## Mass gravity walls

Figure 11.9 shows the pressures that act on a mass gravity wall, assuming that a surcharge exists at ground surface and the water table is located above formation level. Because the back face of the wall is inclined at an angle 0 to the vertical, the effective earth pressures acting on the wall are inclined. The simplification made for reinforced concrete walls, of a Rankine zone behind the wall (see Section 11.4.4), is not valid for this situation.

Figure 11.9. Earth pressures acting on a mass gravity wall

The horizontal component o'ah of the effective earth pressure o'a acting on the back of the wall at depth z below ground surface is given by:

where KaY, Kaq, Kac = active earth pressure coefficients for soil weight, surcharge loading, and effective cohesion, respectively; y = the ground's weight density and c' = its effective cohesion; and q = the surcharge at ground surface behind the wall.

The pore water pressure u acting on the back of the wall at depth z below ground surface is given by:

where yw = the weight density of water and dw = the depth of the water table below the top of the wall.

Uplift from water pressure

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