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Geostatistical analysis of spatial variability of the liquefaction potential – Case study of a site located in Algiers (Algeria)

Salah Eddine Bouguerba
Salah Eddine Bouguerba
, 
Djawad Zandagui
Djawad Zandagui
 and 
Souad Benhchilif
Souad Benhchilif
   | Jun 30, 2021
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Article Category: Original Study
Published Online: Jun 30, 2021
Page range: 155 - 168
Received: Nov 26, 2020
Accepted: Mar 29, 2021
DOI: https://doi.org/10.2478/sgem-2021-0009
Keywords
© 2021 Salah Eddine Bouguerba et al., published by Sciendo
This work is licensed under the Creative Commons Attribution 4.0 International License.

Figure 1

Geographical location of the study region and location of the CPT surveys.
Geographical location of the study region and location of the CPT surveys.

Figure 2

Example plots showing key steps in calculating liquefaction potential at one CPT (BH34): (a) tip resistance (qc); (b) side friction (fs); (c) soil type index (Ic); (d) corrected equivalent tip resistant (qc1N)cs; (e) cyclic stress ratio (CSR) and cyclic resistance ratio (CRR); (f) factor of safety (FS).
Example plots showing key steps in calculating liquefaction potential at one CPT (BH34): (a) tip resistance (qc); (b) side friction (fs); (c) soil type index (Ic); (d) corrected equivalent tip resistant (qc1N)cs; (e) cyclic stress ratio (CSR) and cyclic resistance ratio (CRR); (f) factor of safety (FS).

Figure 3

Spatial distribution and histogram of liquefaction potential index.
Spatial distribution and histogram of liquefaction potential index.

Figure 4

Trend analysis for the liquefaction potential index data.
Trend analysis for the liquefaction potential index data.

Figure 5

Experimental and theoretical semivariograms for the liquefaction potential index.
Experimental and theoretical semivariograms for the liquefaction potential index.

Figure 6

Anisotropic semivariogram of liquefaction potential index variorum for directions 0°, 45°, 90°, and 135°.
Anisotropic semivariogram of liquefaction potential index variorum for directions 0°, 45°, 90°, and 135°.

Figure 7

Anisotropic semivariogram model for the liquefaction potential index.
Anisotropic semivariogram model for the liquefaction potential index.

Figure 8

Cross validation of the semivariogram model for the liquefaction potential index (isotropic analysis A, anisotropic analysis B).
Cross validation of the semivariogram model for the liquefaction potential index (isotropic analysis A, anisotropic analysis B).

Figure 9

Liquefaction potential hazard map predicted by ordinary kriging (a) and corresponding standard deviation map (b) for earthquake magnitude of 6.8 and peak ground acceleration of 0.3 g (isotropic analysis).
Liquefaction potential hazard map predicted by ordinary kriging (a) and corresponding standard deviation map (b) for earthquake magnitude of 6.8 and peak ground acceleration of 0.3 g (isotropic analysis).

Figure 10

Liquefaction potential hazard map predicted by ordinary kriging (a) and corresponding standard deviation map (b) for earthquake magnitude of 6.8 and peak ground acceleration of 0.3 g (Anisotropic analysis).
Liquefaction potential hazard map predicted by ordinary kriging (a) and corresponding standard deviation map (b) for earthquake magnitude of 6.8 and peak ground acceleration of 0.3 g (Anisotropic analysis).

Figure 11

Liquefaction potential hazard map for peak ground acceleration of 0.2 g (a) and 0.25 g (b) (Isotropic analysis).
Liquefaction potential hazard map for peak ground acceleration of 0.2 g (a) and 0.25 g (b) (Isotropic analysis).

Computation of LPI for peak horizontal ground acceleration of 0.3 g corresponding to Mw = 6.8.

