| dc.description.abstract | In Taiwan, most pipelines are buried under the road pavement, and the five vital pipelines are important for people′s livelihood. The underground condition of the pipelines is staggered and complicated. To maintain the existing pipelines and new pipelines, repeated excavation and backfilling are often carried out on the pavement, thus affecting the road pavement service and causing difficulties for the road authorities to maintain and manage the pavement. It is an important subject to understand the influence of pipeline excavation engineering on pavement service.
Considering that there is no set of matching design regulations for CLSM in China at present, in addition, there is no exact regulation on the time and thickness of resurfacing after temporary repair, which is often suspected of unstable quality, excessive design, or insufficient design strength. Therefore, this study first referred to ACI-211, ACI-229, and construction specifications, and adjusted the CLSM ratio design process suitable for domestic by the regulations under the consideration of seasonal influences. Then, the finite element method was used to analyze the pavement structure of pipeline excavation, analyze the influence of pipeline backfilling on the pavement, and discuss the mechanical behavior of pavement structure. Subsequently, in-situ test laying of pipeline excavation was carried out according to the proposed matching process, and relevant effectiveness tests were carried out on the surface layer and CLSM of the testing process, to verify the rationality of the matching design process and structural analysis adjusted in this study.
In this study, parameters including CLSM parameters and tube depth were discussed. Finite element analysis was used to understand the influence of different parameters on the surface layer of temporary repair, to analyze the strength development of CLSM during the temporary repair period, and to the optimal tube depth. The structural analysis showed that the strength of CLSM could reach a stable state after 4 days of temporary repair and maintenance. In addition, the Clegg impact test was carried out on CLSM for 4 days after temporary repair in the site test, and the result can meet the requirement that the bottom strength CBR is greater than 80% in the construction specification. Based on the above structural analysis and the results of in-situ test laying, it can be seen that the pipeline excavation with CLSM backfill can be carried out in a comprehensive surface planning operation after 4 days of temporary repair and maintenance.
In addition, the structural analysis of different planing thicknesses is also carried out. The ESALs values of the common planing thickness of 10 cm and 20 cm are analyzed. From the structural analysis, the ESALs values of the traffic volume of 20 cm are about 3~4 times that of 10 cm. In addition, the light deflection instrument test (LWD) was carried out for the section of 10 cm surface layer and 20 cm surface layer in the ground test pavement. The test results show that the strength of the 20 cm AC surface layer is about 3 times that of 10 cm, which verifies the rationality of the above structural analysis.
Finally, the results of the field test were discussed. It can be seen from the results that the matching design process of CLSM established in this study can meet the requirements of relevant specifications, and the results of the structural analysis were verified. Therefore, the relevant specifications of CLSM were discussed at last in this study, hoping to improve the construction and design quality of CLSM in China by using the results of this study. | en_US |