Geology and Tunneling Economics in Montreal
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51 2. H. G. Mason and J. A. Bishop. Measurement of Shaft in Clay. Texas Transportation Institute, Earth Pressure and Deflection Along the Embedded Texas A&M Univ., College Station, Res. Rept. 211- Portion of a 40-ft Steel Pile. ASTM, Special Tech. 1, Nov. 1977. Publ. 154-A, 1954, pp. 1-21. 13. M. T. Davisson and S. Prakash. Review of Soil 3. W. J. Heijnen and P. Lubking. Lateral Soil Pres Pole Behavior. HRB, Highway Research Record sure and Negative Friction on Piles. Proc., 8th 39, 1963, pp. 25-48. International Conference on Soil Mechanics and 14. D. L. Ivey, K. J. Koch, and C. F. Raba, Jr. Foundation Engineering, Moscow, USSR, Vol. 2 .1, Resistance of a Drilled Shaft Footing to Overturning 1973, pp. 143-147. Loads: Model Tests and Correlation with Theory. 4. J. I. Adams and H. S. Radhakrishna. The Lateral Texas Transportation Institute, Texas A&M Univ., Capacity of Deep Augered Footings. Proc., 8th College Station, Res. Rept. 105-2, July 1968. International Conference on Soil Mechanics and 15. C. 0. Hays, J. L. Davidson, E. M. Ragan, and Foundation Engineering, Moscow, USSR, Vol. 2.1, R. R. Risitano. Drilled Shaft Foundation for High 1973' pp. 1-8. way Sign Structures. Engineering and Industrial 5. B. McClelland and J. A. Focht, Jr. Soil Modulus Experiment Station, Univ. of Florida, Gainesville, for Laterally Loaded Piles. Journal of the Soil Res. Rept. D647F, Dec. 1974. Mechanics and Foundations Division, Proc., ASCE, 16. K. Terzaghi and R. B. Peck. Soil Mechanics in Vol. 82, No. SM4, Oct. 1956, pp. 1081-1 to 1081- Engineering Practice, 2nd ed. Wiley, New York, 22. 1967, pp. 198-200. 6. H. Matlock. Correlations for Design of Laterally 17. J. B. Hansen. The Ultimate Resistance of Rigid Loaded Piles in Soft Clay. Proc., 2nd Annual Off Piles Against Transversal Forces. Danish Geo shore Technology Conference, Houston, TX, May technical Institute, Copenhagen, Bull. 12, 1961. 1970, pp. 577-594 (paper OTC 1204). 18. L. C. Reese. Discussion of paper, Soil Modulus 7. L. C. Reese, W. R. Cox, and F. D. Koop. Analy for Laterally Loaded Piles, by B. McClelland and sis of Laterally Loaded Piles in Sand. Proc., 6th J. A. Focht, Jr. Trans., ASCE, Vol. 124, 1958, Annual Offshore Technology Conference, Houston, pp. 1071-1074. TX, May 1974, pp. 473-483 (paper OTC 2080). 19. D. L. Ivey. Theory, Resistance of a Drilled Shaft 8. L. C. Reese, W. R. Cox, and F. D. Koop. Field Footing to Overturning Loads. Texas Transporta Testing and Analysis of Laterally Loaded Piles in tion Institute, Texas A&M Univ., College Station, Stiff Clay. Proc., 7th Annual Offshore Technology Res. Rept. 105-1, Feb. 1968. Conference, Houston, TX, May 1975, Vol. 2, pp. 20. D. L. Ivey and W. A. Dunlap. Design Procedure 671-690 (paper OTC 2312). Compared to Full-Scale Tests of Drilled Shaft 9. R. C. Welch and L. C. Reese. Lateral Load Be Footings. Texas Transportation Institute, Texas havior of Drilled Shafts. Center for Highway Re A&M Univ., College Station, Res. Rept. 105-3, search, Univ. of Texas at Austin, Res. Rept. 89- Feb. 1970. 10, May 1972. 21. D. L. Ivey and L. Hawkins. Signboard Footings 10. F. J. Duderstadt, H. M. Coyle, and R. E. to Resist Wind Loads. Civil Engineering, Vol. 36, Bartoskewitz. Correlation of the Texas Cone No. 12, Dec. 1966, pp. 34-35. Penetrometer Test N -Value with Soil Shear 22. J. F. Seiler. Effect of Depth of Embedment on Strength. Texas Transportation Institute, Texas Pole stability. Wood Preserving News, Vol. 10, A&M Univ., College Station, Res. Rept. 10-3F, No. 11, Nov. 1932, pp. 152-168. Aug. 1977. 23. B. B. Broms. Lateral Resistance of Piles in Co 11. W. V. Wright, H. M. Coyle, R. E. Bartoskewitz, hesive Soils. Journal of the Soil Mechanics and and L. J. Milberger. New Retaining Wall Design Foundation Division, Proc., ASCE, Vol. 90, No. Criteria Based on Lateral Earth Pressure Measure SM2, March 1964, pp. 27-63. ments. Texas Transportation Institute, Texas A&M Univ., College Station, Res. Rept. 169-4F, Aug. Publication of this paper sponsored by Committee on Foundations 1975. of Bridges and Other Structures. 12. V. E. Kasch, H. M. Coyle, R. E. Bartoskewitz, *V. R. Kasch was at the Texas Transportation Institute when this and W. G. Sarver. Lateral Load Test of a Drilled research was performed. Geology and Tunneling Economics in Montreal Hugh Grice, Department of Geological Sciences, McGill University, Montreal Marc Durand, Department of Earth Sciences, Universite du Quebec a Montreal The economic construction of transportation projects depends in part on the presence of weathered zones in limestones and shales, where they the availability of all relevant geological and geotechnical data. In have been faulted or intruded, increased actual costs to six times the nor· Montreal, Canada, all of the 120 km (75 miles) of subways, major mal unit price in good limestone. The contracted cost was 12.5 times