916473 Contribution to the convergence-confinement method by the principle of similitude (In French) Corbetta, F; Bernaud, D; Minh, D N Rev Fr Geotech N54, 1991, P5-11

The convergencc-confinement (characteristic lines) method is useful in design of supported tunnels with no time dependent effects, but the effect of distance from the tunnel face at the time of support installation on convergence is not taken into account. A simple method including this distance when calcu- lating convergence is developed for elastic-perfectly plastic ground. Final support pressures and final convergences are also evaluated including ground plasticity and distance from the face when support is installed.

916474 Present and future of mechanised tunnel works in soft ground Fukuchi, G Tannlg Underground Space Technol V6, N2, June 1991, P175-183

Various cases of shield tunnelling in Japan with precast seg- mental concrete lining are introduced. A new model for analy- sis of such linings is presented, which takes into account the lower rigidity of the lining joints. Calculated and measured stresses are compared. Effects on stresses of driving a second adjacent tunnel and of time are examined. The development of a steel bar-reinforced extruded lining as an alternative to seg- mental lining in very soft ground is described.

916475 Pilot bore excavation with TBM for the design and construction of larger tunnels Pelizza, S Tannlg Underground Space Technol V6, N2, June 1991, P185-189

The use of 3.5-5m diameter TBM driven pilot bores for much larger tunnels in Italy is described. The main functions of the pilot bore in planning, design, and construction of the final bore are discussed. The major advantages are in the volume of rock excavated by the TBM, reduced specific explosive con- sumption, reduced extent of site investigation, and easier dewatering, degassing, and ventilation. Cost comparisons with traditional methods are made.

916476 Sydney Harbour Tunnel - driven and cut-and-cover tunnels Baxter, D A; Hilton, J A; Nye, E J Tannlg Underground Space Technol V6, N2, June 1991, P227-233

Land approaches to the immersed tube crossing are described. The main tunnels and access drifts were constructed by roadheaders, there being some restrictions on vibrational levels permitted and on access in some areas, which precluded the cheaper cut and cover option. Primary ground support and tunnel linings are described. Cut and cover was used only around the portals. Some initial results on durability and water flow are presented.

916477 Jet setting under Bonn McWilliam, F Tunn Tunalg V23, N4, April 1991, P29-31

Tunnelling in urban areas has its own particular problems. The case of a 500m section of metro tunnel in irregular, loose, unconsolidated gravels containing sand layers and with silt layers near one portal is considered. The D shaped tunnel is being driven beneath arches of secant jetted piles, with 3m

RMMS28/6--J

© 1991 Pergamon Press plc.

391A

overlap between each arch. A complex multistage roadheader excavation is employed, with open surfaces shotcreted after each lm cut. Ground movement is continuously monitored. Settlement is within limits and the project on schedule and within budget.

916478 Double-barrelled Angel Darling, P Tann Tunnlg V23, N5, May 1991, P44-46

Problems in construction of a second running tunnel and enlargement of the Angel underground station in north London are examined. In addition to the normal constraints of urban tunnelling, there is limited surface access and the need to minimise disruption to the railway. Step plate junc- tions constructed around the existing running tunnel will allow trains to run during the junctioning sequence of the project. The ground is London Clay and Woolwich Beds, mined by a backhoe excavator. Despite logistical problems not related to geotechnics, the project is meeting schedule.

916479 Support for tunnels subjected to changing rock loads: comparison of design methods Speers, C R Excavate and Support in the 90s, Proc SANCOT Seminar 1990, South Africa, November 1990 P31-40. Publ South Africa: Goldfields Press, 1990

Among the methods for designing support in tunnels subjected to changing rock loads, empirical methods based on mass clas- sification and analytical methods based on numerical stress analysis are widely used. The application of Rock Mass Rat- ing (RMR) and the Tunnelling Quality (Q) approaches is analysed and their advantages and disadvantages presented. Numerical analysis indicates that support pressure may be seriously underestimated using the Q method. Numerical anal- yses also allow optimisation of bolt length and spacing required to control convergence, an objective oriented crite- rion rather than a stability criterion.

916480 Tunnel waterproofing Fenner, H F Excavate and Support in the 90s, Proc SANCOT S e m i ~ 1990, South Africa, November 1990 P41-45. Publ South Africa." Goldfields Press, 1990

Many different techniques are applied to waterproof tunnels. Rigid cement based, bituminous, membrane, and liquid poly- mer based systems have been developed. Additives for gunite and their chemical reactions with cement, high-polymer mem- brane linings, and their design and application and installation are described.

916481 Tunnel face stability in slurry shield tunnelling Balthaus, H Proc 12th International Conference on Soil Mechanics and Foundation Engineering, Rio de Janeiro, 13-18 August 1989 II2, P775-778. Publ Rotterdam: A A Balkema, 1989

In slurry shield tunnelling, the face pressure must be balanced to provide adequate safety against face collapse whilst preventing overburden heave. A method to calculate optimum pressure is presented which considers soil mechanical proper- ties, stratification, surcharges, groundwater level, overburden depth, and spatial earth pressure effects. It is compared to other methods and an example of its use is illustrated.

Reproduction not permitted