Study On Seepage Monitoring Method Of Soil And Stone Dam Based On Distributed Optical Fiber Temperature Measurement Technology

In view of the current safety of soil and stone dams,seepage problem is an important factor,if it is found that seepage is not treated in time or not in place,it is very likely to cause pipe surge,flow of soil and other phenomena,resulting in dam collapse.However,the seepage problem of soil and rock levees has the characteristics of randomness and concealment,and the treatment is not significant.The early use of point-type monitoring will often have a certain blind area,so that its monitoring range is not comprehensive enough,it is very easy to appear leakage supervision.The seepage monitoring method based on distributed optical fiber temperature measurement technology is proposed and applied,so that the comprehensive monitoring of seepage field has an opportunity to be realized.Based on the model test,this paper studies the realization Princple and method of DTS temperature measurement technology based on the reasonable design of the test platform and the test process,taking the leakage quantity of homogeneous Earth dam and the monitoring and identification of fiber geomembrane breakage as the goal.The main research contents of this paper include the following aspects:(1)Designed a set of DTS tenperature measuring host,water supply system,heating system and other components of sand soil seepage monitoring test platform,the heating system has been improved,the use of silicone rubber plus tropical fiber heating,followed up to improve the form of optical fiber layout,The spatial resolution of the monitoring is improved by combining it with the PVC tube.Through the test platform,the seepage quantity and heating temperature are selected as the influencing factors,the seepage monitoring test of sandy soil based on distributed fiber is studied,and it is inferred that there is a certain linear relationshp between the leakage quantity and the temperature dielectric value,and then the size of the leakage is approximate.(2)A homogeneous Earth dam model is designed,starting with three la yers of optical fiber and silicone rubber heating cable inside the model,and then the geomembrane is laid on the upstream of the dam,and the fiber is laid on the inner surface of the geomembrane.Taking the breakage of geomembrane as the influencing factor,this paper studies how to determine the location of geomembrane breakage by using optical fiber,and finds that the leakage effect is better by using optical fiber geomembrane.By observing the temperature change of the optical fiber inside the Earth dam model,the leakage channel generated by the Earth dam caused by the breakage of the geomembrane is inferred.Finally,the silicone rubber heating fiber optic cable proposed in the second chapter is applied to the Earth Dam model,and the actual leakage amount is basically in agreement with the leakage quantity calculated in the second chapter.(3)The coupling relationship between seepage field and temperature field and the basic principle of saturation-unsaturated seepage analysis are briefly described,and the coupling of seepage field and temperature field of homogeneous Earth Dam model is analyzed and calculated by using COMSOL software.The analysis results show that the calculation re sults of finite element software are basically the same as those of optical fiber monitoring,and the change trend is basically consistent,but there are also about 10%errors in fitting value and measured value.