The effect on the passive pressure coefficient when there is a ground slope on the active side 1

[DimzK]

Hi All,

I am a structural engineer and I have a simple Geotech question.
Where there is a ground slope on the active side of the retaining wall, that increase thee Ka value when using coloumb theory.
But when the ground slope on the passive side is flat (horizontal), is it reasonable to also have the Kp value increased due to the ground slope on the active side?

According to my Geotech notes from New Zealand (shown below), I interpret it as being yes, it is also ok to increase the Kp due to the ground slope on the active side.
But this feels unconservative. Would like to hear your opinion on this, or if possible please point me towards some relevant literature.

Thanks,

 

[r13]

The Ka & Kp are refer to the same side with slopped back fill - 1) when the wall is pushed by the soil, active pressure develops behind the wall on the fill side, and 2) when the wall is pushed into the soil, passive (resistant) pressure develops behind the wall, also on the fill side. Both active and passive pressures are increased due to the slopping fill as indicated in the formulas.

The passive earth pressure at the toe of the retaining wall will be calculated using coefficient, Kp, for leveled ground though.

 

[DimzK]

Thank you for that explanation, so if this was a traditional upside down T type retaining wall with heel and toe, I am better off using the kp for levlled ground.
Where as for an embedded retaining wall, it is more appropriate to use Kp calculated using sloping ground , say in the case of brohms analysis for cohesionless soil condition?

 

[r13]

The sketches below depict the typical retaining wall design cases, and the exceptional cases (force crush onto wall).