Soil Mechanics Exam Study
Guide – Practice Questions with
Verified Answers. GRADED A+.
Latest 2026/2027 Update
What is an aquifer and the difference between confined and unconfined? -
Answer ✔✔
<<<<<💕💕💕✔✔Layer of soil or rock that stores and transmits water. An
unconfined is when the top is open to the atmosphere (water table is the water
level and recharge occurs through rainfall). A confined aquifer would be one
trapped between two impermeable layers (water is pressurized).
Perched Groundwater Table - Answer ✔✔The water level of a perched aquifer
above an impermeable layer that is above the main aquifer and water table level.
Why do Geotechs care about water? - Answer ✔✔Predict the quantity of flow,
the rate of flow, and the pore water pressure
What is the equation for Terzaghi's Effective Stress? - Answer ✔✔Effective
Stress (σ') = Total Stress (σ) - Pore Water Pressure (uw)
, Total Stress - Answer ✔✔Self weight and external loads. Carried by the skeleton
and pore pressure.
Effective Stress - Answer ✔✔Total stress minus that taken away by pore pressure.
This stress governs engineering behavior (strength, volume change, etc.).
Darcy's Law - Answer ✔✔Volumetric Flow (Q) = Hydraulic Conductivity (k) x
Hydraulic Gradient (i) x Cross-Sectional Area of Flow (A)
What is the hydraulic conductivity (k) of a soil? - Answer ✔✔Measures how easily
water flows through a soil. Depends on soil properties (such as grain size and void
ratio) as well as the fluid properties (viscosity and density). Units of m/s. Sand
(high porosity) has high k value while clay (low porosity) has low k value.
What is the permeability (K) of a soil? - Answer ✔✔"intrinsic permeability" Also
measures how easily water flows through a soil.
Dependent on the pore size, soil structure, and grain arrangement. Units of m².
NOT dependent on the properties of a fluid.
Hydraulic Gradient - Answer ✔✔Total Head Loss (∆h) / Distance Over Which Head
Loss Occured (∆L)
What are the assumptions of Darcy's Law? - Answer ✔✔- Steady state (Qin =
Qout)
- Saturated Soil
Guide – Practice Questions with
Verified Answers. GRADED A+.
Latest 2026/2027 Update
What is an aquifer and the difference between confined and unconfined? -
Answer ✔✔
<<<<<💕💕💕✔✔Layer of soil or rock that stores and transmits water. An
unconfined is when the top is open to the atmosphere (water table is the water
level and recharge occurs through rainfall). A confined aquifer would be one
trapped between two impermeable layers (water is pressurized).
Perched Groundwater Table - Answer ✔✔The water level of a perched aquifer
above an impermeable layer that is above the main aquifer and water table level.
Why do Geotechs care about water? - Answer ✔✔Predict the quantity of flow,
the rate of flow, and the pore water pressure
What is the equation for Terzaghi's Effective Stress? - Answer ✔✔Effective
Stress (σ') = Total Stress (σ) - Pore Water Pressure (uw)
, Total Stress - Answer ✔✔Self weight and external loads. Carried by the skeleton
and pore pressure.
Effective Stress - Answer ✔✔Total stress minus that taken away by pore pressure.
This stress governs engineering behavior (strength, volume change, etc.).
Darcy's Law - Answer ✔✔Volumetric Flow (Q) = Hydraulic Conductivity (k) x
Hydraulic Gradient (i) x Cross-Sectional Area of Flow (A)
What is the hydraulic conductivity (k) of a soil? - Answer ✔✔Measures how easily
water flows through a soil. Depends on soil properties (such as grain size and void
ratio) as well as the fluid properties (viscosity and density). Units of m/s. Sand
(high porosity) has high k value while clay (low porosity) has low k value.
What is the permeability (K) of a soil? - Answer ✔✔"intrinsic permeability" Also
measures how easily water flows through a soil.
Dependent on the pore size, soil structure, and grain arrangement. Units of m².
NOT dependent on the properties of a fluid.
Hydraulic Gradient - Answer ✔✔Total Head Loss (∆h) / Distance Over Which Head
Loss Occured (∆L)
What are the assumptions of Darcy's Law? - Answer ✔✔- Steady state (Qin =
Qout)
- Saturated Soil
