Contractor Italian-Thai Development passed through two unexcavated stations and one ventilation shaft along the route. The next, eastbound bore will require the crossing of two already excavated stations which the machine will need to be dragged through.
Geology consisted of complex stiff clay and Bangkok’s aquifer sand with large gravels and sand stone at the deepest parts of the alignment. As well as high water pressure, the TBM passed under historical buildings in an old area of the city. Settlement control was key, said a Terratec spokesman. "The TBM was equipped with a 2-liquid type backfilling system and a special Clay Shock injection system through the shield. The combination of both was proven to be very effective and restricted the settlement to less than 10mm in those critical areas.
"The EPBM had to bore through as many as eight diaphragm walls, as well as several obstacles such building foundations. This was expected at the beginning of the project and Terratec selected a cutterhead design with conical shape to overcome those smoothly without disrupting the soil around.
"The TBM achieved the planned average rates of 18 meter per day or 82 meter per week during the boring cycles."
Now the TBM is being dismantled and moved to initiate the eastern bore by beginning of August.
