Technical - Page 5
Stay up to date with the latest technical features from the global tunnelling industryMeeting challenges under pressure Traditional compressed air work in tunnelling, also referred to in some quarters as caisson work and diving, has all but disappeared in modern tunnelling, but new challenges have been thrown up by deeper tunnels and those of larger section. These are being taken up by sophisticated procedures to ensure the safety of those involved in necessary work. Maurice Jones reviews some leading practitioners and their tunnelling work and equipment. Additional material from Nicole Robinson
Soil conditioning for clays in EPBMs – part two In the second part of this paper, commenced in the October 2011 issue of T&TI, the authors further explain the mechanisms in clayey soil and machinery interactions and the testing of means of reducing adhesion
Modern compressed air and gas work Work in compressed air has its origins in the early-to-mid 19th century. It is relatively uncommon these days and consequently few tunnellers have had experience of current practice. Donald Lamont of Hyperbaric & Tunnel Safety reviews its development, current practice and its context in tunneling
Send in the divers The expertise, ingenuity and bravery of commercial divers working with tunnels is unsurpassed. The services of divers can be called upon during normal operations as well as emergency situations, with each task placing its own demands on men and equipment. Maurice Jones, with Nicole Robinson, has been checking up on what is needed and why
Tunnelling below China’s ancient past Below the city made world famous by the 1974 discovery of the Terracotta Army, tunnellers tread carefully to avoid disturbing other historical wonders of the 3,100-year-old resting place of the first Emperor of China, Qin Shi Huang. Desiree Willis, Robbins technical writer, presents this report
Laser guided segment precision T&TI visits the Morgan Sindall precast facility at Ridham Dock in Kent, UK. The plant is currently supplying segments for Thames Water’s Lee Tunnel. Alex Conacher takes the grand tour
Soil conditioning for clays in EPBMs In this, the first of a two-part paper, the authors review previous work on the properties of soils including clay and the problems it can cause in its excavation with particular reference to slurry shield and EPB machines. The second part will be published in the November issue of T&TI
Holding it together: the birth and life of a fibre As a more light-hearted look at the subject of steel fibre reinforcement of precast concrete, but with serious content, this article is an insight into the sometimes dynamic life of a fibre from manufacture to being held in position in the structural lining of a tunnel. Maurice Jones followed its progress
Segment handling and installation While the long-term function of segmental tunnel linings is to withstand the loads imposed when in the ground, the designs have to encompass not only the ground loads but also the loads during manufacture, transport and erection of the lining. Yogini Vimalanathan of Mott MacDonald and Lesley Parker of FP McCann Precast describe some of the issues that need to be taken into account when designing segmental tunnel linings
Getting across Colin Lawrence and Jonathan Taylor of Hatch Mott MacDonald presented this paper about design of tunnel cross passages at the 2011 RETC
Where the wild things are Energy provider AltaGas is constructing a new hydroelectric facility in northwestern British Columbia. While the tunnelling portion of the project is anticipated to be fairly straightforward the remoteness of the region creates other challenges for the work, Nicole Robinson reports
Precast in practice Water shortages, rogue quarries and supply constraints are tackled at the Peenya precast plant in India. Alex Conacher speaks with Yogini Vimalanathan of Mott MacDonald and Russell Brown of CEC
Prepared for the long haul Since precast concrete segmental tunnel lining was invented, there has never been so much development of the ‘product’ as in recent years, even though, superficially, it may look the same. Maurice Jones looks at some of these developments aimed at increasing tunnelling progress whilst avoiding mishaps
Mitigation and alternatives: making hand mining better A current trend in tunnelling, as in many other industries, is against manual labour, but in many situations hand mining seems the logical first choice until one considers the hazards involved that are arguably greater then those associated with large-section tunnelling. Maurice Jones checks on the current status of the activity, mitigation to improve hand mining, and the alternatives offered by some equipment manufacturers.
HAVS in the law Whatever the arguments and attitudes about applicability, the legislative framework intended to protect the health of the tunnelling workforce, and those encountering vibration in many other industries is inescapable. The editorial team checked on current legislation in some main tunnelling locations
An innovative approach to landslide prevention The construction of two drainage tunnels and the associated sub-vertical drain system at the Po Shan area in Hong Kong was completed late last year. This project is the first of its kind to utilize drainage tunnels and a network of sub-vertical drains to regulate the groundwater table to enhance the long-term stability of hillsides. The success of the project offers a feasible and effective solution for future landslide prevention and risk mitigation on steep and hilly terrain, a topography found in many parts of Hong Kong. Aecom senior engineer Dr Johnny Cheuk authors this paper on the work
Lab test for EPB ground conditioning This article describes the cooperation between the Politecnico di Torino and construction materials manufacturer Mapei, both based in Italy, in the field of laboratory testing of ground to be excavated by EPBM after suitable conditioning, and comparison with actual site conditions
Standards set for pre-grout drilling Anders Ostberg of contractor Veidekke and Gunnar Nord of equipment manufacturer Atlas Copco explore the use of a four-boom drill rig for structural grouting on the Swedish Hede-Alvangen tunnel
Forecasting tunnelling behavior Most rock characterisation and ground behaviour prediction has concentrated on TBM drives, but the authors of this paper go into forecasting tunnel behaviour for feasibility and planning purposes when using conventional tunnelling methods, using new methodology from Spain. Prof Richard Z T Bieniawski of US-based Bieniawski Design Enterprises, David Aguado and Benjamin Celada of Geocontrol and Alejandro Rodriquez CDIAM (both companies in Spain) present the argument
Collapse and recovery in Abu Dhabi A cut and cover tunnel is to be constructed in a congested urban area of Abu Dhabi. During construction of diaphragm retaining walls, some panels experience a sudden loss of bentonite resulting in the collapse of the excavation trench. Tahar Messafer of Parsons International UAE presents this report
