I'm stuck with how to work out the total pressure and centre of pressure in this example.
At an outdoor boundary between two properties there is a stepped change in ground level of the clay soil. The ground abruptly changes level by H (roughly 0.9 - 1.2m if it matters). A vertical retaining wall is present, whose design is not relevant here. The soil's depth is much greater than the wall height so there are no relevant local boundaries or property changes in the soil below the retaining wall (however deeply it is embedded in the soil). There are no buildings or other sources of pressure on the soil other than its own weight and soil mechanics, and hydrostatic effects of any water it contains. There is considerable rainfall at times, so the soil will periodically become saturated.
I'm ignoring for now, any other issues, such as bearing, shear and other failure modes, but for safety I should probably assume active rather than passive pressure, I think. I want to find the maximum design lateral pressure such a wall must resist in the presence or absence of built-up hydrostatic pressure, and the height above the lower ground level at which that pressure should be taken as being exerted for calculation purposes.
Specifically I think what I'm trying to find is the maximum design lateral pressure exerted by the soil and any ground-water on the wall, and the point at which that pressure is exerted for calculation purposes (a) if there are ample weepholes/drainage, (b) if there are no weepholes/drainage. I'm expecting the answer to depend on the characteristics of the specific clay to an extent, but I can't work out which characteristics are critical and how much they affect the answer.
Update Sketch as requested: