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PIEZOCONE TESTS (CPTU)

Publicado em 24/12/2016

PIEZOCONE TESTS (CPTU)
 

CPT-u (Cone Penetration Testing) is an in-situ test used to obtain data on several soil aspects. Well known worldwide as one of the most traditional and precise geotechnical investigation tool, it enables determining foundation dimensions and estimating settlement rates, among other operations.

While the cone is being driven down, its sensors make three readings at each centimeter:

  • Tip resistance (qc)
  • Sleeve friction (fs) (fs)
  • Pore pressure (u2))

The information is transmitted to the surface in real time and processed by computer.

Excess pore water pressure are read by means of a porous element situated at the base of the cone and saturated with silicone oil by vacuum pump. When needed, it is also possible to perform pore pressure dissipation testing during the test.

In addition to the data read in real time during the test (qc, fs and u2), the following properties can also be obtained through correlations:

  • Stratigraphy;
  • Geotechnical profile (Soil behavior);
  • Consolidation coefficient (Ch and Cv);
  • Relative density (Dr);
  • Undrained shear strenght (Su);
  • Effective friction angle of sands (Ø);
  • Stress history (preconsolidation stress, OCR);
  • Permeability coefficient (K).

ensaio-cptu
Piezocone equipment


Saturation vacuum pump




 

See also posts about Piezocone Tests:
 
Dissipation Tests
 
Nearshore tests