A commercial project near Battlefield Boulevard needed deep foundation design for a four-story structure. The design team required undisturbed samples to measure true cohesion and consolidation behavior. Standard split-spoon samples would have disturbed the sensitive silty clay layers found across Chesapeake. Shelby tube sampling became essential. Thin-walled tubes collected intact specimens from depths between 15 and 40 feet. Each tube was carefully extruded and sealed on-site to preserve moisture content. The lab then ran triaxial and one-dimensional consolidation tests. Results directly informed the bearing capacity analysis and settlement predictions. For similar projects, combining Shelby tube extraction with pavimento flexível helps link subgrade behavior to long-term pavement performance. The entire process followed ASTM D1587 protocols to ensure data quality.
Shelby tube samples preserve the in-situ soil structure, allowing engineers to measure real consolidation rates and shear strengths for Chesapeake's coastal plain soils.
Approach and scope
Site-specific factors
Chesapeake experiences high seasonal rainfall and a shallow water table. These conditions make undisturbed sampling more challenging. Boreholes can collapse or swell before the tube reaches the target depth. Drilling mud or casing is often needed to stabilize the hole. If the tube is advanced too fast, the sample may compress or shear internally. The lab must reject any tube with visible cracks or voids. Another risk comes from transportation. Vibrations during transit can remold sensitive clays. Technicians use padded crates and drive slowly on secondary roads. These steps protect sample integrity from field to lab.
Service video
Relevant standards
ASTM D1587-15, ASTM D2487-17, ASTM D2435-11 (consolidation)
Related technical services
Standard Shelby Tube Sampling
Conventional thin-walled tube sampling for cohesive soils. Used when undisturbed strength and consolidation parameters are needed for foundation design. Follows ASTM D1587 with wax sealing and vertical transport.
Piston Sampler Extraction
A fixed-piston sampler for very soft or sensitive clays. Reduces sample disturbance further by preventing soil from entering the tube prematurely. Ideal for Chesapeake's organic marsh deposits and low-plasticity silts.
Typical parameters
FAQ
What is the difference between Shelby tube and split-spoon sampling?
A split-spoon sampler disturbs the soil during driving, providing only blow counts and disturbed material. A Shelby tube uses a thin-walled tube pushed slowly to collect an undisturbed specimen suitable for strength and consolidation tests.
How is sample disturbance minimized in Chesapeake's wet soils?
Operators use drilling mud to stabilize the borehole and prevent water inflow. The tube is advanced at a controlled rate of 1 to 3 ft/min. Samples are sealed with wax immediately and transported in padded crates to avoid vibration damage.
What tests can be performed on undisturbed Shelby tube samples?
Common tests include unconfined compression, triaxial shear (UU, CU, CD), one-dimensional consolidation, and hydraulic conductivity. These tests yield design parameters for settlement, bearing capacity, and slope stability.
How much does undisturbed sampling in Chesapeake typically cost?
The typical range is between US$450 and US$900 per sample, depending on depth, soil conditions, and number of tubes. Volume discounts may apply for multiple boreholes. Contact us for a project-specific quote.