| It is an important means to evaluate the stability of the panel surface of concrete face rock fill dam through monitoring Deformation and landslide deep body underground displacement, which has been widely used in stability prediction of the dam and the rock mass. But the shape measurement technology for high accuracy, good stability is far behind the development of national economy, especially in the part of the water conservancy project investment increased significantly in recent years, so real-time, accurate monitoring of dam, slope deformation stability problem is very importantIn order to meet the demand of dam monitoring, fiber optic sensing technology has been developed in recent years, combined with the concrete face rockfill dam and slope monitoring engineering practice, in view of the current shortage of monitoring techniques, to carry out research on distributed optical fiber sensing technology based on winding. Firstly, the characteristic of deformation monitoring method of distributed optical fiber sensor was analyzed, then a physical model of winding fiber optic strain sensor was established. Based on fiber optic sensor monitoring mechanism, the relation of distributed optical fiber displacement and optical loss was analyzed. again a kind of distributed optical fiber strain sensor is put forward. An experimental study was conducted on the performance of optical fiber sensors distributed. finally the monitoring system of distributed optical fiber sensor was applied to practical engineering. Based on the above studies, the following main results are made:(1) A physical model of winding fiber optic strain sensor was established. the monitoring mechanism was studied for the spiral optical fiber sensor. the effect of different strata and strata dip angle on displacement optical loss were explored. The results show that:the combined light source monitoring system at1550nm and1310nm, can make the system initial sensing displacement smaller, also can make the system wide measurement range; the main factors affecting the distributed fiber optical loss in addition to sliding displacement, and spacing (rock interlayer thickness), rock slip angle the wavelength of the incident light, and fiber type. The use of hollow rubber rod, can increase the test path, enlarge the displacement range, and further improve the positioning accuracy of event points. (2) a kind of distributed optical fiber strain sensing measurement device were put forward. the effect of rubber tube diameter, coil pitch on the sensitivity of the sensor were researched. The results show that:in the optical fiber loss and effective regional deformation displacement curve, displacement and the optical loss of linear relationship between deformation and displacement, in certain conditions, the greater the diameter of the rubber tube, the lower is the optical fiber sensing displacement sensitivity; the more fiber coil pitch more, the lower is the perceived displacement sensitivity, the diameter of40mm, spiral spacing for rubber tube optical fiber sensor15mm can guarantee the high sensitivity and can guarantee the dynamic range is larger.(3) The distributed optical fiber were embedded in the concrete face rock fill dam to monitor the deformation. Firstly, through the finite element analysis and calculation of concrete face rock fill dam, the maximum area of the rock fill dam displacement were analyzed. Finally the position of the embedded optical fiber sensors and fiber arrangement optimization method were determined, which can save a large number of embedded optical fiber, reduce costs.(4) The distributed optical fiber sensor based winding were implanted in deep rock mass of yellow lawn, and compared with the oblique monitoring results. The results show that:the displacement reaction of distributed optical fiber sensor and the traditional inclinometer deformation data consistency was good at sensor performance. The distributed optical fiber sensor based winding is high sensitivity, stable and reliable. |
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