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Proceedings Papers

Paper presented at the 15th ISRM Congress, October 9–14, 2023
Paper Number: ISRM-15CONGRESS-2023-029
... single bore length of approx. 20 km. tunnel india government geologist rock type construction sedimentary rock asia government portal indian himalaya bridge footing tunnel axis alignment structural geology national highway nh-21 reservoir characterization approx pandoh highway...
Proceedings Papers

Paper presented at the 15th ISRM Congress, October 9–14, 2023
Paper Number: ISRM-15CONGRESS-2023-020
... in urban centers and railway networks. This article deals with one of the tools for solving these problems: the fire plan for controlled rock blasting when opening tunnels and their portals, especially when the work of art is built under restricted conditions; geographic location, rock mass structural...
Proceedings Papers

Paper presented at the 14th ISRM Congress, September 13–18, 2019
Paper Number: ISRM-14CONGRESS-2019-022
... metals & mining fh tunnel completion ground transportation permafrost kl tunnel underground excavation tunnel lining rail transportation tibetan plateau excavation maintenance tunnel sandstone portal mountain reservoir characterization construction engineering invert...
Proceedings Papers

Paper presented at the 14th ISRM Congress, September 13–18, 2019
Paper Number: ISRM-14CONGRESS-2019-077
... of the Tamoios highway crossing the Serra do Mar, and by the SP-055, a two lane/single lane highway that runs inside Caraguatatuba and São Sebastião cities. portal alignment natm highway tunnel reservoir characterization tunnel highway nova tamoio contorno investigation serra tunnel portal paulo...
Proceedings Papers

Paper presented at the 14th ISRM Congress, September 13–18, 2019
Paper Number: ISRM-14CONGRESS-2019-101
... tunnel jurassic oxfordian 2 wbi 2010 strata reservoir characterization brown jurassic figure proposal contract ler tunnel construction portal breakthrough white jurassic structural geology tbm investigation lining ata hl tunnel Abstract The article provides...
Proceedings Papers

Paper presented at the 12th ISRM Congress, October 16–21, 2011
Paper Number: ISRM-12CONGRESS-2011-026
... broad gauge rail tracks. There is also a provision of one trolley refuse in the tunnel. The empirical and the numerical approach used for the analyses and design of the tunnel have been discussed in the paper. reservoir geomechanics Barton portal railway tunnel parallel ground transportation...
Proceedings Papers

Paper presented at the 12th ISRM Congress, October 16–21, 2011
Paper Number: ISRM-12CONGRESS-2011-192
... Preliminary investigation consisted of: Geological mapping of at least 1600 m wide area in the scale 1:5000, and in areas of more interest tunnel portals and areas of more important geological features) 1:1000, including geomorphology, structural geology, hydrogeol- ogy, engineering geology and karstology...
Proceedings Papers

Paper presented at the 10th ISRM Congress, September 8–12, 2003
Paper Number: ISRM-10CONGRESS-2003-194
... valley flanks. The different geotechnical conditions of these 4 tunnel portals, their design and construction are described within this publication. The two southern portals of the tunnel Dölzschen are situated within a vertical 65 m high former quarry slope, 25 m above the valley floor. The slope...
Proceedings Papers

Paper presented at the 10th ISRM Congress, September 8–12, 2003
Paper Number: ISRM-10CONGRESS-2003-128
... The knowledge of the geological sequence and hydrological conditions in the area of portals was the basis for the design of the entry of the highway into tunnel Trojane. Mudstone, claystone and sandstone dominate the rock layering, which is tectonically reworked and contains structural anomalies...
Proceedings Papers

