The TBM from CRCHI - China Railway Construction Heavy Industry – is the largest TBM ever to be used in China. It reached the intermediate air shaft after excavating nearly 4.8km over the past 16 months. Along the way, it set a 542m excavation record for a single month, according to the manufacturer.
Even so, CRCHI reported that it had to overcome technical difficulties such as shallow overburden during the initial excavation and crossing long-distances in high-density sand layers. The slurry TBM continuously crossed the Beijing-Harbin Railway and Beijing sub-centre comprehensive transportation hub.
The maximum excavation diameter of the 150m-long Jinghua is 16.07m with a total weight of 4,300tonnes.. CRCHI says that the machine has the fourth-generation accessible cutter exchange technology, telescopic main drive, extreme high pressure auto-compensation, large power slurry circulation system and synchronous double-liquid grouting.
The successful application of synchronous double-liquid grouting technology allowed millimetre-level control of ground settlement and ensured zero disturbance to nearby during TBM operations. The complex geology is mainly sandy soil, water-rich and high-density sand, interactive layers of silt and cohesive soil. The project also faces construction difficulties such as super-deep soil cover.