Hi, I constructed a simple model in AutoPIPE to try to understand how the soil springs work. However the result is not what I expected. I have a straight pipe with soil spacing of 1000mm. I applied a UDL in the -Z direction (Z is vertical in this model), and tried various magnitudes of loading. Soil properties for vertical direction are: Vert Dn K1 N/mm/mm 13.95 Vert Dn P1 N/m 2125993 Vert Dn Yld Disp. mm 152.4 K2=0 The soil yield occurs at the displacement I expected, around 152.4mm. But the stiffness of the soil springs is very different from my expectation. I expected a UDL of 2,125,993 N would approx 152mm of displacement, soil yield. But instead soil yield occurs at a much lower load of around 600,000 N. I also checked the soil spring stiffness, which I expected to equal K1. The stiffness is consistent until soil yield at 3966 N/mm per soil spring, or 3.966 N/mm/mm. Much lower than the Vert Dn K1 value in the tables. So obviously there is something I am not understanding about how the stiffness of the soil spring is calculated for the soil springs in AutoPIPE. How is the initial soil spring stiffness determined in AutoPIPE ? And am I correct that this does not match the K1 value ? Best Regards Fergus
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