Research And Application On Remote Automatic Monitoring System Of Subgrade Settlement Based On Optical Fiber Micro Coding

After entering the 21 st century,China has made leaps and bounds in the construction of high-speed railway,especially with the proposed 13 th Five-Year traffic planning strategy and high-speed eight hour traffic circle concept.At present,China's railway construction scale unprecedented,but he advanced detection technology need to innovate continuously and match it.As far as the current testing technology is concerned,it is not only time-consuming and laborious,but also easy to occur more data error.Therefore,due to the lack of existing technology or performance,or narrow scope of application,the existing technology can not achieve a wide range of areas within the automatic detection.And it is urgent to achieve large-scale,long-range real-time detection of new technologies.Under this background,optical fiber sensing technology is gradually applied to the field of railway infrastructure safety inspection,which is typical of the settlement of the roadbed,because of its characteristics of automatic,real-time,small error and low cost.This paper will mainly rely on large indoor embankment settlement simulation test and field application test.For optical fiber sensing technology research and development,combined with indoor and field monitoring and measurement test,the following results are achieved:1)The choice of core diameter should be as large as multimode fiber when selecting fiber;2)The choice of the formula of light intensity distribution of optical fiber output beam,When selecting larger core diameter;3)The theoretical calculation formula of the coupling light intensity of the fiber is different with the r value,and it is proved that the theoretical value agrees well with the experimental value.It is proved that the theoretical formula of the light intensity is deduced correctly.In addition,this study adopts the chemical etching method and the melt-pulling method to improve the coupling efficiency of the fiber;4)The 3rd generation prototype system is improved mainly in the improvement of the basic principle,the improvement of the optical system,the improvement of the light source,the improvement of the detector,the improvement of the optical switch and the positioning of the first signal of the pulse train;5)Through a large indoor roadbed settlement simulation test can be obtained,the telescopic end of the device based on monitoring of railway subgrade settlement by optical fiber sensing is connected with a mechanical micro displacement lifting platform.The reliability of the fiber optic sensor,the accuracy of the test and the feasibility of the practical engineering application are proved by comparing the measured values of the optical fiber sensor with the drop value of the sedimentation platform.6)From the field monitoring and measurement results,the device based on monitoring of railway subgrade settlement by optical fiber sensing shows good working performance and measuring accuracy.By comparing and analyzing the data of traditional manual monitoring method,the settlement data of the two monitoring methods are basically the same.It shows that the automatic settlement detection system based on optical fiber micro optical coding can replace other monitoring methods in practical engineering...