1. General question: Are there recognized correlations for cohesion - either effective or total - as a function of % passing 200 (0.075mm) for a clayey sand. Say, 5% to 15% FC, with the balance of the soil non-cohesive.
2. For earth pressure evaluation, when is it justified to use cohesion together with the friction? That is, c-phi behavior for either long term or short term.
3. Same question slope stability evaluation.
I understand that traditionally, phi-only for long term slope stability.
The reason for the question: recent technical literature for seismic earth pressures, like the Caltrans funded UCLA Shamsabadi tech paper and NCHRP 611, show that small values of cohesion (100psf = 5kPa) can significantly reduce the seismic active earth pressures. Given the uncertainty of cohesion, it would be useful to define a “safe” lower bound cohesion value based on FC or PI. Say, a relationship with 3 sigma (99.7%).
2. For earth pressure evaluation, when is it justified to use cohesion together with the friction? That is, c-phi behavior for either long term or short term.
3. Same question slope stability evaluation.
I understand that traditionally, phi-only for long term slope stability.
The reason for the question: recent technical literature for seismic earth pressures, like the Caltrans funded UCLA Shamsabadi tech paper and NCHRP 611, show that small values of cohesion (100psf = 5kPa) can significantly reduce the seismic active earth pressures. Given the uncertainty of cohesion, it would be useful to define a “safe” lower bound cohesion value based on FC or PI. Say, a relationship with 3 sigma (99.7%).
