ZHA Xu-dong, SUI Zi-fan, ZHANG Jun-xuan, XU Hai-xin
Manholes are important ancillary facilities on urban roads and are prone to subsidence, tilting, and damage under the action of increasing traffic loads. Additionally, the pavement around manholes experiences various types of distress such as cracking, settlement, and loosening. When vehicles pass through distressed manhole covers-surrounding pavement, a decline in driving safety and comfort is noticeable and noise pollution is generated, which negatively affects the road performance and quality of life of neighboring residents. For these reasons, by collecting and sorting the relevant research results, the inducing mechanisms of distress for manhole covers-surrounding pavement were analyzed based on experimental, theoretical, and simulation methods. The development status of distress treatment technology was reviewed from the perspectives of structural optimization, material selection, and equipment innovation. Combined with the concept of intelligent transportation system construction, the achievements and limitations of the research on intelligent detection and supervision technology of manhole cover-surrounding pavement distress were evaluated, and the development trends in this field were investigated. The results show that the distress rate of the manhole cover-surrounding pavement is as high as 58.9% under dynamic driving loads, and the main distress types encompass structural settlement and pavement cracking. Specifically, the former primarily occurs within 3 cm, whereas the latter is concentrated in an area of 15-40 cm around the manholes. Various factors contribute to these distresses, including a crushed mortar cushion under the manhole cover, lack of manhole rings, substandard compaction of the subgrade and pavement, and low bearing capacity of the manhole cover. Successful methods have been proposed for effective distress delay and treatment, such as optimizing the structure of the manhole cover-surrounding pavement, improving the properties of materials used in the manhole cover cushion and surrounding pavement repair, and refining the approach leveling for manhole covers. The incorporation of data collected from mobile mapping systems, unmanned aerial vehicles, smartphones, and other equipment into deep learning algorithms allows for the automatic and efficient identification of manhole covers, the surrounding pavements, and their distress. Through technologies such as joint information processing, network transmission, and perception recognition, a relatively complete intelligent supervision system can be built to realize an integrated management of the construction, management, and maintenance for manhole covers-surrounding pavement.
