Test No. 109 - "Koolau Basalt Load Tests"
(Part 2)

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June 14, 1977
Stewart Ct. Laboratory
Sunnyvale, CA

Copyrighted © by The Townsend Brown family. All rights reserved.


To observe the effects of forced polarization (increased self-potential) upon load carrying capability.


Normally, the self-potential of the Koolau rock is in the range from 300 to 500 mV. In this test, a higher voltage (700 mV) was obtained by forced polarization (30 minute charging by a 9 V battery). The polarizing circuit was then disconnected and the rock's emf was allowed to decay to a relatively stable bottom at approx. 700 mV.

Load tests were performed by 5-second shunting with resistors of progressively lower, then higher, values, as in Test No. 108.


Shown in the attached curve. Slight depolarization and loss of charge (during the 6-hour run) resulted in a 30 mV downward displacement between the beginning and ending of the test. Otherwise the curve has the same characteristics as that obtained at the lower (normal) voltage.

Graphic - Figure 2


Load-carrying characteristics are unaffected by output voltage.

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