Research On Optical Fiber Sensing Technology Based On Fused Deposition And Its Application In Underground Structure Monitoring

Fiber grating sensing technology has played an important role in many fields.As a sensing element with excellent performance,it is important in the field of civil engineering,and structural health monitoring.Combining the sensing characteristics of fiber gratings,it is an important and meaningful subject to develop measurement devices to meet the actual characteristics of civil engineering,and meet the actual needs of engineering and can be suitable for practical engineering applications.3D printing technology is a technology,it has developed rapidly in recent years.Fused deposition technology is widely used in many fields,and its uses is becoming more and more extensive.3D fused deposition technology with fiber grating sensing technology to develop a measurement device,the sensor suitable for underground structure monitoring,it has making a one-time molding,and ensuring high sensitivity and high precision.This paper develops a measurement device suitable for underground engineering monitoring,that based on 3D fused deposition technology and the principle of fiber grating sensing,and that conducts indoor calibration experiments,indoor and outdoor model experiments and practical engineering applications.The main research work and achievements are as follows:(1)The feasibility of combining 3D fused deposition technology with fiber grating sensing characteristics to make a measurement device suitable for civil engineering was verified.Aiming at the important and often measured earth pressure in engineering,the principle of fiber grating sensing was explained firstly,and then the structure type and specific size of the sensing element were determined through structural feature analysis and numerical simulation analysis.A new pressure sensor was developed with the help of fused deposition technology.After completing the laboratory calibration experiment and the bolt pulling experiment to verify its performance,the experimental effect was excellent,which meet the design requirements and practical engineering application needs,and further verifies the combination of fused deposition technology and fiber grating sensing technology to make engineering application sensors feasibility.(2)Displacement is a common physical quantity in civil engineering and underground engineering monitoring.Two different types of displacement measuring devices were proposed based on different engineering application requirements.The sensing elements were determined through structural feature analysis and numerical simulation.The form and size of the device were fabricated by fused deposition technology.The sensing characteristics of the fabricated displacement measuring device were analyzed.The temperature characteristics were considered,and the calibration results obtained excellent results.(3)The developed high-precision small-range displacement measuring device was applied in the engineering site.A complete monitoring system was established to conduct long-term and stable real-time monitoring of the displacement and temperature of the underground rock and soil mass,and analyzed the impact of temperature and external environment on the rock mass.The monitoring results showed that the developed high-precision small-displacement measuring device has reliable and stable performance,and had practical application value and application prospects.(4)The high-precision large deformation displacement measurement device and the weak fiber grating array sensor carried out the indoor convergence deformation model experiment of multi-sensing technology.Applying multi-level loads,changing the loading point and other working conditions,Experiments verified the accuracy and reliability of the developed measurement device,and explored the model convergence deformation law.Experiments showed that the error gap between the two results was small,and the designed displacement measuring device can meet the experimental requirements,which can provide a reasonable monitoring method for subsequent practical engineering applications.