the sewers, and aqueducts constructed during the last 18 years have been af· normal for a transition from an open cut into a tunnel in soil or rock. fected by local geological factors. Contracted costs for subway tunnels in Variations of costs for contractors were estimated from rates of advance, shale were about 20 percent higher than for those in limestone. Locally, amounts of concrete required to backfill overbreaks, and numbers of 52 steel arch ribs used for roof supports. Tunnel-boring machines were discuss the Metro, sewer, and aqueduct systems. First, more sensitive to geological surprises than were normal construction abnormally high volumes of concrete used in lining tun methods. Comparisons were made between data from prnr.nnstnu:tion nels can indicate local zones of excessive overbreak (1) investigations and both construction records and site mapping. It was (although this effect can be caused by poor technique as confirmed that, although preconstruction data usually give general warn ing of problems, precise notice is often lacking. Even the use of tech well as by poor rock conditions ). Second, relative rates niques such as the mcosurcmont of rock-core lengths gives only a µ~r LiHI of advance by A given excavation method are possible indication of actual tunneling conditions, which emphasizes the need indicators of costs and soil and rock quality when the for continuous detailed mapping during construction. effects of a number of nongeological factors (such as local experience of crew, size of crew, efficiency of equipment, and strikes and holidays) are taken into ac The costs of constructing facilities for road, rail, sea, count. Third, details of the types and extent of sup and air transportation systems include the factors of ports generally indicate the stability of a cut or tunnel availability of contractors for an acceptable construc (althoug h local occurrences of poor technique must be tion schedule, costs of rights-of-way or land, the sur remedied by otherwise unnecessary support and some face topography and geometry of geological units, and methods of support may be used as a minimum through the geological conditions. out some contracts as a practical comp1·omise). This paper reviews some of the major geological features of Montreal that have been significant in trans LOCAL DATA portation tunneling engineering. Examples are given from the subsurface Montreal Metro system, now about There are several reports and maps of the physical 40 km (25 miles) long, as well as from the deep tunnels cha1·acteristics of the Montreal region (2) and of the of the sewer and aqueduct systems, which have similar geology of the area (3-8) that summarize the observa problems within their 75-km (46-mile) length. Attempts tions from outcrops,-temporary excavations, and drill are made to relate costs to geological features, even holes. The locations of some data are more or less though it is very difficult to separate the effects of geo closely described, but most information has been cor logical and nongeological factors. related and generalized .on maps having scales of 1 cm to 180 m (1 in to 1500 ft) (1:18 000) to 1 cm to 633.6 m TYPES OF DATA (1 in to 1 mile) (1:63 360). Some sections are also available. Most of the early geotechnical records are Three different classes of geological and geotechnical qualitative and describe troublesome problems such as data are available: marine clays and quicksands (3). Clark ( 5) has deduced and plotted an extensive fault pattern chiefly from strati 1. Original field and laboratory notes and records graphic studies, as there are few positive indications in which data are related precisely to their source lo of faults on the surface except in quarries. cations on past and current projects, A major construction period started in about 19 60, 2. Detailed compilations and analyses of the original and there was a great increase in the amount of explora records (these usually have limited circulation), and tory drilling. Much has been summarized in the latest 3. Generalized compilations and interpretations with reports and maps and, in 1972, data from some 25 000 some detailed examples such as are often published by holes were coded in computer format. Unfortunately, government agencies. there was insufficient funding for the implementation of a computer system having ready availability of selective Newly acquired data for a current project are usually printouts. An earlier pilot system did produce tabular by far the most valuable; however, their cost is very and graphic output (9), but that too could not be kept op- high compared with that of retrieving existing data. The erational. - latter should always be examined, even though they Thus, at present, although there are the above-cited usually provide only useful generalizations and so must published reports and others on particular areas (1, 10- be supplemented by new detailed investigations.