Large scale underpinning for an underground urban railway station

400A 926466 Casting and dozing recovers deep seams Coal V87, N4, April 1992, P55-58 Profitability of a mountaintop coal mine in Virginia has been maintained by adopting innovative blasting methods. The top 30m of burden in removed by truck and shovel to access the first seam. The next 30m is cast blast, the extra blasting costs being more than compensated for by the fact that over half the shot overburden is already in its resting place. Bulldozers shift the unshot burden. Difficulties with dragline operation below the top seam and lack of power facilities make the cast blasting the preferred method. 926467 Irresistable advance of the continuous miner Leeming, J J Colliery Guard 11240, N 3 , April 1992, Pl10-115 Room and pillar mining is still the most widely used method in underground coal mines across the world. Room and pillar mining methods and systems of mechanised pillar recovery are outlined: advancing/developing room and pillar, open ended retreat mining, pocket and wing, split and fender, rib pillar extraction, Wongawilli, and short wall mining. Advances in mechanised machinery and in methods of room and pillar mining are assessed. 926468 Special mixed shield concept for the construction of the twoway Grauholz Railway Tunnel (In German) Balmer, P Felsbau VIO, N1, March 1992, P32-38 The Grauholz tunnel near Bern, Switzerland, will be 6.3kin long and 10m finished diameter. Its alignment is through a central motasse core (52%) with chaotic glacial material on either side. Water table is up to 30m above the tunnel. A standard mix-shield TBM was modified to cope with this ground. It supports the moraine by slurry pressure and removes excavated materials under saturated conditions, yet in the molasse it acts as a conventional hard rock machine, removing material under dry conditions. Details are presented of the machine, muck removal, and tunnel lining procedures. 926469 Large diameter hard rock boring machines: state of the art and development in view of alpine base tunnels Robbins, R J Felsbau VIO, N2, May 1992, P56-62 Any new tunnel through the base of the Alps must pass through far from ideal geological conditions. The excavation system chosen has to be versatile and adaptable to cope with expected and unforeseen difficulties. The relation between advance rate and diameter and problems in predicting advance rate are examined. The ability of different construction techniques to cope with the difficult geological conditions is discussed. Ability to provide active support immediately behind the face is advantageous in highly stressed and squeezing ground. The Walking Gripper Shield machine is suggested for driving long alpine tunnels. 926470 Preliminary design for NATM tunnel support in soil Leca, E; Clough, G W J Geotech Engng Div A S C E Vl18, N4, April 1992, P558-575 The NATM technique has recently been used as an economic alternative to shield tunnelling in cohesive soils. The finite element code EXCAVATE is used to analyse N A T M in soils.

The softening technique currently used for analysis is improved and applied to a parametric study of ovoid tunnels in undrained clay. From this, a simplified design method for preliminary design of NATM tunnel support is developed. Design values are primarily dependent on soil properties, initial stress conditions, and stress relief prior to shotcreting. These values are reasonable and conservative compared to those from other methods.

926471 Large scale underpinning for an underground urban railway station Masuda, Y; Minoshima, T; Makino, H Tunnlg Underground Space Technol V7, N2, April 1992. P133-140 Construction of underground facilities beneath existing structures in urban environments requires care. An underpinning technique has been developed for use under such conditions. Cast-in-situ diaphragm walls are first constructed for groundwater control. Existing structures are supported by temporary cast-in-situ piles, the soil excavated, the new structure installed, and the load transferred from the temporary piles to the new permanent structure. The temporary piles can now bc removed. The construction of Nagoya station in Japan by this method is described, with particular reference to new, cost saving measures adopted.

926472 Uphill work for TBMs Hambach, P Tunn Tunnlg V24, N4. April 1992, P42-44 Inclined shafts have many and varied applications. Mechanical methods of excavation have important safety and operational advantages over blasting,which is rarely used. TBM construction, using machines modified to cope with gravitational effects, and raise boring are the preferred construction methods. Suitable TBM equipment is illustrated. Raise boring and TBM methods are compared, considering minimum and maximum economic drives, diameter range, and inclination.

926473 Changes in mining methods and mine layout when starting to utilize efficient modern mining equipment Pulkkinen, M Proc A u s l M M 1990 Annual Conference, The Mineral Industry in New Zealand, Rotorua, 18-21 March 1990 P179181. Publ Parkville: AuslMM, 1990 Exploitation of narrow, vein type orebodies has increased in recent years,despite lower metal prices. Poorly mechanised methods and equipment in cut and fill or shrinkage stoping have been used in many cases. The mechanical methods which may be employed, and their advantages, are described: mechanised cut and fill, sub level stoping, underground benching, and mechanised shrinkage stoping. Jumbos for drilling in cut and fill stoping, longhole drilling, and mucking machines complement these methods. Mine layout changes required are often minor.

:~'~) 1992 Pergamon Press Ltd. Reproduction not permitted