Triangular Unstructured Finite Element GPR Forward Modeling

For the numerical simulation of the actual geophysical model,grid division is very important for fitting the geophysical model.It directly affects the efficiency of solving the finite element numerical simulation and calculation accuracy.In general,grid generation technology can be divided into structured and unstructured grids in two categories.The structured grid has the structural features unified,generation speed,single structure,but can not meet the numerical simulation of complex geophysical model.At present,the unstructured mesh technology in the application of finite element numerical simulation of GPR in less relevant research literature is relatively small.Therefore,this paper studies the finite element numerical simulation of radar triangle the unstructured grid under the ground,established the geological geophysical model,simulated two-dimensional GPR finite element numerical analysis,it summarized It is of great significance for the interpretation of the actual data to study the propagation of radar waves in different geological and geophysical models.In this paper,on the basis of previous studies,re derived triangle meshes of the GPR wave equation based on finite element method,and gives a detailed solution to the wave equation.The numerical simulation,the load transmission boundary conditions and no load transmitting boundary condition uniform model to carry out numerical simulation,analysis of the treatment effect the boundary;a brief analysis of the radar wave propagation in the medium of water and air,analyzed the difference;established the road subgrade model,tunnel geological prediction model and the model of physical and mathematical model of pipe jacking void,analyzed the law of radar wave propagation in different models.Through the numerical simulation can be found: the transmitting boundary condition can suppress the interference wave model of boundary place good;through multiple reflection radar wave propagation in the medium of Potter syndrome to distinguish between water and air medium;through the tunnel geological prediction is combined with the measured data,provide the basis for judging the radar wave propagation characteristics better in such a model;through the numerical simulation of pipe jacking void model,found the ground penetrating radar for cement concrete slab jacking can obtain good results for detection,separation effect of steel pipe jacking is not obvious,consistent with the measured results.By reducing the thickness of the steel pipe wall,can detect the void.But the effect is not obvious.Research shows that: the unstructured grid has good adaptability for complex geoelectric model parameters;the quality of unstructured mesh generation,the unit is easy to control,can realize the adaptive finite element method,to improve the modeling accuracy.