Monitoring And Assessment Technologies For Vulnerability Of Asphalt Pavement In Cold Regions

As an external structure,asphalt pavement in cold regions has been constantly affected by the harsh environment(e.g.,extreme low temperature,large temperature difference and heavy rainfall,etc.)and ultimately results in extremely vulnerable structure.Although the relevant assessment system can reflect the vulnerability characteristics to a certain extent,but it weakens the influence of regional differences and pavement structure and materials on pavement vulnerability.In addition,traditional data acquisition methods,such as artificial collection and detection,are difficult and complex in the process,leading to different data types,high degree of disability and certain hysteresis,which seriously affects the accuracy and reliability of the assessment.Therefore,it is necessary to establish a highly targeted vulnerability assessment system for asphalt pavement in cold regions and adopt a stable and efficient data acquisition method.As a result,this paper aims to establish the vulnerability index system of asphalt pavement by analyzing the influence of extreme climate in cold areas.Combined with the structure health monitoring technology,the asphalt pavement vulnerability assessment under extreme scenarios is completed.Firstly,according to the results of vulnerability research in disaster science and transportation infrastructure,the concept of pavement vulnerability was put forward,and the ‘Expose-Vulnerability-Resilience’ evaluation model of asphalt pavement was established.Based on the study of the service environment characteristics of asphalt pavement in cold areas,an evaluation index system of asphalt pavement vulnerability was established for different extreme weather events.In view of the above research,the vulnerability assessment process of asphalt pavement in cold areas is analyzed.Secondly,the monitoring and assessment methods of asphalt pavement vulnerability were studied and the relationship between pavement vulnerability evaluation index and monitoring index is established.Relying on the actual project,the design and application of pavement vulnerability monitoring system were completed.Based on the measured data,the distribution characteristics of the pavement temperature field and dynamic response and possible damage forms of asphalt pavement under extremely low temperature environment were explored.And the specific evaluation index of pavement vulnerability in service was determined at last.Thirdly,the pavement temperature field distribution was calculated by using COMSOL software,and the pavement temperature stress in service under different periods was analyzed to complete the temperature fatigue life evaluation.According to the measured dynamic response,the load fatigue life evaluation of service pavement was completed.The results show that the service pavement has better resistance to temperature fatigue and load fatigue during the analysis period.Then the crack index of service pavement is calculated as 6.5,and the results show that the pavement surface is in good condition.Finally,the weight of the vulnerability index system of asphalt pavement in cold regions was determined through network questionnaire survey.After taking the above research results into consideration,AHP-Fuzzy comprehensive evaluation method was adopted to complete the vulnerability evaluation of pavement in service under extreme low temperature climate and extreme freezing-thawing days.The former,whose pavement vulnerability index is 0.6985,belongs to severe vulnerability,while the latter,whose pavement vulnerability index is 0.2828,belongs to mild vulnerability.In the case of extreme high temperature,the pavement shows severe vulnerability(Once in twenty years)and extreme vulnerability respectively(Once in a hundred years).However,under the circumstance of extreme rainfall,the pavement all shows mild vulnerability.