By Lynda Myer
The first breakthrough has been achieved on Beijing’s East Sixth Ring Road Reconstruction project.
Following excavation of 4.77km over 16 months, China Railway Construction Heavy Industry Corp Ltd’s (CRCHI) slurry TBM, Jinghua, attained the intermediate air shaft last month.
As the largest shield machine ever used in China, the slurry TBM16.07m diameter, 150m long and weighs 4300 tons.
Including a shallow overburden and a long section crossing high-density sand layers, the TBM overcame technical difficulties during the excavation process. The slurry TBM continuously crossed the Beijing-Harbin Railway and Beijing’s sub-center transportation hub, with micro-settlement and non-disturbance.
Although 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’s monthly excavating record is 542m.
Fourth-generation accessible cutter exchange technology, a telescopic main drive, extreme high-pressure auto-compensation, a large power slurry circulation system, as well as synchronous double-liquid grouting, are the contents of this TBM.
According to CRCHI: “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.”
Currently, the intermediate air shaft Jinghua is due to dig the final 2.6km to the retrieval shaft.
