Final answer:
The allowable foundation pressure for clay, sandy clay, and silty clay soils depends on their strength and bearing capacity. Clay soils have the highest allowable foundation pressure, followed by sandy clay and then silty clay.
Step-by-step explanation:
Foundation pressure refers to the maximum pressure that the soil can support without causing excessive settlement or failure of the foundation of a structure. The allowable foundation pressure for clay, sandy clay, and silty clay soils depends on their strength and bearing capacity.
Clay soils are cohesive and have good load-bearing capacity. The allowable foundation pressure for clay is typically higher compared to sandy clay and silty clay.
Sandy clay soils have a higher proportion of sand particles, which reduces their cohesive strength. Thus, the allowable foundation pressure for sandy clay is lower than that for clay.
Silty clay soils have a higher proportion of silt particles, which decreases their cohesive and load-bearing capacity. Consequently, the allowable foundation pressure for silty clay is generally lower than for both clay and sandy clay.