NCEES PE Civil: Geotechnical MCQs NCEES PE Civil: Geotechnical TestPrep NCEES PE Civil: Geotechnical Study Guide NCEES PE Civil: Geotechnical Practice Test
NCEES PE Civil: Geotechnical Exam Questions
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NCEES - PE Civil Engineering - Geotechnical 2024
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A geotechnical engineer is conducting a groundwater exploration program using a combination of piezometers and observation wells. The groundwater flow direction is determined to be towards a nearby river. If the hydraulic gradient is measured at 0.05 and the hydraulic conductivity of the soil is 10 m/day, what is the estimated seepage velocity of the groundwater in the soil?
0.5 m/day
2 m/day
5 m/day
10 m/day
Explanation: The seepage velocity (v) can be calculated using Darcy's law: v = K ⋅ i, where K is the hydraulic conductivity and i is the hydraulic gradient. Thus, v = 10 m/day ⋅
0.05 = 0.5 m/day.
During a site investigation, a soil sample is retrieved from a depth of 10 m below ground level. The soil is classified as silty
sand (SM) based on the Unified Soil Classification System (USCS). If the sample has a moisture content of 12%, what is the specific gravity of the solids if the dry density of the soil is 18 kN/m³?
1.65
1.70
1.75
1.80
γw
Explanation: The specific gravity (G) can be calculated using the formula G = γd , where γd is the dry density, and γw is the unit weight of water (approximately 9.81 kN/m³). Thus, G =
18 kN/m3 ≈ 1.83
9.81 kN/m3 .
A laboratory consolidation test is performed on a clay sample, and the results indicate an initial void ratio of 1.2. After applying a vertical stress of 100 kPa, the void ratio decreases to
0.9. What is the coefficient of volume change (mv) for this clay
if the applied stress is uniform and the test duration is sufficient for primary consolidation?
A. 0.003
0.02
0.03
0.05
e0 −e
calculated using the formula mv = Δσ
, where e0 is the initial
void ratio, e is the final void ratio, and Δσ is the change in
1.2−0.9
stress. Thus, mv = 100
= 0.003.
A site has been found to have contaminated soil containing heavy metals. During a geotechnical assessment, the engineer decides to perform a series of chemical tests to determine the leachability of the contaminants. Which of the following tests is most effective in assessing the potential for contaminants to migrate through groundwater?
pH test
Toxicity Characteristic Leaching Procedure (TCLP)
Standard Proctor Test
Atterberg Limits Test
(TCLP) is designed specifically to evaluate the leachability of contaminants from soil into groundwater, making it the most relevant test for this scenario.
A geotechnical engineer is evaluating the electrical resistivity of a clay soil to assess its suitability for a buried pipeline installation. If the resistivity of the soil is found to be 50 ohm- m, what can be inferred about the soil's ion concentration and potential for corrosion of the pipeline?
High ion concentration, low corrosion potential
Low ion concentration, high corrosion potential
High ion concentration, high corrosion potential
Low ion concentration, low corrosion potential
In a thermal conductivity test on a saturated sand sample, the thermal conductivity is measured at 1.5 W/m·K. If the temperature gradient across the sample is 10 K over a
thickness of 0.5 m, what is the heat flux through the sample?
10 W/m²
15 W/m²
20 W/m²
30 W/m²
ΔT
law: q = k ⋅ L
, where k is thermal conductivity, ΔT is the
temperature difference, and L is the thickness. Thus, q =
0.5
1.5 ⋅ 10
= 30 W/m2.
During a laboratory test, a soil sample exhibits a plasticity index of 18 and a liquid limit of 40. What is the soil's classification based on the Unified Soil Classification System (USCS)?
CL
CH
ML
MH
(LL), the soil is classified as CL (Clay of Low Plasticity) since it falls within the range for clay with a liquid limit greater than 20 and a plasticity index less than 25.
A geotechnical investigation reveals that a site contains a layer of compacted fill overlying soft clay. The engineer needs to calculate the effective stress at a depth of 5 m below the fill. If the fill has a unit weight of 18 kN/m³ and the water table is at 2 m depth, what is the effective stress at the 5 m depth?
