Study On Thermal Properties Of Asphalt Pavement And Its Influence On Temperature Field Of Frozen Soil Foundation

The thermal property parameters of road materials are important parameters for the study of road temperature field,and the thermal property parameter values of different materials for pavement materials,base layer,and subbase layer of road materials vary greatly depending on the type of materials and test methods,and at the present stage,domestic and foreign scholars The test methods for thermal properties of mixed materials are not the same,resulting in large changes in the values of thermal properties,and there is no unified method for defining the values of thermal properties.By collecting and comparing the existing experimental data,the thermophysical properties and influencing factors are classified and compared.This provides a reference for the accurate selection of the thermal physical properties of the asphalt mixture that is closer to the actual road temperature field.First of all,through the study of the domestic and international tests on the thermal physical properties of road structure materials,the domestic and foreign asphalt mixture,inorganic binders,granular materials,soil-based thermal properties tests and latent heat of phase change parameters are used to determine the thermal properties of road materials.Types of material types,voidage,temperature,moisture content,test conditions,etc.were classified and analyzed to analyze the distribution rules and influencing factors of thermal properties of various materials under different conditions.Then based on the measured data of temperature field after asphalt pavement of some highways on the Qinghai-Tibet Plateau and field measurement data of Sichuan Expressway,a 2D road finite element model was constructed by deducing the finite element formula of the road temperature field.The measured environmental parameters and thermal properties were measured.The parameters are input into the model and the calculated results are compared with the measured data to verify the rationality of the temperature field model.Next,the theoretical analysis of the temperature field is combined with the material design of the pavement structure,and the thermal physical parameters of the asphalt pavement materials are studied at home and abroad.Based on the comprehensive analysis,the domestic and foreign research results on the thermalphysical properties of the asphalt pavement materials are fully used for reference.The main thermal properties of various types of road materials were summarized and compared,and the sensitivity analysis was performed.The results showed the sensitivity of the thermal properties of various structural layers and the sensitivity of the external environment,among which the sensitivity of the surface layer was the highest and the thermal conductivity was the highest.The sensitivity is lower and the sensitivity is higher in the base layer.Therefore,in order to reduce the perturbation to the frozen soil,the appropriate thermal physical parameter values can be selected from the absorption rate of the surface layer material and the thermal conductivity coefficient of the base layer material.Finally,the ABAQUS finite element analysis software was used to input the measured environmental parameters to analyze the temperature field of the road surface of the road in the permafrost region.The temperature field distribution in the subgrades of different structures and the method of using fixed parameter values under multi-parameter conditions were studied.Determine the temperature field variation rule under single factor conditions,obtain the spatial and temporal distribution of temperature field in the frozen soil area and the reasonable value range of the thermal properties parameters and the road structure;study the influence of the filling height of different roadbeds on the temperature of the roadbed top surface in permafrost regions.Regularity,put forward a reasonable road embankment filling height.