Method Of Producing Tunnel Or Like Structure

Abstract

A tunnel section is produced by enclosing an annular ring of expanded metal within an outer covering of plastic material. The expanded metal has inward projections struck out from it which are small enough to enter the spaces or to enter into openings provided in another sheet. The inner surface of the expanded metal is then sprayed with concrete, the thickness of the layer formed being less than the length of the struck out tongues. After the concrete is sufficiently cured, another layer of expanded metal is placed on the inside wall, with the tongues of the first layer passing through openings in it, and the tongues are bent over to secure the latter layer in position and to connect the layers together. The second layer also has inwardly projected tongues. The second layer is then sprayed in the same manner as the first. This is continued until the desired wall thickness is obtained.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to the production of reinforced concrete structures such as tunnels or the like.

2. The Prior Art

In the past, enclosed concrete structures have been produced in general by constructing a frame work of reinforcing bars held together in various ways, to which concrete is then applied. Such structures have either been formed in advance or have been formed in situ.

SUMMARY OF THE INVENTION

The present invention provides a less expensive and more efficient method of producing tunnels or similarly enclosed concrete structures. According to the invention, the concrete structure is produced by enclosing an annular ring of expanded metal within a plastic cover, the expanded metal having inwardly projecting tongues. This structure is then sprayed from the inside with concrete, the thickness of the layer of concrete being less than the length of the tongues. When the concrete is sufficiently cured, another layer of the expanded metal is placed on the inside, with the tongues of the first layer passing through holes of the second layer. Another layer of concrete is sprayed on. This procedure is repeated until the necessary thickness is achieved.

The structure of this nature can be produced very economically, requiring considerably less labor than other procedures for obtaining structures of the same strength. The resulting structure is sturdy and withstands strain and stresses. Expensive molds are not required, as all that is needed is something on the outside of the expanded metal to prevent the escape of the concrete and its contact with the surrounding soil, metal section or the like.

BRIEF DESCRIPTION OF THE DRAWING

The drawing shows in cross-section a portion of a wall structure produced according to the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT

According to the invention, a sheet 2 of perforated metal, such as expanded metal, is arranged inside a container sheet 4 which may be of plastic or similar material. The sheet 2 has struck from it prongs 6. On the interior of the assembly, a layer of concrete 8 is sprayed, preferably in the manner described in the application to Cornwell et al., Ser. No. 841,298 filed July 14, 1969. The thickness of the layer 8 is less than the length of the prongs 6. A second layer 10 of expanded metal or the like is then placed over the concrete, and the ends 12 of the prongs are bent down to hold the second sheet in place. A second layer 14 of concrete is then sprayed on and this procedure is repeated until the desired thickness of the wall is achieved.

Claims

I claim:

1. A method of forming a concrete wall which comprises spraying a slurry of concrete on a perforated metal member having tongues projecting inwardly therefrom and having an imperforate backing, the thickness of the layer of concrete being less than the length of the tongues, applying a second sheet of perforated metal over the sprayed concrete with the tongues of the first sheet extending through openings in the second sheet, bending down at least some of the tongues of the first sheet over the second sheet, and spraying a second layer of concrete on the surface of the second sheet.