February 14, 2023
The Stockholm metro is currently being expanded, and 17 new stations and an underground service hall for trains will be opened over the next ten years. For the contractor Implenia, the work is not just about getting through rock and under lakes. It is equally important to seal both fractures that were present in the rock from the beginning, and the drill holes that were created during the course of the work. Otherwise, large quantities of water will leak into the tunnel, which may lead to lower levels of the surrounding groundwater.
“Sealing rock has traditionally been an intuitive task. When an operator saw a hole, they filled it with cement and normally documented the work with handwritten notes. The problem with this method is that no one knows with certainty that the correct hole was filled,” says Software Developer Johan Broström, Epiroc Digital Solutions.
The fact that the work has been based more on feel than facts has also resulted in a number of conflicts between contractors and clients when the end result has not been as expected. Without precise documentation, it has also been difficult to determine who made a mistake.
To get better control of this work, Epiroc developed the Underground Manager software. It helps the operator seal the rock correctly while creating complete documentation of the work performed. “In practice, the rock drill that goes first automatically analyzes the rock and registers its own work. The information is then sent digitally to the grouting machine that will follow,” says Broström.
He continues: “The operator thus gains precise knowledge of the cracks in the rock and where the drill holes that must be filled are located. The system also notifies the operator of the volume of a hole and the cement to be used to get the best results.” By tying together the drill rig used for tunneling with the grouting equipment, the contractor also gains full control over how long the work will take – a solution that has not yet been available on the market. For the customer, this means that the work can be adapted to actual conditions, which makes the project more predictable while at the same time making better use of resources.
“Because each drill hole has a unique identity, it becomes possible to evaluate the work in detail, both during and afterwards,” says Broström.
This means that problems can easily be identified and handled, and also discussions – about how the work has been carried out and whether the right amount of cement has been used – that were previously common have been minimized. This makes the work more predictable at the same time as the water leakage into the tunnel is reduced.
Since last summer, Implenia has been using Epiroc’s Underground Manager software for the tunnel construction in Stockholm. The system facilitates day-to-day work and also means that the handwritten notes, which were previously used to document the work, have been replaced by digital documentation. In this way, Implenia can assure the quality of the entire project, which gives both them and the client greater security.
The operator's constant control over the condition of the rock introduces for the first time conditions to enable high-quality work and opportunities to later show why the job has been performed in a specific way. “This complete solution is unique in the industry, not least because our customers can now offer a function, a watertight tunnel, instead of just buying the equipment that powers the rock in the past,” says Broström.