Recently, the 5.5-meter open-type TBM (DZ301), designed and manufactured by CRCHI and used for construction by Sinohydro Bureau 4 Co., Ltd., officially reached the completion of its tunneling task section. It is reported that the total tunneling mileage of this machine reached 26 kilometers, setting a world record for the longest single-machine tunneling by an open-type TBM. This is another world record refresh following CRCHI's open-type TBM surpassing 21 kilometers of single-head tunneling in a project!

Challenging Early Days After Launch

On September 25, 2017, China Railway 18th Bureau Group officially began tunneling with this machine. The project served by the equipment is located in a desolate Gobi desert with complex geological conditions and harsh natural environment. This section required tunneling over 18 kilometers under relatively high rock strength, placing high demands on the equipment's support performance and reliability. The machine still withstood numerous tests and achieved an efficient launch, with average monthly advance exceeding 1,000 meters in the first three months, and completed the 2-kilometer trial tunneling support task in just over two months.

Outstanding Performance as Tunneling Began

During tunnel construction, the equipment encountered various complex construction challenges such as broken surrounding rock, collapses, and rapid geological changes, with some strata experiencing seepage, dripping water, and flowing water.

Facing these difficulties, CRCHI's TBM still forged ahead, setting high-production records including a maximum daily advance of 56.61 meters, a maximum monthly advance of 1,280 meters, and an average monthly advance of 720 meters for the entire section. The TBM's average utilization rate was 39.62%, and the average equipment availability was 94.6%. Monthly advance exceeded 1,000 meters multiple times, setting the highest TBM construction record for tunnels of the same type, earning high recognition and praise from the owner and setting a benchmark for other projects under construction.

Rock Breaking and Breakthrough: CRCHI Speed

The equipment's construction task for the China Railway 18th Bureau Group section (total task of 20.551 kilometers) was successfully completed on July 2, 2020, at least 9 months ahead of schedule. It was the first section among the 18 TBMs along the project to achieve breakthrough, and it was also the first time a domestic TBM achieved continuous tunneling exceeding 20.54 kilometers. The average monthly advance for the entire section exceeded 700 meters, demonstrating "CRCHI Speed."

Green Construction and Continuous Efforts

On November 18, 2021, after maintenance by CRCHI, the equipment was transferred to Sinohydro Bureau 4 Co., Ltd. for construction. During this period, it endured numerous challenges including long-distance stepping, sudden mud and large water inflow, and machine jamming in fractured zones, yet still completed the designed mileage of 5.45 kilometers on schedule. With cumulative tunneling of 26 kilometers, it set the world record for the longest single-machine tunneling by an open-type TBM.