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Rock Stability 

GEO5

Geotechnical software

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Influence of seismic effects

The programs allows for taking into account the earthquake effects using two variables – coefficient of horizontal acceleration Kh and coefficient of vertical acceleration Kv.

The coefficient of acceleration is a dimensionless number, which represents the seismic acceleration as a fraction of the gravity acceleration. Earthquake effects are introduced through the seismic force S, which is determined by multiplying the weight of the rock subjected to earthquake (i.e. rock block) by the coefficient of acceleration. When assuming seismic waves only in the horizontal direction the seismic force is given by:

where: Kh - coefficient of horizontal acceleration
W - weight of the rock body

The seismic force always acts in the center of gravity of the rock body. Usually, only seismic effects in the horizontal direction are considered. Nevertheless, the program also allows for treating the vertical direction (with the help of vertical coefficient of acceleration Kv). Effects in both directions are then combined.

M_C_S grade horizontal acceleration coefficient of horizontal acceleration
(MSK-64) [mm/s2] Kh
1 0,0 - 2,5 0,0 - 0.00025
2 2,5 - 5,0 0,00025 - 0.0005
3 5,0 - 10,0 0,0005 - 0.001
4 10,0 - 25,0 0,001 - 0.0025
5 25,0 - 50,0 0,0025 - 0.005
6 50,0 - 100,0 0,005 - 0.01
7 100,0 - 250,0 0,01 - 0.025
8 250,0 - 500,0 0,025 - 0.05
9 500,0 - 1000,0 0,05 - 0.1
10 1000,0 - 2500,0 0,1 - 0.25
11 2500,0 - 5000,0 0,25 - 0.5
12 > 5000,0 > 0.5

The values of factor Kh correspond to individual degrees of earthquake according to M-C-S scale

Literature:

Charles A. Kliche:Rock slope stability, SME, USA, 1999,ISBN 0-87335-171-1

Language: english