China Railway Construction Heavy Industry Corp Ltd’s (CRCHI) slurry TBM, Jinghua, reached the intermediate air shaft last month after excavating 4.77km over 16 months.
The slurry TBM – the largest shield machine ever used in China – has a 16.07m diameter, is 150m long and weighs 4300 tons.
During the bore the TBM overcame technical difficulties such as a shallow overburden and a long section crossing high-density sand layers. The slurry TBM continuously crossed the Beijing-Harbin Railway and Beijing’s sub-centre transportation hub, with micro-settlement and non-disturbance. It set a record of excavating 542m in a single month.
The geology along the tunnel alignment is mainly sandy soil, water-rich and high-density sand, with interactive layers of silt and cohesive soil.
The TBM incorporates fourth-generation accessible cutter exchange technology, a telescopic main drive, extreme high-pressure auto-compensation, a large power slurry circulation system, and synchronous double-liquid grouting.
CRCHI says the successful application of synchronous double-liquid grouting technology has enabled the millimeter-level control of ground settlement, ensured no disturbance to existing buildings, and filled the gap of synchronous double-liquid grouting in mega slurry TBM construction in China.
From the intermediate air shaft Jinghua will now excavate the final 2.6km to the retrieval shaft.
