不连续岩体温度场的复合单元模型初步研究

 基于复合单元法原理和不稳定温度场的隐式解法，提出针对不连续岩体温度场的复合单元法。该算法的特点是每个复合单元可以含有任意的不连续面，如断层或节理，且当结构中含有需在计算中离散处理的不连续面时，网格的生成不受不连续面的数量、位置和方向的影响。初步研究针对含1条节理的复合单元模型展开，假定岩块中无对流和辐射影响，推导岩块子单元和不连续面的热传导计算式，得到不连续岩体温度场的复合单元算法基本方程组，然后将该算法整合到传统有限元分析程序中。分别采用传统有限单元和复合单元法模拟热水流过单条裂隙时岩体温度场的变化过程，二者的计算结果非常接近，表明不连续岩体温度场的复合单元算法是合理和有效的，但其配套的温度场等值线后处理程序有待进一步完善。该算法的提出为深部岩体的多场耦合研究提供又一思路。

PRELIMINARY RESEARCH ON COMPOSITE ELEMENT MODEL OF TEMPERATURE FIELD FOR DISCONTINUOUS ROCK MASSES

A composite element algorithm for temperature field of discontinuous rock masses is implemented based on the principle of composite element method(CEM) and the implicit expression of unsteady temperature field. The remarkable feature of the algorithm is that each composite element has the possibility of containing arbitrary discontinuities segments such as faults and joints. And the mesh generation of the rock structures with discontinuities requiring explicit treatment in the calculation will not be restricted by the number，position and orientation of the discontinuities. In the phase of preliminary study，assuming the influence of heat convection and radiation in rock are ignored；the thermal conductivity equations of rock sub-elements and discontinuity are deduced for the composite element model containing one joint. Consequently the fundamental equations set of composite element algorithm for discontinuous rock masses temperature field is derived. And then the algorithm is incorporated into the conventional finite element analysis program. Finite element method and composite element method are applied respectively to simulate the varying process of temperature field when hot water flows along a single fracture in rock masses. The computation results of the two methods agree with each other very well. It shows the validity and robustness of the composite element algorithm for temperature field of discontinuous rock masses. But the corresponding post-process program needs more improvement to describe a fine contour of temperature field. Thereby the algorithm will provide one more way in the research of multi-fields coupling of deep rock masses.