$4;~

833173

833174

833175

A finite element techr~que is used to simulate the closure of an in sltu test room developed during excavation of a deep potash mine. For the calculations~ a constitutive model for creep was determined from laboratc~'y tri~xial tests of salt and short cylinder compressive tests of potash, and was Incorp(~rated into a coupled ther- mOmechanical formulation for analysing creeping viscous flow. 41 refs.

INTERACTION n~'~CTS AssOCIATED WITH LONGWALL CO~ MINING

Styler, ~ N; Dunham, R K Proc 23rd Symposium on Rock Mechanics, Berkeley,

25-27 August 1982, PII07-II14. Publ N~ York: A~,~, 1982

The results of 2 studies into the effects of unde~minlng offshore roam and pillar workings by longwall faces are presented. 9ubsldence and convergence were measured. The first stilly indicated no potential instability from under- mining one level of room and pillar workings. On the basis of this it was decided to under- mine two levels of room and pillar workings, again monitoring pillar stability. The results showed no signs of increased instability.

~40DELING OF D~WP SHAP'fS IN CENTRIFUGE TES~fS Lade, P V; Jessberger, H L; Makowskl, E Proc lOth International Conference on Soil

Mechanics and Foundation Engineering, Stockholm, 15-19 June 1981, VI, B683-691. Publ Rotterdam: A. A. Balkema, 1981

A series of centrifuge model tests was perfca'med to study the behavlour of and the effective horizontal e~th pressures developing on deep vertical shafts during excavation. The corres- ponding prototype shafts are constructed using ground freezing techniques. The model shafts were made of Vellnex and provided with strain gaUges to measUre horlzontsl strains. Fluids of two different densities, one to model the vertical pressure at the bottom of the shaft and the other to model the internal horizontal earth pressUre, were removed in stages from the initially full shafts to model the effects of excavation. Earth pressure cells located at the lower one third level of the shafts were ins- talled to measure the vertical, radial, and tangential pressures near the shafts and near the wall oS the tub in which the models were contained. Instruments were installed across the tub to measure surface settlements~ bottom movements, and shaft lining movements.

Tunnels

See also: 833189

VICTORIA FEEDS ON CONFIDENCE Ferguson, H New Civ Engr, N522, 6 Jan 1983, P12-15

A case study of the Victoria Dam, Srl LarVa where tmexpected geological problems were encountered: a much larger volume of foundation rock had to be excavated due to the presence of a large area of soft rock and a vast llme- stone cavity. A seriOUs rock fall and subsequent reallgr~nent of the surge shaft tunnel also con- tributed to the delay. Production was speeded up with the relaxation of the requirement to rock bolt the crown of the tunnel regardless of rock condition, and the introduction of shcter etlng.

833176 TUT~ID ~ECTION~ FOR T}~ BT~ ~ LO 7"~0 Torpey, K W Tunn Tunr/g, V!4, ~_l, Dec ~:;~:i, P19-.2

Describes the construction of the first :~=[~Ay underground light rail system in "~orth /meric~.. Fullface tunnel boring ~chines were used to excavate two 4.88m diameter t11nnels through Jointed sedimentary rock. Contiruous ~ones of badly fractured ~nd solutioned rock, p.~rt of an aquifer, were found along much of the rock tunnel section snd l~rge ~ter inflows were expected. Dewatering using deep-~-ell points was c~rrled out prior to tunnelling. The principal support system used wss 2.4m untensioned resin- bonded rock bolts used with steel str'::pplng or mesh, followed by ~ cast-in-pl::ce concrete lining.

833177 UNDERSEA TUNNELs C/d~RY NOR'JEGIA[: 'PLUTO' ASHORE Martin, D Tunn Tunnlg, V~4, Nil, Dec ]982, P24-26

Three largely unlined hard rock tunnels total- ling 12km in length are being driven using drill and blast techniques through mixed hard rock geology under three of Nor~y's l~gest fjords. The tunnels will dip to ~ ~ximum 180m below mean ses level, where leakage water will be pumped to the surface. 3ystematic grouting ahead of the face is being c~ried out to pre- vent possible water inflow :~nd improve tunnel stability.

833178 BENTONITE SHIELD TUNNELLi~G IN EUROPE Becker, C H; Sawinski, J Tunn Turaulg, V15, hq, Jan 1983, P13-17

See item 831119.

833179 HADES AND RHODES WATER TUNNELs ~E ;~REETs ~IHEAD OF S CHEVJLE

Martin, D Tunn Tunm_Ig, VI5, NI. Jan 1983, PIS-I 9

Two wster aqueduct tunnels hsve been s~ccess- fully driven through shales and limestones in north eastern Ut~h, USA, using ~J Robbins TI~4. A split heading technique was used in very soft ground. A number of problems were encount- ered including squeezing ground, an area of fine running sand and an infl~ of spring run- off ~ter to ~ depth of 3 feet.

833180 THREE LONG DRIV~S FOR NO~4EGIAt~ ROAD TUNNELS ~4artin 3 D Tunn Tunnlg, V~5, Ni, Jsn 1983, P31-34

Progress in 3 Norwegian road tunnelli~E projects is described: the Vallavlk Tunnel, the FJaerland Tunnel, and the Bride's Veil Tunnel. it the FJaerland Tunnel extensive spalling and rock burst occurred to slow down production. At the Bride's Vell Tunnel, weak fissured rock required the use of rock bolts and concrete.

833181 OBSERVATIONs ON TI{E BEHAVIOUR OF A PILOT TUNNEL IN LONDON CL\Y AC THE ~,t~IN TIYNNEL W•j DRIVEN

Thomas, H S H Inst Civ Engr Proc, V74, Feb 1983, P15-24

The structural behavlour of a pilot tunnel as it was unloaded by excavation of the main tunnel is described. The hoop stress increased from the time when the nmin face was 75 to 85ft away until it was 7 to 15~t ~way. ~ne horizontal dlsmeter reduced [~nd the vertic~Jl die, meter in-