Freeing stricken TBMs in tough Asian conditions Mar 2012
SELI News Release
- Engineers have successfully released a stricken hard rock TBM that became trapped in poor ground during a 19.8km water tunnel drive in China.
Trapped TBM can now be modified
- The news comes ten months after SELI signed a €20 million (US$26.5 million) contract to carry out the rescue operation on China's Yinhongiishi Water Diversion Project in Shannxi Province.
- The Chinese rescue is the fourth major TBM recovery carried out by SELI in Asia over the last 12 months.
- The tunnel is a mix of drill+blast and TBM construction methods, but operations ground to a halt when the TBM became trapped 6km into its 11.1km drive.
- Having successfully carried out the design and construction of a tunnel enlargement to create a cavern around the trapped TBM, engineers will now complete the modifications and refurbishments needed to enable it to continue its drive. Any heavy components that are necessary will be lifted through large hoists suspended to the rib structure.
- With the TBM now completely free, SELI engineers have begun disassembly but the current configuration of the rock double shield is not yet adapted for excavation of the remaining 5.1km of tunnel, where SELI engineers expect to encounter severe hydro-geological conditions.
- A wide range of modifications are currently being prepared, and it is expected the drive will restart in June, more than a year after the TBM first became trapped.
- Meanwhile, on the Veligonda project in India SELI engineers successfully freed two TBMs that became stuck after encountering mud and water pressure faults. On Veligonda-1, a double shield 8m diameter TBM was stuck for nearly a year before being freed, while on Veligonda 2, a double shield 10m diameter TBM was trapped for several months after encountering similar ground faults.
- And at Sleemanabad in India SELI carried out another rescue, this time of a 10m diameter EPBM that had encountered a series of operational difficulties.
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