GP Sampling

Gel-Push Sampling

Gel-Push (GP) sampler was developed by Kiso-Jiban Consultants in cooperation with Professor Tani, of Graduated School of Engineering, Yokohama National University, to obtain high quality undisturbed soil samples.
One of the major features of this sampling method is that polymer solution of high concentration is used as its drilling fluid for lubricant and not circulated unlike conventional drilling fluid. The polymer solution is coated on a surface of a soil sample, and reduces friction between the sample tube and the sample during the sampling process. The effect of reducing the friction was confirmed during extrusion of the soil sample as well. The relationship of piston thrust pressure and displacement of piston during sample extrusion is shown in Figure-1. Polymer Gel reduces friction during sampling process and soil extrusion and it work to maintain sample in high quality.
The GP sampler can obtain high quality sandy and gravelly soils with fines which was inapplicable to be obtained by freezing sampling method famous for high quality.

Figure-1. Relationship of Piston Thrust Pressure and Displacement of Piston

Figure-2. Sand Sample Obtained by GP Sampler

There are four types of GP sampler, designed for different soil types of obtaining soil samples. The type of GP samplers and the applicable soil type are presented as follows:

Figure-3. Type of GP Sampler

Table-1. Applicable Soil Type of GP Sampler
Sampler TypeApplicable SoilsSample Diameter
GP-R GP-DGRAVEL with fine sand SILT CLAY Fill Material Fractured RockGP-R:100-300mm GP-D 100-200mm
GP-TrHard SILT/CLAY Dense SAND73.5-83.0mm
GP-SSoft SILT/CLAY Loose SAND with fines72.1mm