FinMeas’ automatic measuring devices monitor the safety in many large construction sites in Finland and abroad. Below are a few example projects in which the customer has with our technology achieved major benefits in both safety and expenses.
The construction project got a green light in the Norwegian National Transport Plan 2014-2023, where politicians earmark funding to infra projects. PEAB delivered the most valued offer for the Aas-Jakobsen designed project and the project kicked off early 2016. The stretch of road will run through one of Norway’s largest areas of highly sensitive clays, which necessitates the use of a robust monitoring programme, as well as extensive stabilisation and mass-shift efforts.
Large scale quick clay stabilisation The first and perhaps the most critical step in the project is ground condition stabilisation. Quick clay is a type of sensitive clay that is frequently found in Sweden, Norway, Finland, Russia and Canada due to the ice age. It is characterised by its liquid structure, which, if distressed by human activity or erosion, can collapse. This leads to so-called quick clay slides in which many lives and properties have perished throughout the years.
For this project to even be feasible, lime-cement stabilisation on a grand scale had to be set into motion with the help of The Norwegian Geotechnical institute. “We’ve drilled more than 44 000 boreholes and filled them with 50/50 lime and cement to ensure the masses are stable and resistant to external pressure. Due to excavation and the depth of the clay deposits, each hole is 25 m deep and has a diameter of 600 mm. So quite a unique large-scale stabilisation effort,” says Geotechnical Engineer Lars Andreas Solås from Norwegian Public Roads Administration.
In addition to lime cement stabilisation, the project called for moving of more than 2M cubic meters of masses, of which 500 000 cubic meters were moorland properties. Quality clay was shifted and will be re-used for another stretch of the road but then laid out in thin layers and compressed to ensure stability.
Before mass-shifting began, the project team decided to follow-up the pre-filling of one of the embankment of the road project using automatic intelligent devices to monitor and understand the settlement. The choice of methodology landed on FinMeas’ liquid-filled settlement hose. The tool works so that pressure cells are placed at given intervals, and they measure settlement down to 5 mm. Signals are transferred from the pressure cells via a control unit to an online system which is equipped with graphs and deformation limits and alarm in case they are exceeded.
“The settlement system has given the project team a unique chance to post-calculate the settlement curve from the prefill, and to understand the settlements taking place after prefilling removed” states Geotechnical Engineer Stian Berre from Multiconsult. Other deliveries from FinMeas to the project include four inclinometers, which are used to measure the displacement of retaining walls. The 40-m deep inclinometers are situated close to the large excavation in quick clay to monitor if there are any movements and possible landslides.
The data from all FinMeas' monitoring equipment is logged continuously to FinMeas Online, through which the PEAB project team can easily monitor the conditions on the construction site at all times. The alarm-equipped system saves the project team not only time and money, but also gives them a chance to act early should anything go wrong.
The new stretch of the E6 is scheduled to be completed by spring 2019.
In October of 2009 Tampere University of Technology (TUT) and the Finnish Rail Administration conducted a full-scale railway embankment failure experiment in Salo, Finland.
A new, small railway embankment was built in place of an old, de-commissioned blind track on a clayey soil. Four steel frameworks, each 12 meters long, were used to simulate short railway cars with bogie carriages. The frameworks were loaded with modified shipping containers which were gradually filled with sand.
The test area was extensively instrumented with 40 pore pressure gauges, 9 inclinometer tubes, 2 total stations monitoring a total of 27 prisms, 9 earth pressure gauges, 3 settlement tubes and 76 slip surface measuring pipes. In addition, the weight of the containers was measured with strain gauges on the frameworks. Acceleration gauges were used to measure the tilt angle of the containers. The fall test lasted for appr. 24 hours. During this time considerable overload was loaded onto the carriages.
All devices detected movements before the actual failure of the railway structure. In normal conditions the alarm system gives an alarm immediately when movements are detected, which gives enough time to ensure safety.
After the carriages had tipped over, the horizontal movements were approx. 1000 mm. All measurement devices operated perfectly also after the large movements.
