Real-time monitoring and performance of retaining structures

Abstract

The advent of reliable real-time monitoring devices has changed the way we monitor the construction of geotechnical infrastructure. This paper presents a case study where Shaped Accel Arrays (SAA) were employed as part of the real-time monitoring regime for the construction of two retaining structures that utilised a combination of secant and sheet piles. To improve their structural rigidity, a capping beam and horizontal props were employed. The retaining structures were erected to facilitate the launching and retrieval of a Tunnel Boring Machine (TBM). The monitoring regime detected structural sway and toe movement of the sheet pile walls. Adjustment methods for these effects are discussed within this paper, along with a comparative study between manual and real-time monitoring. Adjusting for the effects of sway and toe movement can considerably change the maximum deflection from that registered by an SAA, therefore, it is important to account for these effects when employing SAAs to monitor the movement of a retaining structure. Furthermore, a cost comparison of using real-time monitoring in place of manual monitoring suggests that for a project of this nature where monitoring is required for more than 6 months, real-time monitoring becomes more cost effective.