In our increasingly urbanized society, tunnels are in high demand for a variety of purposes, including metros, water and wastewater conveyance, and other civil uses. Oftentimes, these tunnels must be built in challenging environments that include high water pressures and seismic areas, requiring precisely designed and built tunnel segment gaskets.
To get a better sense of the market as it relates to gaskets, TBM sat down with Peter Tiedemann, Key Account Manager Tunnel & Rail, at SEALABLE Solutions GmbH, to discuss the recent development of the company, as well as the current state and future of the market. The company, based in Waltershausen, Germany, and operating around the globe, is a key player in the design and supply of gasketed systems. The company’s resume includes hundreds of projects worldwide, including major projects in North America.
TBM – Tell us about SEALABLE Solutions GmbH and its role in the tunneling market.
Tiedemann – SEALABLE Solutions was formed in April 2020 as the result of a management buyout of Datwyler’s civil engineering division. Effectively, only the name has changed. It’s essentially the same company with the same people. We focus on the tunneling industry, as well as products for industrial and railway applications. Including our experience as part of Datwyler and previously Phoenix, we have been in the tunneling business for more than 40 years. Personally, I have been involved with the division for more than 23 years here in the United States.
To date we have been very active with 16 projects running at the moment, including major projects like the Hampton Roads Bridge-Tunnel, and the Eglinton and Scarborough lines in Toronto. We have projects all over the world, including in Europe, Japan, Australia, Egypt and others.
TBM – How is the tunnel market evolving?
Tiedemann – It is more common to use TBMs with segmental lining for tunnel construction, and we are seeing tunnels being built in environments with higher water pressures. We are working on a project in Japan that has segments being tested up to 100 bar, and we are capable of going up to 120 to 130 bar. These high pressures are experienced when you are tunneling through mountains or when you go very deep.
TBM – What are some of the common issues you see concerning gaskets?
Tiedemann – The three main considerations in gaskets are the location of the gasket within the segment, the potential for segment spalling, and performance vs. force. All these things work together within a system.
Gaskets always seem to get pushed out to the edge of the segment in the design so that it is out of the way for TBM operations. We like to get involved in the segment design process early so that we can ensure that the gasket is further inside the segment and that the groove dimension is correct. Having the best gasket design and groove dimension helps to prevent spalling and ensure a good seal. The gasket has a very important role to play, but sometimes the gasket design can be overlooked.
Also there needs to be a balance between workability and performance. Contractors prefer a soft gasket because it is easier to install, but there is always a compromise. You need a gasket that is soft enough to install but has enough force to provide a proper seal. You have to have both of these characteristics in the right dimension.
TBM – Are there any new developments in segment design?
Tiedemann – We have a new design with rounded flanges that is currently being used on a tunnel project in Poland. The design helps reduce forces at the edges of the segment, especially for segments with anchored gaskets, so that the force is not directly driven into the segment which can cause spalling. Another option is the fiber anchored gasket. In North America, we have used the fiber anchoring approach on projects in the South Hartford and REM Montreal projects, as well as internationally.
TBM – What are the main factors to consider during the design process to ensure the best system is implemented?
Tiedemann – It is very important to define at an early stage the maximum gap offset and test pressure requirements to choose the right system. Nowadays, gaskets are highly price driven, and they are built very close to the exact design tolerance. However, it is safer to have room for uncertainties that you always face in the tunneling environment.
TBM – What trends do you see affecting the market in the future?
Tiedemann – Sustainability is a hot topic in construction, and that is true in the tunneling industry also. We are seeing segments being built smaller to reduce the amount of concrete used, which reduces the carbon footprint. We at SEALABLE are working on reducing our carbon footprint as well, including using different types of polymers. It is becoming more and more important to demonstrate how we can contribute to reducing a project’s overall carbon footprint.
TBM – When does SEALABLE get involved in a project?
Tiedemann – We like to get involved very early in the process. It is important that we have as much information as possible to design the best system. The more details we have, the better. Sometimes we just get the basic requirements, but it is also helpful to know where the tunnel is, the ground conditions, and the expected challenges. The more information we have, the better solution we can offer.
TBM – How are the lingering impacts of the pandemic affecting the gasket market?
Tiedemann – The last three years have been challenging with the pandemic and the war in Ukraine. We had to fight with sharp increase in cost and stuck in fixed price contracts. At least availability of rubber compound was not a problem for us, and we could supply all running projects in time. We supported our customers and contractors but at a high price for us. Shipping was a very big challenge as well, due to container shortages and availability. Usually, our products were ready, but container ships were not available or already booked vessels with the forwarder were pushed to later vessels. The situation has improved recently but it is not back to where it was before the pandemic, especially the pricing.