See the video filmed by Tampere University of Technology.
Source: Finnish Rail Administration
FinMeas’ automatic measurements ensure that the bored pile wall restraining the cave-in in Frihamnen’s port area is working the way it should. Measurements help improve harbour safety and give new information to support upcoming investments.
Frihamnen’s quayside filled up on top of muddy seafloor. Erosion has caused soil settlement and the embankment has sinked into the seabed.
“At worst the waterfront fell into the sea 1-2 meters in a year”, says construction manager Peter Sundström, who is in charge of the maintenance of Frihamnen’s quayside.
Ground movements threatened to endanger the safety of harbour buildings in the area. Displacement of soil could also lower the maritime channel that goes right next to the quayside. Correspondingly the dredging of the maritime channel accelerated the displacement in waterfront embankments.
That is why plans were made in the harbour for stopping the ground movements. A Finnish engineering company Arcus Oy designed a bored pile wall which supports the embankment and stops its movements. This makes it also possible to continue the maintenance dredging, which is important for the maritime channel.
Passengerships to Riga and Saint Petersburg run from Frihamnen and it is used by approximately half of all the cruisers that arrive to Stockholm. Also a large container terminal is situated in the harbour.
Investing pays itself back
Building of the bored pile wall started in fall 2014. A bored pile wall in this kind of environment is a relatively new solution so the measurements were supposed to give information also about how the wall itself was working. That is why FinMeas’ automatic displacement inclinometers and anchor force sensors were installed in the piles of the wall, not in the ground.
“Now we can monitor the wall’s movements in real time and make sure that it is behaving the way the designers have planned it to work”, says Sundström.
The bored pile wall is altogether 60 meters long and 30 meters high. Water level around the wall varies from 6 to 12 meters.
The measurements indicate that the structure is working: the ground movements have been stabilized.
“According to the measured data the bored pile wall seems to be an extremely well-working solution for this kind of problem. This is important for us to know because similar challenges exist also in other parts of the harbour area. This is why investing to FinMeas’ measuring technology will pay itself back”, says Sundström.
Stockholms Hamnar is currently developing Värtahamnen’s and Frihamnen’s area together with the city of Stockholm. New apartments and business premises are being built in the area and some of the current docks will be filled. The quayside will be extended further to the bay.
Reliable and easy-to-use solutions
Sundström appreciates the real time information given by FinMeas’ automatic measuring devices. Arcus monitors the wall movements but also Sundström regularly visits FinMeas’ webservice to check measuring data.
In Arcus Oy, hydraulic engineer Kim-Andersson Berlin takes care of following the measuring data and modeling the structures. According to him, monitoring structures during a project is more common in Sweden than it is in Finland. It is used specifically to improve working safety.
Andersson-Berlin thinks that the measuring results of Frihamnen’s bored pile wall awakens also academic interest in larger scale because reliable information of similar structures is not commonly available.
Sundström is pleased with both the wall’s and the measurements’ functionality.
”FinMeasin mittalaitteet ovat luotettavia ja palvelua on helppo käyttää. Yhteistyö on sujunut erittäin hyvin. He ovat oman alansa ammattilaisia, ja olen kumppanuuteemme hyvin tyytyväinen.”
“FinMeas’ devices are reliable and the service is easy-to-use. We have had a good co-operation. They are experts in their branch and I am very pleased with our partnership.”
FinMeas’ automatic inclinometers and anchor force measurements were used as a solution in this project.Download PDF
FinMeas is involved in performing measurements for the demanding excavations associated with the West Metro. Under construction next to the Esport Center, the Urheilupuisto station has been entirely built as an open excavation project. It is the only station of its kind where this has been done. The varied soil types brought additional challenges.
FinMeas’ technology was used at the Urheilupuisto station to measure the anchor force of retaining walls, soil displacements and rock movements. All of the measurements were commissioned by Ramboll Finland, acting as a sub-consultant for Sweco.
