SU1374062A1 - Seismometer - Google Patents

Abstract

The invention relates to seismometry and is intended to record seismic vibrations. The purpose of the invention is to increase sensitivity and accuracy. Equipping the seismometer with an i-shaped case, the horizontal part of which has a larger cross section and branches (equal) smaller sections, makes it possible to measure the horizontal component of oscillations and significantly increase its sensitivity and accuracy in proportion to the ratio of the recording sections of the U - different body. The supply of an additional bellows and reservoir with the possibility of a dosed change in the volume of the inertial fluid in the seismometer body allows you to change your own oscillation period and extend the frequency range of the seismometer operatively during the measurement process. The expansion bellows ensures that accuracy is maintained when the temperature changes in a given range, 3 Il,. (L

Description

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The invention relates to seismology, in particular, to seismic instruments for recording forced vibrations of soil and structures caused by earthquakes and other sources of vibration.

The purpose of the invention is to increase the sensitivity and accuracy.

FIG. 1 shows a seismometer, general, view; in fig. 2 — node I in FIG. 1 (closed part of the measurement of the branches of the U-shaped housing with a light source); in fig. 3 shows section A-A in FIG. 2 (window-diaphragm for light output on the line of optical fibers.

The seismometer contains a U-shaped hollow body 1 with measuring branches 2 of small section and an elongated horizontal connecting part 3 of a larger section equipped with a temperature compensation bellows 4 and an additional bellows 5 equipped with a twisting screw device 6 for changing the volume of the horizontal part 3. Inside the housing 1 An inertial opaque liquid (mercury) is placed 7. Case 1 is rigidly mounted on the base 8. The liquid level in the branch x 2 of the case 1 in the initial state (quiescent state) is indicated by h, in position and one of the phases of the oscillatory motion of the level difference in branching x 2 denotes LN and the inertial movement of liquid in the horizontal part & L. The measuring branches 2 are provided with a reflective inner coating 9 with transparent windows 10 and 11, which are respectively the input and output diaphragms forming the light flux in the seismometer.

The input ends of the optical fibers 12 arranged in a ruler are installed against the windows 11 symmetrically to the position of the level of the inertial fluid 7 in the measuring branches x 2. The output tor1 of the optical fibers 12 are inserted into the fiber optic encoder (WOCU) 13 and are differentially connected. WOK 13 is connected to a recording device or computer (not shown). Against windows 10, light sources are installed, consisting, for example, of incandescent lamp 14, reflector 15 and casing 16.

The horizontal part 3 of the housing 1 is hydraulically connected by a hose 17 to an additional reservoir 18 containing an inertial fluid 7. Spang

17 is provided with a locking element 19, and the reservoir 18 with a measuring ruler 20 with a metric scale.

The device works as follows.

In the initial state, in the absence of soil oscillations, the level of the inertial fluid 7 in the branches x 2 of the housing 1 is on the border of the fiber packets 12, divided into two groups vertically to register the opposite phases of the inertial fluid movement: up (positive) and down (negative) relative to the initial position. The boundary position of the light rays, i.e. The situation when all the ends of the package of optical fibers related to the positive phase are lit, and all the ends of the package of optical fibers related to the negative phase are shaded to correspond to a zero value of the oscillation intensity. In the event of

soil oscillations in the horizontal plane, the inertial fluid 7 in the horizontal part 3 of the housing 1, which has a large mass (enclosed in a volume with a large cross section), makes an oscillatory motion relative to the housing. The inertial fluid 7 in the associated measuring branches x 2 in this case successively overlaps the ends of the optical fibers from light rays entering them. Depending on the amplitude of oscillations, the inertial fluid level moves from the equilibrium position to the extreme positions, which corresponds to the seismometer readings from the minimum value of the measured value to the maximum.

Moving the volume of inertial fluid & L in horizontal part 3

will cause a change in the heights of the liquid column in both branches x (in one of the branches the level will decrease, in the other it will increase). This change will be & h, which is expressed as

M. yp- p)

2

where S, is the cross-sectional area of the horizontal part of the body (of larger diameter),

S is the cross-sectional area of the body branches (of smaller diameter). As it follows from the above ratio, as many times as what

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A a

P

Claims (1)

Claim A seismometer containing a hollow body partially filled with an inertial liquid mass, an element for expanding the frequency range of the seismometer and a recording device, characterized in that, in order to increase sensitivity and accuracy, its body is made in the form of a closed ϋ-shaped tube, the branches of which are smaller than the horizontal section parts of the tube, branches are made in the form of optical fibers equipped with light sources, with walls reflecting inside, having transparent aperture windows, against which the input ends of the pa fibers of the optical fibers arranged in a line, and the output ends of the fiber packets are connected differentially and optically connected to a fiber-optic encoder, the horizontal part of the U-shaped tube made in the form of a bellows equipped with a bone change device in the horizontal part 3, with vertical movements of its base volume, while the bellows is connected by a hose to the tank. (rie.2 AA fie.Z