Substrate Modification and Magnetic Water Treatment on the Maintenance of Tunnel Drainage Systems. I: Feasibility Tests

Abstract

Calcium carbonate deposits are known to clog tunnel drainage systems and clogging is a major concern to tunnel operators worldwide. After analyzing several industrial solutions for treating calcium carbonate, experiments were conducted to evaluate the use of substrate modification and magnetic fields in inhibiting calcium carbonate deposition. For substrate modification tests, laboratory experiments showed the least amount of deposits on polytetrafluoroethylene and polydimethylsiloxane coatings, while polyvinyl chloride (PVC) pipes showed the most. Simulated tunnel drainage test results showed PVC pipes inclined at large gradients and PVC pipes with installed magnets to have slightly less calcite deposits than PVC pipes without magnets. The amount of deposits suggested the influence of magnetic fields to be minor and secondary relative to water velocity.