Geotechnical probesThe perforation technology used to carry out CPTU surveys is such that, by using special devices, samples can be taken, not only of soils, but also of water and gases.

 

BAT water & gas sampler

This survey allows the extraction of samples of gas and water from the subsoil by insertion of a suction device which functions due to the difference in pressure between the exterior water and the sampler.

It is suitable for use both in soft soils - where the device is introduced into the ground by means of static penetration - and hard soils, where a borehole must be made previous to sampling. The sample container has a 35 ml volume, allowing samples of up to 34.8 ml to be taken.

      

 

Igeotest has developed their own procedures to guarantee both quality and quantity of extracted samples. These procedures are applied throughout the survey, starting with the preparation phase, through the sampling stage and on to sample conservation and transportation to the lab.

 

Advantages

The basic advantage of the test is the possibility of extracting gas samples hermetically at the desired depths while avoiding potential contamination between aquifers due to unwanted connections.

 

Soil sampler: MOSTAP

The MOSTAP sampler is an open sampler which allows the extraction of high quality, undisturbed samples, in both cohesive and granular soils.

The survey procedure is similar to that used for the CPTU test, but the cone has a blind cutting edge which is opened once the test depth is reached and the sampler is inserted in the ground. During the sampling process, a special sleeve eliminates the friction between the sampling tube and the sample. The tubes are available with diameter 35 or 65 mm, and length of 1000, 1500 or 2000 mm.

The 35 mm diameter samples can be used to carry out standard lab tests for identification and state: granulometry, Atterberg limits, humidity, density and chemical analysis. In addition, the 65 mm samples can be used to carry out resistance and compressibility tests.

The MOSTAP-PS sampler is a model which is suitable for working in contaminated soils. It is made of stainless steel to prevent any chemical reaction with the soil. The samples are collected in a bipart or continuous stainless steel tube.

 

Advantages

  • High quality samples
  • No previous bore needed for sample extraction
  • Sealing mechanism prevents sample contamination due to handling
  • Suitable for cohesive and granular soils

 

DELFT continuous soil sampler

As its name suggests, the continuous soil sampler allows the continuous collection of undisturbed samples by static perforation, without the need for pre-boring. This allows the soil structure to be maintained more effectively than in conventional samples.

The Delft sampler is introduced into the ground in a continuous fashion, by the addition of rods. The sampler has a PVC tube and a nylon net which wraps the ground during the survey, thereby protecting the sample. A thick liquid between the nylon and the PVC acts as a lubricant and confines the sample, simulating the horizontal push of the initial soil.

The process is monitored by external control of the perforation parameters. The result is a sample up to 19.0 m in length wrapped in a protective sleeve. On rejection, or once the anticipated depth has been reached, the tubes are removed, exposing the PVC which is cut into 1.0 m lengths. The extremities are protected by plugs and the sample is maintained in an upright position until it reaches the laboratory.

The Delft sampler has a diameter of 66 mm.