Upload
dinhkhue
View
229
Download
0
Embed Size (px)
Citation preview
Pengantar Kegempaan Geoteknik (Geotechnical Earthquake Engineering) Dr.Eng. Agus S. Muntohar Program Teknik Sipil – FT UMY
1
Pertemuan ke-12: 1-6 Juni 2015
Kegempaan Geoteknik berkaitan
dengan :
• Penentuan gerakan permukaan tanah (ground motions) –
terutama pengaruh kondisi lokal tanah.
• Likuifaksi (Liquefaction) dan bahaya ikutannya (penurunan,
gerakan tanah lateral, dll.)
• Evaluasi gerakan tanah pada lereng
• Bendungan/embankments
• Desain struktur penahan tanah
• Analisis fondasi
• Struktur bawah permukaan tanah (Underground structures)
: terowongan, dll.) 5
Struktut lantai dasar yang lemah (Soft first story)
Loma Prieta earthquake damage in San Francisco. The soft first story is due to construction of garages in the first story and resultant
reduction in shear strength. (Photo from: http://earthquake.usgs.gov/bytopic/photos.html)
On October 17, 1989, at 5:04:15 p.m. (P.d.t.), a magnitude 6.9 (moment magnitude; surface-wave magnitude, 7.1)
Sambungan fondasi yang tidak memadai
House shifted off its foundation, Northridge earthquake.
(Photo from: Dewey, J.W., Intensities and isoseismals, Earthquakes and Volcanoes, Vol. 25, No. 2, 85-93, 1994)
Foundation and column of a dwelling at the long-bean-shaped hill
(Kashmir October 8, 2005)
Keruntuhan pilar jembatan
Sand blow in mud flats used for salt production southwest of Kandla Port, Gujarat
Sand boiling selama gempa
Cracked Highway, Alaska, 1964
Lateral spreading in the soil beneath embankment causes the
embankment to be pulled apart, producing the large crack down the
center of the road.
How Richter magnitude (ML) was
measured
ML = log10 of the maximum ground motion (in millimeters) recorded on a
Wood-Anderson short-period seismometer 100 km from the earthquake
Source Study of the 1906 San Francisco Earthquake by David J. Wald David J. Wald, Hiroo Kanamori and Donald V. Helmberger
Bull. Seism. Soc. Am., 83, 981-1019, 1993
Other magnitude scales
Magnitude Symbol Wave
Local (Richter) ML S or Surface Wave*
Body-Wave mb P
Surface-Wave Ms Rayleigh
Moment Mw Rupture Area, Slip
Moment Magnitude - Mw
• Mw = (2/3)log10Mo – 10.7
• Mo = Seismic Moment
Mo = μAu
o μ = shear modulus (typically 30 x 109 N/m2 or 30 x 1010
dyne/cm2)
o A = area of fault rupture
o u =average displacement along fault