The new museum of the Viking Age – Assessment of vibration from groundworks to avoid damage to artefacts

Abstract

Construction activities such as blasting, pile driving, compaction, excavations, and construction traffic can cause damage to neighbouring buildings and structures. The situation is even more critical when the nearby buildings are museums with fragile collections. This case study presents vibration assessment work performed in connection with the planning of the construction activities for the planned Museum of the Viking Age on Bygdøy, outside of Oslo, Norway. The planned museum will be built as an extension of the existing Viking Ship Museum, where one of the world's foremost collections of artefacts from the Viking age is displayed. Although the existing museum will be closed during the construction period, objects that are considered too large or too fragile to be temporarily relocated will remain in the museum. Therefore, one of the main challenges during the construction of the new museum is to ensure that vibrations from the ground- and construction work do not damage the fragile objects in the existing museum. Strict vibration limits have been set based on the daily vibration values during normal operation of the museum. The vibration limits are given both as vibration peak limits and as vibration root mean square (RMS). Early calculations showed that especially the RMS limits will be difficult to meet. A “vibration budget” was established, which provides a systematic overview of the vibrations from different construction activities with the expected total time at different RMS levels and with the associated dominating frequency. Based on the results, the most critical construction activities are identified, and effects of mitigation measures are estimated. In addition, the results can form a basis for adjustments of the RMS limits for activities that are expected to last for only a short time. As the main vibration mitigation measure, a screen made of jet-grout columns is planned in the ground between the existing museum and the main construction area. FE-calculations show that the screen may reduce the vibration values by up to 80%. However, since not all activities are affected by the screen, the effect on the vibration budget is somewhat lower.