Plate Bearing Test and Modulus of Subgrade Reaction

Plate Bearing Test (PBT) is a type of in-situ test conducted to determine the bearing capacity of soil and to estimate the modulus of subgrade reaction (k) value. It is a simple test that involves placing a steel plate of a specific size onto the soil surface and applying a static load on it. The deflection of the plate is measured at different load increments, and the results are used to calculate the modulus of subgrade reaction.

Standard Plate Size for PBT

The standard plate size for PBT is 75 cm (30 inches) in diameter. This plate size is commonly used in most PBTs because it provides a good balance between accuracy and practicality. Larger plate sizes can provide more accurate results, but they require more time and effort to conduct the test. Smaller plate sizes are less accurate and may not be suitable for all types of soils.

Advantages of 75 cm Plate Size

The 75 cm plate size has several advantages over other plate sizes:

1. It is suitable for most types of soils, including cohesive, non-cohesive, and mixed soils.

2. It provides reliable and consistent results, which can be used to estimate the bearing capacity and settlement of the soil.

3. It is easy to handle and transport, making it suitable for field testing.

4. It is cost-effective compared to larger plate sizes.

Conclusion

In conclusion, the standard plate size for PBT is 75 cm in diameter. This plate size is widely used in the industry because it provides accurate and reliable results while being practical and cost-effective. However, the plate size may vary depending on the specific requirements of the project and the type of soil being tested.