Research On Status Evaluation And Preventive Maintenance Of Guangdong National And Provincial Highway Subgrade

By the end of 2013, the mileage of national and provincial highway of Guangdong Province was 3 760 km and13 950 km respectively. From the construction and use cycle of highway network, for Guangdong Province highway transportation, the Twelfth Five-year Plan period is transitional period from large-scale construction period to sustainable maintaining period,highway maintenance is becoming the new subject of our province’s highway development. Subgrade is an importance portion in highway engineering and the foundation of the pavement. Therefore, subgrade maintenance is particularly important in highway maintenance. In order to keep each part of subgrade in good condition and ensure its function well, the scientific evaluation on subgrade condition is needed. Timely preventive maintenance, repair and reinforcement can prevent the occurrence and spread of subgrade damages, thus prolong the service life of subgrade.This paper aimed at building the national and provincial highway subgrade maintenance evaluation index system and evaluation model in Guangdong taken the national and provincial highway in Guangdong Province as the research object. So engineers can make a scientific evaluation for subgrade technical condition, as a result, the maintenance would be more standardized, scientific and modernized.First of all, according to road network layout structure and highway maintenance project, the paper was mainly to study soft soil subgrade and cut subgrade, systematically summarized and concluded the types and forms of subgrade damages, introduced the reasons of each damages from natural factors, geological conditions, design, construction and maintenance, etc.Secondly, according to the functional characteristics of each part of soft soil subgrade, it′s divided the whole system into main subgrade body, shoulder, slope, drainage facilities, subgrade protection and retaining walls; according to the functional characteristics of each part of cutting slope, it′s divided the whole system into rock and soil mass, drainage measures, retaining and reinforcement measurement and protective measurement. For each evaluation object, builded the evaluation index that can reflect its function characteristics. By analytical hierarchy principle, the maintenance evaluation index system of soft soil subgrade and cutting slope was developed. Under this premise, based on statistic, multianalysis and modeling theory, the relations among evaluation index, objects and subgrade technical condition were studied about national and provincial highway subgrade, and evaluation model of national and provincial highway subgrade is developed.Then, based on the basic concept of preventive maintenance, the paper simply discussed the basic principles, the main contents and requirements, the technical state standard, technology, implementing countermeasure of subgradet preventive maintenance and forecasted the subgrade technical state by using time sequence method.Finally, the research conclusions were used in two practical engineering in Guangdong, which specify the application of the evaluation model.