Principle and application
Shelby sampling recovers an undisturbed sample of soft to medium soils by pushing a thin-walled tube statically, without hammering. With the natural structure and moisture preserved, the sample represents the ground faithfully and supports laboratory tests such as the triaxial and consolidation tests, which require undisturbed material.
Typical applications: soft soils, embankments, dams, port works and settlement studies.
The sampling in motion
One way to reach the sampling depth is to advance the hole with a hollow-stem auger: the stem stays in the ground and holds the hole open. The Shelby tube is lowered through the stem and pushed just below the auger, recovering an undisturbed sample of soil the drilling never touched.
The test in stages
Static push
The thin-walled tube is pushed by continuous pressure, without hammering, minimising disturbance.
Recovery
The sample is extracted keeping its natural structure and moisture.
Sealing
Both ends are sealed to preserve the moisture until the laboratory.
Careful transport
Packaging that prevents vibration and water loss.
Quality controls: sound, sharp tubes within dimensional standard, controlled static push to reduce disturbance, immediate sealing and sample traceability and chain of custody to the laboratory.
As an undisturbed sample
| Sample | Undisturbed, for special tests |
|---|---|
| Moisture | Preserved from the field condition |
| Structure | Kept for triaxial and consolidation |
| Identification | Traceability by borehole and depth |
| Undisturbed samples | Tubes sealed and labelled by borehole and depth |
| Record | Log with depth and recovery condition |
| Forwarding | Straight to the soil laboratory, when integrated |
| Typical lead time | According to the field campaign |
Performed to the same QA/QC, safety and site standard as every Damasco Penna service, described in Quality and field operations.
Frequently asked questions about Shelby sampling
What is Shelby sampling used for?
Shelby sampling recovers an undisturbed sample of soft to medium soils by pushing a thin-walled tube statically, without hammering. With the natural structure and moisture preserved, the sample represents the ground faithfully and supports laboratory tests such as the triaxial and consolidation tests, which require undisturbed material.
Why does the sample need to be undisturbed?
Tests such as triaxial and consolidation measure the strength and deformability of the soil structure. If the sample is disturbed, the results do not represent the ground, and the design starts from a wrong figure.
Shelby or Denison?
Shelby (thin wall) is ideal for soft to medium soils. In stiffer soils, where the Shelby cannot penetrate without damage, the double-tube Denison sampler is used.
Related services
Shelby sampling for your project
Tell us about your project and we will prepare the investigation plan and the quote.