What is UT-Mobile?
It is the name of a mobile laboratory which is developed for underground mechanized excavations. UT means the capital letters of Underground Technology.
Underground Technologies and Mechanized Excavations
Tunnel boring machines have advanced for over 100 years. Nowadays in underground constructions (metro, sewerage, power, water tunnels) TBMs are preferred because of reduction in construction costs and time, high advanced rates, safe working conditions.
The performance of TBMs can be enhanced by having control on three discipline which are soil mechanics, TBM technology and polymer chemistry.
Reasons of Forming UT-Mobile
In mechanized tunneling especially in EPB TBM applications the geology must be ideal for excavations. If the soil doesn’t have ideal conditions to excavate, by using soil conditioning additives, soil become ideal for EPB TBM excavation. Soil conditioning is the science deals with this subject.
Soil and additives are main issues in soil conditioning. That’s why, soil must be examined in laboratory and all mechanical properties of soil must be determined. Both in Turkey and worldwide projects, after taking soil samples from tunnels some mechanical and physical properties of soil change and the samples can be disturbed. Although having a lot of samples, the results of the laboratory tests would be wrong because of the changed properties of the samples.
Carrying the samples to laboratory, analysis of the samples and evaluation of the results, preparing the reports would be all time loss. The problems mentioned above will also increase the costs.
As the mechanized tunneling started to take part in our region, in order to develop the correct and unique system and infrastructure for Slurry/EPB TBM and hard rock TBM applications for both in situ and lab, IKSA decided to start R&D projects which also covers injection and grouting. As an output of our first underground project, we build a mobile laboratory which carry out all soil mechanics and concrete tests; also foam tests for EPB and rheology tests for slurry. UT-Mobile is also able to give the necessary feedback about correct and useful chemicals that can be used during boring operation.
In addition, by participating in known scientific programs, the R&D of IKSA shares views and exchanges technological know-how with different branches of universities and the construction sector engineers. We have been running R&D projects which are sponsored by Turkish Scientific and Research Council (TUBITAK). The topics of the projects are as follows.
First Project Name: Developing the real time soil analysis and chemical conditioning system regarding to underground technologies and mechanized tunneling applications.
Project Date: 01.01.2008 – 30.06.2009
Project Status: Successfully completed
Second Project Name: Examination of material's nano/macro grain size properties in mechanized tunnel supporting techniques, interactions and developing the formulas of soil conditioning, segment, grout and shotcrete design.
Project Date: 01.12.2009
Project Status: Continuing
One of the members of R&D team who works on these projects had completed his MSc. in Mining Engineering Department in Istanbul Technical University regarding mechanical excavations. The other member of the team continues her MSc. program in Chemical Engineering Department in Ankara Hacettepe University regarding surfactants.
- UT-Mobile has gained some features mentioned below;
- System has installed on a mobile platform to visit more than one construction site.
- Consist of an office room, a laboratory and storage.
- Laboratory has climatization at -5 and +25 °C for adapting to tunnel conditions.
All needed laboratory equipment are installed into mobile unit.
UT-Mobil has formed to optimize soil conditioning chemicals regarding EPB and Slurry TBMs which excavates in soft grounds (sand, silt, clay). Tunnel and TBM conditions simulated in laboratory and producing the chemicals and carrying out tests could be achieved.
IKSA R&D team is studying on second project for developing soil conditioning system and all chemicals which are needed in a TBM project including grout design, shotcrete and segment concrete designs. By research and development works, UT-Mobile can give rapid solutions on site.
Soil Conditioning
Especially in EPB TBM tunneling, machines need ideal soil properties for a successful excavation. In that way, soil must be in plastic consistency, compressible, impermeable, low internal friction, etc. If the soil doesn’t have these properties, by using soil conditioning chemicals, properties of soil can be change and the soil will be ideal for TBM. Soil conditioning is the key to fast and successful tunneling.
Foam and polymers are the main soil conditioning agents. By using foam and polymers, torque needed at cutterhead and the stress on motors reduces, excessive heat at cutterhead and clogging of soils can be prevent. Soil will become impermeable, lower internal friction and cohesion, more compressible. Foam and polymers also reduce abrasion and wear on cutterhead, screw conveyor and metal surfaces. Blockages and cloggings will reduce and transportation of the excavated soil would be easier.
As a result, by application of soil conditioning;
• Low density
• Low internal friction angle
• Low torque
• Less adhesion and sticky problems
• Low permeability
• Low abrasion
• Easy transportation
• Success at stability of face
Working Procedure of UT-Mobile
First of all, UT-Mobil Team takes soil samples from the TBM tunnel. After carrying out soil mechanics tests on the samples which came from underground, the test results send to main laboratory in real time. The staff in main laboratory develops chemical formulas according to received results from the mobile laboratory. When the preparations of formulas completed, results send back to the mobile laboratory in real time. According to new formulas UT-Mobile staff carries out new tests by mixing the chemicals and soil samples. Aim of these tests is examination of the interaction between the soil and soil conditioning chemicals.
Soil conditioning applications in laboratory and on site can produce different results. So, laboratory results could be checked and supplementary works could be done in real tunnel conditions. After laboratory works, UT-Mobile Team brings all results to underground and makes supplementary works and tests on TBM.
The data flow and contact between UT-Mobile and the main laboratory of IKSA can be achieved by special software which is developed by a software consultant company.
|
