Cone Tip and Sleeve Friction:

ETL 1110-1-171

31 Jan 96

b. Description of Sensors and Associated System

Capabilities:

(1)

Cone Tip and Sleeve Friction:

(a) The cone and sleeve, or penetrometer portion of the

probe, profiles subsurface stratigraphy through soil strength

measurements. The cone tip and sleeve friction sensors are

individual load cells. Computer-based routines use load cell

gauge readings, calibration curves and empirical equations to

determine soil classification in the field. The empirical

equations are based on Olsen (1988). The cone tip sensor

provides a voltage output proportional to the axial force exerted

on the tip of the sensor by the subsurface material. The sleeve

friction sensor, directly above the cone tip, provides an output

proportional to the frictional force applied to the free floating

cylindrical sleeve.

(b) The configuration of the cone and sleeve conforms to

ASTM D-3441-86 Standard Test Method for Deep, Quasi-Static, Cone

and Friction-Cone Penetration Tests of Soil.

(2)

Laser Induced Fluorescence:

(a) Chemists have used the fluorescence method for dozens of

years as one technique to analyze for chemical compounds.

Fluorescence is distinguished from most other analytical methods

because of its extremely high sensitivity. Fluorescence is a

type of luminescence; in general, luminescence occurs when an

electronically excited molecule emits light or electromagnetic

radiation. The phenomenon of fluorescence is characterized by

the light emission event occurring approximately 50 to 250

nanoseconds (1 nanosecond = 10-9 second) after the excitation

event.

(b) Fluorometry frequently uses monochromatic light, that is

light at a single wavelength or one color, to excite a defined

population of molecules. One type of fluorometer provides a

burst or pulse of monochromatic light to the group of molecules

to raise them to an excited state. Once the pulse ends and the

outside energy source is gone, the molecules lose that energy by

a combination of mechanisms. Some energy is lost by molecular

vibration (or heat generation). Energy is also lost through the

release of electromagnetic radiation (sometimes in the form of

visible light). One of the first principles of light is that

shorter wavelength light is more energetic than longer wavelength

light. Since some of the energy of an excited molecule is lost

to vibration, the energy left for fluorescence is less than that

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