This simple and quick field test will give you a rough idea of the carrying capacity of the soil.

Table of Contents

**Process**

- Dig a pit of required depth. (preferably equal to the depth of the foundation)
- Take a solid ball or square cube of known weight and dimension.
- Drop the ball or square cube several times on the bottom surface of the excavated pit from a known height.
- Calculate the average depth of the raid several times over the bottom surface of the excavated pit. Let “d” be the average depth of the impression.

**calculation**

Calculate the ultimate resistance (R) of the soil using the formula given below.

**r = (w * h) / d**

Where,

R = ultimate resistance of soil (in kg)

d = Average depth of impression (in cm)

w = weight of solid ball or square cube (in kg)

h = Height (in cm) of falling of solid ball or cube

If “A” is the cross-sectional area of a solid steel ball or cube, the soil resistance per unit area is calculated using the following formula.

Soil resistance per unit area (in kg/cm)^{2}) = r / a

Safe Bearing Capacity (in kg/cm)^{2}) = R / (A * FOS)

Where,

FOS = Factor of Safety

**notes to remember**

- The FOS varies from 2 to 3 depending on the type of structure and site conditions.
- To get reliable test results, perform this test on a variety of soil types and then use your judgment to reach a conclusion.
- Instead of using solid steel ball or square cube, we can also use CBR test plunger, or cone (used for cone penetration testing)

**presumptive bearing capacity**

The table below shows the estimated bearing capacity values for different soil types. This table will guide you to reach any conclusion after conducting the exam.

soil/rock type |
Safe / Acceptable Bearing Capacity (kg/cm.)^{2}, |

Rock | 32.40 |

soft stone | 4.40 |

coarse sand | 4.40 |

medium sand | 2.45 |

fine sand | 4.40 |

soft shell / hard clay | 1.00 |

soft clay | 1.00 |

very soft clay | 0.50 |

**notes to remember**

- Values for non-adhesive soils should be reduced by 50% if the water level is above or near the base.
- These values should only be used for the initial design. The actual bearing capacity of the soil should be calculated as per the standard code.

**Read also: How to calculate bearing capacity of soil at site using n-value**

**Also read: How To Calculate Soil Bearing Capacity From Plate Load Test**

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