断层气氡在不同类型覆盖层中 迁移规律的数值模拟

断层气氡浓度是探测断层位置与断层活动性的一种有效手段. 该文基于Abdoh和Pilkington提出的氡迁移二维偏微分方程与相应的边界条件， 建立内部含裂隙、 裂隙系-断层带和非均质等3种覆盖层物理模型， 在Matlab平台上运用偏微分工具箱(pdetool)与非线性求解函数(pdenonlin), 对模型求解以及模拟覆盖层中氡迁移. 通过对3种模型的模拟结果分析， 分别解释了地表氡异常点与断层带位置不同步现象, 覆盖层厚度对氡浓度曲线形状的影响, 以及土壤结构性质对氡异常强度和异常形态的影响.

Numerical simulation for migration rule of fault gas radon in different overburden

Measuring the concentration of the fault gas radon is an effective method to explore fault location and fault activity. Based on Abdoh and Pilkington’s two-dimensional partial differential equation and corresponding boundary conditions of radon migration, we establish three physical models of the overburden: internal fracture, fracture-fault and heterogeneous overburden. Then we solve these models and simulate radon migration in the overburden using partial differential toolbox (pdetool) and non-linear solution function (pdenonlin) on the Matlab platform. Finally, we analyze the simulation results of the three models, which explain the phenomena that the radon abnormal points on overburden surface are out of sync with the fault location. It is also interpreted the effect of thickness of overburden on the shape of the radon concentration curve, and impactions of the soil structural properties on the radon anomaly intensities and shapes.