Principle and application
Denison sampling recovers undisturbed samples of stiff to hard soils: stiff clays, dense silts and residual soils where the thin-walled Shelby tube cannot penetrate without damage. The sampler is a double-tube core barrel with an inner liner: the outer tube rotates and cuts the soil with a tungsten-carbide shoe, driven by a rotary rig with water injection, while the inner tube remains stationary and protects the core, which enters the liner without rotation and without contact with the fluid.
With the natural structure and moisture preserved, the sample supports laboratory tests such as triaxial, consolidation and shear in materials that would otherwise only be characterised by disturbed samples.
The test in stages
Drilling to the target elevation
The borehole is advanced and cleaned to the sampling depth with a rotary rig.
Shoe adjustment
The projection of the inner tube relative to the bit is adjusted to the soil consistency: further ahead in weaker materials, retracted in hard materials.
Cutting and advance
The outer tube rotates and cuts with water injection; the core enters the stationary inner tube, protected from the fluid and the rotation.
Recovery and sealing
The liner is sealed at both ends, labelled by borehole and depth and transported with cushioning to the laboratory.
As an undisturbed sample
| Sample | Undisturbed, from stiff to hard soils |
|---|---|
| System | Double-tube core barrel with inner liner and tungsten-carbide shoe |
| Advance | Rotation with water injection, by rotary rig |
| References | Sampling quality criteria of ISO-22.475-1 |
Quality and field operation
Data quality
- Sharp shoe with projection adjusted to the sampled material.
- Rotation and injection controlled so the core is not washed.
- Immediate sealing and traceability by borehole and depth.
- Chain of custody to the laboratory.
Site standard
- Qualified for high-compliance areas: mining, industry and ports.
- Organised, signed work front with an HSE procedure in place.
- Own crews and fleet, including night shifts.
The deliverable
| Undisturbed samples | Liners sealed and labelled by borehole and depth |
|---|---|
| Record | Log with depth, recovery and sample condition |
| Forwarding | Straight to the soil laboratory, when integrated |
| Typical lead time | According to the field campaign |
Sectors and project types
Frequently asked questions about the Denison sampler
When to use the Denison sampler?
When the project requires an undisturbed sample and the soil is too stiff or dense for the Shelby tube: stiff clays, dense silts and residual soils. The double-tube barrel cuts the material with a tungsten-carbide shoe while the stationary inner tube protects the core, preserving structure and moisture.
Shelby or Denison?
Shelby (thin wall, static push) is ideal for soft to medium soils. Denison (rotary double-tube barrel) takes over where the Shelby cannot penetrate without damage. The technical team decides based on the soil profile and the intended test.
Does the water injection damage the sample?
No, because the fluid circulates only between the outer and inner tubes. The core enters the stationary inner tube, protected from rotation and washing, and adjusting the shoe projection to the material keeps the cutting ahead of the flushing.
Denison sampling for your project
Tell us about your project and we will prepare the investigation plan and the quote.