Principle and application
Sampling varies with the analytical objectives, the soil type and the depth. Drilling opens the borehole to the target elevation, and sampling recovers the portion of soil to be tested. Undisturbed samples preserve the structure, moisture and void ratio of the soil in the field, allowing representative strength, compressibility and compaction tests.
From drilling to the sample
Drilling to the target elevation
The borehole is advanced to the target elevation by hollow-stem augers and driving, or by rotary rig with water injection.
Choice of sampler
The technical team selects the sampler according to soil consistency, depth and the intended test.
Sample recovery
The undisturbed sample is recovered while preserving structure, moisture and void ratio. In less cohesive soils, the stationary piston improves recovery.
Handling and storage
Samples are sealed and labelled by borehole and depth for shipment to the laboratory.
Shelby, Denison and continuous cut
| Shelby | Undisturbed samples of fine soils (clays and clayey silts), in accordance with NBR 9820 and ASTM D1587, with drilling by hollow-stem augers and inner rods. In less cohesive soils, the stationary piston improves recovery. |
|---|---|
| Denison | Undisturbed samples of stiff, dense soils, with a triple-tube core barrel and a tungsten-carbide cutting shoe, driven by rotary rig with water injection. |
| Continuous cut | Sampler developed by Damasco Penna for compacted fills, with recovery in inner tubes and determination of the degree of compaction in deep layers. |
| Block | Undisturbed samples of the highest quality, hand-carved in inspection pits or trenches in accordance with NBR 9604, with structure, moisture and orientation preserved. |
Which sampler for which soil?
| Soft to medium soils | Shelby sampling: thin-walled tube statically pushed, without blows. The reference for soft clays and for consolidation and triaxial tests. |
|---|---|
| Stiff to hard soils | Denison sampler: rotary double-tube core barrel with a tungsten-carbide shoe, where the thin-walled tube cannot penetrate. |
| Highest quality | Block sampling: hand-carved in an inspection pit (NBR 9604). The least possible disturbance, limited by the depth of the pit. |
| Continuous profile | Continuous soil sampler: 101.6 mm liners every 1.40 m inside hollow-stem augers, dry. The stratigraphy with no gaps, including the degree of compaction of fills. |
The technical team defines the combination for each campaign: the same borehole can bring together the continuous description of the profile and the premium sampling points the laboratory requires.
Quality and field operation
Data quality
- Sampling in accordance with NBR 9820 and ASTM D1587 for Shelby sampling.
- Samples labelled by borehole and depth, with technical documentation of the recovery.
- Sampler selected by the technical team according to soil, depth and test.
- Associated laboratory tests: Mini-Proctor, hydrostatic balance and natural moisture content.
Site standard
- Manual recovery or with hydraulic drill rigs, according to the campaign.
- Organised, signed work front with an HSE procedure in place.
- Focus on the well-being of the field crew, including night shifts.
- One native seedling planted per service, our One Tree programme.
The deliverable
| Undisturbed samples | Sealed and labelled by borehole and depth |
|---|---|
| Associated tests | Mini-Proctor, hydrostatic balance and natural moisture content |
| Degree of compaction | Determination in fills, including in deep layers |
| Documentation | Technical record of the recovery in accordance with the applicable standards |
Technical summary
| Standards | ABNT NBR 9820 and ASTM D1587 (Shelby) |
|---|---|
| Samplers | Shelby, Denison (triple-tube core barrel) and in-house continuous cut |
| Method | Hollow-stem augers and driving, or rotary rig with water injection |
| Application | Clays and silts, stiff soils, compacted fills |
| Laboratory | Mini-Proctor, hydrostatic balance and natural moisture content |
Frequently asked questions about the Drilling and sampling
What is soil drilling and sampling used for?
Sampling varies with the analytical objectives, the soil type and the depth. Drilling opens the borehole to the target elevation, and sampling recovers the portion of soil to be tested. Undisturbed samples preserve the structure, moisture and void ratio of the soil in the field, allowing representative strength, compressibility and compaction tests.
What is the difference between a disturbed and an undisturbed sample?
The undisturbed sample preserves the structure, moisture and void ratio of the soil in the field. This allows representative strength, compressibility and compaction tests, unlike the disturbed sample, which loses its original structure.
When to use Shelby, Denison or continuous cut?
The choice depends on soil consistency, depth and the intended test. Soft soils call for Shelby or the piston, stiff soils call for Denison, and control of compacted fills is done with the continuous-cut sampler. The technical team defines the right combination for each campaign.
What is the continuous-cut sampler?
It is a sampler developed by Damasco Penna for compacted fills. Recovery is carried out in inner tubes and allows the degree of compaction to be determined in deep layers.
Bulletin 01: the Shelby sampler in competent soils
How to achieve recovery and representativeness of the undisturbed sample in fine soils, with drilling by hollow-stem augers and a stationary piston.
Undisturbed sampling for your project
Tell us about your project. Our technical team defines the combination of samplers and prepares the quote.