Have you heard of horizontal and vertical shaft

or even inclined shaft tunneling?

But

have you ever seen a TBM

tunneling upward at a large pitch angle

like a "dragon raising its head"?

A remarkable machine arrives

Take a look

Recently, at the construction site of the State Grid Xinyuan Hunan Pingjiang Pumped Storage Power Station, the variable-diameter inclined shaft rock tunnel boring machine (TBM) independently developed by CRCHI successfully completed the world's first R50m ultra-small vertical curve, tunneling upward at a large pitch angle like a "cobra maneuver" and entering the 50° inclined shaft section for excavation, marking another major historic breakthrough in China's TBM technology.

The vertical curve section formed by TBM tunneling

It is understood that the water conveyance inclined shafts of pumped storage power stations are usually arranged in two stages, each about 500m long, with a sharp transition curve of about R50m between the horizontal tunnel and the inclined shaft. In previous TBM development and application, the minimum vertical curve turning capability of a TBM was generally between R500 and R1000m. For the tunneling demand of sharply and substantially changing gradients such as water conveyance inclined shafts in pumped storage power stations, an R50m vertical curve means that for every 0.5m of tunneling, the cutterhead pitch angle would reach a maximum of 1.2°. Previously, industry peers at home and abroad all stated that this was difficult for TBMs to achieve.

Relying on its strong accumulation of technical strength, and on the basis of successively overcoming technologies such as large-gradient tunneling by coal mine TBMs and horizontal turning by TBMs for drainage galleries of pumped storage power stations, CRCHI, with the support of State Grid Xinyuan Hunan Pingjiang Pumped Storage Company, jointly with Sinohydro Bureau 8 Co., Ltd., PowerChina Zhongnan Engineering Corporation, and Guangdong Keyuan·Hunan Electric Power Consulting Consortium, carried out dedicated independent research and development. They completed the development and application of more than ten key core technologies, including the vertically steerable TBM shield body, the variable-zone stepless back-pressure regulation hydraulic thrust system, the laser plus multi-sensor fusion TBM guidance measurement system, the adaptive variable-lift fluid medium transport technology, the multi-stage gradient-change mucking technology, and the rapid launch technology without a turning guide platform.

50° ultra-large gradient working condition

It is reported that the R50m curve tunneling of the variable-diameter inclined shaft TBM, with the joint efforts of all participating parties, overcame many difficulties such as complex transport routes with many curves and steep slopes inside the tunnel, the narrow lifting space of the 60m assembly cavern, an assembly and commissioning period of only 40 days, the complex split-launch process, and the challenges in tunneling, mucking, guidance, and material transport during the turning process. The tunneling of the curve section was completed in only 19 days, with a maximum daily advance of 5m, greatly shortening the transition period from horizontal to inclined tunneling and creating favorable conditions for the subsequent rapid construction of the straight section of the water conveyance inclined shaft of the Pingjiang Pumped Storage Power Station.

Equipment assembly site inside the tunnel