Nippon Screw Weight System

In the year of 2012 the NARO[1] announced an on-site ground survey machine, the Nippon Screw Weight System (NSWS),[2] designed to overcome problems with the standard penetration test;[3] The NSWS was developed with the specific aim to encounter the recent weather abnormalities and natural hazard, saving human lives.[4] The creator of NSWS, Kozo Okita, was the member of 311 earthquake disaster committee [5] of the Japanese Geotechnical Society.[6] The society released a report in June, 2012 proposing to Japanese government a use of NSWS to investigate the 3.11 aftermath.[7]

It is compact, weighs 120 kg,[8] and highly-mobile because the wheels are attached, suited to measure the ground in the crowded residential areas.[9] It costs about only half of what used to cost with the conventional SPT test and triaxial compression test.[10] The NARO has released the cost index table.[11]

Features for detecting weak spots:

  1. it can measure very soft zones, converted N-value of zero in the ground that had been considered difficult.
  2. It has 1.08 cm interval, far finer than SPT
  3. SPT conducts the test every 50 cm, and 30 cm interval out of 50 cm is tested so the rest, 20 cm, is not measured; that means 40% of an entire hole is unknown. NSWS does not suffer from such a limitation.
  4. NSWS can penetrate the ground diagonally.
  5. NSWS can cut soft gravels.

Features for conducting in-situ shear test and sampling at a different hole:

  1. In-situ shear test capability, the result of the joint research with NARO[12] and Okita-Ko Co.,Ltd[13][14]

Features for conducting Stability Analysis:

  1. NSWS can prepare converted N-value, density, in-situ shear data for Stability Analysis.
  2. Since NSWS enables multi-point surveying due to its diagonal penetration capability and high-mobility. The multiple spots on the weak layers can be analyzed.
  • A comparison of boring log to NSWS log
  • Cross sectional area of railway embankment with NSWS data

See also

References
  1. "The National Agriculture and Food Research Organization of Japan".
  2. Inazumi, Shinya (2011). "In-Situ Ground Surveying by the NSWS Testing Machine" (PDF). International Journal of GEOMATE.
  3. "2) The Analysis Method for Ponds and Levees Preparing for Heavy Rain, and Earthquake test" (in Japanese). National Agriculture and Food Research Organization. 2012.
  4. Inazumi, Shinya (2011). "In-Situ Ground Surveying by the NSWS Testing Machine" (PDF). International Journal of GEOMATE.
  5. "About Public Subscription for 311 Earthquake Disaster Committee". Japanese Geotechnical Society. 2011.
  6. "Japanese Geotechnical Society". Japanese Geotechnical Society.
  7. "About Publication of Challenge and Countermeasure for Earthquake Disaster at the Cause of Earthquake – Lessons and Proposition for 2011 East Japan Earthquake Disaster　(1st Edition)" (in Japanese). Japanese Geotechnical Society.
  8. The older version weights 70kg. The newer NSWS, ver. 7, weights 120 kg but has more capabilities.
  9. Inazumi, Shinya. "A Presentation of Soil Investigation Example for Residentaial Embankment on Inclined Rock Mass and a Proposal of Reinforcement Material and Method".
  10. "Simplified strength analysis method for the slope of embankment such as a pond,in-situ rotation shear test(BST probe), Test manual(proposal) 1st edition" (PDF) (in Japanese). National Agriculture and Food Research Organization of Japan. 2013.
  11. "Rotational Shear Test in Borehole (BST Probe) Guideline for Cost Index (Proposal)" (PDF) (in Japanese). National Agriculture and Food Research Organization of Japan. 2013.
  12. "The National Agriculture and Food Research Organization of Japan".
  13. "NSWS(Nippon Screw Weight System)". Okita-Ko Co.,Ltd.
  14. "2) The Analysis Method for Ponds and Levees Preparing for Heavy Rain, and Earthquake test" (in Japanese). National Agriculture and Food Research Organization. 2012.
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