The correct answer is C. both allowable settlement and ultimate bearing capacity.
Allowable bearing pressure is the maximum pressure that can be applied to a foundation without causing excessive settlement. It is determined by the ultimate bearing capacity of the soil and the allowable settlement. The ultimate bearing capacity is the maximum pressure that the soil can support without failing. The allowable settlement is the maximum amount of settlement that is considered acceptable for a foundation.
The allowable bearing pressure is calculated by dividing the ultimate bearing capacity by a safety factor. The safety factor is a number that is used to account for the uncertainty in the soil properties and the possibility of other factors, such as construction errors, that could affect the settlement of the foundation.
The allowable bearing pressure is an important factor in the design of foundations. It is used to determine the size and depth of the foundation, as well as the type of foundation that is required.
A. allowable settlement only is incorrect because the allowable bearing pressure is also affected by the ultimate bearing capacity of the soil.
B. ultimate bearing capacity of soil only is incorrect because the allowable bearing pressure is also affected by the allowable settlement.
D. none of above is incorrect because both allowable settlement and ultimate bearing capacity affect the allowable bearing pressure.