Experimental Research On Monitoring Earth Dam Seepage And Lithium Battery Strain By Weak Grating System

With the advancement of society and the development of science and technology,sensing technology has been widely used.As a new type of grating sensing field,weak fiber grating has the characteristics of large capacity,long distance and high precision.It can meet the monitoring needs of large projects and large equipment.It is one of the irreplaceable research directions in the field of sensing.The main research content of this paper can be divided into two aspects according to the weak grating temperature measurement technology and the strain measurement technology: the experimental research of the seepage monitoring model and the strain monitoring of lithium battery charging and discharging.(1)In Experimental study on seepage model of earth-rock dam: a cylindrical soil test study and model test study of earth-rock dam were carried out.(1)The experimental research of seepage monitoring model can be divided into:cylindrical soil seepage test and earth-rock dam model seepage test.The main research contents of the cylindrical soil seepage test include: analysis of the heat transfer process of porous media in seepage and non-seepage,put forward the theoretical formula of thermal grating seepage monitoring,design test model and test plan.The test results show that: the heated weak grating array can measure the temperature change in the seepage field;when the seepage monitoring of different water temperatures is carried out,the temperature change and the seepage flow rate meet a number of quantitative relationships;and the temperature change and the excess temperature meet the seepage monitoring Theoretical formula,different seepage water temperature obeys the same law,according to the known thermal conductivity,density,porosity and other parameters of the porous media into the seepage theoretical formula to calculate the seepage flow rate.The main research contents of the earth-rock dam model test include: analysis of the thermal conductivity ratio coefficient under dry,saturated,and seepage conditions;definition of the leakage strength discrimination coefficientsμ、η;design and production of the earth-rock dam model.The test results show that: the thermal conductivity coefficient can reflect the porosity and permeability of the porous medium;the leakage channel can be found by comparing the thermal conductivity;the leakage strength discrimination coefficientsμ、ηcan both reflect the leakage situation,which can be measured according to The value of the discriminant coefficient is used to calculate the seepage flow velocity.(2)The main research contents of lithium battery charge and discharge strain measurement include: expounding the mechanism of temperature and strain change during lithium battery charge and discharge;derive the rectangular lithium battery temperature and strain measurement formula through the weak grating measurement principle;analyze the maximum lithium battery according to the stress-strain theory The magnitude and direction of the main strain are used to detect the safety and health status of lithium batteries;a lithium battery strain and temperature monitoring program has been designed and produced.The test results show that the temperature and strain of a lithium battery are closely related,and the strain will increase as the temperature rises,indicating that thermal stress is the dominant factor in the strain of lithium batteries;the temperature and strain formula derived from the weak grating measurement principle can be used very well In the monitoring of lithium batteries,the temperature and strain values of lithium batteries can be measured separately;stress-strain theory and thermal conduction theory can analyze the safety performance of lithium batteries during the entire charging and discharging process.