Paper presented at the 9th ISRM Congress, August 25–28, 1999
Paper Number: ISRM-9CONGRESS-1999-281
... < Messtechnische Oberwachtmg mit ROckkopplung fOrden Bau von StraBentunneln - I ' A. P.CUNHA, Labor~t6rio Naeional de Engenharia Civil, Usboa, Portugal , ., '! ABSTRACT: Several important road tunnels in rock were built in Portugal inthe last years. The author was involved in the geotechnical studies for their basic designs, including rock mass zoning and definition of excavation and support methods, and in the intensive close-loop monitoring of the tunnels during the construction, which appeared as the most effective tool for the optimization of these underground structures. RESUME: Plusieurs tunnels routiers en roche ont ete construits au Portugal pendant les dernieres annees. L'auteur a ete engage dans les etudes geotechniques pour leur projet preliminaire, y inclus Ie zonage du massif rocheux et la definition des methodes d'excavation et soutenement, et a aussi conduit l'auscultation intensive des tunnels pendant la construction sous une optique de conduite assistee des travaux, qui s'est montree l'outille plus effective pour l'optimization de ces ouvrages souterrains. , ,. , ' ZUSAMMENFASSUNG: Mehrere wichtige StraJ3entunnel in Felsen wurden in Portugal wahrend der letzten Jahre gebaut, Der Verfasser war beteiligt an den geotechnischen Untersuchungen rur ihre Vorprojekte, einschlieBlich der Gebirgseinteilung und der Definition der Abbau- und Ausbaumethoden, und der intensiven meBtechnischen Oberwachung mit Riickkopplung der Tunnel wahrend des Baus, die sich als das effektivste Hilfsmittel rur die Optimierung dieser Arbeiten herausstellte.j , , I - INTRODUCTION Reliable geotechnical information required for the final design of tunnels can only be obtained, in most cases, during the construction, due to severe limitations of the cost-benefit relation of the geotechnical studies for the preliminary design. In spite of the interest of such studies, the results of any structural analysis and (or) empirical methodologies at design stage should be considered working hypotheses subject to confirmation' or modification during construction, rather than definitive solutions to be built up on site.· Therefore, the observational method, based on a closed-loop intensive monitoring of the tunnel behaviour appears as the most effective means for the optimization of tunnel construction. 'In Portugal, the construction of the road tunnels of Gardunha, Varosa and Regua started with detailed preliminary designs, establishing the geotechnical zoning of the rock masses and the most probable caracteristics of such zones, from which the likely most suitable construction methods and primary and secendary supports were derived. However, intensive monitoring during the construction, following detailed tunnel survey plans, have played the major role in the up-dating of the construction methods and support requirements to the effective geotechnical conditions revealed by the excavations. Such decisions were I taken under consensus by a working team involving engineers of the owner (Junta Aut6noma de Estradas, JAB), his technical ! adviser (Laborat6rio Nacional de Engenharia Civil, LNEC), the designer (COBA) and the contractors. . " . Convergence and r settlement measurements, and piezometer,' inclinometer,' multiple-borehole" extensometer readings and detailed geotecnical mapping of the excavated ., r surfaces were currently carried out included in closed-loop monitoring procedures as basic tools for the final design of the tunnels. The intimate connection between monitoring results and constructive decisions is dully emphasized in the paper. 2 - THE GARDUNHA TUNNEL 2.1 - Geotechnical studies and design I This two-directional tunnel, crossing the Gardunha mountain , included in the In highway (northeast central zone of Portugal) is about 1600 m long, with a 220 m maximum overburden and a 84 m2 cross section area, excavated in granitic and schistous rock masses. The rock weathering reaches a depth of about 50 m, thus affecting mainly the portal zones, where the tunnel was constructed in a saturated residual granitic soil with random boulders: The geotechnical studies for the detailed preliminary design included surface reconnaissance, borehole drilling, seismic tomography, Lugeon and dilatometer in situ tests and laboratory 0ees such as uniaxial compression and joint shear tests. ! The weathering and fracturing degrees, defined by means of the ISRM basic classification, together with the in situ seismic velocities, allowed the rock mass zoning and from the laboratory and in situ tests the most probable average values of the relevant mechanical parameters for each zone were derived. Then, by using geomechanical classifications (Bieiuawski, Barton, Rocha) and numerical structural analysis,' the most suitable excavation methods and most probable primary support requirements for each geotechnical zone were established, as 1425 The excavation of zones ZG1 and ZG2 followed the traditional