| Budget Amount *help |
¥3,700,000 (Direct Cost: ¥3,700,000)
Fiscal Year 2005: ¥1,600,000 (Direct Cost: ¥1,600,000)
Fiscal Year 2004: ¥2,100,000 (Direct Cost: ¥2,100,000)
|
|---|
| Research Abstract |
During a period of three years from 2003 to 2005, a series of international round-robin tests on Toyoura sand using bender elements was performed by participation of twenty-three laboratories in eleven countries. The program aimed at providing a valuable data to develop the recommendation for procedures referred to the bender element test. The outcomes may be summarized in the followings :
1.Results on rigid boundary apparatus exhibited higher scatter distributions. The reasons seemed the effects of friction of lateral face, near-field-effect due to short tip-to-tip distance, compression wave and so on.
2.Identification of travel time.
(1)Start-to-start is simple and popular techniques, and the scatter was relatively small, and the results corresponded to others tests results. However, it is difficult to find the first arrival point depending on the waves due to the near field effect and so on. Therefore, to eliminate the effects, it is necessary to use several input frequencies.
(2)Peak-to-peak may provide reasonable data independent of the effect of near field effect, when the frequencies of input and received waves are the same. However, the frequencies of input and received waves are not the same. Therefore, it is necessary to use several input frequencies, to find a relevant frequency.
(3)Cross correlation and Frequency domain techniques have the advantage that it can be automated and hence have potential to provide user independent results. However, there is a possibility of underestimate of shear modulus depending on waves. So, educated judgment is required in interpreting the cross correlation peaks and frequency domain to get the correct time delay.
3.Based on the outcome from the program, recommendation for procedures referred to the bender element test was developed.
|
