Front Wall of Overfilled Arched Reinforced Concrete Underpasses

The invention deals with the front wall of overfilled reinforced concrete arches.

Usually, such arches are cut off at their end either slanting--depending on the slope inclination of the earth fill--or they are limited by a vertical reinforced concrete wall, placed in front of them, that abuts on the end of the arch. The earth pressure of the overfill of the arch acts upon this front wall.

The disadvantage of these conventional methods consists in the case of the slanting cut-off in the difficult practical design and construction of the end portions of the arch. In the case of prefabricated arches with reinforced concrete shells, the outer elements have to be chosen especially strong and they have to be partially fastened in the foundation, since these elements do not connect forming a complete arch because of the cutout in the apex portion. In the case of using conventional front walls, there exists the disadvantage in the costly procedure of casting on-site in the fact, that in the case of a solid connection with the edge of the arch, the front wall and the edge of the arch influence each other statically in an unclear manner, while in the case of a front wall not solidly joined to the arch, the horizontal earth pressures from the overfill can be transmitted to the lateral wing walls only with heavily built-up, heavy front wall constructions.

According to the invention, these disadvantages are eliminated inasmuch as the front wall is built from two prefabricated reinforced concrete elements, that are connected to each other and to the arch only in the apex portion, and namely in such a manner that the connection with the arch in the apex portion does induce only horizontal forces into the arch, whereas in the case of vertical relative movements between the center of the front wall and the arch apex there are not transmitted any stresses in a vertical direction from the arch to the front wall, and vice versa. This is achieved in that one or several metal rods in the apex portion are embedded in concrete in the arch itself as well as in the front wall. In such case, the metal rods can be firmly embedded in concrete over a determined length at their ends, thus being pinended, or they can be connected jointed at their ends with anchoring elements embedded in the on-site cast joint portion.

In the first case, an encasing tube concentrically surrounding the metal rod in the central portion of the steel rod allows the free movement in the case of vertical relative movements between arch and front wall. The central portion of the metal rod, surrounded by the encasing tube, is designed in a flexible but tensile-strength manner. In the second case, the metal rod rotates in the joints in the event of relative movements and, again, this rotation is made possible by a similar encasing tube. The diameter of the encasing tube has to be chosen in both cases to be large enough, so that the metal rod can move freely in the case of the relative displacements to be expected.

The embodiments of the invention are described in the following figures:

FIG. 1 shows the horizontal projection of an arch (in this example, out of prefabricated reinforced concrete shell elements).

FIG. 2 shows a view of the front surface of the arch.

FIG. 3 shows in detail the position of the metal rods.

FIG. 4 shows a section taken at line A--A of FIG. 3.

Not shown is the reinforcement extending from the front wall elements (see also FIG. 2) from left to right into the on-site cast joint, which, together with the on-site cast concrete, assures the tensional connection of both front wall elements.

In FIG. 1, 1 represents the reinforced concrete shell elements of the arch, 2 represents the front wall elements, 3 represents the on-site cast concrete apex joint, 4 represents the arch foundations, and 5 the wing walls. The metal rods 6 are indicated in a general manner in the apex portion at both arch ends in FIG. 1, which is represented as horizontal projection without overfill.

FIG. 2 shows a frontal view of the arch as seen from the undercrossing traffic path. 13 denotes the apex portion of the arch.

FIG. 3 is an enlargement of the arch horizontal projection in the apex portion at the front wall with the metal rods 6, whose end portions 9 are embedded in concrete and are thus pinended into the on-site cast concrete of the apex joint 3, on one hand, and into the on-site cast concrete of the joint 8 between the two prefabricated front wall elements, on the other hand. The central portion 10 is enclosed in an encasing tube 11.

FIG. 4 shows a cross section A--A vertical to the axis of the metal rod 6, wherein 6' indicates the position of the metal rod before the relative displacement. Indicated by dotted lines are the end plates 12, which induce the traction forces into the arch, resp. into the on-site cast concrete of the front wall.