| 摘要(英) |
The geologic structures such as faults, joints, bedding planes, inter-bedding, and foliation, are very common in Taiwan. The rock formation associated with these features, of course, yields a mechanical behavior totally different from that of a homogeneous, intact mass. The main objective of this thesis is to numerically study the bearing mechanism of a rigid strip foundation of width (B) sitting on a mass of two layered formations, and to establish a predictive model of bearing capacity for such a case, which has never arrived at a unified form in the literature.
The bearing behavior of such a mass was simulated by the FLAC code, in which finite-difference scheme is employed for both the spatial and time domains. The foundation loading mode used is strain-controlled, and the ultimate bearing capacity (qu) is determined from the loading versus settlement curve and the disturbed zone beneath the foundation is localized according to the displacement vector plots. For understanding the distinct bearing behavior of a two-layered formation system, two cases were selected: Case A with a hard sandstone layer (HS) of thickness (H1) overlying a soft shale (SS), and Case B with SS overlying HS, each material assigned with typical mechanical properties. Besides, the neural networks analysis with backward propagation algorithm (NNAB) was adopted to develop a general bearing capacity formulas for a two-layered formation system, and about nine hundreds of cases were run by FLAC with formation properties (for common soils): the friction angle (f) varying from 0 to 30° and cohesion (c) from 0 to 1MPa. Three situations were considered: both layers cohesionless, one cohesionless and another cohesive soils, and both cohesive.
The simulation results of HS-SS system show that qu increases with H until H approaches 4B for Case A, qu decreases with H until H approaches 2.5B for Case B, and both (f,c) values of two formations affect qu to some certain extent (but not merely qu of each formation). The NNAB established a fair predictive model of qu for a two-layered soil system, with a prediction error less than 10%. In its linear model analysis, the most influential factor for each situation was also identified, and for instance, such a factor is the friction angle of the top layer (f1) for a two-layered cohesionless system with a weaker top layer. |
| 參考文獻 |
王乙翕 (2000) 「層狀岩盤之承載力」，碩士論文，國立中央大學土木工程研究所
洪如江 (1991) 「初等工程地質學大綱」，財團法人地工技術研究發展基金會
張俊雄 (1993) 「類神經網路在土木工程上之應用研究」，碩士論文，國立中央大學土木工程研究所
黃哲君 (1998) 「層狀土壤之基礎承載力」，碩士論文，國立中央大學土木工程研究所
梁至仁 (1999) 「層狀地層之承載力」，碩士論文，國立中大學土木工程研究所
Brady, B.H.G. and Brown, E.T. (1985) Rock Mechanics for Underground Mining, Chapman and Hall, London.
Bell, F. G. (1992) Engineering in Rock Masses, Butterworth — Heinemann, Oxford, 580p.
Bowles, J.E. (1988) Foundation Analysis and Design, 4th Edition, McGraw-Hill, New York.
Burd, H. J. and Frydman, S. (1997) “Bearing capacity of plane-strain footings on layered soils,” Can. Geotech. J., Vol. 34, No. 2, pp. 241~253.
Chen, W.F. and William O. McCarron (1990) , “Bearing Capacity of Shallow Foundations,” in Foundation Engineering Handbook, Chapter 4, Ed. By Fang, Hsai-Yang, 2nd Edition, Van Nostrand Reinhold, New York, pp. 144~165.
Das, B.M. (1984) Principal of Geotechnical Engineering Engineering, 3rd Edition PWS, Boston.
FLAC (1993) Fast Lagrangian Analysis of Continua, Volume 1: User’s Manual, Itasca Consulting Group Inc., USA.
FLAC (1993) Fast Lagrangian Analysis of Continua, Volume 2: Verification Problems and Example Applications, Itasca Consulting Group Inc., USA.
FLAC (1993) Fast Lagrangian Analysis of Continua, Volume 3: Appendices, Itasca Consulting Group Inc., USA.
