these two methods, to study the coupled thermal, hydraulic, mechanical and chemical evolution of syntaxial crack-seal veins in bi-directionally coupled PFM and DEM models. For this we will develop exchange routines to translate the spatial domains of DEM to PFM and vice versa, to model the fracturing process with DEM and the sealing processes with PFM. Observations of syntaxial vein microstructures will provide data on microstructure, vein crystal morphology and facet crystallography for comparison of our results with natural prototypes. The coupled models will lead to a better understanding of the feedback mechanisms between fracturing and sealing processes, quantify the evolution of mechanical and transport processes, help define new diagnostic microstructures in natural veins and form the basis for upscaling our models. A parametric study of syntaxial quartz and calcite veins will test hypotheses on (i) evolution of vein microstructure, (ii) rate of opening versus rate of crystal growth, (iii) relative strength of vein cement and host rock, and of the (iv) connectivity of vein porosity and evolution of permeability in hydrothermal, syntaxial crack-seal veins.