EP1553230B1 - Method for rehabilitating retaining walls - Google Patents

Description

The invention relates to a method for intercepting retaining walls with pending soil behind by subsequent attachment of load distribution bodies, wherein on the wall rear side generated in lateral intervals cavities and are precipitated with the load distribution body forming material.

In the rehabilitation of retaining walls, such as heavyweight walls, which should remain intact for the sake of monument preservation, but are no longer statically suitable to absorb the earth pressure of the underlying soil, it is known to arrange on the back of the wall load distribution body, the earth pressure partially or completely to relieve the retaining wall to be renovated. For this purpose, different embodiments and functions of this load distribution body are known.

For example, as viewed from the closest prior art NL 9 201 356 A It is known to stabilize a pile wall built on a bank thereby and additionally statically support that on land side immediately next to the sheet pile wall a band-like monolithic structure of a suitable filler and a binder is produced that absorb the forces acting on the sheet pile wall forces and thereby the Sheet pile can relieve. If such a method were not applied to sheet pile walls in the shore area, but in the rehabilitation of retaining walls, as a result built a second retaining wall, which can absorb the forces occurring behind the first, to be rehabilitated retaining wall.

Furthermore, it is known ( AT-B-217 676 ), on the back wall to be rehabilitated retaining walls vertical, spaced apart partitions to erect to intercept the earth pressure. In this known method, the partitions are formed by injections are made successively in several adjacent areas of the soil. In order to connect these areas to form a partition, anchors are driven from the retaining wall into these areas. Between the partitions, a silo effect is achieved in the soil, through which the Earth pressure is recorded. These measures are relatively expensive, which is uncertain in each case due to the different nature of the soil, whether the dividing walls thus formed receive a statically sufficient relationship.

It is also known ( DE-OS 34 08 461 ), along the entire retaining wall on the back of the wall to create a cavity by rinsing, which is then filled by pressing a mortar mass, which forms after setting a related to the retaining wall masonry body, which is a complete heavyweight wall whose stability is also statically detectable. The required amount of work and mortar mass is relatively large. The retaining wall to be rehabilitated is not relieved of the earth pressure, but converted into a statically verifiable heavyweight wall.

In another known method ( EP 0 272 473 B1 ) are flushed through horizontal holes through the retaining wall at the back of the wall by high pressure water flushing cavities, which are filled with cementitious material and form load distribution body in the form of pillar reserves. Again, the effort to produce the necessary cavities for rinsing, relatively large. The contours of the cavity created by the flushing process are often irregular and not exactly testable, so that the resulting dimensions of the pillar reserves created make a static determination and verification difficult.

Finally, it is also known ( EP 0 290 941 B1 ), to produce by such by horizontal holes in the retaining wall flushing cavities to form, for example, disc-shaped load distribution bodies, which are anchored by introduced from the front wall front anchor in the ground and so absorb the earth pressure. Again, the relatively expensive measure is required to produce the cavity by rinsing. Because of the difficulty of providing the contours of the cavity and thus of the load distribution body with sufficient accuracy, the load distribution bodies are often made larger than would be required from a static point of view.

The described known methods, in which cavities are produced by flushing behind horizontal holes of a retaining wall to form there each a load distribution body, while having the advantage that no interference from the 'earth surface are required on the back wall. These methods are therefore suitable in those cases where the earth's surface is not accessible behind the retaining wall to be rehabilitated, for example, because there are buildings or historic cemeteries. In many cases, however, immediately behind the retaining wall on the surface at least to a limited extent an access option, even if there is insufficient space available to make extensive excavation work.

The object of the invention is therefore to provide a method of the type mentioned in such a way that under Utilization of often limited access options behind the back of the wall load distribution body can be made, which are also statically verifiable.

This object is achieved, according to claim 1, according to the invention solved in that for the formation of each cavity from the earth's surface starting directly on the back wall of a shaft is sucked off by sucking the earth material, wherein at the earth's surface only a very small, essentially by the ground plan dimensions Load distribution body predetermined space is required, which is sufficient for the suction, and that the load distribution body forming material is introduced.

The load distribution bodies formed on the rear side of the wall at a distance from one another in particular absorb the earth pressure of the soil lying behind, in particular by vaulting, thus relieving the retaining wall. On the back of the wall load distribution body are generated with predetermined dimensions and testable quality, wherein at the earth's surface only a very small, essentially predetermined by the floor plan dimensions of the load distribution body space is required, which is sufficient for the suction.

These load distribution bodies are preferably enabled by the earth pressure to be anchored in the ground by essentially horizontal ground anchors introduced from the front of the wall on the principle of self-supporting earth nailing. This can also load distribution body of small dimensions for Recording high forces are used in statically verifiable and verifiable form.

