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GROUND RESPONSEANALYSES IN KATHMANDU

VALLEY

Dipendra Gautam

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OUTLINES

Introduction

Geology of Nepal

Geology of Kathmandu Valley

Seismicity

Research Objectives

Methodology

Results

Discussions

Conclusion

Research Horizon

Acknowledgements

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 INTRODUCTION

Effects of Earthquakes:

 Ground Shaking

Structural Hazards

Liquefaction

Landslides

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 INTRODUCTION

Ground Shaking

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Source: www.google.com

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 INTRODUCTION

Structural hazard

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Source: www.google.com

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 INTRODUCTION

Landslide

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 INTRODUCTION

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Site Effects

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Ampli tude r(t)= source signal e(t)*

distance from source p(t)* local site

effects s(t)

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 INTRODUCTION

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Seismic Hazard Map of

Nepal ( After DMG)

Kathmandu

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INTRODUCTION

Site Effects are important

 1985 Mexico City earthquake (Mw=8.1) 1989 Loma Prieta earthquake (Mw=7.1)

 NEPAL: An earthquake prone area…! 

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GEOLOGY OF NEPAL

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Kathmandu

After Uprety and Le Fort, 1999

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GEOLOGY OF KATHMANDU

VALLEY

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GEOLOGICAL CROSS SECTION

OF KATHMANDU VALLEY

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 SEISMICITY

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Rupture zones of large Himalayan earthquakes since 1800 (After

Bilham et. al., 2001, modified by Feldl, 2005)

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 SEISMICITY

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Intense micro-seismicity monitored between 1994 and 2005 (

after DMG, 2006)

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 RESEARCH OBJECTIVES

Work out equivalent linear site response

analyses of soft sediment deposit of Kathmandu

valley

Comparison of computed parameters with the

damage pattern of 1934 Bihar-Nepal earthquake

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 METHODOLOGY

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BOREHOLE LOCATIONS

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INPUT MOTION

(Uttarkashi earthquake) TimeHistory

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Response spectra

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 RESULTS

 PEAK HORIZONTAL ACCELERATION

 PEAK SPECTRAL ACCELERATION

 AMPLIFICATION FACTOR

 PREDOMINANT PERIOD

 PEAK SPECTRAL VELOCITY

 AVERAGE SHEAR WAVE VELOCITY

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 RESPONSE OF SOIL

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Filling materials 

Sandy silt 

Medium to stiff clayey

silt of low plasticity 

30 m Input motion: 6.9 Magnitude earthquake

with epicentral distance of 34 km, PHA =

0.32 g 

Surface: Amplified 7.788 times 

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 Peak Horizontal Acceleration (g)

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BKTPATAN

THAMEL

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 Peak Spectral Acceleration (g)

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BKT

THAMEL

PATAN

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 Amplification factor

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 Peak Spectral Velocity (cm/s)

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THAMEL

BKT

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RESEARCH HORIZON

Development of Vs-N relationship for Kathmandu

valley

 Assessment of signal attenuated at local site

 Development of site specific design spectra using

‘  NONLIN’  

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ACKNOWLEDGEMENTS 

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6/29/2014 33

Thank you for your kind presence !!!

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