Crackings in reinforced concrete structures can lead to a considerable reduction of the repair-free occupancy period. Especially massive or monolithic construction units are at risk. The main reason for durability-relevant cracking are combined mechanically, hygrally and thermically induced tensions. To be able to predict cracking in newly built tunnels, it is important to experimentally determine the time-dependent spreading of moisture and temperature in the concrete using a tunnel model produced in advance. Based on this model, it is possible to obtain a forecast referring to the risk of cracking in tunnel constructions.
Solution
Carrying out of experimental measurements on a tunnel model (spreading of moisture and temperature, deformation).
Parameter study to establish a suitable curing concept.
Numerical simulation of hygral and thermic tensions and cracking which are to be expected in tunnel constructions.
Judgement
Based on the results of the numerical simulation, it was possible to establish an optimized concrete and curing concept and to therefore avoid the development of durability-relevant cracking despite the difficult conditions. The knowledge gained from this project about development and influence of thermically and hygrally induced cracking has served as a basis for an increase in durability of similar constructions.
Facts
Object:
New building of the highway sector A5 Yverdon-Lutterbach, roofing Lüsslingen and Spitalhof, Tunnel Birchi, tunnel model Lüsslingen.
Duration of the project:
March 1997 to August 2003
Building owner and client:
Civil Engineering Office Kanton Solothurn
