**BEARING CAPACITY OF SOIL **
**PROCEDURE**
- Excavate a pit of required depth. (preferably equal to the depth of foundation)
- Take a solid ball or square cube of known weight and dimension.
- Drop the ball or square cube several times, from a known height on to the bottom surface of excavated pit.
- Calculate the average depth of impression made several times on the bottom surface of the excavated pit. Let “d” is the average depth of impression.

**CALCULATION**
Calculate the ultimate resistance of soil ( R ) 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 the solid ball or square cube (in kg)

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

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

Resistance of soil per unit area (in kg/cm2) = R / A

Safe bearing capacity (in kg/cm2) = R / (A * F.O.S)

Where,

F.O.S = Factor of safety

**NOTES TO REMEMBER**
- F.O.S varies from 2 to 3 depending upon the type of structure and site condition.
- In order to get reliable test result, perform this test on different types of soil and then use your judgment to reach at any conclusion.
- Instead of using solid steel ball or square cube, we can also use CBR test plunger, or Cone (used for cone penetration test)

**PRESUMPTIVE BEARING CAPACITY**
The table given below shows the presumptive bearing capacity values for different types of soils. This table will guide you to reach at any conclusion after conducting the test.

**Type of Soil / Rock** | **Safe / Allowable Bearing Capacity (kg/cm2)** |

Rock | 32.40 |

Soft rock | 4.40 |

Coarse sand | 4.40 |

Medium sand | 2.45 |

Fine sand | 4.40 |

Soft shell / Stiff clay | 1.00 |

Soft clay | 1.00 |

Very soft clay | 0.50 |