Texas Geotechnical Technician License
Practice Exam Questions And Correct
Answers (Verified Answers) Plus
Rationales Q&A | Instant Download Pdf
1. Explain the difference between cohesion and friction in soil
mechanics.
Cohesion refers to the molecular attraction between soil particles,
while friction is the resistance to sliding between particles.
Rationale: Cohesion contributes to shear strength in fine-grained
soils, while frictional resistance is dominant in coarse-grained soils.
2. Describe what a Standard Penetration Test (SPT) measures.
SPT measures soil resistance to penetration by driving a split-barrel
sampler into soil using a standard hammer.
, Rationale: SPT provides an in-situ estimate of relative density,
strength, and stratigraphy of soil.
3. Identify the primary difference between clay and silt.
Clay has smaller particle size and higher plasticity than silt.
Rationale: Clay particles are <0.002 mm and exhibit plastic behavior
when wet, while silt particles are 0.002–0.075 mm and have low
plasticity.
4. Explain the significance of Atterberg Limits in geotechnical
engineering.
Atterberg Limits define the consistency and plasticity of fine-grained
soils.
Rationale: Liquid limit, plastic limit, and plasticity index are used to
classify soils and predict shrink-swell potential.
5. What is the primary purpose of a Proctor Compaction Test?
To determine the optimal moisture content and maximum dry
density of a soil.
Rationale: This information guides field compaction to ensure
stability and prevent settlement.
6. Describe the difference between effective stress and total stress.
Effective stress is the stress carried by the soil skeleton; total stress
includes pore water pressure.
Rationale: Shear strength and settlement depend on effective stress,
not total stress.
,7. Explain why permeability is critical in geotechnical design.
Permeability determines how easily water flows through soil.
Rationale: High permeability soils drain quickly, while low
permeability soils can cause excess pore pressure and instability.
8. What is the function of a piezometer in the field?
A piezometer measures pore water pressure in soil.
Rationale: Monitoring pore pressure helps assess consolidation, slope
stability, and seepage potential.
9. Define consolidation in soil mechanics.
Consolidation is the gradual reduction of soil volume under load due
to water expulsion.
Rationale: Consolidation leads to settlement, particularly in clay
layers, and must be considered in design.
10. Explain the difference between primary and secondary
consolidation.
Primary consolidation is caused by excess pore water pressure
dissipation; secondary is due to creep of soil particles.
Rationale: Primary occurs relatively quickly, secondary occurs over
long periods after primary settlement has finished.
11. Why is grain size distribution important in geotechnical analysis?
It determines soil classification, permeability, and strength.
Rationale: Coarse soils drain quickly but may be unstable if loose;
fine soils retain water and may swell or shrink.
, 12. Describe what a soil classification system achieves.
It categorizes soils based on texture, plasticity, and grain size.
Rationale: Proper classification informs foundation design, drainage
considerations, and compaction requirements.
13. Explain the principle of effective stress in saturated soil.
Effective stress equals total stress minus pore water pressure.
Rationale: Soil strength and deformation depend on the stress
carried by the solid particles, not the water.
14. What is meant by relative density in sands?
Relative density is a measure of the compactness of granular soil.
Rationale: It helps predict settlement, liquefaction potential, and
shear strength.
15. Describe how a vane shear test is conducted.
A vane is inserted into soil and rotated to measure torque required
for failure.
Rationale: Provides undrained shear strength of soft clays in-situ.
16. Explain the difference between active and passive earth
pressure.
Active pressure occurs when soil moves away from a wall; passive
when soil resists wall movement.
Rationale: Design of retaining structures depends on calculating both
pressures correctly.
Practice Exam Questions And Correct
Answers (Verified Answers) Plus
Rationales Q&A | Instant Download Pdf
1. Explain the difference between cohesion and friction in soil
mechanics.
Cohesion refers to the molecular attraction between soil particles,
while friction is the resistance to sliding between particles.
Rationale: Cohesion contributes to shear strength in fine-grained
soils, while frictional resistance is dominant in coarse-grained soils.
2. Describe what a Standard Penetration Test (SPT) measures.
SPT measures soil resistance to penetration by driving a split-barrel
sampler into soil using a standard hammer.
, Rationale: SPT provides an in-situ estimate of relative density,
strength, and stratigraphy of soil.
3. Identify the primary difference between clay and silt.
Clay has smaller particle size and higher plasticity than silt.
Rationale: Clay particles are <0.002 mm and exhibit plastic behavior
when wet, while silt particles are 0.002–0.075 mm and have low
plasticity.
4. Explain the significance of Atterberg Limits in geotechnical
engineering.
Atterberg Limits define the consistency and plasticity of fine-grained
soils.
Rationale: Liquid limit, plastic limit, and plasticity index are used to
classify soils and predict shrink-swell potential.
5. What is the primary purpose of a Proctor Compaction Test?
To determine the optimal moisture content and maximum dry
density of a soil.
Rationale: This information guides field compaction to ensure
stability and prevent settlement.
6. Describe the difference between effective stress and total stress.
Effective stress is the stress carried by the soil skeleton; total stress
includes pore water pressure.
Rationale: Shear strength and settlement depend on effective stress,
not total stress.
,7. Explain why permeability is critical in geotechnical design.
Permeability determines how easily water flows through soil.
Rationale: High permeability soils drain quickly, while low
permeability soils can cause excess pore pressure and instability.
8. What is the function of a piezometer in the field?
A piezometer measures pore water pressure in soil.
Rationale: Monitoring pore pressure helps assess consolidation, slope
stability, and seepage potential.
9. Define consolidation in soil mechanics.
Consolidation is the gradual reduction of soil volume under load due
to water expulsion.
Rationale: Consolidation leads to settlement, particularly in clay
layers, and must be considered in design.
10. Explain the difference between primary and secondary
consolidation.
Primary consolidation is caused by excess pore water pressure
dissipation; secondary is due to creep of soil particles.
Rationale: Primary occurs relatively quickly, secondary occurs over
long periods after primary settlement has finished.
11. Why is grain size distribution important in geotechnical analysis?
It determines soil classification, permeability, and strength.
Rationale: Coarse soils drain quickly but may be unstable if loose;
fine soils retain water and may swell or shrink.
, 12. Describe what a soil classification system achieves.
It categorizes soils based on texture, plasticity, and grain size.
Rationale: Proper classification informs foundation design, drainage
considerations, and compaction requirements.
13. Explain the principle of effective stress in saturated soil.
Effective stress equals total stress minus pore water pressure.
Rationale: Soil strength and deformation depend on the stress
carried by the solid particles, not the water.
14. What is meant by relative density in sands?
Relative density is a measure of the compactness of granular soil.
Rationale: It helps predict settlement, liquefaction potential, and
shear strength.
15. Describe how a vane shear test is conducted.
A vane is inserted into soil and rotated to measure torque required
for failure.
Rationale: Provides undrained shear strength of soft clays in-situ.
16. Explain the difference between active and passive earth
pressure.
Active pressure occurs when soil moves away from a wall; passive
when soil resists wall movement.
Rationale: Design of retaining structures depends on calculating both
pressures correctly.
