Bart De Pauw

New Railway Connection below Brussels Airport

This paper discusses how access to Brussels Airport by car or by train from the Northern part of Belgium has become very difficult. For this reason, a new railway connection is being built below the airport. The new link will connect the existing train station to a new 24 kilometer long railway section from Brussels to Mechelen, which is located in the central reservation of the motorway between these two cities. The most important part of the connection is a 1,084 meter long twin tube bored tunnel that passes below the runway and taxiways of the airport. Because of this location, an adequate design load for aircraft actions had to be chosen that complies with modern aircraft characteristics. The paper gives particular attention to the boring of tunnels below an aircraft maintenance hangar with pile foundations. Although passive protective measures are taken in order to prevent damage to the building, an accidental loading case of concentrated pile loads on the tunnel lining must be considered. In addition, concrete cracking of lateral diaphragm walls of the cut and cover sections of the new railway tunnels are being considered.

Efficiency assessment of CFRP laminate reinforcement of a partly deficient post-tensioned fly-over

Immediately after construction, five spans of a newly built concrete fly-over showed insufficient concrete resistance. Carbon fibre reinforced polymer (CFRP) laminates with little compression stiffness were glued to the lower surface of the superstructure to strengthen the concrete slab decks. After installing, assessment of this reinforcement was made by a first loading test, during which concrete strain measurements with wireless gauges were carried out. In addition, the fundamental frequencies have been determined by accelerometers and impact excitation of the viaduct. Comparing the results from these tests on acceptable and deficient decks confirms the insufficient concrete quality of the suspect spans. The time-dependent evolution of creep changes this situation and the CFRP laminates actively influence the characteristics of the five strengthened decks. Hence, strains were monitored constantly during a period of 5 months. Finally, loading tests with trains as well as acceleration measurements were carried out to confirm the effect of the reinforcement.

The Combined Bypass Railway and Tangent Road Project Near the Station of Mechelen (Belgium)

In extending the existing railway infrastructure from Brussels to Antwerp, a new double track railway is foreseen as a by-pass along the railway station in the city of Mechelen. In combination to this project, an underground parking building and a new road connection indicated as the tangent-project between the southern and northern part of the city and in improving and extending the accessibility of the railway station will be built. The alignment of the road connection is situated in parallel to and even underneath the alignment of the new railway by-pass for half of the project. This results in a variation of heavy concrete road tunnel and railway viaduct infrastructures in an urban context. In designing the project, the process in obtaining a building permit in the city center was very difficult dealing with these historical and urban environmental conditions. A lot of attention was given to the architectural integration of concrete structures resulting in among other things integrated and curved double track railway viaducts. A variation of designs can be found in the application of inner and external post-tensioning in different types of railway viaducts (with and without outer beams) and skew railway slab bridges with outer main beams in rounded shapes. In December 2017, the project will be finished.

Autonomous Systems for Strain and Vibration Measurements

This paper will describe how it is often necessary to resort to monitoring of certain structural parameters when studying the long-term behavior of structures. This paper discusses two such applications. A first prototype was used to monitor strains in a concrete fly-over with carbon fiber reinforced polymer (CFRP) reinforcements. The second prototype was used recently to monitor the vibrations in a continuous fashion during four weeks of speed tests on a new section of the European High Speed Train network. This paper gives an overview of these experiences and lessons learned concerning power supply and possible electromagnetic interference in harsh construction site conditions. In addition, the paper describes the intention to build a new completely autonomous third prototype for thermal strain monitoring. Furthermore, the most important results of both test cases are discussed, including the effectiveness off the CFRP-reinforcement and the natural frequencies of a massive concrete fly-over.