In particular, Pasi Kolomainen, in charge of rock mechanical monitoring for the West Metro project and ground investigations at Ramboll Finland, appreciates the automatic remote reading feature of FinMeas’ measuring devices. This feature saves time and effort during manual measurements. In addition, automatic measurements enable the more accurate identification of when changes occur.
“FinMeas’ remotely readable measurement devices represent an entirely new concept compared to traditional methods. It is much easier and more efficient to monitor measurement results directly from an online user interface, than to check manual measurement equipment on site on a weekly basis,” says Kolomainen.
In addition, measurement devices used in highly demanding construction projects such as metro tunnels can be located in relatively inaccessible places. Under circumstances such as these, measurement devices that can be read remotely are an unbeatable option. These too can be installed in fairly inaccessible locations.
Inclinometers in rock and soft ground
The pit for the Urheilupuisto metro station was entirely built using the open excavation method. It is more than 20 metres deep, in an area with a great deal of soft ground. Located right next to the pit is the Esport Center sports hall, which has continued to operate normally throughout the construction period.
FinMeas’ four automatic inclinometers measured movements in the ground structure between Esport Centre and the pit. Only a few metres separate the sports hall from the pit and on-site traffic was busy in some places.
However, measurement of anchor forces ensured that the pit was sufficiently propped. Support structures could be dimensioned properly, saving on costs and improving safety.
“Measurement of anchor forces and movements played an important role in the monitoring of site safety,” Kolomainen explains.
Under the FinMeas system, inclinometer measurement rods are inserted into the soil and measurement data is transmitted wirelessly to an intuitive internet service. The operator can set alarm limits: if these are exceeded, he or she is informed in realtime by email or text message. Automatic monitoring is more reliable and economical than traditional methods.
FinMeas’ inclinometers were also used for rock mechanical monitoring. Kolomainen cannot recall a similar case in which automatic inclinometers were installed in rock. The challenge lies in the fact that the measuring devices have to be installed as close as possible to the surface being excavated, otherwise they will not provide sufficiently accurate information.
”We installed the inclinometers one or two metres from the excavation line. The devices withstood the considerable forces and impetus caused by the explosion. Although there is still some room for developing the use of inclinometers in rock mechanical measurements, FinMeas has been highly proactive in this regard.”
Accurate information on the times of any changes
Kolomainen believes that FinMeas’ measuring devices have the edge over competing devices, by allowing the measurement interval to be changed flexibly in line with the phase of construction. During the excavation, measurements were performed as frequently as every 12 hours. Overall, rock mechanical movements will be monitored for a couple of months after the completion of the excavations.
”More frequent measurements enable the more precise linkage of potential changes to the time of blasting and, for example, to the explosives used. Similarly, we can easily select the measurements we want online – monitoring is very smooth.”
Rock mechanical monitoring for the West Metro has focused on station halls. These halls were modelled on the basis of ground investigations: the expected movements and directions of the rock were calculated in advance. Preliminary calculations can be verified using measurement results, enabling a response to deviations at the earliest possible stage. In the case of the West Metro station, for example, it was known beforehand that the type of stone at Matinkylä station would be demanding – the results confirmed that reinforcement work was required at the station.
Ease of automatic measurement is a competitive advantage
Since completing his work on the West Metro, Kolomainen has moved on to the ground investigations under planning for the Pisara line. Blasting there, too, will be exceptionally demanding, as the line passes under parts of central Helsinki. This means that measurements will also be important in this case.
Kolomainen believes that, thanks to their ease of use, the remotely readable measurement devices used at West Metro’s Urheilupuisto station will be adopted more widely in the future – in railway line projects and many other construction projects of a demanding nature. In addition to FinMeas’ easy-to-use measurement devices, Kolomainen praises the company’s attitude to service.
“Co-operation with FinMeas has gone well and communication has been active. They understand the needs of engineers and builders and are proactive if they notice any deviations in measurement results.”
FinMeas’ automatic inclinometers and anchor force measurements were used as a solution in this project.Download PDF
Skanska has opted to trust in FinMeas measurement technology in several construction sites. One of the largest and most challenging of these was the IsoKristiina shopping centre in downtown Lappeenranta.
