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Slope Stability:Seismic Force - Design Calculator

Problem Statement

This slope stability calculator utilizes a pseudo-static analysis to determine the factor of safety (FS) of a geosynthetic lined slope. This calculator assumes that no seepage forces are present. The unit gradient calculator can be used to calculate the required transmissivity of the drainage geocomposite to assure adequate drainage.

Subtitle "D" of the U.S. EPA regulations requires a seismic analysis if the site has experienced a 0.1 g horizontal acceleration, or more, in the past 250 years. For the continental USA, this does not only include the western states, but major sections of the midwest and northeast as well. The map below shows the seismic coefficients for various zones in the USA.

Legend
Zone 0:	No damage
Zone 1:	Minor damage; corresponds to intensities V and VI on the modified Mercalli intensity scale
Zone 2:	Moderate damage; corresponds to intensity VII on the modified Mercalli intensity scale
Zone 3:	Major damage; corresponds to intensity VIII and higher on the modified Mercalli intensity scale

Seismic coefficients corresponding to each zone
Zone	Remark	Modified Mercalli Scale	Average Seismic Coefficient (Cs)
0	No damage	-	0
1	Minor damage	V and VI	0.03 to 0.07
2	Moderate damage	VII	0.13
3	Major damage	VIII and higher	0.27

Input Values

References

R. M. Koerner, and T-Y. Soong, 1998. "Analysis and Design of Veneer Cover Soils". Proceedings of 6^th International Conference on Geosynthetics, Vol. 1, pp. 1-23, Atlanta, Georgia, USA.

Design Inputs
Slope characteristics
Thickness of cover soil (h)		m
Slope angle (ß)		degrees
Lenght of slope measured along geomembrane (L)		m
Soil characteristics
Unit weight of the cover soil (g)		kN/m³
Friction angle of the cover soil (f)		degrees
Cohesion of the cover soil (c)		kN/m²
Interface friction(d)		degrees
Interface adhesion (Ca)		kN/m²
Seismic characteristic
Seismic coefficient (Cs)		g