Preferably, the load distribution bodies are formed by setting material and the ground anchors are after the setting of the material introduced by preferably horizontal holes from the front wall of the front.

However, the method is also suitable to form pillar reserves as a load distribution body, which are preferably non-positively connected to the retaining wall and enable them to absorb the earth pressure on the heavy weight principle in a statically verifiable manner.

A region of each cavity created by aspiration above the load distribution body can be filled with earth material, preferably again with the previously extracted earth material.

In development of the invention it is provided that the shaft walls are secured by a shaft wall formwork. This allows the process to be used even on difficult, non-cohesive soils.

Thus, the shaft walls can be secured by a shaft wall formwork entrained during sinking, in which case the shaft wall formwork is pulled out of the shaft during the concreting process and the material forming the load distribution body is introduced. The shaft wall formwork, for example, consist of releasably connected formwork segments.

The use of the temporary shaft wall formwork or chess liners, which are designed, for example, as box elements, makes it possible to use the method of extracting soil material in order to produce cavities of predetermined dimensions, which are attached to the Wall back often have to be relatively narrow and deep, so that the exact work with other funding procedures is excluded.

The drawback associated with the method of extracting soil material is that the walls of the created cavity are irregular, and that at greater depths and / or loose soil there is a risk of loose soil falling into the cavity, becomes easy in difficult, non-cohesive soils overcome by the use of the continuously entrained shaft wall formwork, which are pulled out when filling the cavity again.

According to another advantageous embodiment of the invention it is provided that the shaft wall formwork is formed by a series of injections, through which a support liquid is pressed into the soil. In this way, even in cohesion-less, non-cohesive soils a fuse of the shaft is achieved without the need for separate formwork elements should be used.

Further advantageous embodiments of the inventive concept are the subject of further subclaims.

• Fig. 1 in einem vereinfachten senkrechten Schnitt den Vorgang bei der Herstellung eines Hohlraums an der Rückseite einer Stützmauer,
• Fig. 2 eine Ansicht der mit Lastverteilungskörpern bestückten Rückseite der Stützmauer in einer Ansicht in Richtung des Pfeiles II in Fig. 1,
• Fig. 3 einen Schnitt längs der Linie III-III in Fig. 2,
• Fig. 4 in einer Darstellung entsprechend der Fig. 1 eine abgewandelte Ausführung des erfindungsgemäßen Verfahrens, wobei beim Abteufen eine Schachtwandschalung mitgeführt wird,
• Fig. 5 in räumlicher Darstellungsweise das in Fig. 4 dargestellte Verfahren und
• Fig. 6 bis 8 jeweils in einem Horizontalschnitt mehrere Stufen einer anderen Ausführungsform des erfindungsgemäßen Verfahrens.

The invention will be explained in more detail using an exemplary embodiment, which is shown in the drawing. It shows:

• Fig. 1 in a simplified vertical section the process in the production of a cavity at the back of a retaining wall,
• Fig. 2 a view of the equipped with load distribution bodies back of the retaining wall in a view in the direction of arrow II in Fig. 1 .
• Fig. 3 a section along the line III-III in Fig. 2 .
• Fig. 4 in a representation corresponding to the Fig. 1 a modified embodiment of the method according to the invention, wherein a shaft wall formwork is carried along when sinking,
• Fig. 5 in spatial representation the in Fig. 4 represented method and
• Fig. 6 to 8 each in a horizontal section several stages of another embodiment of the method according to the invention.

As in Fig. 1 1, a cavity 4 is produced directly on the rear side 1 of a retaining wall 2 to be rehabilitated in the soil 3 present behind it. For this purpose, starting from the earth's surface 5 by suction, a shaft 6 is sunk. A suction lance 7, which is designed in the simplest embodiment as a vertical tube, is connected via a line 8 to a vacuum source 9, for example a vacuum pump. In the suction line 8, a separator 10 is arranged, which separates the subsidized earth material from the suction air stream.

After the shaft 7 has reached the desired depth for the cavity 4 (in Fig. 1 shown with a dotted line), the cavity 4 is filled with setting, preferably cementitious material after the suction lance 7 has been pulled out. Since the excavation cross-section is so small that sets a vaulting effect in the soil and a collapse is not to be feared, a formwork is not required for cohesive soils.

After the material required to form a load distribution body 14 has been introduced into the shaft 6, a region 15 (FIG. 2) remaining above the load distribution body 14 can be used. Fig. 2 ) of each shaft 6 are filled with earth material.

After setting of the load distribution body 14 forming material ground anchor 17 are introduced through bores 16 from the front wall front, which anchor the load distribution body 14 in the ground 3. The load distribution body 14 largely absorb the earth pressure and carry it off into the upcoming soil 3, so that the retaining wall 2 to be rehabilitated is relieved.

