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Effective stress Principle calculator
What is effective stress principle
Effective stress principle was termed by Karl Von Terzaghi in 1936 and is very useful in Geotechnical engineering.
Effective stress is an abstract stress as it cannot be determined in laboratory directly, but it can algebraically be found by 2 determinable quantities which are the total stress and the pore water stress.
\text { Effective stress }(\bar{\sigma})=\text { Total stress }(\sigma)-\text { Pore water pressure }(\mu) \pm \text { Seepage pressure }
Effective stress in soil is affected by the capillary action, surcharge acting, water table and seepage conditions.
The capillary rise of water in soil increases the effective stress in the soil, whereas the water table reduces the effective stress in soil. This is because the saturated density of soil is converted to submerged density.
The surcharge acts constant throughout the depth of the soil and increases the effective stress.
As far as seepage conditions are concerned a downward seepage increases the effective stress whereas an upward seepage decreases the stress.
How to use calculator
Step 1: Select the units for depth and unit weight.
Step 2: Input the thickness of individual layer of soil and its corresponding soil density.
Step 3: If water table is present, enter the depth at which water table exists.
Step 4: If surcharge is present, enter the depth at which surcharge exists and enter its intensity, the units for depth and intensity can be changed according to users preference. For a surcharge on ground depth has to be put 0.
Step 5: For capillary action (if any) enter the depth at which capillary action starts and thickness of capillary layer i.e for how much depth capillary action exists.
Step 6: If seepage condition is present, select the type of seepage from dropdown (upward or downward) and enter the head which is causing seepage.
