On Feb. 23rd, 2019, CRCHI earth pressure balance shield machines (EPB) achieved double breakthrough between the air shaft and the Caoqiao Station, which is another milestone in the construction of the Beijing new airport subway line, following by the breakthrough that another two CRCHI two large EPBs made for the longest phase in the project on Aug.28th, 2018.
As one of the supporting traffic facilities of Beijing Daxing International Airport, Beijing new airport line has a total length of 41.365 kilometers, with the fastest designed speed of 160 kilometer per hour and the largest diameter. The new subway line will use self-driving trains and the travel time from the downtown of Beijing to the terminal will be only 19 minutes.
CRCHI EPBs (φ9100mm) have completed the construction of two tubes, the left side being 3075 meters long, the right being 3065 meters and the max. burial depth being 24.3 meters.
As EPBs mainly tunneled in the pebble layer, the machines were designed to have:
1.4.8m main bearing, enough torque and power reserve.
2.capabilities of muck discharge and rock breaking that work together to handle sandy pebble stratum.
3.a heavy-type 6-spoke cutterhead whose cutters and opening ratio can be adjusted to treat sandy pebble stratum and mudstone stratum.
4.a segment handling system that directly delivers the segment in the erector area and a segment unloader to improve construction efficiency.
5.a continuous belt conveyor system (PDJ17006, PDJ17007), turn-back belt conveyors, ground muck discharging belt conveyors, movable belt conveyors, improving high efficiency in excavation.
These two EPBs have finished the construction of two tubes after about 1 year since they were launched respectively on Feb.8th and Mar. 7th, 2018. During driving, the max. daily advance rate is 36.8 meters, max. monthly advance rate is 670 meters and more than 1500 meters were successfully tunneled for one time in the pebble stratum.