Developed on the basis of EPB TBM and combined with concepts and merits of both air pressure and hard rock TBMs, a mix-type TBM is mainly developed to bore tunnel in soft and hard characterized by sandy gravels and weathered rocks.
Beijing Metro Project
TBMS CREC-03 and CREC-04 were developed at Lot 12 Beijing Metro Line 10, and the stratum crossed thereof is of sand and cobble amongst which cobbles with diameters larger than 300mm accounts for over 30%. The design philosophy of the above TBMs was shifted from the conventional "cobble breaking method" to the "cobble discharging combined with breaking method" in which the cutterhead opening was increased and for the first time the ribbon screw conveyor was introduced. The two machines completed 2191.20 meters and 2196 meters boring lengths respectively with maximum daily progress of 24 meters and maximum monthly advance of 456 meters. During tunnelling in the sandy cobble stratum, the achieved maximum ground settlement is 7mm and the cumulative average settlement 3mm, which was highly commended by the Employer and Beijing Municipal Government.
Shenzhen Metro Project
gravel clay, granite, etc.
A total number of 17 TBMs are respectively applied at Shenzhen Metro Line 9 and Line 11 among which 6 are large-face electric-drive machines with diameters of 6.98m. In view of crossing in the long MW and SW granite section, the design spacing of cutting tools on the cutterhead was reduced to increase the cutterhead drive torque as well as to enhance the bearing capacity of both cutterhead and main bearing in case of offset load. All TBMs demonstrate excellent geological adaptabilities in Shenzhen. TBM CREC-68 has now bored 2600 meters accumulatively with daily advance of 24m and monthly maximum progress of 558m.
Malaysia Metro Project
sandy mudstone, flaky mudstone, etc.
TBM CREC-50 and TBM CREC-51 with boring diameters 6670m and main drive power 1120KW have been supplied to Malaysia Kelang Valley MRT Line and the geology thereof is characterized by sandy mudstone, flaky mudstone, HW mudstone, crushed gravel, and Kenny Hill eluvium. This interval is very complex and rich in underground water, furthermore, buildings are/or structures which are required to be crossed are quite many. TBM CREC-51 achieved highest monthly advance of 347.2 meters which hit Malaysia tunnelling record. The final settlement and upheaval are controlled within 2mm.