Research On Posture Monitoring Of Hydraulic Supports Based On Optical Fiber Sensing Technology

Automation and intelligence level of equipment has a direct impact on the safe and production efficiency of coal mining faces.The hydraulic support is one of the most important mechanical equipment in the fully mechanized coal mining face,and its working status has a great influence on the safety and production of the mining face.At present,the monitoring of hydraulic supports in China mostly focuses on the monitoring of the work resistance of the supports.This monitoring method cannot get posture of the supports during working and information of roof,which is directly related to the stope disaster.Also,the results are not in real time.Besides,the complex working conditions of the mining face make the electromechanical equipment face many challenges in information acquisition,long-distance transmission,and data processing and analysis.The various aspects of monitoring work of hydraulic supports require a lot of human and material support,which is not conducive to current mine intelligence and unmanned development.Optical fiber sensing technology is a research hotspot in the engineering field.Its superior sensing performance makes it extremely adaptable to the complex environment for mines.In this paper,the optical fiber sensing technology is used as the monitoring method,and the posture of hydraulic supports is taken as the research object.The goal is to realize the high-precision,anti-electromagnetic interference,intrinsic safety and real-time monitoring of posture of hydraulic supports.The monitoring results will be checked by industrial tests.The main research content is as follows:(1)Sensing principles of the stress-strain and temperature based on optical fiber sensing technology are analyzed.The system structure of posture monitoring of hydraulic supports is established,and the basic principle is analyzed.(2)Kinematics principle of posture monitoring of hydraulic supports is studied,and the kinematics model of two-column shielded hydraulic supports is established.Through the analysis of theoretical angle of the roof beam of the support,the relationship between the posture and the working resistance,the coupling theory of stiffness of the surrounding rock and the support,and the stability of the support,an indicator system for posture monitoring of hydraulic supports is established.Monitoring indicators include basic indicators,stability indicators and structural indicators,and the safety scope of the indicator parameters is clarified.Through this indicator monitoring system,it is possible to fully reflect the motion of the roof,the coupling relationship between the support and surrounding rock,the stability of the support,and the key structural conditions of the support.(3)Based on the stress-strain sensing theory of optical fiber sensing technology,a twodimensional tilt sensor is designed which consists of two cantilever beams.Numerical simulations are finished by Ansys Workbench,and sensing performance of the sensor is tested.The results showed that the angular sensitivity of the cantilever 2 as a sensor structure was 32.4pm/°,and the average linearity was 0.9992,in the range from-30° to 30°.In the general inclination state,the cantilever beam 1 had an angle sensitivity of 32.6 pm/° and an average linearity of 0.9998.The FBG2',which acted as a temperature compensation,had an effective temperature compensation function.(4)The industrial test of the posture monitoring of hydraulic supports based on optical fiber sensing technology is carried out at the mining face No.101 of Longde Coal Mine.The monitoring results indicated that the average inclination angle of the roof beam of hydraulic supports at the mining face was 3~5°.The elevation angle of the roof beam was larger in the central monitoring area and was smaller at the two sides.The inclination of the base had a random variation from-1 to 1°.The cover beam angle was about 25~27°.The left and right inclinations of the supports were distributed crosswise,and the lateral inclination angles were unevenly distributed from-2 to 2°.The column length was 2100~2200mm.The posture of the supports during advancement of the mining face could reflect the movement characteristics of the roof during the periodic weighting,the initial support force,and posture of the roof beam of the supports,which was complementary to the monitoring of the working resistance and could fully reflect rock conditions at the stope and conditions of hydraulic supports.