Monday, 24 November 2014

New Testing Plans: Drilled Steel CT-pile Wall at Isosuo Landfill in City of Naantali



Today we are provaiding you article written by Liisa Larkela, who teaches geotechnics in Turku University of Applied Sciences. Enjoy!
 

New Testing Plans: Drilled Steel CT-pile Wall at Isosuo Landfill in City of Naantali

General
Turku University of Applied Sciences has done research of micropiles. During last few years it has created a new innovative open section C-pile and tested it in different locations and soil profiles.
If the C-pile has a special T-part it may be used as a pile wall. This so called CT-pile wall profile in is planned to be tested in Naantali Isosuo Landfill on December 2014.

Where CT-pile wall could be suitable?
Installation of usual sheet pile wall can be challenging for example in rocky soils. In many cases, drilled wall would be handy but conventional drilled pile walls on market are heavy and expensive for small construction sites.
In some areas, for example landfills, water proof structures is a requirement to prevent pollution leakage. A CT-pile wall can be grouted with cement to almost waterproof structure (depending on the cement mixture). If prevention structures are not built beforehand, CT-pile wall could be one option.

Testing plan
In Naantali, CT-pile wall of 20 pcs and to length of 6 to 8 meters will be drilled to ground. The soil profile consists of clay, silt, gravel and moraine and possibly bedrock. The CT-pile wall has never been drilled to inhomogeneous soil before.
Five piles of the wall will be injected with cement. Diameter of one CT-pile is 139.7 mm and the wall thickness is 6mm. Drilling bit diameter is 150mm. During the test deflections and observations will be conducted. 

Measurements of movements
Soil surface displacements will be measured after installation of the wall. It is predicted, that some movement will take place but it is also assumed that the benefits of the small diameter drilling bit (and pile) will be found and the settlements/movements will be quite small.

Author: Liisa Larkela, Turku University of Applied Sciences
General Organizer: Turku University of Applied Sciences
Drilling Work: Suomen Teräspaalutus Oy
Provider of Test Area: City of Naantali
Pile Manufacturer: Trameta Oy, Turku
Drill Head Manufactures: Robit Rocktools Ltd

Monday, 17 November 2014

Geotechnics day 06.11.2014
The student's point of view

Atmosphere at the Geotecnical day
I am studying civil engineering for the fourth year. I heard of geotechnical engineering for the first time a couple of years ago and since then I have tried to learn everything possible about the subject, resources and leisure time within the area of this discipline.

When I read on the SGY's (Finnish Geotechnical Society)  website about the geotechnics day I thought that I have to get to the scene. As luck would have it the Turku University of Applied Sciences had booked a few extra tickets for students. So by train we went to Helsinki. The occasion itself was in Bio Rex, a few hundred meters from the Helsinki railway station.

The occasion began early in the morning and when I got there I realized how big of an occasion it was. There were probably hundreds of people. The atmosphere was casual and networking with the professionals was possible to. Surprisingly, there were even a few familiar faces, mainly the guest speakers from the University of Applied Sciences.

Presentations started and I was pleased that, although I did not have a lot of experience in geotechnics, however, I was able to follow and understand almost everything in all presentations.

The agenda was long with 15 different topics. Excluding breaks presentations were continued until the afternoon.

There were a lot of interesting subjects, but particularly memorable were topics related to the construction of the metropolitan area densely populated environment. Improvement of Ring III due to continuous growth in traffic, re-piling pier's in the South harbour of Helsinki, the City of Helsinki problems with groundwater, when the impervious surfaces are gaining more and more space, etc.

The presentations were dealing with a lot of the actual projects success and problems, that the engineers had come across. I must say that for me these problems seem to be insurmountable problems, but however include engineer's daily basis in working life.

On the agenda one can notice that recovered materials have become important in foundation engineering. Also new water permeable pavements and road structures have progressed from CLASS (Climate Adaptive SurfaceS) projects to pilot projects. This is good news for the Helsinki metropolitan area groundwater.


Geotechnics day as a whole was very interesting and a well-organized occasion. As a student I got a lot of new ideas in this field and I saw what kind of problems and plans professionals are working with. Even at this stage it is clear that I will take a part in geotechnics day next year.

Monday, 10 November 2014

ENERGY MICROPILES IN UNDERPINNING PROJECTS - Rauli Lautkankare, Vesa Sarola, Heli Kanerva-Lehto



ABSTRACT

The biggest challenge in the utilization of energy micropiles in underpinning projects is related to the through holes for geothermal energy collector pipes in the load transfer structures. In the FIN-C2M project (Case 2 Micropile Research Project in ISM collaboration) several technical solutions were studied and the most suitable load transfer structure cases for the use of energy micropiles were defined. There are thirteen known load transfer structure cases and energy micropiles can be used with nine of them. In five of the cases, the through holes for collector pipes can be made as found in new buildings. In the other four cases, where pretensioning is achieved by jacking directly above the micropile, the construction of through holes needs further development . There are already some possible solutions and the challenge is to bypass the jack.

 USING DEEP FOUNDATIONS AS GROUND HEAT COLLECTORS

The first projects where openings in pile casing were used to install heat exchange piping are from the early 21st century. The research for energy piles started the late 1990’s. All the cases have been large new construction projects where the load bearing soil layer has been several metres beneath the surface.

These projects include Zurich Airport terminal E and Main Tower in Frankfurt.

In this article the recovery of ground heat in underpinning projects is studied.

The focus is on load transfer structures transferring the load from old to new foundations, the through holes of ground heat collector piping and their technical implementation in these load transfer structures.

This study is part of FIN-C2M project. FINC2M project is part of Case 2 Micropile Research Project in International Society for Micropiles collaboration.

