Geotechnical design and analysis Subject:
Submarine Slope Stability with Slope/W Software
I'm Andrea Spigarelli, I'm working for an Italian engineering Company.
I'm using our license of Slope/W (v. 6.20) to perform the stability analysis of a submarine slope (Soil type = Very Soft Clay). I perform this analysis using the submerged unit weight instead of a region with no-strength (water). I have the following problem: I don't know how to apply the horizontal acceleration to execute a pseudo-static analysis.
The PGA (Peak Ground Acceleration) at seabed, for a 100 years return period is 0.13g. Should I insert 0.13g in Slope/w or should I multiply this value for the ratio total unit weight/submerged unit weight as follow:
Soil = Very Soft Marine Clay Su = 1.15+1.5z (0<z<15m below sea floor) PGA 100 Years R.P. = 0.13g Total Unit Weight = 14 kN/m3 Submerged Unit Weight ≈ 4 kN/m3
Value to be applied in Slope/W = 0.13X(14/4) = 0.455g.
Moreover do you think that the application of 100% PGA (in the present case 0.13g) is correct or should I consider the 50/60% of the PGA value as indicated for example in Kramer (1996)?