Presumption manner of surface ground structure and creation manner null of surface ground

摘要

PURPOSE:To pair a number of measuring points, perform tremor observation as to vertical motion at two points and horizontal motion at one point, regard measured values as being obtained at the same hour by means of a transfer function, determine the dominant frequency of surface ground from the horizontal motion, calculate the response values of the components of the vertical motion around the dominant frequency, and estimate the ground structure from the central value. CONSTITUTION:A number of measuring points are made in pairs of each of adjacent ones, for tremor observation as to vertical motion at two points and horizontal motion at one point. A transfer function is used so that the observation results can be regarded as being obtained at the same hour. The dominant frequency of surface ground is determined from the tremor observation for the vertical motion, and a frequency band is determined so that the components of the vertical motion around the dominant frequency can be extracted. Integral values of velocity, acceleration and displacement waveform, etc., are mentioned as examples of the central value of response to the vertical motion. The ground structure is estimated by means of the central value. For the above purpose, a method of roughly estimating the surface ground structure by means of soil survey by boring or a geological survey map may be employed.