Optical fiber drilling strain gauge

Abstract

The invention discloses an optical fiber drilling strain gauge, which comprises a strain cylinder, liquid, an end cover, a corrugated pipe, a bolt, measurement gratings, a protective cover, an optical cable and ground demodulation equipment, wherein the strain cylinder is used for sensing strain; the liquid is filled in the strain cylinder and used for transferring the strain sensed by the strain cylinder; the end cover is used for sealing; the corrugated pipe is arranged at the bottom of the strain cylinder and used for sensing the change of pressure in the strain cylinder; the bolt is arranged at the bottom of the strain cylinder and used for filling liquid and sealing; the measurement gratings are fixed at the end of the corrugated pipe and the bottom of the strain cylinder and used for measuring the end displacement of the corrugated pipe; the protective cover is arranged at the bottom of the strain cylinder and used for protecting the internal structure of the optical fiber drilling strain gauge; the optical cable is connected with the optical fiber drilling strain gauge arranged at the bottom of a well and the ground demodulation equipment; and the ground demodulation equipment is used for demodulating the wavelength change of the measurement gratings so as to obtain a ground strain value. By using the optical fiber drilling strain gauge, the problems of electromagnetic interference, lightning stroke resistance and null shift of the conventional drilling strain gauge are solved.

Description

technical field [0001] The invention relates to the technical field of seismic detection, in particular to an optical fiber borehole strain gauge. Background technique [0002] The crust will deform under the action of the regional stress field, and the observation of borehole strain is an important means to study the crustal deformation and the change of the in-situ stress field. The borehole strain gauge can continuously record the crustal deformation before and after the earthquake and volcanic activity in minutes or even close to the sampling time of seismic measurement. Therefore, it plays an important role in earthquake prediction and geophysical research. [0003] Existing borehole strain gauges include volume strain gauges and component strain gauges (Qiu Zehua, et al., "Development Status of Borehole Strain Observation Abroad", Acta Seismological Journal, 2004). However, no matter which strain gauge is used, electrical sensors are used for detection. For example,...

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Problems solved by technology

[0007] In view of this, the main purpose of the present invention is to provide an optical fiber drilling strain gauge to solve the problems of electromagnetic interference, lightning protection and zero drift of existing drilling strain gauges

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