This Presentation consists of brief introduction about Dilatometer Test, and basic correlations of DMT with various soil properties. Also It covers the assessment of Liquefaction potential of soil by DMT, including a case history of Chi-Chi Earthquake, Taiwan 1999. I Hope it will be beneficial. Best Regards: Engr. Muhammad Ali Rehman

1. USE OF DMT IN GEOTECHNICAL
DESIGN WITH EMPHASIS ON
LIQUEFACTION ANALYSIS
Presented By: Muhammad Ali Rehman

2. Overview
 Introduction
 Data Interpretation
 DMT Correlations
 Liquefaction
 Liquefaction Assessment
 Case Study
 Conclusions
 References

3.  DMT
 Equipment Layout
 Test Procedure
INTRODUCTION

4. Dilatometer Test (DMT)
 Developed by Professor Silvano
Marchetti (Italy).
 Published test procedure &
correlations in 1980.
 DMT measures the lateral deflection
of soil.

5. Equipment Layout
Fig: General Layout of DMT

6. Test Procedure
 DMT in-situ testing involves expanding membrane
by using nitrogen gas.

7.  The primary way of using DMT results is to
interpret them in terms of common soil
parameters.
DATA INTERPRETATION

8. Dilatometer Test Parameters
 Primary parameters of DMT.
 Material Index
ID = (p1 – p0) / (p0 – u0)
 Horizontal Stress Index
KD = (p1 – p0) / σ´v0
 Dilatometer Modulus
ED = 34.7 (p1 – p0)
 Pore-pressure Index
UD = (p2 – u0) / (p0 – u0)

9. • DMT parameters, ID, KD, and ED are used in
subsequent soil analysis.
DMT CORRELATIONS

10. Correlations
 Soil Behavior
 Over-consolidation
 Relative Density
 Undrained Shear Strength
 Constrained Modulus
 Compression Ratio
 Settlement Prediction
 Skin friction of Driven Piles
 SPT N-value and Dilatometer Modulus

11. 1. Behavior of Soil
 Soil behavior chart introduced by Marchetti et al.
(1980).
 ID<0.6 : Clays
 0.6≤ID≤1.8 : Silts
 ID>1.8 : Sands

12. 2. Over-Consolidation Ratio (OCR)
 Original correlation proposed by Marchetti et al.
(1980):
OCRDMT = (0.5 x KD)1.56
 Confirmed by a comprehensive collection of data
by Kamei & Iwasaki (1995) for clays.
 Finno (1993)

13. Over-Consolidation Ratio (OCR)
Kamei & Iwasaki (1995) Finno (1993)

14. 3. Relative Density
Reyna & Chameau (1991)
and
Tanaka & Tanaka (1998)
Robertson & Campanella

15. 4. Undrained Shear Strength
 Marchetti et al. (1980):
cu = 0.22 σ'v0 (0.5 KD)1.25

16. Undrained Shear Strength
 Comparison of undrained shear strength by DMT
and other tests, at National Research Site,
Bothkennar (UK):
Nash et al. (1992)

17. 5. Constrained Modulus : MDMT
 Obtained by applying correction factor RM to ED
MDMT = RM . ED
 RM is the function of material index (ID) and
horizontal stress index (KD).
 Increases with KD while ID has lesser effect on the RM
value.
 Generally varies from 1 to 3.

18. 6. Compression Ratio
 Marchetti et al. (1980)
 Pre-consolidated Clays
M = σ’p (2.3/CR)
 Normally Consolidated Clays
M = σ’v (2.3/CR)

19. 7. Settlement Prediction
 Predicting the settlement of shallow foundations
(particularly for Sands) is one of the best
applications of DMT.
 Calculated by means of expression:
S = [ Δσv/MDMT ] ΔZ
Totani, Marchetti, Monaco &
Calabrese (2001)

20. 8. Skin Friction for Driven Piles in Clay
 Powell et al. (2001 b), developed a method for the
design of piles driven in clay.
 Method predicts pile skin friction qs, from ID and (p1
- p0):
 ID < 0.1 : qs /(p1 - p0 ) = 0.5
 0.1 < ID < 0.65 : qs /(p1 - p0 ) = -0.73077 ID + 0.575
 ID > 0.65 : qs /(p1 - p0 ) = 0.1

21. 9. SPT N-value & ED
Mayne & Frost

22.  Introduction
 Liquefiable Soils
 Liquefaction Assessment
LIQUEFACTION

23. Liquefaction
 “Transformation of coarse grained soil from a solid
state into a liquid state”
 Excessive hydrostatic pressure build-up & reduction of
effective stress
 sudden shock
 cyclic loading.
 Devastating effects of structure:
 Tilting of high rise buildings
 Ground subsidence
 Surface rupture
 Collapse

