OFDR (Optical Frequency Domain Reflectometer) - based optical fiber monitoring and testing method and device for tensile mechanical behavior of soils

Abstract

The invention relates to an OFDR-based optical fiber monitoring and testing method and a device for tensile mechanical behavior of soils. The strain sensing optical fiber is laid horizontally in the soil beam. The tester is mainly composed of a counterforce bracket, a loading system, an OFDR signal demodulating and processing module, and a digital image capturing and analyzing device. The OFDR signal demodulating and processing module is connected with the strain sensing optical fiber in the soil beam, collects the strain distribution data inside the soil beam in real time, and displays the amount of light waves and the strength of the soil beam, etc. The digital image capturing and analyzing device tracks the position change of the soil beam surface, and obtains a strain field and a displacement field after the soil beam is deformed by force, and performs checking with the measured data of the optical fiber mutually. According to the OFDR-based optical fiber monitoring and testing method and the device for tensile mechanical behavior of soils, the crack deformation information of the surface and the interior of the soil beam and the space-time evolution law of the tensile strain can be monitored in real time during the four-point flexural test, the tensile strength of the soils under different conditions like water content, dry density can be measured, and the elastoplastic stress-strain constitutive relationship of the soils after being pulled can be grasped.

Description

technical field [0001] The invention relates to the field of rock and soil stress deformation, strength test technology, and distributed optical fiber monitoring engineering technology, in particular to an OFDR-based optical fiber monitoring and testing method and device for tensile mechanical properties of soil. Background technique [0002] Tensile mechanical property is one of the basic mechanical properties of rock-soil media, which plays a very important role in the process of deformation and failure of rock-soil mass, and thus produces many related geotechnical engineering problems. The tensile strength of the soil is the same as the compressive strength, shear strength and other indicators, which are important parameters to measure its mechanical properties. During the formation process of the soil, the integrity and integrity of the original rock were damaged to varying degrees. In terms of mechanical properties, it still has a certain compressive strength and shear ...

AI Technical Summary

Problems solved by technology

Since these studies did not use special, standardized and integrated test equipment, the entire test process and boundary conditions cannot be controlled, so only some qualitative conclusions can be obtained, which are of little significance for engineering reference

Due to the long test time, the optical fiber readings are also affected by ambient temperature, humidity, etc., and the reliability of the analysis results is poor

In addition, the direct burial method is more convenient in construction, but the interaction mechanism and coordinated deformation between the soil and the strain sensing optical fiber cannot be guaranteed, and there is no scientific basis for the selection of the strain sensing optical fiber and the setting of the anchor point Therefore, the validity of the optical fiber strain monitoring results has great uncertainty, which greatly restricts the popularization and application of this technology in engineering.

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