Soil Mechanics Final Exam with
Complete Solutions
TF: The fundamental property of clay soil that is the basis for its undrained shear strength is
actually apparent friction Correct Ans-False. Cohesion
In the equation for clayey sand soil, which part applied for the clay component of the soil?
Correct Ans-Capp
TF: In a C-U triaxial test, the Su of an over-consolidated clay will only increase when the effective
confining pressure is raised to a pressure greater than the maximum effective vertical stress that
existed in the ground when the sample was retrieved by using the Shelby tube sampler during
subsurface exploration Correct Ans-True
If the unconfined compressive strength of a clay sample is 1800 psf, what will be the cohesion of
the clay when it is tested in unconfined compression? Correct Ans-900 psf
TF: The diameter of the Mohr's circle graph from a triaxail test represents the deviator stress,
and equals to the maximum shear strength of the clay, regardless of the internal pore water
pressure Correct Ans-False. The maximum shear strength equals to its radius
Briefly explain the fundamental reason that causes there to eventually be an increase of shear
strength of a normally consolidated clay soil which is below a newly constructed embankment,
the increase happening slowly with time after the embankment is constructed Correct Ans-
,The water leaves the clay at a slow rate so the shear strength will increase when the pore water
pressure decreases
TF: The initial indrained shear strength of stiff clay soil below the bottom of a deep excavation is
much greater than the drained shear strength that will develop after many months of unloaded
condition caused by excavation Correct Ans-True
TF: If in a C-U triaxail test on stiff clay, confining pressure = 10 psi, and the axial stress = 30 psi,
and the pore water pressure = 5 psi at failure, then the deviator stress at failure was 25 psi
Correct Ans-False
What range of theta values is usually found in Montmorillonite clay? Correct Ans-5-6
What town in Norway suffered a major quick clay landslide in 1978? Correct Ans-Rissa
Write Darcy's equation, that is used to calculate the quantity of groundwater flow? Correct
Ans-Q = KiA
Name of the groundwater stratum overlain by a clay layer and under pressure Correct Ans-
Artesian
Name of the zone of soil above the GWT Correct Ans-Vadose
, Another name for the GWT Correct Ans-Phreatic surface
Name of the soil stratum through which groundwater will not flow freely Correct Ans-
Aquiclude
Explain why the permeability of clay soil is so slow and seemingly not affected by the total
volume of voids in the soil, even though clay has 2 to 5 times the voids of sand Correct Ans-
Clay's voids are very small so water can't pass though very quickly and water adhesives to clay
due to the diffuse double layer
What soil type causes the greatest problem with capillary rise and subsequent frost heave when
a road's subgrade soils are subjected to winter freezing ? Correct Ans-Silt
TF: The in-field pumping test is the best way to determine the overall permeability of the overall
soil deposit Correct Ans-True
What are the names of the two different types of equipment that may be installed to in
completed boreholes to determine groundwater level or pressure in a soil deposit Correct
Ans-Observation well and piezometer
What is the symbol used to indicate the hydraulic gradient? Correct Ans-i
What is the equation used to determine the hydraulic gradient? Correct Ans-i = delta(h)/L
Complete Solutions
TF: The fundamental property of clay soil that is the basis for its undrained shear strength is
actually apparent friction Correct Ans-False. Cohesion
In the equation for clayey sand soil, which part applied for the clay component of the soil?
Correct Ans-Capp
TF: In a C-U triaxial test, the Su of an over-consolidated clay will only increase when the effective
confining pressure is raised to a pressure greater than the maximum effective vertical stress that
existed in the ground when the sample was retrieved by using the Shelby tube sampler during
subsurface exploration Correct Ans-True
If the unconfined compressive strength of a clay sample is 1800 psf, what will be the cohesion of
the clay when it is tested in unconfined compression? Correct Ans-900 psf
TF: The diameter of the Mohr's circle graph from a triaxail test represents the deviator stress,
and equals to the maximum shear strength of the clay, regardless of the internal pore water
pressure Correct Ans-False. The maximum shear strength equals to its radius
Briefly explain the fundamental reason that causes there to eventually be an increase of shear
strength of a normally consolidated clay soil which is below a newly constructed embankment,
the increase happening slowly with time after the embankment is constructed Correct Ans-
,The water leaves the clay at a slow rate so the shear strength will increase when the pore water
pressure decreases
TF: The initial indrained shear strength of stiff clay soil below the bottom of a deep excavation is
much greater than the drained shear strength that will develop after many months of unloaded
condition caused by excavation Correct Ans-True
TF: If in a C-U triaxail test on stiff clay, confining pressure = 10 psi, and the axial stress = 30 psi,
and the pore water pressure = 5 psi at failure, then the deviator stress at failure was 25 psi
Correct Ans-False
What range of theta values is usually found in Montmorillonite clay? Correct Ans-5-6
What town in Norway suffered a major quick clay landslide in 1978? Correct Ans-Rissa
Write Darcy's equation, that is used to calculate the quantity of groundwater flow? Correct
Ans-Q = KiA
Name of the groundwater stratum overlain by a clay layer and under pressure Correct Ans-
Artesian
Name of the zone of soil above the GWT Correct Ans-Vadose
, Another name for the GWT Correct Ans-Phreatic surface
Name of the soil stratum through which groundwater will not flow freely Correct Ans-
Aquiclude
Explain why the permeability of clay soil is so slow and seemingly not affected by the total
volume of voids in the soil, even though clay has 2 to 5 times the voids of sand Correct Ans-
Clay's voids are very small so water can't pass though very quickly and water adhesives to clay
due to the diffuse double layer
What soil type causes the greatest problem with capillary rise and subsequent frost heave when
a road's subgrade soils are subjected to winter freezing ? Correct Ans-Silt
TF: The in-field pumping test is the best way to determine the overall permeability of the overall
soil deposit Correct Ans-True
What are the names of the two different types of equipment that may be installed to in
completed boreholes to determine groundwater level or pressure in a soil deposit Correct
Ans-Observation well and piezometer
What is the symbol used to indicate the hydraulic gradient? Correct Ans-i
What is the equation used to determine the hydraulic gradient? Correct Ans-i = delta(h)/L
