| Slope deformation monitoring is one of the important research topics in the development of soil mechanics.Distributed optical fiber sensing(DOFS)technology,as a rapid development of the slope deformation monitoring technology in recent years,has made huge progress.However,how to identify and predict the data from the distributed optical fiber sensing data effectively,it has become one of the most important bottlenecks to restrict the development of optical fiber monitoring technology.In this paper,the reliability research of strain monitoring data is taken as the starting point,and a series of optical fiber monitoring experiments and numerical simulation are carried out on several typical working conditions,on the basis of this,using force theory and Seoul Kulun failure criterion of soil mechanics and fundation bearing method,combined with particle image velocimetry(PIV,Particle Image Velocimetry)the local loading and excavation slope deformation mechanism and uniform settlement of bilateral slope are analyzed.The main achievements were as follows:(1)This paper introduces the research background and the research progress of the slope deformation monitoring technology at home and abroad,and expounds the current research situation of slope monitoring in slope engineering and several typical methods for evaluating the reliability of optical fiber measurement data.(2)On the base of introduction of the finite element analysis software PLAXIS2D.the dynamic changes of strain,displacement and safety factor in the virtual monitoring lines of the local load-excavated slope and uniformly loaded bilateral slope were studied respectively.Comparing with shear strain data and displacement monitoring data,the reliability method of axial strain monitoring data applied to slope stability evaluation was quantitatively verified,establishing a theoretical foundation for the implementation and analysis of optical fiber monitoring experiments in the following chapters.(3)Based on the local loading excavation and local loading-excavated composite conditions,several groups of soil slope deformation tests based on FBG and BOTDA techno logy were carried out,and the variation law of the internal strain field in the soil slope was studied,Moreover,the characteristics of optical fiber monitoring results and finite element analysis results were compared quantitatively,and the optical fiber strain data and the PIV data were compared.Based on the above data,the reliability of soil strain monitoring data was verified quantitatively.(4)The feasibility study of a bilateral slope deformation unit test based on BOTDA technology was carried out,and the PIV technique was used for observation simultaneously.Using the actual measurement results,the deformation law of uniformly loaded bilateral slope was studied.Moreover,according to the force and deformation characteristics of fiber of uniformly loaded bilateral slope,theory of calibration method for optical fiber monitoring reading in the process of slope deformation was discussed.Based on the above,a theoretical approach to judge the reliability of optical fiber monitoring reading was provided.(5)Through the foundation bearing capacity theory and the Mohr-Coulomb criterion,the deformation stage characteristics of the local loading-excavated slope were analyzed in detail.Finally,by comparing the finite element analysis,PIV analysis and optical fiber monitoring results,the deformation range of the local loading-excavated slope and the uniformly loaded bilateral slope was quantitative zoning. |
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