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Use of DMT for Settlement Prediction of Shallow Foundation And How to use DMT Settlement Software

Use of DMT for Settlement Prediction of Shallow Foundation And How to use DMT Settlement Software Dr. Eng. Francesca Buselli. francesca@marchetti-dmt.it. Studio Prof. Marchetti s.r.l. Via Bracciano 38 00189 Rome - Italy. Main Application: settlement prediction.

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Use of DMT for Settlement Prediction of Shallow Foundation And How to use DMT Settlement Software

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  1. Use of DMT for Settlement Prediction of Shallow Foundation And How to use DMT Settlement Software Dr. Eng. Francesca Buselli francesca@marchetti-dmt.it Studio Prof. Marchetti s.r.l. Via Bracciano 38 00189 Rome - Italy

  2. Main Application: settlement prediction 1-D formula in 1-D problems large rafts 3-D formula in 3-D problems  small isolated footings Boussinesq solutions M=MDMT (simpler, engineer independent) E  0.9 MDMT(elasticity, =0.2) (uncertainties in  and Dx e Dy )

  3. Graphs • Tabular Output • Report Settlement Calculation Example usingDMT Settlement Software .UNI file = Input for allsubsequent software SDMTElab • DMT Settlements • Laterallyloadedpiles (.dos) • CPTe-IT (Robertson) • 3rd party Software “DMT Settlements” program downloadable: www.marchetti-dmt.it/software/indexUpdate.htm

  4. How to generate .Uni file from SDMTElab Software Export  Create UNI files

  5. .Uni file example

  6. Structure of the .Uni file name of the DMT current vertical zi(m) zf (m) zw(m) zabs(m) date of the DMT test n lines u (kPa) . . . . . s (kPa) z (m) p0 p1 (kPa) g (kN/m3) ID KD ED (MPa) K0 OCR M (MPa) cu (kPa) class . . . . . . . . . .

  7. How to use DMT Settlement Software(Diego Marchetti, v.1.1 2014) Load Area  Output, Internal calculations: all in S.I. units

  8. How to use DMT Settlement Software(Diego Marchetti, v.1.1 2014) Load Area

  9. How to use DMT Settlement Software(Diego Marchetti, v.1.1 2014) Soil Parameters

  10. How to use DMT Settlement Software(Diego Marchetti, v.1.1 2014) Soil Parameters

  11. How to use DMT Settlement Software(Diego Marchetti, v.1.1 2014) Soil Parameters

  12. How to use DMT Settlement Software(Diego Marchetti, v.1.1 2014) Calculation Options

  13. How to use DMT Settlement Software(Diego Marchetti, v.1.1 2014) Settlement Prediction (Mono - Dimensional Conventional Method) • Settlement Calculation Point: • below: • the center • the corner • the median point of the short side • the median point of the long side Note that horizontal stresses are unneeded and the Poisson’s ratio is not required in the calculations!

  14. How to use DMT Settlement Software(Diego Marchetti, v.1.1 2014) Printouts

  15. How to use DMT Settlement Software(Diego Marchetti, v.1.1 2014) Graphs

  16. How to use DMT Settlement Software(Diego Marchetti, v.1.1 2014) Report (automatically generated)

  17. How to use DMT Settlement Software(Diego Marchetti, v.1.1 2014) Report – Cover (automatically generated) INPUT DATA • Load Area details • Soil data Input (M) • Calculation Options OUTPUT DATA • Settlements Calculation

  18. How to use DMT Settlement Software(Diego Marchetti, v.1.1 2014) Report – Graphs (automatically generated) settlement layer total settlement

  19. How to use DMT Settlement Software(Diego Marchetti, v.1.1 2014) Report – Printouts (automatically generated) Note that the profile of vertical effective stresses is also read from the unified DMT profile Moduli used in the calculations are the values at the center of each layer obtained by interpolation between the adjacent available values !!

