Cemented sands may have highly variable cohesion in addition to friction angles. Even with small cohesion, safe steeper slopes may utilized as temporary slopes to reduce the cost of earthworks/shoring for deep excavations.
Characterizing cementation is not an easy task especially if the cemented sand is weakly cemented or it has some gravel that prevent obtaining "undisturbed tube samples". Block samples may be obtained from test pits but the depth of sampling is limited by the depths of test pits.
The natural of cementation is another issue that needs to be considered. For example, if the cementation is due to suction in , it may be dangerous to consider it if there is possibility of wetting that will eliminate the suction.
Please share your experience in characterizing and utilizing cementation in particularly temporary earth slopes and shoring.
Perform the geophysical tests to determine the shear wave velocity. See the following article
http://link.springer.com/chapter/10.1007%2F978-3-642-32238-9_95
Thanks. Your paper seems very interesting and relevant to the question.
I would like to know how the strength parameters are correlated with the shear wave velocity. Would you please send me a copy of your article?
A huge number of laboratory and field tests were performed to develop the relationship
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Chapter A Simplified Technique for Slope Stability Assessment Based ...
In installing your temporary support and excavating the cut you will disturb the material, and other than in strongly cemented soils (borderline rocks) I think it would be dangerous to design based on cohesion even for the temporary condition (especially if man access to excavation is being contemplated. .
Thanks for the shared materials.
I agree that it can be more dangerous but we usually allow for lower factor of safety in temporary works than permanent works. Can we use the same logic to allow using the cohesion/cementation part of the strength?
Not in my opinion - because the disturbance will remove the cohesion instantaneously - it is "brittle" - and is either there or it is absent - it does not reduce from peak to post peak / residual strength in a smooth manner
I suggested chemical treatment method for stabilized soil by flue gas desulphurization (FGD). It improved shear strength and water absorption.