Effective Stress Calculator
Our soil & sediment mechanics calculator computes effective stress accurately. Enter measurements for results with formulas and error analysis.
Formula
sigma_prime = sigma - u (Terzaghi Effective Stress Principle)
This Effective Stress Calculator computes results from your provided inputs using the calculator's underlying model.
Frequently Asked Questions
What is effective stress in soil mechanics?
Effective stress is the stress carried by the soil skeleton (solid particles) at a point, calculated as the total stress minus the pore water pressure. The concept, introduced by Karl Terzaghi, is expressed as sigma_prime = sigma - u, where sigma_prime is effective stress, sigma is total stress, and u is pore water pressure. Effective stress controls virtually all measurable soil behavior including shear strength, compressibility, and volume change. It is considered the most fundamental concept in soil mechanics.
How does the water table affect effective stress?
The water table position directly determines the pore water pressure distribution in the soil profile. Below the water table, pore water pressure increases linearly with depth at a rate equal to the unit weight of water (9.81 kN/m3) times the depth below the water table. Above the water table, pore pressure is typically zero or slightly negative due to capillary suction. When the water table rises, pore pressures increase throughout the profile, reducing effective stresses and consequently reducing the shear strength and bearing capacity of the soil.
Why is effective stress important for foundation design?
Effective stress determines the shear strength and compressibility of soil, which are the two most critical properties for foundation design. Bearing capacity calculations use effective stress to determine how much load a foundation can safely support. Settlement calculations depend on changes in effective stress caused by the foundation load. Seasonal water table fluctuations, construction dewatering, and loading changes all alter the effective stress profile and must be considered in design to ensure adequate safety and performance.
What formula does Effective Stress Calculator use?
The formula used is described in the Formula section on this page. It is based on widely accepted standards in the relevant field. If you need a specific reference or citation, the References section provides links to authoritative sources.
Is my data stored or sent to a server?
No. All calculations run entirely in your browser using JavaScript. No data you enter is ever transmitted to any server or stored anywhere. Your inputs remain completely private.
How accurate are the results from Effective Stress Calculator?
All calculations use established mathematical formulas and are performed with high-precision arithmetic. Results are accurate to the precision shown. For critical decisions in finance, medicine, or engineering, always verify results with a qualified professional.