  20. COMPUTER PROGRAM Input load Input Mdmt   e.g. for a building is possible to select at end of DMT : Shallow foundation Piles Ave load : each floor approx 8 kPa : 9 floors x 8 kPa = 72 kPa If s < 5 cm nopiles (ok shallow) (Limit for a footing:2.5 cm Terzaghi 1964)

  21. Comparisons between DMT predicted and measured settlement

  22. Settlement Prediction from DMT • Lacasse & Lunne (1986) “Dilatometer Tests in Sand”. Proc. In Situ '86 ASCE Spec. Conf. Virginia Tech, Blacksburg.“Very good agreement between DMT-predicted and measured settlements under a silos at a sandy site” • Steiner W. (1994) “Settlement Behaviour of an Avalanche Protection Gallery Founded on Loose Sandy Silt”.Settlement '94 ASCE Conf. at Texas A&M.“The DMT-predicted settlements agreed well with observed settlements“ • Mayne & Liao Tianfei (2004) “CPT-DMT interrelationship in Piedmont residuum” . Proc. In ISC’2 Porto.“Over two decades of calibration between the DMT and measured foundation performance records have shown its value & reliability in settlements computation” • Vargas (2009), Bullock (2008), Monaco (2006), Lehane & Fahey (2004), Mayne (2001, 2004), Failmezger (1999, 2000, 2001), Crapps & Law Engineering (2001), Tice & Knott (2000), Woodward (1993), Iwasaki et al. (1991), Hayes (1990), Mayne & Frost (1988), Schmertmann (1986,1988), Steiner (1994), Leonards (1988), Lacasse (1986)…………….

  23. Summary of comparisons DMT-predicted vs. observed settlements • Large no. of case histories  good agreement for wide range of soil types, settlements,footing sizes • Average ratioDMT-calculated/observed settlement 1.3 • Band amplitude of data points (ratio max/min) < 2i.e. observed settlement within ± 50 % from DMT-predicted (Monaco et al. 2006)

  24. M at Sunshine Skyway Bridge, Tampa Bay – Florida (Schmertmann – Asce Civil Engineering – March 1988) World record span for cablestayed post-tensioned concretebox girder concrete construction Modulus M from DMT : M 200 MPa (1000 DMT test points) M from laboratory : M 50 MPa From obs. Settlements : M 240 MPa Conclusion: DMT=good evaluation of constrained modulus M

  25. Observed vs. predicted by DMTSilos on Danube Bank (Belgrade) D. Berisavijevic, 2013 DMT Settlement prediction: 77 cm Measured Settlement: 63 cm DMT +22%

  26. Main SDMT Applications • Settlements of shallow foundations (MDMT) • Monitoring soil improvement / compaction control (KD, MDMT) • Slip surface detection in OC clay slopes (KD) • Quantifyσ'hrelaxationbehindretainingwalls(KD, K0) • Laterally loaded piles (ED, p0) • Diaphragm walls • FEM input parameters • Liquefability evaluation (KD, Vs) • Seismic design (Eurocode 8, NTC 2008) (VS, VP) • In situ G-g decay curves (MDMT, GDMT)

  27. Thank you for your attention !!

  28. Observed vs. predictedby DMTThe case of a four-story steel framed office building in Florida • Measured settlements slightly less than DMT estimated … • Using DMT NO more expensive and time consuming soil improvement … • SPT cannot measure the strength and compressibility as accurately as DMT, • SPT underpredicted the modulus… Jacksonville, Florida $ 130,000 - $ 140,000 saved !! SPT  total settl. < 51 mm DMT  total settl. < 32 mm (M. Woodward et al., 1993 - ASCE Journal)

  29. Concluding Remarks • THE PRIMARY WAY OF USING DMT RESULTS IS THE INTERPRETATION IN TERMS OF COMMON SOIL PARAMETERS • Settlementpredictionofshallowfoundation • Liquefabilityevaluationofsandylayers • Ignoring or disregarding the benefits of stress history, inevitable when the investigation is carried out with probes, modestly sensitive to it, leads to inaccurate-often excessive settlement and CRR, resulting in an overconservative and uneconomical design. • Sensitivity of DMT’s KD to SH permits a more economical design • (+accurate settlements, + accurate CRR  +economical design) • DMT Settlement Software leadstocalculatesettlements fast and well (immediatelyafterthat the test isfinished)

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