Geology 229 Engineering Geology Lecture 27. Earthquake Engineering (Reference West, Ch. 18)

Transcription

1 Geology 229 Engineering Geology Lecture 27 Earthquake Engineering (Reference West, Ch. 18)

2 Earthquake Engineering 1. General introduction of earthquakes 2. Seismic Hazards 3. Strong ground motion

3 Exactly 100 years ago, Today, April 18, 1906, at 5:13 a.m., the Great San Francisco Earthquake hit the San Francisco Bay Area. This was the first significant, and longest memorized earthquake in North America. The famous elastic rebound hypothesis (Reid) was intrigued by the 1906 San Francisco Earthquake.

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5 Earthquake Engineering: Studies of the effects of earthquakes on people and their environment, with methods of reducing these effects. Earthquake Engineering involves: geology, seismology, geotechnical engineering, structural engineering, risk analysis with also social, economic, and political factors. Seismic Hazards: Natural hazards associated with the occurrence of earthquakes.

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9 Body wave: P-wave Sv-wave Surface wave Rayleigh wave Love wave

10 Seismic Hazards include: Ground shaking: ground failure, lateral spreading; Structural hazards: damage of engineering works (buildings, bridges, highways, etc.); Liquefaction: loss shear strength of the foundation; Landslides: mudflow, slope failure; Retaining structure failure: retaining walls, dams, breakwater, quarry-walls; Lifeline hazards: fire, hazardous gas, loss of drinking/fire-fighting water; Tsunami (ocean) and seiche (lake) hazards.

11 Lateral Spreading caused by the 1906 San Francisco Earthquake at Moss Landing, CA (USGS Professional Paper 993)

12 Ground failure scarp caused by the 1906 San Francisco Earthquake in Pajaro River, CA (USGS Professional Paper 993)

13 San Francisco in flames after the 1906 Earthquake (downtown, S. F., CA, USGS Professional Paper 993)

14 On April 18, 1906, the Great San Francisco Earthquake hit the Bay Area at 5:13 a.m., causing more than $2 million in damage at Stanford. The men's gymnasium, above, sustained major damage.

15 A gigantic landslide buried the Village of Yungay, Peru, after the 1970 Peruvian Earthquake. (Kramer, 1996)

16 Foundation failure by liquefaction after the 1964 Niigata Earthquake. (USGS)

17 Tsunami Destruction at the Resurrection Bay, Kodiak Island after the Great Alaska Earthquake (March 27, 1964)

18 Tsunami Destruction at the Resurrection Bay, Kodiak Island after the Great Alaska Earthquake (March 27, 1964)

19 Sand boils after the 1906 Earthquake, Milpitas, CA (USGS Professional Paper 993)

20 Louis Agassiz Statue in Stanford University after 1906 San Francisco Earthquake Louis Agassiz (Harvard Professor, ). I have devoted my whole life to the study of Nature, and yet a single sentence may express all that I have done.... Louis Agassiz, 1869.)

21 The Damage of Sewerage Structures 7 Kushiro (town) Lifted-up Manhole and gushed Soil during Liquefaction 2003 Hokkaido Earthquake Lifted-up Manhole

22 The Damage of Sewerage Structures 9 Failure Mode Sand Boiling (notice : this is only concept) Sand Boiling Crack or Residual Strain Rigid Pipe Manhole Flexible Pipe Residual Strain Original Soil (Liquefied) Lift-up Force Replaced Soil (Liquefied)

23 The Damage of Embankment Structures 10 Toyokoro Collapsed Embankment

24 The Damage of Embankment Structures Collapsed Embankment 11 Liquefied Soil Liquefied Soil Toyokoro

25 The Damage of Embankment Structures 13 Failure Mode (notice : this is only concept) Settlement Embankment Land Slide Lateral Spread Liquefied Stratum

26 Earthquake Intensity Map of the 1906 San Francisco Earthquake (USGS Professional Paper 993)

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30 Modern time microseismicity in the New Madrid Seismic Zone, 3 great earthquakes occurred here in winter.

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32 A model of the Zhang Heng Seismograph invented in China about 2000 years ago in the Han Dynasty

33 An old German Seismograph for recording strong earthquake motions

34 Modern Strong Ground Motion Seismograph, (Kramer, 1996)

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37 Recordings from the October 21, 2004 earthquake (Md2.5) at the vertical strong motion array, VSAS. (A) surface, (B) 30 m deep, (C) 260 m deep.

38 Strong Ground Motion Earthquake motion of sufficient strength to affect people and their environment. It is recorded by 3- component acceleration seismometers. Strong ground motion at one site is determined by: Earthquake source location; Physical properties of earth material along the path of seismic wave propagation; Local site effects (soil characteristics); Strong ground motion is characterized with ground motion parameters.

39 Ground Motion parameters: Amplitude Parameters Peak acceleration; Peak velocity; Peak displacement. Frequency content parameters: Ground motion spectra (Fourier spectra, Power spectra, response spectra); Spectral parameters (predominant period, Bandwidth, Central frequency, shape factor).

40 Duration Bracketed duration; Corner period (corner frequency); Other ground motion parameters Cumulative absolute velocity (CAV): the integration of the absolute acceleration; Spectral Intensity (SI): the integration of the pseudovelocity (PSV) response spectrum; acceleration spectrum intensity (ASI): the integration of the acceleration response spectrum.

41 1989 Loma Prieta Quake recorded at (1) Rock site (2) Soil site at the same location

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