Application Research On Distributed Optical Fiber Sensing Technology For Monitoring Of Slope Engineering

Slope deformation monitoring is an important means of slope stability evaluation, which is being widely applied in landslide predictions. But now deformation monitoring popularization of slope falls behind in the national economic construction development. Along with increasing investment in railways, highways, plenty of slopes are being excavated, which seriously threaten the communications and the lives of people.To meet the requirement of slope engineering monitoring, on the basis of the engineering practice, application research on distributed optical fiber sensing technology for slope engineering is being developed. This paper studied the problem of working out monitoring plan with distributed optical fiber sensing technology and the characteristics of slope deformation monitoring. Optical fiber monitoring system is designed according to the characteristics of slope deformation. Many problems in the implementation and operation of monitoring system are studied to find solutions. Compatible deformation about optical fiber and monitoring objects is a basic requirement of optical fiber. According to the practice of slope deformation monitoring, after the analysis of limitations about using embedding and stick to fix optical fiber in slope engineering, new optical fiber fixation is explored. Based on anti-sliding piles being used as carrier of slope deformation in depth, deformation in depth is studied. Using optical fiber sensor in slope deformation monitoring in depth and applying monitoring results, how to determine anti-sliding pile internal force and push on piles is being discussed. Combined distributed optical fiber monitoring technology and grey correlation theory, which are applied in the deformation monitoring and result analysis of double-row anti-sliding piles, comprehensive correlation decision-making model is being put forward to study on compatible deformation characteristics of double-row anti-sliding piles.Based on the research on the above-mentioned, some results are concluded as follows:(1) For the difficulties of optical fiber layout in the slope, a new method of fixation by twisting fibers is proposed to ensure coordinated deformation about optical fibers and monitoring objects. Monitoring figures of optical fibers by twisting show that there is false response near the winding section. The length of twisted fiber is determined according to not only the rod material and geometry but also distance resolution.(2) According to the strain monitoring data of anti-sliding piles, a new method to determine landslide thrust is proposed. The model to determine the thrust on piles is established by the functional relationship among moment, normal stress, shear stress. Through this model, some variables can be obtained such as the distribution of the pile load intensity, the value of landslide thrust, the distribution form of landslide thrust.(3) A method to internal force of anti-sliding piles is proposed by strain monitoring data. According to the calculation theory of flexure member and the parameters of reinforced concrete, internal force against the anti-sliding pile is calculated. On the basis of the theoretical values about internal force, the safety of anti-sliding piles is evaluated.(4) Comprehensive correlation decision-making model that can be used to analysis compatible deformation characteristics of double-row anti-sliding piles is proposed by combining distributed optical fiber monitoring technology and grey correlation theory. Aiming at specific engineering, the research provides corresponding analytical method.