Final answer:
The preferred backfill material for a retaining wall is determined based on the lateral soil pressure coefficient from Table 1610.1 Lateral Soil Load from the IBC and the USCS soil classification.
Step-by-step explanation:
The preferred backfill material for a retaining wall can be determined using Table 1610.1 Lateral Soil Load from the IBC and the USCS soil classifications provided. The table provides the lateral soil pressure coefficient for different soils based on their classification and angle of internal friction. The backfill material with the highest lateral soil pressure coefficient would be the most suitable choice for a retaining wall.
For example, if the USCS soil classification is fine-grained cohesive soils like clay (CL), the lateral soil pressure coefficient from the table would be used to determine the preferred backfill material. The higher the coefficient, the better the material would be for providing lateral support to the retaining wall.