drilling and blasting method in two stages, top-heading and Large horizontal displacements much greater than benching, with average excavation rates of 3.5 m1day. Primary expected taking into consideration the small overburden, have support required Swellex-type bolts with various spacings and·'1 ocurred systematically, this tunnel section requiring a primary layers of steel fibre shotcrete, 5-15 cm thick. The spacing and r .' support consisting of heavy steel arches with 0.3-1.0 m spacing, thickness -of support components were adjusted based on the') and shotereete over steel mesh, 0.20 m thick. Because of the systematic appraisal of the weathering, fracturing and lithological J horizontal ground pressure, heavy cross beams had to be patterns and on convergence measurements in monitoring installed about every 2 m at the preliminary floor level in order sections 10 m-20 m apart, installed as close to the face as to close the steel arches and stop the horizontal displacements possible. " j" ' including those related to the bench excavation: r 1 . However, the most disturbing difficulties were .found ' These provisional cross beams had to be removed' in ZG3 lone, namely at the nbrth portal, located in a tectonic during benching, in order to allow the construction traffic and, valley with a seasonal stream, which had to be diverted to allow» .atso- the installation of the final concrete lining. and road the tunnel construction. The initial 200 m were excavated in a pavement. The solution was the replacement of the cross beams saturated granitic residual soil (saprolite), with high under compression by sets of subhorizontal bolts. For ensuring deformability, very ,low strength (almost cohesionless in the the equivalent strength of these rather e different structural presence of water and low friction angle) where a few large components, in situ tests of bolt pulling were carried out to yielding surfaces, corresponding to ancient rock mass joints, define the required strength .and stiffness pf the anchors. The showed randomly its presence, determining limit-equilibrium testing programme included the axial pulling by annular jacks of conditions and a self-excavating behaviour of the ground. As a bolts of different sections and lengths, installed on the tunnel consequence, the advance had to be carried out in four or five walls, in order to get information about the supporting capacity stages: two side-drifts with diaphragm walls and a central pillar of the bolt system as a function of the, ground ,confmement J ensuring the top-heading stability and one or two steps for conditions. The step by step replacement of the ,compressive benching (Figure I), allways with very short rounds.. cross beams by the bolt system under tension was carefully monitored and guided by means I, of the, convergence measurements, in order to ensure the tunnel stability. I Since the residual rock mass was self-excavating or _ d easily mechanical excavable, the convergence sections could be, t\antllt: ',2ml .1', _installed close to the face and readings, taken, and analysed f r' ') t .i immediately for close adjustment of the support. The crown. excavation ,was carried out, with. the pre-instalation of an umbrella of 12 m long injected steel tubes (micropiles) and to ensure face stability the central pillar between side-drifts was both drained and reinforced with fiberglass bolts, length 6-12 m (Figure 1). ,I c "r' ,r > , ; iJ !! Nevertheless large settlements. of the surface were recorded, namely reaching about 0.20 m for an overburden of 20 m (Figure 2) in a,monitoring section 40 m away from the north portal. Since the rounds were kept to a minimum, just to create space to install one steel arch and shotcrete...
Proceedings Papers

Paper presented at the 5th ISRM Congress, April 10–15, 1983
Paper Number: ISRM-5CONGRESS-1983-137
... in the studied tunnels: presence of water deformations state of lining state of portals These factors were given a numerical appraisal of 0 to 3, 0 being good and 3 bad. Thus we achieved, for each tunnel, a value representing its condition. 4. RESULTS The classification system is very simple to apply...
Proceedings Papers

Paper presented at the 4th ISRM Congress, September 2–8, 1979
Paper Number: ISRM-4CONGRESS-1979-056
... SUMMARY: Rock conditions usually encountered for portals are described. Planning and localising procedures are discussed. A method of analysing five main factors influencing portal stability is presented. Based on this analysis the conclusions are: The reinforcement should be carried out prior...
Proceedings Papers

Paper presented at the 4th ISRM Congress, September 2–8, 1979
Paper Number: ISRM-4CONGRESS-1979-232
... road tunnel project construction consolidation portal ventilator Neuchatel unstable zone duct excavation tunnel calotte east portal brief review West Portal exploitation ventilation plant Tunnel Project cross section BRIEF REVIEW OF THE CLUSETTE ROAD TUNNEL PROJECT Bret apercu du...

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