Dynamic Cone Penetration Testing (CPT)
Introduction
Dynamic penetration tests with continuous recording are a type of dynamic penetrameters, used in the characterization of a geotechnical reconnaissance of a terrain.
Of the dynamic penetrometers, except for the standard penetration test or SPT, (which is a type of penetrometer that is carried out exclusively inside a borehole and during its execution), the rest, (DPSH, DPH, Borros and CPT), are considered continuous penetrameters, since they provide a continuous measurement of the resistance to penetration, from the surface to the maximum depth to be reached with the test, or until rejection of driving is obtained.
They consist of driving an element with a generally conical tip into the ground, from its surface to the desired depth or until rejection is reached, measuring the energy necessary to deepen intervals of defined length, this energy being the number of impacts of a club that is raised to a certain height and allowed to fall freely.
Unlike the well-known and widespread SPT test, which usually provides rather discreet information and at widely spaced intervals, the CPT, DPSH, DPH, Borros are capable of providing more reliable information and at intervals as small as 20mm, which allows establishing precise profiles and evidencing small changes that may occur between soil strata.
The Cone Penetration Test, known as CPT, is a versatile, fast and precise method, used to determine soil properties but which, through additions, is capable of measuring groundwater pressure, as well as other parameters of interest in the area of Geotechnics. It is also known as a piezocone test, CPTU, SCPT or SCPTU, depending on whether it can measure pore pressures or includes a seismic module.
Types of dynamic penetration tests with continuous recording
There is a wide variety of dynamic penetrometers, differing in the shape and dimensions of the penetration tool, the value of the penetration interval or length, the weight of the hammer, and the free fall height.
In Spain, the dynamic continuous recording penetrometers are the DPSH and the DPH.
The Borros penetrometer, despite not being standardized, has always been widely used.