| 摘要 |
PURPOSE:To detect easily the soil nature by driving a buried pipe by an acoustic wave sound source installed to a branch pipe exposed on the ground, processing a detecting signal by an acoustic wave receiver on the ground by synchronizing it with a driving signal, and deciding the peripheral soil nature from a detecting signal level. CONSTITUTION:A water pipe 1 is driven by an ultrasonic wave, and a synchronizing signal detector of a soil nature detecting device (omitted in the figure) on the ground and an ultrasonic microphone are brought close to or adhered tightly to the ground surface and moved in the axial directions X1, X2 of the pipe 1. Also, the detecting signal becomes an attenuation factor H1, an attenuation factor H2 and an attenuation factor H3, in a section A of a gravel nature, in a section B of soil which is finer than gravel, and in a section C of gravel or soil containing a clod, respectively. Also, a table for showing a relation of the detecting level and the soil is prepared in advance, and also the detecting signal by the pipe of a prescribed buried depth has a constant attenuation factor with respect to the driving signal, therefore, this attenuation factor is calibrated, and also the attenuation factor by a difference of the soil nature is calibrated, by which the peripheral soil of the pipe 1 can be detected with high sensitivity. |
