| Budget Amount *help |
¥3,680,000 (Direct Cost: ¥3,500,000、Indirect Cost: ¥180,000)
Fiscal Year 2007: ¥780,000 (Direct Cost: ¥600,000、Indirect Cost: ¥180,000)
Fiscal Year 2006: ¥2,900,000 (Direct Cost: ¥2,900,000)
|
|---|
| Research Abstract |
In recent years, defective homes have emerged as a social issue. It is reported most of the defective homes are caused by ground and/or foundation failures. Some ground and foundation failures are caused by local nonuniform ground, such as local soft ground, buried industrial junks and buried roots of a tree. However, previous geophysical investigation methods can not find out local nonuniform ground in many cases. Therefore, a method is presented for identification of local nonuniform ground position based on measurement of the angle between arrival wave and a vibration source. Vertical ground motion is measured using a circular array of six sensors. The angle between the arrival wave and the source can be determined, based on F-k spectrum analysis of the data. To examine the validity of the proposed method, field investigations and 3D FEM analysis were performed.
The proposed method was performed at a housing site to locate nonuniform ground position. Rayleigh wave method, Swedish sounding test, dynamic penetration test and H/V spectrum were performed at the place where the proposed method indicated local nonuniform ground was located. The results of Rayleigh wave method, Swedish sounding test and dynamic penetration test at the place were different from those around the place. On the other hand, predominant periods of H/V spectrum remained unchanged. After the subsurface investigations, a lot of buried baked-muds were found at the place.
3D FEM analysis was performed to investigate the effects of local nonuniform ground on wave propagation. It is shown that (1) the arrival wave angles differ from the source angle in case that local nonuniform ground locates between the sensor array and the source ; (2) effects of local soft ground on the wave propagation is greater than that of local hard ground.
|
