1985 Fiscal Year Final Research Report Summary

Development of a simple system to measure shear modulus of soft ground surface

Research Project

Project/Area Number	59850085
Research Category	Grant-in-Aid for Developmental Scientific Research
Allocation Type	Single-year Grants
Research Field	基礎・土質工学
Research Institution	Tokyo Institute of Technology
Principal Investigator	OHMACHI Tatsuo 東京工業大学, 国立大(その他), 助教授 (90126269)
Project Period (FY)	1984 – 1985
Keywords	in-situ measurement / shear modulus / torsional vibration / 軟弱地盤
Research Abstract	A simple system has newly been developed for in-situ measurement of shear modulus of soft ground surface. It utilizes a fact that a fundamental period of a single degree of freedom system is elongated when the system is situated at a soft soil surface. The system is made up of a torsional free-vibrator, piezo-electric measurement devices, a A/D converter and a hand-held computer, having total weight less than 2 kgf. The vibrator is mode of stainless steel, having the fundamental rotating period about 1/10 sec. The system takes only 5 minutes or so to indicate a single test result. The system was applied to a sand deposit model with different compaction levels. Test results were compared with shear modulus values obtained by the plate-shooting method, demonstating its usufulness in practical use for soft soil having shear modulus about 50 - 150 kgf/sq.cm.