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The type of boring, used for making deep excavations is _________
Cylindrical augers
Percussion boring
Rotary boring
Wash boring
Cylindrical augers
Cylindrical augers are specifically used for soil exploration in cohesive soils where deep excavations are required. They operate by screwing into the ground and withdrawing soil samples, making them ideal for stable, deep boreholes.
Cylindrical augers are specifically used for soil exploration in cohesive soils where deep excavations are required. They operate by screwing into the ground and withdrawing soil samples, making them ideal for stable, deep boreholes.
DhтАЛ=kтЛЕN
Where DhтАЛ is the hole depth and N is the number of rotations.
The auger is attached to a drill rod and rotated into the soil. Once the auger is filled with soil, it is lifted to the surface for sample recovery. This cycle is repeated to increase the depth of the excavation, which is particularly effective in stiff clays.
Used primarily in cohesive, stiff, or semi-stiff soils.
Not suitable for cohesionless soils (sands) as the borehole wall collapses without casing.
Efficient for depths up to 20-30 meters in controlled environments.
Provides disturbed soil samples.
Simple equipment setup
High sample recovery in cohesive soils
Cost-effective for shallow to medium-depth exploration
Not suitable for gravelly or very hard rock strata
Borehole stability is an issue in loose sand
Depth limited compared to rotary drilling
Soil sampling for highway subgrade investigations
Building foundation depth analysis
Geotechnical site reconnaissance
Percussion boring (Option B) is typically used for hard rocks or large-diameter wells, not standard soil exploration.
Wash boring (Option D) involves a water jet to soften soil, which can alter the natural properties of the sample, making it less representative than auger-sampled soil.
Rotary boring (Option C) is suitable for much deeper exploration and rock drilling.
A is correct тАФ Cylindrical augers are the preferred tool for making deep excavations in cohesive soil deposits for geotechnical exploration.
Always remember: if the soil is sandy/loose, choose percussion or rotary with drilling mud; if the soil is clayey/stiff, choose cylindrical auger.