Abstract
The present study deals with the reliability analysis of basal heave caused by excavation considering uncertainty in the soil properties. The case study considered in the present work has been analyzed deterministically by Hsieh et al. (Can Geotech J 45:788–799, 2008). Taiwan building code is adopted in the method for analyzing the basal heave failure. The random variables (undrained shear strength and total unit weight of clay) are assumed to be normally distributed and uncorrelated. A series of parametric studies have been conducted to calculate the reliability index on the basis of the matrix formulation for the second moment method by Hasofer and Lind (J Eng Mech ASCE 100(1):111–121, 1974) considering different coefficient of variation of undrained shear strength and total unit weight of clay layers. It has been found that for a particular value of coefficient of variation of total unit weight, the reliability index with respect to occurrence of basal heave failure decreases with increase in the coefficient of variation of undrained shear strength. Moreover, the reliability index also decreases when the coefficient of variation of total unit weight increases. It has also been found that the probability of basal heave failure is lower with respect to factor of safety equals to 1.2, as compared to factor of safety equals to 1.0. Sensitivity analysis shows that the undrained shear strength of the bottommost layer and total unit weight of the second layer are the most significant random variables affecting the reliability index. Guidelines are provided for reliability based design where, for ‘target’ reliability index of 2.5 and 3.0, the factor of safety can be chosen such that all the related uncertainties are taken into account, especially with regard to undrained shear strength of the bottommost layer and total unit weight of the second layer. Design guidelines have been provided for this purpose.
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Abbreviations
- B :
-
Width of excavation
- D e :
-
Maximum excavation depth (final stage)
- D b :
-
Embedment depth (final stage)
- E :
-
Young’s modulus of soil
- F :
-
Failure region
- G :
-
Shear modulus of soil
- K :
-
Bulk modulus of soil
- K o :
-
Coefficient of lateral earth pressure at rest
- K n :
-
Interface normal stiffness between wall and soil
- K s :
-
Interface shear stiffness between wall and soil
- M :
-
Vector of mean value of random variables
- M r :
-
Resisting moment
- M d :
-
Disturbing moment
- N :
-
Average SPT value of soil
- n :
-
Number of random variables
- P f :
-
Probability of failure
- S i :
-
Undrained shear strength of ith soil layer
- t :
-
Thickness of the wall
- X :
-
Vector of random variables
- γ :
-
Total unit weight of soil
- β :
-
Reliability index
- λ i :
-
Sensitivity factor of the ith random variable
- Φ(·):
-
Standard normal cumulative distribution function
References
Bjerrum L, Eide O (1956) Stability of strutted excavations in clay. Geotechnique 6(1):32–47
Christian JT, Baecher GB (1999) Point-estimate method as numerical quadrature. J Geotech Geoenviron Eng ASCE 125(9):779–786
Duncan JM (2000) Factors of safety and reliability in geotechnical engineering. J Geotech Geoenviron Eng ASCE 126(4):307–316
Goh ATC, Kulhawy FH, Wong KS (2008) Reliability assessment of basal heave stability for braced excavations in clay. J Geotech Geoenviron Eng ASCE 134(2):143–153
Hasofer AM, Lind N (1974) An exact and invariant first-order reliability format. J Eng Mech ASCE 100(1):111–121
Hoeg K, Muruka RP (1974) Probabilistic analysis and design of a retaining wall. J Geotech Eng ASCE 100:349–365
Hsieh PG, Ou CY, Liu HT (2008) Basal heave analysis of excavations with consideration of anisotropic undrained strength of clay. Can Geotech J 45:788–799
Kung GTC, Juang CH, Hsiao ECL, Hashash YMA (2007) Simplified model for predicting wall deflection and ground surface settlement caused by braced excavation in clays. J Geotech Geoenviron Eng ASCE 134(6):731–747
Low BK, Tang WH (1997) Efficient reliability evaluation using spreadsheets. J Eng Mech ASCE 123(7):749–752
Low BK, Tang WH (2001) Reliability of embankments on soft ground using constrained optimization. In: Proceedings of the third international conference on soft soil engineering, Hong Kong, pp 123–128
Low BK, Teh CI, Tang WH (2001) Efficient reliability based design using spreadsheet optimization. In: Proceedings of the eighth international conference on structural safety and reliability, ICOSSAR, Newport Beach, California, pp 1–8
Luo Z, Atamturktur S, Juang CH, Lin PS (2011) Probability of serviceability failure in a braced excavation in a spatially random field: fuzzy finite element approach. Comput Geotech 38(8):1031–1040
Luo Z, Atamturktur SCY, Juang CH (2012) Simplified approach for reliability-based design against basal heave failure in braced excavations considering spatial effect. J Geotech Geoenviron Eng ASCE 138(4):441–450
Meyerhof GG (1982) Limit states design in geotechnical engineering. Struct Saf 1(1):67–71
Puller M (2003) Deep excavations: a practical manual, 2nd edn. Thomas Telford Ltd., London
Rosenblueth E (1981) Two point estimates in probabilities. Appl Math Model 135:329–335
Schuster M, Kung GTC, Juang CH, Hashash YMA (2009) Simplified model for evaluating damage potential of buildings adjacent to a braced excavation. J Geotech Geoenviron Eng ASCE 135(12):1823–1835
Smith GN (1985) The use of probability theory to assess the safety of propped embedded cantilever retaining walls. Geotechnique 35(4):451–460
Sujit MS, Menon D, Dodagoudar GRH (2011) Reliability analysis and design of cantilever RC retaining walls against sliding failure. Int J Geotech Eng 5(2):131–141
Tang YG, Kung GTC (2011) Probability-based analytical method for evaluating basal heave failure in braced excavation. Disaster Adv 4(3):51–58
Tang YG, Kung GTC (2012) Probabilistic analysis of excavation-induced basal heave—a case study. In: proceedings of the 5th Asian-Pacific symposium on structural reliability and its applications, Singapore, pp 707–712
Terzaghi K (1943) Theoretical soil mechanics. Wiley, New York, p 1943
Wu SH, Ou CY, Ching J, Juang CH (2010). Reliability-base design for basal heave in an excavation considering spatial variability, GeoFlorida 2010, advances in analysis, modeling and design, West Palm Beach (Florida), Geotechnical Special Publication No. 199, pp 1914–1922
Wu SH, Ou CY, Ching J, Juang CH (2012) Reliability-based design for basal heave stability of deep excavations in spatially varying soils. J Geotech Geoenviron Eng ASCE 138(5):594–603
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Chowdhury, S.S. Reliability Analysis of Excavation Induced Basal Heave. Geotech Geol Eng 35, 2705–2714 (2017). https://doi.org/10.1007/s10706-017-0272-2
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DOI: https://doi.org/10.1007/s10706-017-0272-2