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.
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:
Table-1. Applicable Soil Type of GP Sampler
|GRAVEL with fine sand SILT CLAY Fill Material Fractured Rock
|GP-R:100-300mm GP-D 100-200mm
|Hard SILT/CLAY Dense SAND
|Soft SILT/CLAY Loose SAND with fines