How to get out of the FIGS. 2 and 3 detects, the individual, arranged in lateral intervals load distribution body 14 are designed with relatively small width and depth, for example in the dimensions of 30 x 30 cm. At the earth's surface 5, the space requirement for producing the cavities 4 is barely greater than this plan of the respective load distribution body 14.

The in the Fig. 4 and 5 illustrated variant of the method differs from the previously described variant only in that when sinking the shaft in cohesionless, non-cohesive soil a shaft wall formwork 11 is carried. The walls of the shaft 6 produced in this way are secured by the shaft wall formwork 11 carried along during the lowering, which consists of a plurality of shuttering segments 12 which are detachably connected to one another. The formwork segments are connected by only schematically indicated connecting elements 13 tension and pressure resistant together and preferably form box elements.

If the existing of box elements shaft wall formwork 11 has dropped by a degree that corresponds approximately to the height of a circuit segment 12, a new formwork segment at the upper end of the shaft wall formwork 11 is nachgeschoben.

In the illustrated embodiment, the formwork segments 12 in plan are rectangular box elements and made of sheet metal. Instead, the shuttering segments can also be in plan U-shaped box elements and be open to the rear wall 1 back.

A modified advantageous embodiment of the method is based on the Fig. 6 to 8 explained. Serving to secure the shaft to be excavated shaft wall formwork is hereby formed by a series of injections. For this purpose, several vertical injection bores 18 are performed around the manhole to be produced, through which a environmentally friendly supporting liquid, preferably a hydraulically setting material, for example cement material, is pressed. The supporting fluid penetrates into an in each case Fig. 6 indicated by dashed lines surrounding area 19 of each bore 18 and causes by setting a solidification of the loose soil in this area 19th

In the area 20 enclosed by the regions 19 (FIG. Fig. 6 ), the soil is then removed by suction in the manner previously described, and in this way a shaft is sunk, which is secured against collapse. Subsequently, the shaft thus produced is filled with setting material, such as concrete. This results in the back of the load distribution body 14 ( Fig. 7 ).

In Fig. 8 It is shown that in this case too, the load distribution body 14 can be anchored in the ground 3 by one or more Erdvernagelungen 17 introduced from the wall front side.

For non-positive connection between the retaining wall to be rehabilitated and the load distribution element steel rods can be installed in holes with non-positive compression.

The irregular and largely uncovered masonry of the back of the wall is cleaned by high-pressure flushing. The resulting water sludge is sucked to the solid ground.

After reaching the lower edge of the load distribution element concrete is introduced with or without reinforcing cage under compression up to the height of the required load distribution element. The liquid concrete fills and stabilizes all cavities in the wall back; The concrete simultaneously provides the adhesion to unevenness of the surrounding soil and after completion of concreting exactly controllable the statically determined wall supplement dar. The recording of the earth pressure and the traffic load is to prove by vaulting of the wall supplement forming load distribution body together with the old retaining wall, for example as heavyweight wall.

Claims (9)

1. Method for supporting retaining walls having in-situ soil behind them by retrofitting load-distribution bodies, wherein cavities are produced at lateral intervals at the rear side of the wall and filled with material forming the load-distribution bodies, wherein, to form each cavity (4), a shaft (6) is sunk starting from the soil surface (5) directly at the rear side (1) of the wall by extracting the soil material by suction, wherein only a very small space which is substantially predetermined by the plan-view dimensions of the load-distribution bodies (14) is required at the soil surface (5), which space is sufficient for the suction operation, and wherein the material forming the load-distribution bodies (14) is introduced into the shaft (6).
2. Method according to Claim 1, characterized in that the load-distribution bodies (14) are anchored in the soil (3) by means of soil nails (17) introduced from the front side of the wall.
3. Method according to Claim 2, characterized in that the load-distribution bodies (14) are formed by curing material, and in that, after curing material forming the load-distribution bodies (14), the soil nails (17) are introduced through bores (16) from the front side of the wall.
4. Method according to Claim 2, characterized in that the load-distribution bodies form rear pillar supports of the retaining wall (2).
5. Method according to Claim 1, characterized in that a region (15) of each shaft (6) that remains above the load-distribution body (14) is filled with soil material.
6. Method according to Claim 1, characterized in that the shaft walls are secured by a shaft wall formwork.
7. Method according to Claim 1, characterized in that the shaft walls are secured by a shaft wall formwork (11) taken along during sinking, and in that the shaft wall formwork (11) is withdrawn from the shaft (6) and the material forming the load-distribution body (14) is produced.
8. Method according to Claim 7, characterized in that the shaft wall formwork (11) comprises formwork segments (12) releasably connected to one another.
9. Method according to Claim 1, characterized in that the shaft wall formwork is formed by a series of injections by which a supporting liquid is pressed into the soil.

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