JPS635528B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a grouting method which is a construction method for improving and strengthening foundation ground.

Conventionally, in various civil engineering works such as dams or construction works, grouting has been commonly used to inject grouting liquid such as chemical solution or cement milk into cracks and cavities in the foundation ground for the purpose of strengthening the bearing capacity of the ground and improving water permeability. It is being carried out according to

For grouting, as shown in Figure 1, a hole 2 with a depth corresponding to the depth to be grouted (usually around 2 m) is bored in the foundation ground 1 by boring, and a guide pipe 3 with a diameter of about 50 mm is inserted to guide the grouting. A grout injection hole 5 hardened with mortar 4 or the like is provided around the pipe 3, and the injection pipe 6 is inserted into the foundation ground 1 from inside the guide pipe 3, and the gap between the inner surface of the guide pipe 3 and the outer periphery of the injection pipe 6 is fixed with a gasket 7. At the same time, fix the injection pipe 6 in the guide pipe, and then seal it with
This was done by a grouting method in which grouting liquid 8 was injected into the foundation ground 1 from an injection pipe 6 while applying an injection pressure of about Kg/cm ² .

According to such a grouting method, there is no problem when grouting a deep part of the ground, but when grouting a relatively superficial part, the grouting liquid 8 leaks to the ground surface due to cracks 9 etc. in the foundation ground 1.
There was a problem in that only a small amount of the grout liquid 8 injected into the corner remained in the foundation ground 1, and the ground improvement effect by grouting was low.

For example, a grouting method as shown in FIG. 2 has been proposed as a grouting method to solve such problems.

In this construction method, the surface of the foundation ground 1 is covered with a concrete layer (also called cap concrete) 10 about 50 cm thick, leaving grout injection holes 5, and the grout 8 injected into the foundation ground 1 flows from cracks 9 to the foundation ground. 1 to prevent leakage to the surface.

According to such a grouting method, the surface of the foundation ground 1 is completely covered by the concrete layer 10 and pressure is applied due to the weight of the concrete layer 10, so that the grouting liquid 8 is applied to the foundation ground 1.
Leakage from the surface is improved.

Incidentally, grouting is performed by filling cracks 9 or cavities in the foundation 1 with chemicals or cement in the grout 8 while squeezing out the water in the grout 8 using the filter effect inherent in the foundation 1. Ground improvement can be carried out by hardening of cement and cement. However, if this moisture is not squeezed out sufficiently and the grout hardens, the shrinkage rate will increase as the grout hardens. For example, as shown in Figure 3, after the grout 8 hardens, a gap 9A still remains in the crack 9, etc. However, there is a drawback that the effect of grouting is not fully exhibited.

Therefore, according to the grouting method shown in FIG. 2, although leakage of the grout liquid 8 to the surface of the foundation ground 1 is eliminated, the moisture in the grout liquid 8 is sufficiently squeezed out to the surface of the foundation ground 1 by the concrete layer 10. Since this is not done, there is a problem that grouting is not sufficient, especially in the surface layer of the foundation ground 1, and furthermore, the pressure of the concrete layer 10 causes the grouting liquid 8 injected from the tip of the injection pipe 6 to flow out from the tip of the pipe 6. There was a problem in that it was difficult to inject into the upper ground layer.

An object of the present invention is to provide a foundation ground grouting method that eliminates the drawbacks of the conventional grouting methods described above.

This purpose is to cover the ground with a sand layer, further cover the sand layer with a concrete plate provided with drainage windows and grout injection holes, insert an injection pipe into the ground through the grout injection hole, and This is achieved by a foundation ground grouting method characterized by injecting a grouting liquid into the ground through an injection pipe.

The present invention will be explained below by giving an example and referring to the drawings.

FIG. 4 is an explanatory cross-sectional view explaining one embodiment of the present invention, and FIG. 5 is an explanatory plan view.

In the figure, 21 represents the foundation ground, 22 a hole drilled in the foundation ground 21 by boring to a depth approximately half of the depth to be grouted, and 23 a guide pipe inserted into the hole 22.

And 24 is the layer thickness covering the surface of the foundation ground 21 10 ~
A sand layer of about 20 cm, 25 is a concrete plate about 10 cm thick that covers the sand layer 24, and 26 is a concrete plate 2.
Anchor 5 is fixed to the foundation ground 21, 27 is a grout injection hole drilled in the concrete plate 25 and communicated with the hole 22 through the guide pipe 23, 28 is a drainage window also provided in the concrete plate 25, 29 is the drainage window 2 inside the concrete plate 25
8 A water-permeable filter made of lower woven fabric placed directly on the sand layer 24, 30 a grouting liquid injection pipe, 31
3 represents a fixing gasket that fixes the pipe 30 within the guide pipe 23 and seals the inner periphery of the guide pipe 23 and the outer periphery of the injection pipe 30, 32 represents a grout liquid, and 33 represents a crack in the foundation ground 21, respectively. .

