How to Calculate Bearing capacity of the Soil : Safe and Ultimate bearing capacity of soil

Bearing Capacity

Bearing capacity of the soil is the capacity of the soil to support the loads applied to the ground. The bearing capacity of the soil is the maximum average contact pressure between the foundation and the soil which should not produce shear failure in the soil.

From this article you will know how to calculate the bearing capacity of the soil within 5 minutes. If you are planning to build any house then you should know this procedure to calculate the bearing capacity of the soil so you can make house on that site. This question is generally asked in the interviews as well. So here is the blog that how can you check the bearing capacity of the soil.

Procedure to calculate bearing capacity of soil

1.      1. Excavate a pit of required depth

2.      2. Take a iron cube or concrete cube or any iron ball (whose dimension and weight is known)

3.      3. Drop the cube or ball several times from the known height of the excavated pit.

4.      4. Calculate the average depth of impression

Take average value of Depth

Formula for calculating Bearing Calculating Bearing Capacity of Soil (Sand):

UR (Bearing Capacity):

R = (W*H)/d

Where

R= Ultimate Resistance of Soil (kg)

d= Average depth of impression (cm)

W= Weight if solid ball or square cube (in kg)

h= Height of fall of cube (the known height from where the ball or cube was dropped)

So this is the formula for calculation of Bearing Capacity of the Soil and this process involves finding the Ultimate bearing capacity of the soil and this is the last bearing capacity of the soil but we have to find the safe bearing capacity for the proper safety so after finding the Resistance we will convert it into Safe Bearing Capacity.

For Example, Here is the solved numerical to find the bearing capacity of the soil:

Weight of Cube : 5 KG

Height of fall : 150cm

Depth Impression : 8cm+8.9cm+5cm+6cm (this measurement is taken by dropping the ball or cube several times)

Depth Impression Average: (8+8.9+5+6)cm/4 = 6.975 cm

Then,

R = (W*H)/d

    =  (5*150)/6.975

    = 107.5 kg

Then, Resistance of Soil per unit Area : R/A = 107.5/(15*15) = 0.47 kg/cm²

So this is the Ultimate Bearing Capacity but now we will find the safe bearing capacity of  the soil which will make it more safer so that if later on the load increases double then the safe building capacity then also it doesn’t matter and it will be safer.

So the Safe Bearing Capacity = R/A*F_oS

Where,

R = Ultimate Bearing Capacity of soil

A= Area

F_oS = Safety Factor ( It varies From 2 to 3) You should take the value between two to three to find the Safe bearing capacity of the soil

So we will solve it;

So the Safe Bearing Capacity = R/A*F_oS

                                                                       = 107.5/225*2

                                                      = 0.23 kg/cm²

 This is how you can find the safe bearing capacity of the soil.