Derived from EPB TBM and integrated with merits of both EPB TBM and hard rock TBM, the mix TBM is mainly applied to bore in soft and hard ground, such as sandy gravel and weather rocks.
Chengdu Metro Project, China (Sand and Gravel)
CREG supplied thirty-two TBMs to Chengdu Metro. Geology thereof is featured by mudstone and water-rich sandy gravels. CREG tailored designs enabled CREG TBMs to completely adapt to the geology. When boring through built-up areas (i.e. China Mobile Information Hub), TBM CREC-83 created a miraculous record by keeping settlement less than 3.7mm. First breakthrough was made by TBM CREC-65 with maximum daily rate 21m and monthly 339.
Shenzhen Metro Project, China (gravelly clay, granite)
CREG supplied twenty-seven TBMs to Shenzhen Metro Project, Geology therein is mainly featured by slightly weathered granite and boulders. In the TBM design cutter spacing is reduced, cutterhead drive torque increased and cutterhead main bearing capacity enhanced to withstand uneven load. All CREG TBMs are highly geologically adaptable in Shenzhen Metro. TBM CREC-68 achieved maximum daily advance rate 24m and monthly 558m.
Kuala Lumpur Kelang Valley MRT, Malaysia (sandy mudstone, flaky mudstone, hard rock)
Kelang Valley MRT runs in water-saturated sandy mudstone, schistose mudstone, highly weathered (HW) mudstone, Kenny Hill alluvium and built-up areas. TBMs CREC-50 and CREC-51 with 6670mm excavation diameter and 1120KW main drive power were used for this project. CREC-51 TBM achieved 374.2m monthly advance rate record in Malaysia. It was then remanufactured for Delhi Metro where geology is more complex with full-face hard rock.
In the course of tunnelling, the maximum compressive rock strength of the TBM in granular quartz reaches up to 320 MPa and the advancing distance is 255m.