This paper outlines the development of the NSWS (Nippon Screw Weight System) testing machine. In compliance with the Swedish sounding (SWS) test that determines loading and rotational penetration resistance. The NSWS was developed as an in-situ ground surveying device to detect super soft zones in the ground, including hollows and loosening, in detail, by allowing operation in the 0 to 2500N load range, with very close measurements intervals and penetration speed control, the features of which cannot be achieved by the SWS testing machine. Additionally, findings from an in-situ surveying of in-ground hollows identified using the NSWS testing machine are reported in this paper. The machine achieved a conversion N-value measuring intervals of 2.5cm (or 3.8cm), determination of ranges of hollow and loosening zones through pre-setting of penetration speed, and detection of super soft zones of conversion N-values 1 and below with a load range of 0 to 1000N.
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