Slope Stability

Rock Cut Slope Stability:

	Not all rock slopes are conducive to calculations. Some like this one, where the failure mechanism is sliding, can be analyzed using limiting equilibrium analysis.
	Other slopes, whose failure mechanism is raveling, in not conducive to calculation, and design and remediation must be empirically based.
	Slopes like this must be remediated or stabilized by removing loose or supporting loose rock. Scaling is usually more cost effective, and can be done manually by mechanized means. Often the quantities of loose rock are not evident until after scaling begins.
	In some cases the rock must be supported.
	In many cases it is more cost effective to mitigate damages from slope failures rather that to try and prevent them. Mitigation measures include, draped mesh and catch fences to stop or slow down falling rock and sculpting slope and building ditches large enough to contain the failed material.

Viewed from the bigger picture, with a large network of roadways and diminishing budgets, a large number of rock cuts must be analyzed and and remediation efforts need to be prioritized on a RISK basis.

In assessing RISK, both we have to consider both the probability of failure and the consequence of failure. Here again empirical formulation and classification can be used to identify cuts with both high probability of failure and serious consequence to life or property. Add to this equation the cost of remediation for each instance and the process of selecting the optimum number and locations of remediation efforts is achieved.

REFERENCES:

Maerz, H. H., 2000. Highway rock cut stability assessment in rock masses not conducive to stability calculations. Proceedings of the 51^st Annual Highway Geology Symposium, Aug. 29-Sept. 1, Seattle, Washington, pp. 249-259.

Franklin, J. A., and Maerz, N. H., 1996. Empirical design and rock mass characterization. Proceedings of the FRAGBLAST 5 Workshop on Measurement of Blast Fragmentation, Montreal, Quebec, Canada, 23-24 Aug., 1996, pp. 193-201.