Geotechnical Engineering: Exploring Soil Sampling Techniques
How do open drive (heavy-wall sampler) and Shelby tube sampler (thin-wall sampler) differ in terms of sample quality and applicable soil type?
Difference in Sample Quality and Applicable Soil Type
Open drive samplers (heavy-wall samplers) are utilized for obtaining undisturbed soil samples in hard or compacted soils, whereas Shelby tube samplers (thin-wall samplers) are employed for collecting relatively undisturbed soil samples in softer soils. The area ratio between the heavy-wall sampler and the thin-wall sampler is approximately 1.25.
Geotechnical engineering involves various soil sampling techniques to gather representative soil samples for testing and analysis. Open drive samplers, also known as heavy-wall samplers, are specifically designed for extracting undisturbed soil samples from hard or compacted soils. These samplers feature a thick wall that enables them to penetrate tough soil layers effectively.
On the other hand, Shelby tube samplers, also referred to as thin-wall samplers, are employed for collecting relatively undisturbed soil samples in softer soils. These samplers have a thinner wall compared to heavy-wall samplers, minimizing disturbance to the soil during the sampling process.
The area ratio between the heavy-wall sampler and the thin-wall sampler is a crucial factor to consider when choosing the appropriate sampling technique for a specific soil type. Calculating the area ratio involves comparing the cross-sectional areas of the two samplers based on their inner diameter and wall thickness.
In this case, the heavy-wall sampler has an inner diameter of 1.5 inches and a wall thickness of 0.15 inches, resulting in a cross-sectional area of approximately 1.767 square inches. On the other hand, the thin-wall sampler also has an inner diameter of 1.5 inches but with a wall thickness of 0.3 inches, leading to a cross-sectional area of about 1.413 square inches. Therefore, the area ratio between the two samplers is approximately 1.25.