Abstract: A joint for pre-cast concrete twin-leaf arch sections is self-aligning when the two arch sections are initially brought into abutting contact with each other. The joint provides a rigid connection between the twin units and is achieved on site by means of re-inforced cast-in-place concrete. Reinforcement splices for the connection are lap splices, and the joint allows pouring the cast-in-place concrete without the need of formwork. For load distributing purposes, a continuous connection of individual arch rings in the longitudinal direction at the arch crown is possible. An initial abutting contact between the twin units is provided by the joint of the present invention. The contact provided by the joint of the present invention is self-aligning, locking, allows the controlled transmission of the abutting force and allows for a temporary connection. The joint includes mechanical elements for aligning and locking the two arch sections together.

Abstract: An overfilled arch structure includes a spandrel wall that is formed of a plurality of separate segments, each of which is monolithic. The arch structure includes an arch end element having a curb thereon at one end edge, and the segments of the spandrel wall each have a front face that is in abutting contact with the curb and a rear face that is exposed to earth backfill. Vertical support for the segments is provided by the arch end element and the foundation and horizontal support is provided by the curb and the wingwalls. Stabilization is provided by the earth backfill. The lateral segments of the spandrel walls are mirror images of each other and can be formed in a single form. A joining spandrel segment is identical to two lateral segments in edge-to-edge relationship and is used for side-by-side structures. A central segment, like the lateral segments, has at least one arcuate side for snugly abut against the arch element, and can have two arcuate sides.