Modeling stray current and its influence on corrosion of steel sheet piling

Stray currents are known to promote corrosion of nearby metallic structures. Electrolysis is the responsible phenomenon. Where currents enter the metallic structure, the latter is protected. The construction corrodes at the location where currents exit through the ground to be collected by the substation. The extent of such corrosion has until now been hardly predictable and quantified. Thus, authorities are extremely reluctant to accept the use of steel piling solutions in the vicinity of DC-operated systems (railways, tramways, cathodic protection, HVDC lines...). The influence of stray currents on sheet piling structures was assessed using Elsyca\u92s software CatPro® and CPMaster® initially dedicated to the pipeline and cathodic protection industries. Various steel piling designs were modelled meanwhile parameters such as wall/track distance, soil type, soil stratification, number and position of trains, anchors and track position were varied. Corrosion rates obtained on different piling designs were considerably lower than expected. Moreover, zones of potential corrosion risk could be identified, thus cost-effective and practical countermeasures can be resorted to. A first phase of a common TNO - ArcelorMittal project did present the same trend. Current collaboration with TNO and a consortium of other Dutch companies allows installation of a pilot steel piling project (2009) to put modelling results to test