2.30 kPa
5.0 kPa
60.5 kPa
14.0 kPa
Explanation: The effective stress (σ′) can be calculated as σ′ = σ − u, where σ is total stress and u is pore water pressure. Total stress at 5 m is 18 ⋅ 5 = 90 kPa, and pore water pressure at 3 m (5 m - 2 m) is 9.81 ⋅ 3 = 29.43 kPa.
Thus, σ′ = 90 − 29.43 = 60.57 kPa.
In performing a consolidation test, a soil specimen is subjected to a series of loading increments. If the final void ratio after consolidation is 0.5 and the initial void ratio was 1.0, what is the coefficient of consolidation (Cv) if the test duration was 24 hours and the drainage path length was 0.1 m?
0.01 m²/yr
0.1 m²/yr
0.5 m²/yr
1.0 m²/yr
t⋅d2
using Cv = H
, where t is time in seconds, d is drainage path
length, and H is the change in void ratio. Thus, converting 24
hours to seconds and substituting gives Cv ≈ 0.5 m2/yr.
A soil sample has a moisture content of 15% and a specific gravity of solids of 2.68. If the sample's bulk density is measured at 19 kN/m³, what is the degree of saturation of the soil?
30%
40%
50%
60%
w⋅G
using the equation S = γw
, where w is moisture content, G
is specific gravity, and γw is the unit weight of water. Thus,
9.81
S = 0.15⋅2.68 ≈ 0.41 or 41%.
A geotechnical engineer is evaluating the thermal response of a subsurface environment due to a newly proposed geothermal heating system. If the ground temperature at a depth of 5 m is measured at 15°C and the rate of increase is 2°C per 100 m depth, what would be the expected ground temperature at 20 m depth?
17°C
19°C
20°C
22°C
d
calculated as T = T0 + ( 100
rate of increase), where T0
is the temperature at 5 m, d is the depth (15 m additional), and the rate of increase is 2°C per 100 m. Thus, T = 15 + (15/100 ⋅ 2) = 19°C.
A soil layer is identified as a well-graded gravel (GW) with a high degree of angularity. How would this angularity affect the soil's shear strength parameters compared to a rounded gravel of the same grading?
Higher cohesion and lower friction angle
Lower cohesion and higher friction angle
Higher cohesion and higher friction angle
Lower cohesion and lower friction angle
THIS IS SAMPLE FILE, FULL VERSION CONTAINS COMPLETE SET OF QUESTIONS
While utilizing the split-barrel sampling method, an engineer notices that the sample retrieved is excessively compacted. What could be a likely cause of this phenomenon?
Insufficient hammer weight
Incorrect borehole size
Poor soil cohesion
Excessive drilling speed
Answer: D
Explanation: Excessive drilling speed can lead to over- compaction of the soil sample during the split-barrel sampling process. This can alter the sample's characteristics and affect the interpretation of results.
What is the primary advantage of using helical screw piles in areas with limited access and where noise pollution must be minimized during installation?
Their ability to transfer load immediately
The low noise and vibration levels during installation
The speed of installation
Their environmental footprint
Answer: B
Explanation: Helical screw piles are installed with minimal noise and vibration, making them ideal for locations where access is constrained and noise pollution is a concern, while also providing immediate load capacity.
While analyzing data from an inclinometer in a landslide-prone area, you observe sudden and unusual lateral movements. What is the most immediate course of action to take?
Increase monitoring frequency and wait for further data
Implement a slope stabilization plan without delay
Conduct a detailed geological survey of the site
Notify the local authorities and evacuate the area
Answer: D
Explanation: Notifying local authorities and evacuating the area is critical in response to sudden and unusual lateral movements, as this may indicate an imminent landslide or significant risk to public safety.
During the field operation of split-barrel sampling, which aspect is crucial to ensure that the sampler is vertical and achieves accurate penetration?
Manual adjustments by personnel
Using a plumb line
Calibrating the hammer weight
Pre-drilling the sampling location
Answer: B
Explanation: Using a plumb line ensures that the sampler is vertical, which is crucial for accurate penetration and reliable sample retrieval.
A construction project requires the use of auger cast piles in an area with significant groundwater fluctuations. What is the most critical design consideration to mitigate potential issues related to these fluctuations?
Selecting a more robust pile material
Designing for buoyancy effects
Increasing the pile diameter
Implementing a deep excavation strategy
Answer: B
Explanation: Designing for buoyancy effects is crucial in areas with fluctuating groundwater levels, as it ensures that the piles remain stable and do not experience uplift forces due to changes in water levels.
