RU2252294C1 - Combined support wall with gauze anchors - Google Patents

Abstract

FIELD: hydraulic structures, particularly for slope and river or channel bank consolidation.

SUBSTANCE: support wall includes gabions made of gauze and filled with stones. The gabions are laid in layers. Support wall is fastened with gauze anchors to ground embankment from another wall side. Gabions are made as parabolic cylinders connected one to another so that ridge of each upper gabion is offset relative that of previous lower ones to which above upper gabions are connected. Support wall base is protected against erosion by flexible reinforced concrete apron. The wall is covered with concrete coating from working side thereof. Gauze anchors may be continuous or discrete. Number of continuous anchors is more than one.

EFFECT: increased load-bearing capacity and reduced cost.

4 cl, 7 dwg

Description

The invention relates to hydraulic engineering and can be used as a device for strengthening slopes, shore protection structures in eroded riverbeds, canals and other structures.

A device gabion [1], consisting of a metal mesh shell and a filler in the form of active metallurgical slag.

The disadvantages of this technical solution are:

- the gabion net may undergo strong abrasion by sediment during operation;

- bearing capacity for bending and shear of such a structure is quite low;

- the design and method of construction is quite complicated;

- such a technical solution is ineffective to use for fastening high slopes;

The closest technical solution is a combined retaining wall with mesh anchors, including mesh gabions filled with stones and laid in layers, and on the other hand anchored with mesh anchors in a soil embankment [2]. The disadvantages of this technical solution are:

- the rigidity of the gabion structure is insufficient, since there is no connection between the layers inside the gabion and between the gabions;

- the shape of the gabion frame is variable;

- bearing capacity for bending and shear of such a structure is quite low;

- economically, it is not a favorable technical solution.

The purpose of the invention is to increase the bearing capacity when working on bending and shear and to protect the retaining wall from abrasion by sediment.

This goal is achieved in that the combined wall with mesh anchors of rectangular or other section consists of parabolic cylinders. A combined retaining wall with mesh anchors from parabolic cylinders is constructed gradually, for this, first, the lower mesh is laid at the base. The mesh is stacked with offset and overlap. In the overlap place, the nets are interconnected by a connecting wire. The connecting wire is twisted by a device for twisting the wire, which has two special holes for this, into which the ends of the connecting wire are inserted and then twisted with a lever, thereby forming a strong connection. Parabolic cylindrical shapes are laid on the mesh carpet thus formed. The parabola lying at the base of the parabolic cylinder is described by the equation

where X, Y are respectively the abscissa and the ordinate of the parabola lying at the base of the parabolic cylinder;

In _g , h _g - respectively the width and height of the gabions, In _g = (2-4) h _g .

A stone is filled into the loading hole of the mold to form a layer of stones having a similar shape, after which it is removed. On the upper layer of stones having the shape of parabolic cylinders, the upper grid is laid by unwinding rolls, which, hugging it, is attached using a connecting wire to the lower layer of the grid. Each individual parabolic cylinder on one linear meter of length has 6-10 fasteners of the connecting wire, the thickness of which is usually 4-5 mm and the tensile strength can reach 800-1300 kg. Thus attached parabolic cylinders have increased stability against shear and bending construction loads. Next, along the layer of parabolic cylinders, a second layer of gabions of parabolic cylinders is laid, which is attached by a connecting wire to the ridges of the lower layer (Fig. 3). The ridges of the second layer of gabions are shifted relative to the ridges of the lower layer of gabions. The second is followed by the third, and so in succession a high combined retaining wall is constructed, the height of which can reach large dimensions, while the wall remains thin, since the structure is able to work on bending loads.

The most favorable orientation for combined fastening is transverse, since the formed parabolic cylinders with this orientation have increased structural rigidity for compression and bending, therefore they are less deformed during operation and are most stable when working under bending loads.

The most favorable gabion height is h _g = 0.2-0.5 m. At this gabion height, the width varies within B _g = 0.5-1.0 m and the stones under the grid are maximally fixed due to the friction force of the stones about the side surface of the grid. The friction force on the side surface in this case exceeds the weight of the stones, and they will not fall out of the grid, even if gabions from parabolic cylinders are brought into a vertical position.

One side of the retaining wall, which works for compression and abrasion, is concreted. It is known that the compressive strength of concrete is tens of times greater than tensile, and this will significantly enhance the bearing capacity of the structure during bending. The thickness of the concrete layer depends on the magnitude of the calculated bending moment. Concrete is also a reliable wall protection against abrasion by sediment.

On the other hand of the combined retaining wall with mesh anchors, mesh anchors are attached that are embedded in the ground and may have a continuous or discontinuous structure, depending on the height of the retaining wall and the physicomechanical characteristics of the soil going backfill.

To enhance the bearing capacity when working on bending loads, as well as the stability of the structure to capsize, the wall can have a stepped cross-sectional shape with decreasing step width upward (Fig. 1). The flat side of the wall adjoins the supported soil, thereby shifting the center of gravity of the retaining wall and increasing the moment that keeps it from tipping over.

In front of the combined retaining wall with mesh anchors there is an reinforced concrete apron. For this, the apron has a more elongated structure and can be lowered when washing away, without affecting the stability of the structure as a whole. The reinforced concrete apron is made by concreting the previously laid out wicker mesh.

