2-D Forward Modeling And Inversion Imaging About Fixed Point Source IP Sounding

Fixed point source IP(Induced polarization) is a method of induced polarization geophysical exploration.This method can use several receivers to measure data at the same time,so,this method has high work efficiency.And the measure of electrode distance change is flexible, which make this method is convenient and time-saving.Thirdly,different power point location has different conductor polarization field location, then, we can confirm the position of anomalous body more easily.So,this method of fixed point source shock electricity measure depth has been widely applied to the practical work of geophysical.Currently,the research working of quantitative interpretation by Fixed point source IP has obtained some achievements,but there also exist some obvious deficiency and defects.Such as,this method just adapt to some simple terrestrial electricity condition and models,And,affected by the position distribution of point sources greatly,if the position distribution of point sources do not symmetrical from the abnormal body,the isoline of abnormal body will be performance for arc shape.Thirdly,it will cause obvious fake anomaly when we explaining for the combination models,which can cover the information of the real abnormal bodys.To this,this paper studied the optimization inversion method,and then the two methods of interpretation was analyzed and compared.This thesis studied a series of problems which related to the calculation of the finite element forward modeling and the optimization inversion method,which include the finite element forward modeling method base on the undulate topography and the electrical parameters of abnormal body continuous change,and the studied the method of finite element mesh dissection under the condition of undulate topography.This thesis also studied the storage method of large sparse matrix and the fast solving method of large linear equations,the least-square inversion method under constraint condition and the calculation and accelerating technology of partial derivative matrix.And the solving method of generalized linear inversion equation.And then,this thesis research and design algorithm and data structure of finite element method forward modeling and optimum inversion method algorithm,and write the programs.This article studied the calculating method of the arc intersect-relative strength method and wrote the program.Then make some of the terrestrial electricity models as examples,and compared the least-square inversion results to arc intersection-relative strength calculation results.The result shows that the least-square inversion method can adapt to all of the terrestrial electricity models.The calculate results of inversion are better than the arc intersect-relative intensity method in the complex model,the combination model and undulate topography terrestrial electricity conditions.