Stability assessment for highway with large-span box culvert jacking underneath: a case study

A case study of a double-cell, large-span prefabricated reinforced concrete box culvert with a total length of 52 m, a width of 46.8 m, and a height of 9.3 m, which passes beneath the Beijing – Hong Kong –Macau highway, is presented. The culvert is embedded in silty sand and silty clay at a depth of 1.2 m. To ensure the safety and normal operation of the highway, hydraulic jacking with the protection of a pipe roof was adopted for this project. This paper introduces the construction scheme in detail. A three-dimensional numerical simulation of the responses of the highway under which a wide box culvert jacking passes was conducted. The monitoring results on the highway as well as the actual construction process and problems encountered were analyzed. The different development characteristics or trends for the settlement and horizontal displacement of a highway surface are presented. In addition, this paper discusses the reasons for the large deformation of the highway surface as well as proposes reasonable suggestions.