Design Cathodic Protection Ground-bed Arrangement with Finite Element Analysis Method

摘要

A more flexible grounding resistance calculation method,based on finite element analysis (FEA) method,is suggested,which is especially suitable for optimization cathodic protection (CP) ground-bed arrangement.As compared with traditional grounding resistance evaluation method,which is only suitable for the case of each anode rod in a straight line,the FEA method can calculate grounding resistance of ground-bed at any arrangement.Moreover,a realistic soil resistance rate,usually varying with depth,can be included in calculation model.The detailed steps for this method can be summarized as follow: building a 3D geometric model according to general design,meshing the geometric model,setting reasonable boundary conditions,solving and post-solving the grounding resistance with ohmic law.To further explain this procedure,a realistic CP ground-bed displacing project is presented,which includes displacing the original CP ground-bed firstly and re-designing a new ground-bed within a limited area (5m×30m).A new CP ground-bed design,compared with traditional design,2×7,14 anode rods dispersed in two parallel groups,are calculated firstly.The results show that this design can not meet the grounding resistance requirement.Another 4 designs,with anode rods arranged as 2×6,2×8,2×9,3×6 are calculated respectively.Finally,the design 2×8 is recommended from the view of economy and practicability.