CREG High-Pressure Hydro-Coupling TBM Constructing Hard Rock TunnelsWan’an River Water Diversion Project

Hard Rock Tunnel Boring Machine (TBM) is the first choice for the construction of hard rock tunnels because it is a fast, safe, and environmental-friendly construction method.

TBM Specifications
Total installed power: 2160kW
Range of rotation speed: 0~8.5~14.5rpm
Breakout torque: 2022 kNm
Rated torque: 1348kNm
Cutterhead rotation speed: 15.8r/min
Advance speed: 100mm/min
Thrust force: 8970kN@320bar
Curve radius: 500m
Geology: Biotite granite, quartz conglomerate, quartz sandstone, siltstone, conglomerate, argillaceous siltstone, wall rock, etc.

As overburden increases, the ground stress of surrounding rock and the rock strength gradually rises. When the rock strength is more than 200MPa, TBM rock breaking efficiency would be sacrificed. To solve the problem of “hard and slow advance”, various auxiliary rock breaking methods are being studied.

CREG, as a worldwide underground solutions provider, developed the TBM with high-pressure water jet coupled with rock breaking technology on June 18, 2019. It was successfully applied at the Wan’an River Water Diversion Project in the Fujian Province of China, with a total tunnel length of approx. 14.936km and the excavation diameter of 3.83m.

The geology along the tunnel is mainly biotite granite, with the maximum uniaxial saturated compression strength of 226MPa and the average rock strength of 170MPa. The CREG TBM combines the high-pressure water coupling method and the traditional disc cutter rock breaking method, based on the principle that the high-pressure water jet with the nozzle reasonably installed on the cutterhead, is used to wedge the rock, so as to greatly improve the penetration capacity and rock breaking efficiency of the TBM disc cutter and achieve efficient driving.

According to the test data from the site, which includes thrust, penetration, torque of the TBM, when all disc cutters and high-pressure water jet method breaking rocks together, a comparison was made by taking the average value of each parameter, as shown in Table 1.

Table 1: Summary of average values of TBM driving parameters under different water pressures
High-pressure water pressure (MPa) Thrust (kN) Torque (kN·m) Penetration (mm) Field penetration index (kN/mm) Torque penetration index (kN·m/mm)
Only disc cutters 5704 429 2.57 84.6 6.33
150 6100 584 3.25 71.4 6.79
200 6044 609 3.66 62.9 6.30
240 6122 640 4.07 57.6 5.97
270 6156 622 4.56 52.4 5.26
It is evident that the penetration of the TBM increases significantly, the torque of cutterhead increases slightly, and the field penetration index and torque penetration index decreases. Taking 270MPa high-pressure hydro-coupling rock breaking as an example, compared to the TBM with all disc cutters, the thrust of the TBM basically remains unchanged (the mean value increases by 7.9%), and its average penetration rises from 2.57mm to 4.56mm, with an increase of 77.4%.

Field penetration index (FPI) refers to the thrust requested by one disc cutter penetrating 1mm into the rock. The mean value of FPI is 84.6kN/mm when driving with only disc cutters, while it is 52.4kN/mm when driving with 270MPa high-pressure water jet, which means the thrust of one disc cutter to wedge 1m into the rock decreases by about 38.1%. Torque penetration index (TPI) refers to the force of rolling friction requested by one disc cutter penetrating the rock of 1mm. When driving with 270MPa high-pressure hydro-coupling, the TPI value decreases about 16.9% to 5.26kN·m/mm from the TPI value of 6.33kN·m/mm when driving with only disc cutters. The cutting effect on tunnel face is shown in Figure 1.

The cutting effect on tunnel faceFigure 1: Tunnel face

CRCHI Slurry TBM ‘Avni’ Helps Make a Breakthrough in Bangalore Metro Project
The 6.6m Slurry TBM developed by CRCHI exited the tunnel at Vellara Station, Phase II of Bangalore Metro in India, becoming the first TBM to complete the breakthrough for the whole line of the project. Avni is one of the four slurry TBMs provided by CRCHI

Read more ...

The Bolter Miner - A Technology Revolution for Roadway Development in Underground Coal Mining
In India, coal is still the primary source of energy; over the past few years, there has been quantum jump in coal production level, but it was mostly due to the high percentage share from the opencast sector. The country is witnessing a fast

Read more ...

CRCHI emerges as provider of total underground engineering equipment and solutions
China Railway Construction Heavy Industry Corporation Limited (CRCHI) showcased its comprehensive range of equipment and products at bauma that included solutions for the whole industry chain in the field of

Read more ...

Herrenknecht AG wins bauma Innovation Award 2022 for development of continuous tunnelling
Herrenknecht AG won the highly coveted award bauma Innovation Award 2022 in the category “Machine Technology” for the new development of continuous tunnelling. The award was given for the next innovation boost in the mechanized

Read more ...

The Genesis of Underground Engineering
Regardless of the tunnelling technology used, tunnel designers decide the future success or failure at an early project stage. In fact, designers are the real managers of tunnel construction. The choice of design together with selected contract model is

Read more ...