The renovation and expansion of the IsoKristiina shopping centre has been one of the largest projects in the history of construction management contractor Skanska Talonrakennus Oy. Skanska Infra Oy was responsible for providing the foundation pit support for the extension.
This was a challenging task. The pit was 12 metres deep, with the shopping centre just one metre away and a block of flats just three metres distant. The support wall was anchored up to levels 2-3, with a total of 328 anchors installed.
”FinMeas was responsible for the support wall anchor force and displacement measurements. These measurements enabled us to plan and monitor our work more effectively on this demanding site,” say Tarmo Tarkkio and Niko Asikainen of the Skanska Infra foundation engineering unit.
Skanska has benefited hugely from this monitoring of the real-time behaviour of structures.
”For example, such measurements assure us that the support is adequate. This allows us to use lighter structures and reduce costs, which provides a competitive edge, while making construction sites safer for workers.”
When other buildings are located near the foundation pit, the support walls are usually designed in static form. A little room for movement, say 15 millimetres, can be allowed if more space is available.
”Measuring anchor forces and displacement has helped us to ensure that movement remains within the allowed limits, while using as few anchors as possible. In the absence of such measurements, the number of anchors required is usually overestimated – and even then there is no guarantee that the structures are safe.”
Use of measurements has allowed a reduction in the number of anchors used in the IsoKristiina support walls by one third – for a large contracting site, this easily means a saving of thousands of euros.
”Our investment in FinMeas technology soon paid itself back, both in the form of direct cost savings and improved safety. There is no point in compromising over displacement measurement . The investment is relatively small compared to the overall costs on a construction site.”
Automatic measurements save time and money
Skanska is delighted with FinMeas automated measurement systems. Subsidence measurement used to be based on mechanical strain gauges that had to be checked onsite. This form of manual measurement took time and cost money, with no way of knowing precisely when changes were occurring.
Displacements can now be measured using the FinMeas automatic inclinometer. The measuring rod is installed in the soil and the measurement data is automatically transmitted to a designated internet service. The user can set alarm limits: if the displacement limits are exceeded, the service will send an alarm message to the user’s mobile phone or e-mail. Automatic monitoring is more reliable and economic than traditional methods.
”FinMeas equipment is very easy to install and the results can be conveniently checked online. We save valuable working time and know exactly when a change has actually taken place. Due to real-time monitoring, we obtain an up-to-the minute snapshot of the status of structures. We can also easily monitor how forces change, based on which we can loosen or tighten the anchors.”
The project has gone smoothly at the IsoKristiina construction site – no hazardous situations have occurred related to structural durability. Measurements have also provided new, useful information on how structures behave: for example, how deepening the foundation pit affects upper level anchor forces.
Changes in anchor forces are caused by issues such as loads behind support walls and frost heaving of soil. In most cases, anchor forces begin to increase when soil frost increases the pressure on a pile wall. The wall is then heated to diminish soil frost pressure and to ensure that the forces remain within the anchoring capacity. With the help of measurements, such heating can be started at exactly the right time.
In general, support-wall frost protection and the heating they require represent a significant cost. By measuring anchor forces, the heating need can be easily optimised – in the case of projects, this can save up to tens of thousands of euros.
Progressive products, simple service
In addition to praising FinMeas’ products and services, Skanska thanks the company’s personnel. FinMeas’ experts are always easy to reach and they keep their promises.
”FinMeas is a highly proactive operation. They genuinely listen to our feedback, enabling us to take our cooperation to the next level.”
Skanska has a highly positive experience of displacement measurements. Measurements of various kinds are set to play a greater role in its future projects.
”In the absence of precise measurements, walls are typically over-secured. This makes no financial sense and does not provide real-time information on changes in structures. We plan to make greater use of measurement, due to the clear competitive edge it provides.”
