Dahe Grand Bridge, Hubei’s Highest Pylon Bridge Under Construction, Achieves Closure

According to the Hubei Provincial State-owned Assets Supervision and Administration Commission, Dahe Grand Bridge, a key control structure on the Lichuan–Xianfeng Expressway, has been fully closed. Spanning the deep V-shaped valley of the upper Dahe River in Xianfeng County, the continuous rigid-frame bridge features a left span of 1,365 metres and a right span of 1,370 metres. Its main pier stands 170 metres high, with a main span of 170 metres, making it the continuous rigid-frame bridge with the tallest main pier and largest main span currently under construction in Hubei Province.

Pier 23 represents the most demanding segment of the whole route. It rests at the bottom of the Dahe valley on large-diameter deep piles and a massive concrete base. The base sits roughly 110 metres below the mountain summit and 45 metres above the river surface, requiring foundation works at the foot of a steep cliff.

Construction teams faced multiple barriers including limited access, difficult material transport, complex hoisting and concrete pouring. Mountain slopes reached 70 degrees, leaving no route for heavy machinery. A working platform was excavated on the northern hilltop, connected by a 400-metre access track 4.5 metres wide carved along the mountainside. A 70-metre steel trestle and tower crane were then erected to shuttle supplies to the pile foundation site. The 24 pile shafts were excavated manually amid widespread karst formations, using hand tools and diamond drilling. The project team independently designed lifting gear to lower 40-tonne reinforcement cages over a vertical drop of 120 metres via slope tower cranes.

A custom concrete chute system fitted with speed reduction devices was developed to move material down the cliff. After seven rounds of testing, a three-stage delivery sequence transferred concrete from tankers at the hilltop through chutes, storage hoppers and secondary mixing to the pile openings. This vertical conveying technology for an 180-metre drop filled a domestic technical gap.

Additional precision controls were adopted during tensioning and grouting. Valves were fitted at grout inlet and outlet points, and steel alignment bars and custom measuring gauges were deployed to restrict dimensional error. A full-coverage intelligent sprinkling system allowed remote curing via mobile devices.

The construction cycle spanned 1,399 days from the first pile drilling on 27 November 2022 to final closure on 25 September. The completed works comprise 218 pile foundations, 42 bearing platforms, four abutments and a range of pier structures. Teams prefabricated 210 pieces of 40-metre T-beams and cast 246 cantilever box-girder segments, all delivered on schedule to required quality standards. Sixteen national patents, four construction methods and four science and technology awards have been generated during the build.

The Lichuan–Xianfeng Expressway stretches for approximately 84.5 kilometres with an estimated total investment of 19.45 billion yuan. Groundbreaking took place on 29 December 2022 under a 48-month construction timetable, and full opening is scheduled for 2027. Work on the project has reached 97 per cent of total investment. Earthworks, bridge, tunnel and building sections are substantially finished, while surfacing, traffic safety, landscaping and electromechanical installations proceed.