Research On Near-infrared Terrestrial Laser Scanner Monitoring And Application Of Moisture Content Of Similar Material Model

The moisture content of similar material models is one of the key factors that restrict the success of similar material simulation tests.The existing moisture content monitoring methods have problems such as damage models and less data quantity,and cannot fully obtain the spatial distribution of model moisture content.This paper proposes a new method for monitoring the moisture content of similar material models with high spatial resolution using the Near-infrared 3D laser scanner RIEGL-VZ1000.The working wavelength of RIEGL-VZ1000(1550nm)is close to the absorption peak of the near-infrared spectrum of water,and the laser intensity data it provides can accurately describe the moisture content of similar materials.The thesis research has achieved the following results:(1)The interaction between the target's moisture and the near-infrared laser beam is analyzed,and the influence of moisture on the laser intensity data is attributed to the influence of moisture on the laser intensity data by changing the reflectivity of the target;Analyzed the characteristics of laser intensity data,and proposed an average filtering method to process intensity data;The sensitivity of the moisture content of similar materials and the laser intensity is explored through experiments,the results show that there is a good logarithmic function relationship between the moisture content of similar materials and the laser intensity.Near-infrared TLS can be used to invert the moisture content of similar materials;Through experiments,the horizontal distribution law of the moisture content of similar material models is revealed.(2)The influencing factors of laser transmission were explored,and a laser intensity correction model suitable for RIEGL-VZ1000 was proposed.Through experiments,it is concluded that when the incident angle is less than 20° and the distance is between 4m-10 m and 14m-30 m,the influence of the incident angle and distance on the laser intensity can be ignored;The corrected laser intensity data standard deviation will increase,when the incident angle is larger,the corrected laser intensity data standard deviation will be larger,and the intensity data will be more scattered.When using near-infrared TLS to collect intensity data,it should be combined with the actual situation to try to avoid the influence of close-range effects and excessive incident angle on the laser intensity data.(3)Taking the laid similar material model as the monitoring object,using RIEGLVZ1000 to monitor the moisture content of it,designing a monitoring plan for the moisture content monitoring of the similar material model,and obtaining the timevarying characteristics of the moisture content of the similar material model through experiments.The experimental results show that under the condition of natural drying,the moisture content of the model decreases with the increase of the height of the similar material model.The moisture content of the model is the lowest at the top and the highest at the bottom.With the continuous drying of the model,the difference between the top and the bottom of the model decreases continuously.The horizontal moisture content of the model is equal at the initial stage of drying.As the drying of the model continues,the overall moisture content of the model decreases,the volume of the model shrinks,and gaps appear on the boundary of both sides of the model,resulting in the evaporation of water on the side of the model,making the moisture content of both sides of the model lower than other areas of the same level.The absolute error of nearinfrared TLS monitoring the surface water content of similar material models is less than 2%.The method of near-infrared TLS monitoring water content can be used to monitor the water content of similar material models.