Shanghai Qinkai Industrial Co., Ltd. said it will handle the entire process from product design to factory supply on domestic tunnel projects, supplying conduits, steel frame supports, finished frame components and connectors.
A tunnel cable route is not a building route with a roof over it. It is installed where space is fixed, access runs in one direction, humidity is continuous, and the working environment is itself the main constraint on how the material can be installed. The scope Qinkai is taking on covers the steel and conduit system that carries and protects cable along the alignment — designed to the tunnel as surveyed, fabricated in one shop, and shipped in a condition that requires assembly rather than construction underground.
The tunnel decides the geometry, not the drawing
A curved alignment does not accept a nominal dimension
Cable routes follow the tunnel, and the tunnel does not follow a straight line. On a curved alignment, supports are placed at intervals along an arc, and the surface they fix to — whether a segmental lining or a cast-in-place lining — is never a perfect datum. Ring joints, pour lines and construction tolerances mean the attachment surface varies from position to position. A frame designed to a nominal dimension lands correctly on some of them and wrongly on the rest.
The fix is procedural rather than clever: design the frame package against an as-built survey of the lining, and give the assembly enough adjustment to absorb what the survey cannot capture. That work only happens if the party designing the supports is also the party that has to make them.
The attachment surface belongs to the civil contractor
The embedded channels, plates or anchors that frames hang from are normally placed by the civil or lining package, months before the cable support system is installed. If their position drifts, the support package has to absorb the difference. When the support package is designed and fabricated by one supplier, that difference is handled in a shop drawing. When it is not, it is handled with a hammer drill in a confined space, which is the slowest and least verifiable way to make a hole in a tunnel.
“Designing the frame to the survey sounds like an extra step until you have watched a crew drill into a lining at the wrong elevation,” the company said.
Nothing gets welded underground
Finished frame components as a hot-work strategy
Welding inside a tunnel is possible, and almost always expensive. It requires ventilation, a fire watch, a permit window and a crew working in a space that is simultaneously being used by other trades. Every weld that can be moved into a workshop removes that cost from the programme.
That is the role of finished frame components: frames assembled, welded and coated in the shop so that underground work becomes bolting and positioning. The coating benefits as well. A finish applied in a galvanising bath or a coating line covers edges and welds uniformly, under conditions where thickness can be measured and recorded — as opposed to a cut edge touched up by hand at the face, which is the point where corrosion starts.
What the packing has to survive
Access to a tunnel face is usually one-way and often narrow, through a portal, a shaft or the tunnel itself. Crates have to fit the access route, be light enough for the available lifting equipment, and be packed in the order the installation proceeds. Storage space at the face is limited, so material that arrives early becomes material that has to be protected and moved twice.
“The crate is part of the design,” the company said. “If it cannot reach the face, a perfect frame is still a delay.”
The four items in scope
“Every connector is a decision about who owns the interface,” the company said. “We would rather own it in the drawing than discover it at the face.”
Delivering against one-way progress
Installation in a tunnel advances in one direction, so delivery has to advance with it. Material cannot be staged 800 metres inside an unfinished tunnel without cost: it has to be protected, moved and then moved again. What the site needs is a production schedule expressed as arrival order — which crate, at which portal, on which night, for which section of the route.
Documentation travels with the crates on the same logic. Coating records, inspection reports and packing lists have to be usable at the face where the material is being installed, because a record that cannot be produced in a confined space is as much of a problem there as a missing bracket.
Post time: Sep-24-2026