Design And Application Of Distributed Optical Fiber Pressure Sensor Based On Similar Material Model

Stress measurement of similar material model test is one of the key problems to ensure the accuracy of model test.How to measure the evolutionary characteristics of mining pressure field and realize the quantitative measurement of stress changes in model rock mass is the focus of current research.Resistance pressure sensor,as a traditional stress monitoring method,has some shortcomings such as poor anti-interference ability and unstable testing.As a new sensing and monitoring technology,distributed optical fiber sensing technology has many advantages,such as long sensing distance,large transmission capacity and high measurement accuracy.It is helpful to realize large-scale and multi-parameter intelligent testing.Therefore,the study of optical fiber monitoring technology and its measuring device for mining stress is of great significance for quantitative measurement of internal stress in rock mass of similar material model test,and can provide a basis for mine dynamic disaster prediction.Based on Brillouin scattering distributed optical fiber sensing principle,a distributed optical fiber sensor for pressure measurement is designed in this paper.A square type structure with silicone rubber as elastic packaging material is proposed.The packaging structure is analyzed theoretically and the relationship between pressure and fiber strain is clarified.The simulation analysis of the optical fiber pressure sensor is carried out by using ANSYS simulation software,and the rationality of the theoretical analysis is verified.Various single-mode optical fiber silicone rubber packaging tests with different scales were carried out.Corresponding calibration tests and static performance tests were carried out,and the optimal pressure sensitivity coefficient of optical fiber under the same working conditions was obtained.Finally,the distributed optical fiber pressure sensor is applied to similar material model test,and the distribution law of abutment pressure in stope is tested.The validity of the optical fiber pressure sensor is verified by comparing with the traditional pressure sensor.The results show that the strain of the distributed optical fiber pressure sensor designed in this paper has a good linear relationship with the test pressure.The linear fitting degree of the two sensors is 0.99 by using the least square method.The optimal sensitivity coefficient of the optical fiber pressure sensor is 48.23με/KPa,which is obtained by the performance test of the encapsulated structures of different scale sensors.The pressure sensitivity coefficient of 50.25με/KPa is basically the same.By comparing the abutment pressure distribution measured by the traditional pressure sensor,it is found that the distribution law and characteristics of the abutment pressure of the stope reflected by the distributed optical fiber pressure sensor and the traditional pressure sensor are in good agreement.The relative error between the two sensors is less than 4.65%,which proves the accuracy of the measurement results of the optical fiber pressure sensor.The fiber optic pressure sensor presented in this paper has the characteristics of large-scale distributed measurement and high sensitivity measurement.It can provide a new method for measuring the distribution of abutment pressure in stope.