The use of vibrating wire strain gauges for long term measurements on buried gas mains

Abstract

A trial agreement concerned with the effect of adjacent deep excavations on the risk of failure of buried cast iron gas and water mains was implemented by British Gas and National Water Council on 1 January 1983. To complement this agreement, field experiments are being carried out at selected sites throughout the UK. The British Gas Engineering Research Station (ERS) is working in cooperation with the Water Research Centre to install instrumentation to measure pipe strains, joint movement, ground temperature and ground movement.Field measurements impose environmental and operating conditions of much greater severity than those encountered in a laboratory. This note outlines the site techniques developed by ERS which allow reasonably quick and reliable installation of equipment capable of withstanding the adverse conditions typical of backfilled trenches. The principle of operation of the VW gauge, its method of fixing, the factors affecting its output and the interpretation of the readings themselves are described.