ABSTRACT
Polymers in solution have been widely studied and applied by the oil and gas industry. An increasing number of projects where bentonite-based support fluids are replaced is also found in the construction of drilled shafts and in pipe jacking. Yet, so far, existing guidelines concerning stability calculations of slurry-supported earth walls cannot be applied directly. The usage of polymer solutions in geotechnical applications mainly relies on the expertise of polymer manufacturing companies. This paper discusses existing design approaches and presents adjustments within the framework of a calculative assessment of polymer support fluids for temporary tunnel face support formulated in terms of a critical stand-up time. The analytical assessment is supported by laboratory flow tests and rheometer tests with polyacrylamide copolymers. The experimental test results show good accordance with the analytical predictions. Possible improvements for existing formulations considering the influence of polymer properties on the time-dependent penetration are illustrated.
