FinMeas technology monitors rock masses at Kalasatama construction site
Kalasatama in Helsinki has been one of the largest and most visible construction sites in Finland. The enormous project also included excavating the shopping centre’s large parking garages. The shopping centre in Kalasatama has five underground parking garages, four of which are two-storied. The garages have altogether 1150 parking spots. The safety of the work was monitored using automatic extensometers delivered by FinMeas.
The reliability of the measurements was highlighted due to the unparalleled high tower buildings being built above the parking garages over the rock pillars. Due to the high loads, it was necessary to get reliable and accurate information about rock movements. Accordingly, FinMeas measuring devices were situated in all the critical spots.
FinMeas delivered four automatic extensometers for this project to monitor rock movements during the excavation and construction work. The extensometers had three or five anchors at different depths that move along with the rock movements in relation to the reference point. The movement was measured and sent wirelessly to the FinMeas Online service, where the measurement data could be viewed in real time.
The measurement system can also be set up with automatic alarms. If the specified threshold value is exceeded, the person in charge receives is informed immediately by e-mail or SMS message.
The measurement devices were installed in the rock mass already before the excavation started. This way also pre-work information could be collected for future use.
“The rock masses always move during excavation. With automatic extensometers, we can monitor in real time how the rock mass is moving and living. If the movements are greater than we expected, we can react to it and strengthen the foundation if needed,” says Ville Järvinen, Project Manager at SRV Infra, which was responsible for the construction work.
“The soil at Kalasatama is good, and there is an old rock island in the area. At no point was the rock movement close to the preset limits. At one point we decided to make extra reinforcements, after which the rock movement ended,” Järvinen adds.
One challenge with the excavation of Kalasatama’s underground parking garages was that a lot of above-ground construction work was also taking place in the area, including the foundations for the new shopping centre.
“The construction work involved a lot of daily coordination. If there is concrete work going on somewhere, we can’t explode in the same place at the same time.”
Järvinen praises the reliability, effortlessness and cost-efficiency of the automatic measurements. Earlier, the measurements were made manually and someone needed to come weekly and take the readings on the spot.
“In a project as long as this one, the worker gets a lot more time to do other things instead.”
“The devices have worked well and are easy-to-use. The reading scale of the user interface is clear – the colour codes tell immediately if the measurement data is within the set limits,” Järvinen continues.
”It’s a great advantage that the devices are so easy-to-use. In a large and multi-dimensional project like this one, something is happening all the time and in many different places. That is why we want to keep things simple. The FinMeas system helps us greatly in this.”
Järvinen also appreciates the fact that automatic measurements can be made in real time. It is important that all the parties can use the important information.
“The data from the manual measurements first went to the contractor and then to the supervisors and designers. Now all the parties can view the information in the online service whenever they like. This is a major improvement compared to what it was earlier.”