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. The project will deliver an important route for Beijing once complete.
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.