24. Liquefiable Soils
 Loose granular soils are potentially susceptible to
liquefaction.
 Fine grained soils (such as silts and clays) are non-
liquefiable.
 Andrews & Martin (2000) suggested:
 Potentially Liquefiable: soils having, CF < 10% & LL <
32%
 Non-Liquefiable: soils having, CF > 10% & LL ≥ 32%

25. Liquefaction Assessment
 Glaser and Chung (1995):
 Loose granular soils densify on sampling.
 Laboratory measurements demonstrate higher cyclic strength
 In-situ testing is preferred.
 “Simplified Procedure” for liquefaction assessment,
proposed by Seed & Idriss (1971).
 To evaluate the loading to a soil caused by an earthquake (by
CSR)
 To evaluate the resistance of a soil to triggering of
liquefaction (by CRR)

26. Liquefaction Assessment
 Factor of Safety against the occurrence of
liquefaction is defined as:
FS = CRR7.5 /CSR7.5
 If FS < 1, liquefaction will be triggered.

27. Cyclic Stress Ratio (CSR)
 CSR is the measure of intensity of cyclic loading
during an earthquake.
 Obtained by formula, developed by Seed & Idriss
(1971):
CSR 7.5 = 0.65 (amax / g) . (σv0 / σ’vo) . rd
 amax is the peak horizontal ground acceleration
generated by the earthquake.
 rd is the stress reduction factor.

28. Cyclic Stress Ratio (CSR)
 Seed & Idriss porposed:
 rd is the function of stratigraphy and depth.
 Has a value of 1.0 at ground surface, tends to reduce
with depth.
Seed and Idriss (1971)

29. Cyclic Stress Ratio (CSR)
 Youd et al. (2001)
 rd = [1.0 – 0.00765z] (z ≤ 9.2m)
 rd = [1.174 – 0.0267z] (9.2 < z ≤ 23m)
 rd = [0.744 – 0.008z] (23 < z ≤ 30m)
 rd = 0.5 (z > 9.2m)

30. Cyclic Resistance Ratio
 In-situ test Procedures:
 Standard Penetration Test
 Cone Penetration Test
 Shear wave velocity test
 Dilatometer Test

31. DMT Based CRR Evaluation
 Include:
 Marchetti (1980)
 Roberstson & Campnella (1986)
 Reyna & Chameau (1991)
 Monaco et al. (2005)
 Grasso & Maugeri (2006)
 Monaco & Marchetti (2007)
 Tsai et al. (2001, 2009)

32. DMT Based CRR Evaluation
 Marchetti (1980) proposed the basic correlation:
CRR = (KD/10)
 Refined by Monaco et al. (2005):
CRR7.5 = 0.0107KD
3 − 0.0741KD
2 + 0.2169KD – 0.1306
 Grasso & Maugeri (2006) further updated Monaco
et al. (2005) model into:
CRR7.5 = 0.0908KD
3 − 1.0174KD
2 + 3.8466KD – 4.5369

33. DMT Based CRR Evaluation
Curves for CRR (Reyna & Chameau
1991)
 Clean sand is safe against
liquefaction for following KD
values:
 Non seismic areas:
KD > 1.7
 Low seismicity areas :
KD > 4.2
 Medium seismicity areas:
KD > 5.0
 High seismicity areas:
KD > 5.5

34. Performance of DMT Based Liquefaction
Evaluation of Chi-Chi Earthquake, Taiwan (1999)
by Tsai et al. (2001)
Case Study

35. Chi-Chi Earthquake
 21 September 1999, at 1:47 am,
an Earthquake hit Taiwan.
 7.6 magnitude
 Epicenter near Chi-Chi (town in
Nantou County)
 2400 deaths, 8373 Injuries
 Damage of US$30 billion.
 Extensive field investigation after
earthquake was conducted by
NCREE.
 In-situ SPT & CPT were performed.