In a construction project involving the use of piezometers, a reading shows an unexpected drop in pore water pressure after installation. What is the most likely explanation for this observation?
The piezometer was installed incorrectly
There has been an increase in soil suction
The water table has lowered due to nearby dewatering activities
The surrounding soil has consolidated significantly
Answer: C
Explanation: A drop in pore water pressure is likely due to a lowering of the water table, which can occur as a result of nearby dewatering activities, affecting the readings from the piezometer.
A geotechnical investigation indicates that a site has a shallow groundwater table and loose sands. What is the most critical consideration when selecting an exploration technique?
The method's ability to handle saturated conditions
The potential for soil liquefaction
The depth of exploration required
The need for geophysical surveys
Explanation: The exploration technique must effectively manage saturated conditions to prevent issues like collapse or inaccurate sampling, especially in loose sands.
A rock mass with a Rock Mass Rating (RMR) of 40 is encountered during a tunneling project. The RMR indicates which of the following about the rock mass?
Favorable conditions for tunneling
Poor rock conditions requiring careful excavation
Excellent conditions for construction
No need for support systems
Answer: B
Explanation: An RMR of 40 indicates poor rock conditions, suggesting that careful excavation techniques and potential support systems will be necessary.
During a construction project in a seismic zone, the engineer decides to use aggregate piers to improve ground conditions. Which of the following is a critical design factor to consider regarding the performance of the aggregate piers?
The color of the aggregate
The density of the surrounding soil
The moisture content during installation
The spacing between piers and their depth
Answer: D
Explanation: The spacing and depth of aggregate piers are critical design factors influencing their ability to transfer loads effectively and enhance overall stability during seismic events.
In a planning study for a new commercial development, the engineer encounters a report indicating a nearby landslide history. What is the most critical factor to consider when evaluating the site for construction?
The soil type in the area
The proximity to urban infrastructure
The local flora and fauna
Answer: A
Explanation: Slope stability and drainage conditions are vital to prevent future landslides, especially in areas with a history of such events.
During the design of a cofferdam, engineers must assess potential environmental impacts. Which of the following impacts is most critical to evaluate in the context of aquatic ecosystems?
Visual obstruction to boat traffic
Increased noise levels during construction
Changes in sediment transport patterns
Soil compaction in adjacent areas
Answer: C
Explanation: Changes in sediment transport patterns can significantly affect aquatic ecosystems, making it critical to
assess this impact during the cofferdam design process.
During a fill placement operation, the engineer discovers that the underlying subgrade has a high plasticity index. What is the most effective strategy to ensure stability during compaction of the fill?
Allow for natural drainage of the subgrade
Compact the fill aggressively
Stabilize the subgrade with lime or cement
Increase the fill material moisture content
Answer: C
Explanation: Stabilizing the subgrade with lime or cement enhances its load-bearing capacity, reducing the risk of instability during the compaction of the fill material.
In a vane shear test conducted in a soft clay layer, the results
show a shear strength that is significantly lower than expected based on previous studies. What should the engineer's next step be?
Rely on conservative design values
Investigate the possibility of soil improvement techniques
Reassess the project scope to avoid the area
Conduct additional tests to confirm the results
Answer: D
Explanation: Conducting additional tests is essential to verify the results and ensure accurate design decisions are made based on reliable data.
In a soil sampling program aimed at characterizing a saturated clay layer, which aspect of handling and storage is most crucial to preserving the integrity of the samples prior to laboratory testing?
Storing samples in ambient air conditions
Keeping samples submerged in water
Sealing samples in airtight containers
Placing samples in a frost-free environment
Answer: C
Explanation: Sealing samples in airtight containers is crucial to prevent moisture loss and contamination. This practice helps maintain the original water content and soil structure, which are essential for accurate laboratory testing.
A geotechnical engineer is tasked with assessing the risk of frost heave in a newly constructed roadway. The soil profile shows a mix of clay and silt. What immediate action should be taken to evaluate frost susceptibility?
Conduct a visual inspection
Perform a frost susceptibility test
Assume all soils are frost-susceptible
Implement a rapid construction schedule
Answer: B
Explanation: Performing a frost susceptibility test provides quantitative data on the soil's behavior under freezing
conditions, allowing for informed decisions regarding design and construction practices to mitigate frost heave risks.
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