bostonblue
Geotechnical
- May 6, 2025
- 1
Hello All,
I've been working with the updated log-spiral charts from the latest version of DM 7.2 (2025). I noticed using Equation 4-12, I am not able to replicate the results provided in the far-right column of Table 4-2. I understand that the equation is an approximation but some the values are a ways off, particularly as you increase in friction angle / delta/phi ratio. Does anyone have an idea of where the values in the table came from?
For example, using the equation with a friction angle of 35 and a delta/phi of 0.5 I get a Kp value of 6.3. However, the table provides a value of 8.0.
Even checking against Figure 4-13, for a friction angle of 35, the equation provides a Kp value of 7.6 while the chart shows ~8.0.
What level of accuracy is expected when using these equations/charts/tables?
Thank you!
I've been working with the updated log-spiral charts from the latest version of DM 7.2 (2025). I noticed using Equation 4-12, I am not able to replicate the results provided in the far-right column of Table 4-2. I understand that the equation is an approximation but some the values are a ways off, particularly as you increase in friction angle / delta/phi ratio. Does anyone have an idea of where the values in the table came from?
For example, using the equation with a friction angle of 35 and a delta/phi of 0.5 I get a Kp value of 6.3. However, the table provides a value of 8.0.
Even checking against Figure 4-13, for a friction angle of 35, the equation provides a Kp value of 7.6 while the chart shows ~8.0.
What level of accuracy is expected when using these equations/charts/tables?
Thank you!
