Plate Load Test on Soil

The Plate Load Test is a field test used to determine the bearing capacity and settlement characteristics of soil under a foundation.

 

Objective of Plate Load Test

· Determine safe bearing capacity of soil

· Measure settlement under load

· Estimate modulus of subgrade reaction

· Check suitability of foundation soil

Apparatus Required

· Steel bearing plate

· Hydraulic jack

· Reaction beam or loaded platform

· Dial gauges

· Settlement measuring devices

Test Procedure

1. Excavate pit to foundation level

2. Prepare and level the test surface

3. Place steel plate on soil

4. Apply load gradually through hydraulic jack

5. Record settlement using dial gauges

6. Increase load step by step

7. Plot load vs settlement curve

8. Determine safe bearing capacity

Formula

Bearing Pressure (q) = P / A

Where:

P = Applied Load

A = Area of Plate

Example Calculation

Plate Size = 300 mm × 300 mm

Applied Load = 180 kN

Step 1: Area of Plate

A = 0.3 × 0.3 = 0.09 m²

Step 2: Bearing Pressure

q = 180 / 0.09

q = 2000 kN/m²

Interpretation of Result

· Small settlement under high load indicates good soil

· Large settlement under low load indicates weak soil

Advantages

· Direct field method

· Reliable bearing capacity estimation

· Useful for shallow foundations

Limitations

· Expensive and time-consuming

· Applicable mainly for shallow depth

· Results affected by groundwater

Standard Codes

IS 1888 – Method of Load Test on Soils

ASTM D1194

Applications

· Building foundations

· Highway pavements

· Industrial structures

· Bridge foundations