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

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 ...

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 ...

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 ...

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 ...

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 ...

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 ...

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 ...

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 ...

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 ...

Safety in infrastructure sector means preventing accidents, loss and damage to human life and equipment. Being adequately trained and aware of the equipment in use is imperative, especially in the case of heavy equipment

Read more ...

Authors C.P Singh, S.K Ganji, and Madhur Goel elucidate the issues and precautions taken during full face mining, using a TBM for the construction of JPW to Krishna Park Downline Tunnel of Package DC-06. This 5.8 m internal diameter

Read more ...

Uttar Pradesh Metro Rail Corporation Limited Underground Construction On 25 November 2013, LMRCL (now UPMRCL) was incorporated as a Special Purpose Vehicle (SPV) under the Companies Act, 1956. The construction of phase I A of Lucknow Metro (Transport Nagar to Charbagh) started on 27 September 2014

Read more ...

India’s economic growth is closely associated to its energy demand; in fact, India is the 3rd largest energy consumer in the world. A robust growth is expected in the country’s oil and gas sector, which will make the sector

Read more ...

Brijesh Ashokbhai Wala, Engineer, National Highways and Infrastructure Development Corporation Limited (NHIDCL), presents the vagaries and challenges in underground construction, with case studies of projects constructed or planned

Read more ...

Anirban Sen, Business Line Manager – Underground Division, Epiroc Mining (India), explores the technologies, methods and benefits of modern intelligent face drilling equipment, the reasoning behind selection of ‘smarter’ face drills

Read more ...

This case study of the Sewa H.E. Project (120MW) in the Kathua district of Jammu and Kashmir, covers the planning process and various construction features of a 10.02km long, 3.3m diameter horseshoe shaped concrete lined tunnel

Read more ...

Strabag AG implements complex construction projects, particularly in tunneling and infrastructure development, and is represented in around 30 countries worldwide. It has been active in the fields of building construction, civil

Read more ...

Construction is underway on a tunnel as part of a bypass to relieve traffic for communities in Toggenburg, Switzerland. For Doka’s formwork experts, keeping in view the conditions of this project, their new, rentable tunnel system

Read more ...

On 22nd September 2021, hard rock/slurry TBM Urja (DZ670) manufactured by China Railway Construction Heavy Industry Cooperation Limited (CRCHI) achieved a breakthrough from the Cantonment Station to the Shivaj Nagar Station

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.