This document discusses liquefaction of soil during earthquakes and its effects based on case studies. It covers: 1) Examples of liquefaction and its effects observed during earthquakes in Chile 1960, Japan 1964, Alaska 1964, and Caracas 1967 including settlements, tilting of structures, and damage depending on soil thickness. 2) Factors influencing liquefaction potential such as soil type, density, water content, and depth to water table based on a case study of the 1964 Niigata earthquake in Japan. 3) Options for mitigating liquefaction including soil densification, stabilization, drainage, and structural measures like reinforcement and foundation modification.

1. Liquefaction of soil By Dr. J.N.Jha Professor Department of Civil Engineering Guru Nanak Dev Engineering College Ludhiana Email: jagadanand@gmail.com

2. Chile earthquake 1960 : An island near Valdivia- Mag. 9.5 Large settlements and differential settlements of the ground surface - Compaction of loose granular soil by EQ

3. Japan earthquake 1964: Niigata- Mag. 7.5 Settlement and tilting of structures - liquefaction of soil

4. Alaska earthquake 1964:Mag. 9.2 Major landslide - combination of dynamic stresses and induced pore water pressure

5. Caracas earthquake 1967: Mag. 6.6 Response of building during EQ found to depend on the thickness of soil under the building.

10. Site approximately same distance from the zone of energy release

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16. Damage potential coefficient varies with building characteristics and soil depth

17. Relationship between building characteristics, soil depth and damage potential coefficient (S v /k) Structure Fundamental period Damage intensity (D r ) 2 to 3 storey 0.2 sec Remains same regardless of soil depth 4 to 5 storey 0.4 sec Max. damage intensity expected at soil depth of about 20 to 30 m 10 to 12 storey 1.0 sec Damage intensity expected to increase with soil depth up to 150 m or so 15 to 20 storey Damage intensity even greater for soil depth of 150 to 250 m & relatively low for soil depth up to 80 m or so

19. Total stress, Pore water pressure and Effective stress Figure-1 Figure-2 Case Total Pressure Pore Pressure Effective Pressure Figure- 1 475 150 325 Figure- 2 475 250 225

23. Influence of soil conditions on liquefaction potential

24. Liquefaction Damage: 1964 Niigata, Japan

25. Tokachi-oki Earthquake: 2003 The Damage of Sewerage Structures kushiro (Town) Lifted up manhole and gushed soil during liquefaction Lifted up manhole

26. The Damage of Sewerage Structures Failure Mode (notice : this is only concept) Replaced Soil (Liquefied) Lift-up Force Crack or Residual Strain Sand Boiling Sand Boiling Manhole Flexible Pipe Rigid Pipe Residual Strain Original Soil (Liquefied)

27. The Damage of Embankment Structures Toyokoro Collapsed Embankment

28. Place where Embankment was collapsed Abashiri River (1) Shibetsu River (6) Kushiro River (5) Kiyomappu River (2) Tokachi River (66) Under investigation Lateral Spread was observed ( ) : the number of collapsed points Tokachi River The Damage of Embankment Structures

29. Toyokoro Liquefied Soil Collapsed Embankment The Damage of Embankment Structures Liquefied Soil

30. Failure Mode (notice : this is only concept) Liquefied Stratum Embankment Settlement Land Slide Lateral Spread The Damage of Embankment Structures

31. The Damage of Port Structures (at Kushiro Port) Kushiro Settlement behind Quay Wall Trace of Sand Boiling

32. Alaska Earthquake ( 1964 )

34. Caracas ( 1967 )

35. Alaska 2002 Boca del Tocuyo, Venezuela, 1989

36. Lateral spread at Budharmora ( Bhuj, 2001 )

37. Arial view of kandla port, Marked line sows ground crack and sand ejection (Gujrat Earthquake 2001)

38. Adverse effects of liquefaction Most catastrophic ground failure Lateral displacement of large masses of soil Mass comprised of completely liquefied soil or blocks of intact material riding on a layer of liquefied soil Flow develop in loose saturated sand or silts or relatively steep slope (>3 degree) Flow failure

43. Soil conditions in Areas where Liquefaction has occurred : Case Study: Niigata Earthquake

49. Relationship between depth of pile, ‘N’ of sand at pile tip and Extent of Damage (Zone-C)

51. Condition of soil before and after earthquake Relative density (D) of sand with depth before and after earthquake D vs depth of layer of three section charaterized by predominant period T p of microseismic vibrations

53. Case Study: Others sites Site Soil Property Standard Penetration Mino-Owari,Tonankai and Fukui Earthquakes D 10 ~ 0.05 to 0.25 mm Uniformity coefficient < 5 <10 (upper 30 ft) Jaltipan Earthquake D 10 ~ 0.01 to 0.1 mm Uniformity coefficient ~2 to 10 Alaska Earthquake D 10 ~ 0.01 to 0.1 mm Uniformity coefficient ~2 to 4 < 20 to 25

57. Cross-section(Retaining Geogrid Reinforced cohesionless backfill)

58. Field Performance of wall 4 O.P. Fixed in the Wall: To monitor the lateral movement of wall top away from backfill using Electronic Distance Meter for a period of 36 months

60. Hyogoken Nambu Earthquake 1995 Height of wall – 4 to 8 m Conventional Retaining Wall – suffered maximum damage Geo-synthetic reinforced soil retaining wall –Performed very well (due to relatively high ductility of the wall)

64. SAFETY AGAINST LIQUEFACTION Zone Depth below ground level ‘ N’ value III, II, I Up to 5 m 15 III, II, I Up to 10 m 25 I and II (For important structure) Up to 5 m 10 I and II (For important structure) Up to 10 m 20