| 摘要 |
PURPOSE: To couple the energy easily with the wall of a test pit or a casing thereof by imparting an orbital movement at least to a part of an outer wall of a tubular frame means and then generating an orbital transverse wave to he wall of the test pit. CONSTITUTION: The seismic source 10 comprises a frame 26 having upper and lower masses 28, 30 being held by beam sets 32, 33 while being aligned therewith. The inner beam set 32 is secured to define a tubular chamber 34 between the masses 28. 30 and covered with an elastic membrane 52. A drive motor 36 is secured in the mass 28 with the dive shaft 40 being fixed to a shaft 40 and provided with an eccentric disc 42 and the rotation thereof is extended to a circular path f48 around the axis of the shaft 40. consequently, at a point 50 where the disk 42 has the longest radius, the elastic membrane 52 is displaced outward through a fluid in the tubular chamber 34 and displaced inward on the opposite side. Consequently, the outer part of the elastic membrane 52 generates a rotational dipole traverse wave coupled with the wall of pit 12 through the fluid 14.
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