Goodman, R.E. (1980) Introduction to Rock Mechanics, John Wiley & Sons, New York.
Jaeger, J.C. and Cook, N.G.W. (1969) Fundamentals of Rock Mechanics, Chapman and Hall, New York.
Hoek, E. and E. T. Brwon (1997) “Practical Estimates of Rock Mass Strength,” Int. J. Rock Mech. Mining Sci., Vol. 34, No. 8, pp. 1165~1186.
Hoek, E. (1990) “Estimating Mohr-Coulomb Friction and Cohesion Values from the Hoek-Brown Failure Criterion,” Int. J. Rock Mech. Mining Sci., Vol. 27, No. 3, pp. 227~229.
Hoek, E. (1983) “Strength of jointed rock masses,” Geotechnique, Vol. 33, No. 3, pp. 187~273.
Hanna, A.M. and G.G. Meyerhof（1979）“Ultimate Bearing Capacity of Foundations on a Three-layer Soil with Special Reference to Layered Sand,” Can. Geotech. J., Vol. 16, No. 2, pp. 412~414.
Hanna, A.M. and G.G. Meyerhof (1981) “Experimental Evaluation of Bearing Capacity of Footing Subjected to Inclined Loads,” Can. Geotech. J., Vol. 18, No. 2, pp. 599~603.
Holtz, R.O. (1990) “Stress Distribution and Settlement of Shallow Foundations,” in Foundation Engineering Handbook, Chapter 5, Ed. By Fang, Hsai-Yang, 2nd Edition, Van Nostrand Reinhold, New York, pp. 166~222.
Kenny, M. J. and Andrawes, K. Z. (1997) “The Bearing Capacity of Footings on Sand Layer overlying Soft Clay,” Geotecnique, Vol. 47, No. 2, pp. 339-345.
Myslivec, A. and kysela, Z. (1978) The Bearing Capacity of Building Foundations, Elsevier.
Meyerhof, G.G. (1974) “Ultimate Bearing Capacity of Footings on Sand Layer overlying Clay,” Can. Geotech. J., Vol. 11, No. 2,pp.223~229.
Merifield, R. S., Sloan, S. W. and Yu, H. S. (1999) “Rigorous plasticity solutions for the bearing capacity of two-layered clays,” Geotechnique, V. 49, No. 4, pp. 471-490
Pells, P.J.N. and R.M. Turner (1980) , “Endbearing on Rock with Particular Reference to Sandstone,” International Conference on Structural Foundations on Rock, Sydney, pp. 181~190.
Perkins, S. W. (1995) “Bearing Capacity of Highly Frictional Material ,” Geotechnical Testing Journal, GTJODJ, Vol. 18, No. 4, pp. 450-462.
Parndtl, L. (1920) Harte plashecher Korper, Nach. Ges. Wiss. Gottingen.
Reddy, A. S. and R. J. Srinivasan (1967) “Bearing Capacity of Footings on Layered Clays,” Journal of the Soil Mechanics and Foundations Division, Proceedings, ASCE, Vol. 93, No. SM2, pp. 83~99.
Sowers G.F. (1979) Introductory Soil Mechanics And Foundation, 4th Edition, Macmillan, New York.
Terzaghi, K. and Peck, R. B. (1967) Soil Mechanics in Engineering Practice, 2nd Edition, John Wiley ＆ Sons, New York.
Terzaghi, K. (1943) Theoretical Soil Mechanics, Wiley, New York.
Taylor, D. W. (1948) Fundamentals of Soil Mechanics, John Wiley ＆ Sons, New York.
Wyllie, D. C. (1992) Foundations on Rock, Chapman & Hall, London. |
[Endnote RIS 格式]
[相關文章]
[文章引用]
[完整記錄]
[館藏目錄]
[檢視]
plurk
funp
live
udn
HD
myshare
netvibes
friend
youpush
delicious
baidu
Google bookmarks
del.icio.us
hemidemi
facebook
twitter
google
reddit