Use of vibrating wire strain gauges to measure loads in tubular steel props supporting deep retaining walls

Prop loads in braced excavations are often monitored using vibrating wire s train gauges attached to the prop and are generally found to vary significa ntly with temperature, In this paper, the interpretation of strain gauge da ta to determine axial loads and bending moments in tubular steel props is d escribed with reference to measurements made during the construction of Lon don Underground Limited's Jubilee Line Extension stations at Canada Water a nd Canary Wharf. Temperature and end effects are discussed, the accuracy an d potential shortcomings of the technique are assessed, and guidelines for the achievement of accurate and reliable results are suggested.