36. Collection of SPT Data
 Liquefaction sites:
 Wufeng, Nantou, Yuanlin & Zhangbin
 Total 31 SPT Cases
 24 liquefied
 7 non-liquefied

37. Collection of SPT Data
Area Test Number
Triggering of
Liquefaction
Wufeng SPT
9 Yes
1 No
Nantou SPT
7 Yes
1 No
Yuanlin SPT
8 Yes
5 No

38. SPT Based Method
 Seed et al. established chart for estimating SPT
based CRR7.5 :
Seed et al. (1985)

39. SPT Based Method
 The CRR7.5 curves were further modified by Youd et al.
(2001) and formulated as:
CRR7.5 =
𝟏
𝟑𝟒− (𝑵 𝟏) 𝟔𝟎
+
(𝑵 𝟏) 𝟔𝟎
𝟏𝟑𝟓
+
𝟓𝟎
(𝟏𝟎 (𝑵 𝟏) 𝟔𝟎 + 𝟒𝟓) 𝟐 −
𝟏
𝟐𝟎𝟎
 Valid for (𝑵 𝟏) 𝟔𝟎 < 30
 Sandy soils are considered to be non-liquefiable for
(𝑵 𝟏) 𝟔𝟎 > 30.
 Idriss and Boulanger (2006) proposed a new equation:
CRR7.5 = Exp
(𝑵 𝟏) 𝟔𝟎
14.4
+
(𝑵 𝟏) 𝟔𝟎
126
2
−
(𝑵 𝟏) 𝟔𝟎
23.6
3
+
(𝑵 𝟏) 𝟔𝟎
25.4
4
− 2.8

40. DMT Based Method
 DMT parameters, KD and ED are used to develop
DMT based CRR7.5 boundary curves.
 Two boundary curves, CRR7.5-KD & CRR7.5-ED were
established by Tsai et al. (2001), following the
existing CRR7.5-(N1)60 curve.
 Tsai et al. (2001) established the following
correlations to develop DMT based CRR7.5 curves.
 (N1)60-KD
 (N1)60-ED

41. DMT Based Method
 Tsai et al. (2001):
(𝑵 𝟏) 𝟔𝟎 = 0.185KD
3 − 2.75KD
2 + 17KD – 15
(𝑵 𝟏) 𝟔𝟎 = 0.00022ED
3 − 0.02ED
2 + 0.9ED – 3

42. DMT Based Method
 Based on above correlations, Tsai et al. (2001)
developed the DMT based CRR7.5 boundary curves.
CRR7.5 = Exp
𝑲 𝑫
8.8
3
−
𝑲 𝑫
6.5
2
+
𝑲 𝑫
2.5
− 3.1
CRR7.5 = Exp
𝑬 𝑫
49
3
−
𝑬 𝑫
36.5
2
+
𝑬 𝑫
23
− 2.7

43. DMT Based Method

44. DMT Based Method
CRR curves proposed by Monaco
(2005), Grasso & Maugeri (2006)
and Tsai (2009)

45. CONCLUSION

46. Conclusion
 DMT is relatively quick in-situ method which estimates a
number of parameters, that can be effectively used in
geotechnical design.
 DMT is capable of taking into account the soil structure,
aging and consolidation effects, which generally influence
the liquefaction potential of soil (Tsai et al. 2001).
 Tsai et al. (2001) study shows that the accuracy of DMT
based CRR7.5 curves for Liquefaction assessment is
satisfactory.
 Liquefaction assessment is relatively fast and reliable as
compared to SPT, which takes longer time to supplement SPT
with lab testing.

47. Conclusion
 However, it is desirable to directly conduct DMTs in
the liquefied and non-liquefied areas of
earthquake to obtain more KD and ED data of soils
for further validating the developed DMT-based
liquefaction evaluation method although the results
of this study are preliminarily satisfactory

48. REFERENCES

49. References
 Marchetti, S. (1980). "In SituTests by Flat Dilatometer." J. Geotech. Engrg. Div.,
ASCE, 106, No.GT3, 299- 321.
 G.Totani, S. Marchetti, P. Monaco & M. Calabrese. Use of Flat DilatometerTest
in Geotechnical Design, Intl. Conf. on In-situ Measurement of Soil Properties
(2001)
 Monaco, P., Marchetti, S., Totani, G. and Calabrese, M. (2005). “Sand
liquefiability assessment by Flat DilatometerTest (DMT).” Proc. XVI ICSMGE,
Osaka, 4, 2693-2697
 Robertson, P.K., and R.G. Campanella, [1986]. “Estimating liquefaction potential
of sands using the flat plate dilatometer. Geotech.Testing J.,Vol. 9, No. 1, pp. 38–
40.
 Tsai,Tung and Lee (2001) . Performance of DMT based liquefaction evaluation
method on case history of Chi-Chi Earthquake
 Bambang Setiawan,(2011) “Assessing Liquefaction Potential of Soils Utilizing In-
situTesting” M.ScThesis