Managing Geological Complexity in BVC and PAC of Tehri PSP, India - A case study
Tehri hydroelectric project is located on the left bank of River Bhagirathi in the state of Uttarakhand. Tehri Pumped Storage Project (PSP) comprising 4 Nos of reversible pump-turbine units of 250 MW each, involves construction of an underground Machine Hall

Read more ...

TBM driving under low overburden by adopting innovative methodology
TBM mining in urban areas particularly under low overburden (less than 0.5D, D = tunnel Dia) is a big challenge to design team as well as execution team. While working in a Lucknow metro project, the metro authorities encountered a stretch where TBM had to cross

Read more ...

Tunnel Ventilation System Basic Concepts and Designing Principles
The term ventilation combines several functions such as smoke extraction, pollution ventilation, and ventilation for environmental purpose. The design of a ventilation system is usually based on three scenarios: During construction: to provide external

Read more ...

CRCHI Mega Slurry TBM ‘Jinghua’ Assists the First Tunnel Section Breakthrough of Beijing East Sixth Ring Road Reconstruction Project
In September 2022, the Beijing East Sixth Ring Road Reconstruction Project reported another good news: the CRCHI mega slurry TBM ‘Jinghua’ smoothly reached the intermediate air shaft, marking the project’s achievement. The maximum excavation diameter

Read more ...

TERRATEC EPBMs ready to tackle Kanpur Metro’s 1st Underground Section in India
TERRATEC celebrated the successful site acceptance testing of two 6.52m diameter Earth Pressure Balance Tunnel Boring Machines (EPBMs) for Uttar Pradesh Metro Rail Corporation (UPMRC) for Corridor-1 of Kanpur MRTS Project (KNPCC-05) in India. The two 6.52m

Read more ...

Tunnelling Asia 2022 - International Conference on Underground Space
Tunnelling Asia 2022, organized by TAI, which took place in Mumbai during 27th and 28th June, saw a huge gathering of delegates/engineers from all around the world. The theme of the conference: ‘Underground Space: Need of the Day’ focused on

Read more ...

Hydraulic Heave Failure Mitigation Approach for the construction of the Deepest Metro Ventilation and Egress Shaft in India
Dr. Lakshmana Rao Mantri, Assistant General Manager (Designs), and Satya Narayan Kunwar, Project Manager, AFCONS Infrastructure Ltd. , discuss the design and construction challenges of constructing India’s deepest underground metro ventilation

Read more ...

Creating Zero-Carbon Tunnels
Despite a daunting timeline set by the Paris Accord, zero-carbon tunnels are within reach, provided the right solutions are implemented. Er. Vasileios (Bill) Paoulos, CMT, CMRL, L&T Construction Heavy Civil Infrastructure

Read more ...

Readily Biodegradable Soil Conditioning Foaming Agents - A New Technology
Mike A. Sposetti, Global Technical Manager TBM, Underground Construction, Master Builders Solution, Malta, and Manish Gautam, Product Segment Manager - UGC TBM Tunneling Projects, Master Builders Solution, Mumbai, discuss how readily biodegradable

Read more ...

Geotechnical challenges in Tunneling in Himalayas
G.B.Nagendra. General Manager - Projects, Konkan Railway Corporation, gives a first-hand experience of the adverse geological conditions encountered during construction of Tunnel T5 of the Katra-Dharam Section of the USBRL Project and the solutions

Read more ...

Cut & Cover Metro Stations & Other Underground Structures
Vinay Gupta, Director & CEO, Tandon Consultants, discusses the intricacies and issues in the construction of underground metro stations including strata survey during structural design, selection of methods and techniques of construction, traffic management

Read more ...

Importance of Pre-Injections Before Tunnel Front Advancement
Pre-injections or injections ahead of the excavation face in underground construction can, in many situations, offer significant advantages. This is particularly the case in difficult ground conditions like severe water ingress or mechanically

Read more ...

The Next-Gen Sandvik Tunnelling Jumbo Drills offer best-in-class operator comfort and safety
Sandvik's fully automatic, DT 922i and semi-automatic, DT 821C jumbo drills are enabling Max Infra to attain lower drilling costs per meter, with higher machine availability during the ongoing construction of the access tunnel

Read more ...

Tunnelling & Underground Projects Sharing Risks & Responsibilities
Rakesh Kumar Khali, Project Director-Hydro, Hindustan Construction Company Limited, Mumbai, describes the type of risks involved in underground construction projects, gives important guidelines to the tendering authorities and contractors

Read more ...

Recovery & Recycling of Excavated Tunnel Waste
Rock excavated in an average tunneling project is often considered waste and mostly finds its way to a landfill. Depending on the geology and excavation method used, the extracted material can have significant quality deviations

Read more ...

×
Sign-up for Free Subscription
'India Construction Week'
Weekly e-Newsletter on Construction Industry
Get the latest news, product launches, projects announced / awarded, government policies, investments, and expert views.
Click here to subscribe.
×