Here, two footings of different size carry the same uniform load, but the pressure bulb under the larger foundation is much larger and deeper. In each case the maximum vertical pressure occurs immediately below the footing and diminishes to 10 per cent of this value at a depth equal to twice the diameter of the foundation. If the applied stresses within the bulb do not exceed the shear strength of the soil the structure will be stable. Pressure bulbs under large and small round foundations. Non-uniform placement of silage during filling has caused many problems.
Strong winds acting on a tall silo can produce the same effect.
The local overstressing of the foundation soil may cause tilting, and unless the problem is remedied it may increase with time until the silo overturns. Non-uniform and overlapping pressure bulbs. Because pressures are additive, the resulting pressure bulb will be much larger and will extend to greater depths. Leaning twin silos caused by non uniform settlement in zone of overlapping pressure bulbs. As filling proceeds, the loads are applied to the soil skeleton and to the pore water contained within the voids of the clay.