Depth (m) Average Density (KN/m3) Overburden Stress σV0 (Kpa) Effective stress σ′V0 (Kpa) qc (Kpa) fs (Kpa) CRR rd CSR Fs z (m) H (m) w(z) F w(z)*F*H
2.50 19.58 48.95 23.95 2550.00 125.00 0.59 0.98 0.30 1.95 1.25 2.50 9.38 0.00 0.00
3.50 19.58 68.53 33.53 1140.00 41.00 0.19 0.98 0.30 0.62 3.00 1.00 8.50 0.38 3.21
8.50 19.58 166.43 81.43 2430.00 130.00 0.33 0.93 0.29 1.15 6.00 5.00 7.00 0.00 0.00
10.50 19.58 205.59 100.59 1450.00 51.00 0.13 0.89 0.28 0.48 9.50 2.00 5.25 0.52 5.43
14.50 19.58 283.91 138.91 2860.00 112.00 0.18 0.78 0.24 0.73 12.50 4.00 3.75 0.27 4.02
LPI 12.66

Basic statistics of liquefaction potential index.

Number of values Mean Median Standard deviation Minimum Maximum Skewness Kurtosis
62 11.459 8.6759 10.456 0 32.718 0.472 1.793

Properties of the fitted semivariograms of the liquefaction potential index.

Model type Nugget C0 Partial Sill C+C0 Major range a (m) C/C+C0 RSS R2
Spherical 0 120 1800 1 1728 0.943
Exponential 0 135 1060 1 2633 0.885
Linear 38 146 3440 0.735 7272 0.629
Gaussian 5 125 1200 0.96 2205 0.900

Calculated values of liquefaction potential index (LPI).

Borehole Coordinates LPI Borehole Coordinates LPI
Easting (m) Northing (m) Easting (m) Northing (m)
BH1 519039.1 4062223 5.57 BH32 517267.3 4060744 24.11
BH2 519247.8 4061957 0.00 BH33 517582.2 4061421 16.97
BH3 519471.7 4061669 0.73 BH34 516748.6 4060166 12.66
BH4 519697.4 4061414 0.00 BH35 516205.9 4060353 26.85
BH5 519931.9 4061204 0.00 BH36 516494 4060620 26.54
BH6 519925.8 4060761 0.00 BH37 515785.8 4060475 21.12
BH7 519655.4 4061015 0.00 BH38 515446.7 4061284 23.90
BH8 519438.6 4061314 0.00 BH39 515676.1 4061850 30.48
BH9 519187.1 4061546 2.34 BH40 515196.3 4061971 32.72
BH10 518939.2 4061757 5.73 BH41 517075.7 4059634 27.74
BH11 518750.8 4062111 8.60 BH42 516106.9 4061729 29.61
BH12 519674.6 4060860 8.75 BH43 515283.1 4059841 13.44
BH13 519369.7 4060970 3.80 BH44 515430 4060130 12.45
BH14 519124.5 4061169 0.00 BH45 515829.7 4059942 23.93
BH15 518443.2 4061889 9.97 BH46 518340.9 4061656 19.64
BH16 519199.3 4060493 8.61 BH47 517981.9 4061644 6.18
BH17 518900 4060902 5.38 BH48 517343.3 4058514 0.93
BH18 518591 4061257 16.25 BH49 517268.7 4058736 0.00
BH19 518848 4060181 3.69 BH50 517249.5 4058958 0.00
BH20 518474.9 4060857 19.59 BH51 517536.8 4059125 0.21
BH21 518374.6 4060557 24.41 BH52 517465.8 4058892 0.00
BH22 518288 4060102 26.39 BH53 517511 4058648 3.24
BH23 518125.3 4059736 13.89 BH54 517506.3 4058348 0.00
BH24 517678.6 4059724 24.30 BH55 517628.5 4058870 1.83
BH25 517901.1 4060124 28.98 BH56 517669.1 4058681 5.21
BH26 518152.4 4060413 25.75 BH57 517711.5 4058493 1.61
BH27 518130.8 4060901 24.28 BH58 515780.4 4058544 6.00
BH28 517660.5 4060689 13.15 BH59 515724.8 4059143 3.29
BH29 517854.7 4060945 11.10 BH60 515743.1 4059410 4.85
BH30 517444.4 4059335 0.00 BH61 515869.5 4059687 11.92
BH31 517097.9 4061032 20.12 BH62 515898.42 4059487.6 11.66
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