Figure 1 shows a cross section of a combined retaining wall with mesh anchors; figure 2 is a section aa in figure 1; figure 3 - section bb in figure 1; figure 4 - mesh anchors from woven mesh; figure 5 - combined retaining wall with intermittent mesh anchors, axonometry; figure 6 - shows a plot of the bending moments of the combined retaining wall with mesh anchors; 7 is a diagram of the bending moments of the combined retaining wall embedded in the base.

The soil 1 rests on the combined retaining wall of the stepped section 2, consisting of concrete lining 3 of parabolic cylinders 4. The combined retaining wall of parabolic cylinders 4 is constructed gradually and the bottom mesh 5 is laid horizontally at the base, and the stones 6 are covered on top with the upper mesh 7, which is fixed connecting wire 8 to the bottom mesh 6. Flexible retaining wall anchored into the ground by continuous mesh anchors 9 or intermittent mesh anchors 10. Front of retaining wall 2 attached armobetonny flexible apron 11. In the concrete wall are provided structurally-expansion joints 12.

Combined retaining wall is constructed and operates as follows. On the prepared base, the lower layer of mesh 5 is laid. The mesh 5 is stacked with offset and overlap. In the place of overlap, the grids 5 are connected to each other by a connecting wire 8. On the thus formed carpet from the grid 5, shapes having the shape of parabolic cylinders are laid. The parabola lying at the base of the parabolic cylinder is described by the equation

where X, Y are respectively the abscissa and the ordinate of the parabola lying at the base of the parabolic cylinder;

B _g , h _g - respectively the width and height of the gabions, B _g = (2-4) h _g .

Stone 6 is filled into the loading hole of the mold to form a layer of stones having a similar shape, after which it is removed. On the upper layer of stones 6, which are in the form of parabolic cylinders, the upper grid 7 is laid out by unwinding rolls, which, hugging it, is attached using the connecting wire 8 to the lower layer of the net 5. Next, a second layer of gabions from parabolic cylinders is laid along the layer of gabions from parabolic cylinders 4 4, which is attached by a connecting wire 7 to the ridges of the lower layer (figure 3). The ridges of the second layer of gabions are shifted relative to the ridges of the lower layer of gabions. The second is followed by the third, and so in succession a high combined retaining wall is built, the height of which can reach large dimensions, while the wall remains thin.

Moreover, the orientation of the parabolic cylinders can be both transverse and longitudinal with respect to the direction of movement of the water stream. The most favorable orientation is transverse, since the formed parabolic cylinders with this orientation have increased structural rigidity for compression and bending, therefore they are less deformed during operation and are most stable when working on bending loads. The side of the combined retaining wall, which is in contact with water and during bending, works in compression, is covered with concrete cladding 3. It is known that the bearing capacity of concrete during compression is tens of times greater than the bearing capacity of concrete during tensile work. In the concrete cladding 3, structural-expansion joints 12 are provided, providing flexibility and the ability to deform the structure.

The most favorable gabion height is h _g = 0.2-0.5 m. At this gabion height, the width varies within V _g = 0.5-1.0 m and the stones under the net 7 are maximally fixed due to the friction force stones 6 about the side surface of the grid 7. The friction force on the side surface in this case exceeds the weight of the stones, and they will not fall out of the grid 7, even if the gabions from the parabolic cylinders 4 are brought into a vertical position.

As the construction progresses, the wall is anchored with continuous mesh anchors 9 (Fig. 4) into a soil embankment. Mesh anchors may also have a discontinuous structure 10 (Fig. 5) if the retaining wall is not high. As a result of anchoring, the calculated bending moment is reduced (Fig.6), which allows to make the design thinner and more economical. Since without anchors the wall works as a seal with a large bending moment at the base (Fig. 7).

The number of anchors 9 and 10 may be more than one and depends on the height of the wall. With an increase in the number of anchors 9 and 10, the calculated bending moment decreases, and the design will accordingly be more economical.

To increase the bearing capacity when working on bending loads, as well as the stability of the structure to capsize, the wall has a stepped cross-sectional shape with decreasing width of the steps up (figure 1).

In front of the combined retaining wall with mesh anchors, an reinforced concrete apron 11 is provided (Fig. 2), so when washing the flexible apron is lowered, which prevents undermining of the structure.

The proposed combined retaining wall with mesh anchors is cheaper and more reliable in the work of well-known similar technical solutions. At the same time, the cost-effectiveness of these structures is 1.5-2 times greater, since the design is able to work on bending loads, and the calculated bending moments are less than for walls with a seal.

Sources of information:

1. A.S. 1141143 USSR, MKI E 02 3/12. Gabion Saratov I.E., Svirenko L.P. and Sherkov I.A. (USSR); Claim 09/14/83; publ. 02/23/85, Bull. No. 7 (analog).

2. United Kingdom No. 2073281 A, cl. E 02 D 17/18, publ. 10/14/1981 (prototype).

Claims (4)

1. A combined retaining wall with mesh anchors, including mesh gabions filled with stones and laid in layers, and on the other hand anchored with mesh anchors in a soil embankment, characterized in that the gabions have the shape of parabolic cylinders connected to each other with offset gabions of each upper gabion layer relative to the gabion ridges of the previous lower layer, to which gabions of the corresponding upper layer are attached, while the retaining wall at the base is protected from undermining by flexible reinforced concrete apron and, on the operating side is covered with a concrete lining. 2. Retaining wall according to claim 1, characterized in that the mesh anchors are solid. 3. Retaining wall according to claim 2, characterized in that the number of continuous mesh anchors is more than one. 4. Retaining wall according to claim 1, characterized in that the mesh anchors are intermittent.

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