What is the primary advantage of a stationary piston sampler?

It allows for the collection of high-quality, undisturbed samples by preventing overlying disturbed material from entering the tube and helping to retain the sample during withdrawal (Clause 4.3).

What is the significance of the Area Ratio (Ar)?

A low Area Ratio (preferably <10%) is essential to minimize soil displacement and disturbance as the sampler is pushed into the ground (Clause 3.2.1).

Can this sampler be hammered into the ground?

No, the sampler should be advanced by a continuous and rapid push, not by driving or hammering, to ensure the quality of the sample (Clause 4.3.4).

For which soil types is this sampling method most suitable?

It is most suitable for sampling soft to firm cohesive soils like clays and silts which are sensitive to disturbance (Clause 1.1).

IS 10108

: 1982

Code of practice for a sampling of soils by thin wall sampler with stationary piston

CurrentSpecializedCode of PracticeBIMGeotechnical · Soil and Foundation Engineering

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This standard outlines the procedure for obtaining high-quality, undisturbed soil samples, particularly from soft to firm cohesive soils, using a thin-wall tube sampler with a stationary piston. It specifies the equipment requirements, operational procedure, and methods for sealing, handling, and reporting the collected samples for geotechnical laboratory testing.

Code of practice for a sampling of soils by thin wall sampler with stationary piston

Quick Reference Values

Recommended Area Ratio (Ar)< 10%

Recommended Inside Clearance Ratio (Ci)0.5 to 1.5%

Typical Length to Diameter Ratio (L/D)10 to 20

Minimum Piston Travel5 to 10 cm

Sample tube wall thickness1.25 to 1.65 mm for 50mm samplers

Key Formulas

Area Ratio Ar = [(Dw^2 - De^2) / De^2] * 100

Inside Clearance Ratio Ci = [(Ds - De) / De] * 100

Practical Notes

This method is crucial for obtaining samples for consolidation and shear strength tests, as it minimizes sample disturbance.

It is not suitable for hard, cemented, or gravelly soils where the thin-walled tube could be damaged.

The stationary piston prevents loose or disturbed material from entering the tube before sampling starts and helps retain the sample during withdrawal by creating a vacuum.