Current technology and research results make the use of energy piles possible in certain cases. There are altough limitations and possibilities related to energy piles that need to be taken into account when estimating the energy production investments and life cycle of buildings. Two such limitations are

mean distance between the piles and the length of piles. This is vital for ensuring the ground thermal balance. If the underpinning project will be carried out in any case, it might be reasonable to consider energy piles. Also hybrid energy micropiles are one possibility as well. Any piles large enough for the ground heat collector piping are suitable as energy piles.

These include steel pipe piles and concrete piles with holes. Of these two only steel pipe piles have been used in underpinning projects in Finland.

ENERGY PILES AND LOAD TRANSFER STRUCTURES

One of the challenges using energy piles in underpinning projects is the load transfer structures, specifically the through holes for ground heat collector pipes. In the FIN-C2M project this is studied on the basis of load transfer cases by examining which types of load transfer structures are suitable for energy piles. There are

thirteen recognized load transfer cases and according to the studies nine of these are suitable for use with energy piles.

 [...]

INSTALLATION OF GROUND HEAT COLLECTOR PIPES INTO PILE

When the heat collector pipes are fed into the energy pile, the procedure and techniques is a combination of installing pipes into heat wells and installing piles. In regarding the filling material, in Finland piles are typically filled with concrete. The use of concrete is supported by its good thermal conductivity and the way it bonds with steel pile to form a load-bearing composite structure.

The selection of filling material has a great significance in the long run as the increased thermal conductivity affects the energy gain positively throughout its life cycle. Then why is concrete not used always although it has better thermal conductivity than water? Water filling has its own advantages as the pipes can

be replaced more easily if they break or reach the end of their life cycle.

As pipe installations performed alongside underpinning projects are usually done in cramped basements, the chance of breaking the pipes is much higher when compared with the usual piping of heat wells outside the actual building.

Pipes can also break due to other causes than weakening by age. During transportation, moving at the construction site, storage or installation, precision is important as plastic pipes scratch easily and are then unusable.

Nowdays constructions are generally designed with 100-200 year service life and the heat collectior pipes may well need replacement during that period.

CONCLUSIONS

As a result of this research it was found possible to find technical solutions to combine energy micropiles and groud heat collector pipes with nine load transfer structure cases. In five cases the work can be done as in new building.

There is also a special solution if steel beams have to used. In four cases the pipes have to be led out trough the side of the pile before the pile cap or alternatively to use special jack system. The system allows  installing collector pipes right after piling phase and jacking after piping without breaking the pipes.

There are certain challenges and questions, especially concerning the installing process, that have to be researched and tested. The energy micropiles are one solution to produce heat from the ground and furthermore one way to reduce the greenhouse gas emissions in energy production.


Monday, 3 November 2014

Ramboll - Underpinning project



Hi Micropilers,

We want to share an exciting experience with you!  On the 14th of October we went to visit the Ramboll office in Turku and a building site to see how micropiling is done in Turku.

Ramboll is a leading engineering, design and consultancy company and is active in the markets: Buildings, Transport, Environment, Energy, Oil & Gas and Management Consulting. It was founded in 1945 as the "Rambøll & Hannemann" partnership in Copenhagen, Denmark. Since then, Ramboll has expanded in to an international corporation employing 11,000 dedicated specialists in 21 countries. At the moment only in Finland 1900 people work for Ramboll in 26 different locations.  

Geotechnics is one of its main discipline with projects of all sizes and management of every phase – from planning, initial investigation, design and tender, too implementation, inspection and supervision. 

In the last years Ramboll-Finland has been appointed as the structural and geotechnical engineer for:

- harbors, for example in Helsinki;
- 51,3 km of the E18 motorway, which goes from the Southern of the country till the border of Russia;
- the new children’s hospital, Uusi Lastensairaala, in Helsinki;
- many others.

 Reino Heikinheimo has kindly shared his experience about micropiling with us.

In the 1900’s wooden piles were used for the foundations of the houses in Turku, these are still in the ground and are still working. Today the main problems are that the piles are rotting in old houses due to the fluctuation of the water level or they are settling into the ground because they were built in a thick layer of clay (for example the clay layer is 40-50 m deep in Turku).   

The underpinning technique provides the installation of additional piles which can bear the load of the building.  The most important issues to consider are:
- the costs
- the dimension of the machine, because the spaces for working are often very narrow
- the noise and the vibration for the neighbors
- the possibility of corrosion for the steel piles.

 
The building site is situated in the city center of Turku, not far from the market square, along the banks of the River Aura. It's a residential building of 7 floors, with many apartements.


The old foundation consists of friction piles, installed in the clay soil, which covers most of Finland. This type of soil causes big structural problems to the foundations, which over time sink into the ground.
For avoiding these type of problems, a new foundation is settled, without modifing the existing structure. 
 

This system is so called Underpinning.



  


 
The work consists of drilling in to the ground until the bedrock and embedding 87 new steel piles, much deeper than the oldest ones.
The positive aspect is that all the work is done in the basement, leaving the outer structure in function. The residents don't have to move while the work is done!




Drilling
 machine




Steel pile





 

 The hole for the new piles is made with an electronical or pneumatic drilling machine, as it is shown in the picture on the left.



Pile being drilled


Steel pile with concrete











An operator is using the drilling machine and the steel pile is being fixed in the ground in separated parts, which are welded together.
When the pile is fixed, concrete is put inside. The piles used in this project are
Ø140.





The load transfer structure is realised which connects the piles with the existing structure of the building.





The entire structure is first pre-stressed to minimize settlement and aftherwards stressed, for taking the load.


The new piles in the basement. Working and bearing the load.

This system does not change the existing spaces and so it'is a non-invasive system.