The fact that city areas are almost fully built over, with new construction sites typically located right beside other functions or structures, just makes measurement even more important. Construction is becoming denser, leaving practically no room whatsoever for displacement in excavation-pit supporting walls. The earlier the builders notice any changes in structures, the faster they can react to them. This enables the safest and most cost-efficient construction possible.
FinMeas’ automatic inclinometers and anchor force measurements were used as a solution in this project.Download PDF
Measurement technology developed by FinMeas Ltd. is being used in highway tunnel construction work in the city. FinMeas automatic extensometers are being used to monitor rock-bed movements throughout the tunnel construction project, which will take several years.
FinMeas’ client is Tampere Rantatunneli Alliance, whose partner responsible for rock engineering is consulting engineering firm, Saanio & Riekkola Oy. Excavation work on the 2.3 km highway tunnel began in spring 2014 and the finished tunnel is scheduled to open for traffic in 2017.
”In many locations, the excavation and blast sites for the Rantatunneli are located directly below buildings, which makes careful rock engineering vitally important,” says Project Manager Kari Äikäs from Saanio & Riekkola Oy.
Construction work that involves rock engineering usually includes the monitoring of vibrations caused by blasting and drilling, of groundwater surface levels, of possible subsidence affecting buildings and structures, and of rock movements. Inside the Rantatunneli, FinMeas extensometers are being used to monitor vertical movements in the rock at five measurement points. Rock is usually subject to an area-specific level of stress, to which excavation work causes changes around the excavated cavity. During excavation work, such stress causes the walls of the tunnel to move inwards and the roof to rise. Movement of this kind is measured in millimetres.
”This type of movement is normal. We have used modelling to anticipate rock behaviour and conducted measurements to verify the reliability of our modelling. If there is more than a few millimetres of such movement, this means that our calculations are incorrect and the rock may be affected by unforeseen risk factors.”
”If the movements are minor, all is well. However, if the measurements indicate movement that is more substantial than anticipated, people at the construction site can react quickly and, if necessary, add more reinforcement structures, for example.”Download PDF
Kalasatama in Helsinki is one of the biggest and most visible construction sites in Finland. The enormous project continues also under ground where the upcoming shopping centre’s large parking garage is being excavated. The safety of the work is monitored with automatic extensometers delivered by FinMeas Ltd.
Kalasatama’s shopping center will have five underground parking garages, four of which are two-storied. The garages have altogether 1150 parking spots. SRV Infra is responsible for the construction work and the project’s manager is Ville Järvinen.
The reliability of the measurements is highlighted because of the unparalleled high tower buildings that are being built above the parking garage. The towers will be located above the rock pillars. Because the load will be large, it is necessary to get reliable and accurate information about rock movements. Thus, FinMeas’ measuring devices have been situated in all the critical spots.
FinMeas has delivered four automatic extensometers for this project. With these, the rock movements are monitored during the excavation and construction work. The extensometers have three or five anchors at different depths. These anchors move along with the rock movements, in relation to the reference point. The movement is measured and sent wirelessly to FinMeas’ webservice, where the measurement data can 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 information about this immediately as an email or SMS message.
Movements are monitored in real time
The measurement devices were installed in the rock mass already before the excavation started. This way also pre-work information is 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 Järvinen.
Kalasatama’s soil is good and there is an old rock island in the region. The rock movement has not at any point been close to the limits we have set. At one point we decided to make extra reinforcements after which the rock movement ended.”
Remote reading saves valuable working time
One challenge with the excavation of Kalasatama’s underground parking garages is that a lot of above-ground construction work is also taking place in the area – for example the foundations of the new shopping center.
”Construction work involves 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 they 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”, says Järvinen.
”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. FinMeas’ system helps us greatly in this.”
Everyone has access to important information
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 webservice whenever they like. This is a major improvement compared to what it was earlier.”
The planning of the parking garage started in January 2014 and the construction work begun in May 2015. The shopping center and the parking garages are planned to be ready for use in September 2018.
Before the construction of the parking garages can begin, altogether 200 000 solid cubic meters of stone will be mined from the area. In January 2016 almost half of this amount was already mined.Download PDF