Realizing that American engineers rely heavily upon test boring SPT N-values for the strength of subsoils, we correlated the dynamic cone resistances of our Wildcat dynamic cone penetrometer with test boring SPT N-values in sands, silts, and clays. To do this, we Wildcat tested locations adjacent to test borings, examined and tested the borings' soil samples for grain size, calculated the dynamic cone resistances at sample elevations, and compared the borings' N-values with the Wildcat's dynamic cone resistances.

The data of our study showed that the Wildcat dynamic cone penetrometer has a  Q _d /N ratio of approximately 3.5, in sands, silts, and clays, for dynamic cone resistances up to 90 Kg/cm ^2. . For dynamic cone resistances above 90 Kg/cm ² , the correlation breaks down so that we only know that the N-value exceeds 25.

As a result of this study, we incorporated an N ^/ column into our logging software, which lists the correlation-derived SPT N-value of every 4 inch depth of tested soil. Where dynamic cone resistances exceed 90 Kg/cm ² (and N ^/ would be some unknown quantity above 25) our logging program prints a 25+ in the N ^/ column.

NOW A COMPLETED WILDCAT HOLE HAS FURTHER GOOD USE AS A GROUND WATER MONITOR WELL & AS A SLOPE INDICATOR

After the lost point has been driven to its final depth, we pull the rods, with help from the post-popper, leaving a 1.35" diameter partially slurry-filled hole with a lost point embedded in its bottom.

Buildiing material stores sell  3/4" diameter pvc pipe and fittings for water lines.  I buy 10' lengths of 3/4" pvc, drill 1/8" holes in it every 4", and insert these pipes into holes with a closer pvc on the bottom and pvc external couplings to splice pipes.  A closer also gets placed on the top at the end.

The slurry inside and outside the pvc quickly turns to non-viscous water if you add a little Clorox bleach, and the water level within the pvc then follows the water level of the ground.  A fiberglass tape, with a 10" long piece of 3/4" threaded rod hanging from it, can be lowered into the pvc, becoming wet at the ground water level.

And if a slide plane later intersects the pvc, the 10" long piece of 3/4" threaded rod will not fall beneath the bent pvc's slide level.

So, when you do this, you have created and used a water level measurer, and a "poor man's" inclinometer, rapidly and economically.

CORRELATIONS OF WILDCAT DYNAMIC CONE RESISTANCES WITH CBR