The side ends of the concrete plate 25 are fixed within the foundation ground 21 to be grouted. (If the foundation ground 21 is flat, it is bent to wrap around the sand layer 24 as shown in the right part of Figure 4, or it is fixed in the foundation ground 21 with an inclination as shown in the left part of Figure 4. ) After the foundation ground 21 is covered with the sand layer 24 and the concrete plate 25 in this way, the grouting liquid 32 is injected into the foundation ground 21 from the injection pipe 30.

Then, unlike the case shown in FIG. 2, since the top of the foundation ground 21 is covered with a sand layer 24, the grout liquid 32 flows through the cracks 33 etc. and seeps out onto the foundation ground 21, but the sand layer 24, As shown in FIG. 1, due to the weight of the concrete plate 25, the grout liquid 32 itself does not leak out as in the conventional example, and the chemical or cement accumulates in the crack 33, and much of the moisture is removed. It seeps out onto the foundation ground 21. The water seeping into the sand layer 24 is taken out to the outside through the drainage window 28. At this time, depending on the nature of the foundation ground 21, the grouting liquid 32 may have an extremely high moisture content. There is a risk of sand being washed away. A water permeable filter 29 is provided to prevent this sand from being washed away. Therefore, if the amount of water seeping out from the foundation ground 21 is small, the permeable filter 29 may not be provided.

In this way, the moisture in the grout liquid 32 is properly squeezed out within the foundation ground 21 and seeps onto the foundation ground 21, so that the grout liquid 32 is well infiltrated into the surface layer of the foundation ground 21, causing gaps such as the cracks 33. grouting liquid 3 by filling the grouting liquid and squeezing out the moisture.
Since 2 is concentrated in the crack 33, the shrinkage rate after curing is reduced, making it possible to further enhance the effect of grouting.

The anchors 26 that connect the concrete plate 25 and the foundation ground 21 may be provided as necessary, such as when the injection pressure of the grouting liquid 22 is high, or when the drainage window 2
The number and shape of grout holes 8, the number of grout injection holes 25, etc. are appropriately determined depending on the depth, properties, etc. of the foundation ground 21 to be grouted.

Further, although the concrete plate 25 is usually placed at the site where grouting is performed, it may also be divided into predetermined sizes at a factory, etc., and then transported to the site and installed.

After grouting the foundation ground 21, the concrete plate 25, sand layer 24, etc. are usually removed, but if the sand layer 24 is sufficiently hardened with the grouting liquid, it may be used as part of the foundation as is.

As detailed above, the foundation ground grouting method of the present invention covers the ground with a sand layer, further covers the sand layer with a concrete plate provided with drainage windows and grout injection holes, and injects the grout liquid. The method is characterized in that an injection pipe is inserted into the ground through the hole, and grout liquid is injected into the ground through the injection pipe.

Therefore, according to the present invention, even when grouting a relatively superficial part of the foundation ground, the grouting liquid can be evenly injected into the cracks, cavities, etc. of the ground, and the water can be squeezed out well, so the grouting It becomes possible to extremely reduce the shrinkage rate during liquid curing, and it becomes possible to enhance the effect of grouting.

[Brief explanation of the drawing]

Figures 1 and 2 are cross-sectional explanatory diagrams explaining the conventional grouting method, Figure 3 is a cross-sectional explanatory diagram explaining shrinkage when grout liquid hardens, and Figure 4 is a cross-sectional diagram explaining an embodiment of the present invention. The explanatory diagram, FIG. 5, similarly represents a plan explanatory diagram. 1, 21... Foundation ground, 2, 22... Hole, 3,
23...Guide pipe, 24...Sand layer, 25...
Concrete plate, 27... Grout liquid injection hole, 2
8... Drain window, 32... Grout liquid, 33... Crack.

Claims (1)

[Claims] 1. Cover the ground with a sand layer, and then cover the sand layer with a concrete plate provided with drainage windows and grout injection holes as appropriate, insert an injection pipe into the ground through the grout injection hole, and insert the injection pipe into the ground. A grouting method for a foundation ground, characterized by injecting a grouting liquid into the ground through a grouting method.