JPH0216953B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a filler for underground voids, and more specifically, a filler that fills cracks and gaps that continue to fluctuate over time, and that tracks changes over time. This invention relates to an underground filler that can expand or swell to stop water and at the same time increase the strength of the ground.

Therefore, the present invention can be effectively used in technical fields such as prevention of various disasters caused by separation of soil clods in the soil, cracks and the flow of groundwater through them, or prevention of destruction of structures. .

[Prior Art] For example, structures on variable ground often suffer damage due to consolidation subsidence of the ground. The damage is caused to the structure itself, the structure and the surrounding soil,
Or, they often appear as cracks or gaps in the soil side, and these serve as preferential groundwater flow paths, which promote the flow of surrounding soil and expand the voids, causing destruction of structures and disasters. bring. This mechanism often causes the collapse of water storage dams, embankments, and embankments in developed areas due to rainfall, and can lead to disasters.

Conventionally, materials used to fill voids such as cracks or gaps as described above include cement, bentonite, mixtures thereof, and various grout materials.

[Problems to be solved by the invention] However, these fillers are intended to solidify after filling, and they deform and expand in response to changes in the gap after filling, so that they do not maintain their water-blocking effect. It does not have much flexibility. Therefore, when there is a sudden change in the gap over a long period of time or due to an earthquake or the like, there is a risk that the gap will widen again and cause the damage described above.
Therefore, according to the prior art, if a crack or gap occurs, the filling material must be replenished each time, which causes a problem, and there is no time to refill the material, and the Another problem arises in that it is impossible to prevent soil from collapsing due to water. In short, if the gap size continues to fluctuate, filling with conventional fillers that make cracks, gaps, and their surroundings rigid will quickly lose the filling effect; There is a possibility of creating other defects or even making the defects larger.

The purpose of the present invention is to solve the above-mentioned drawbacks of the prior art, and to provide flexibility in elasticity, fluidity, etc. to follow fluctuations in deformation after filling, when filling soil voids with filler. Therefore, the voids are constantly blocked and water is stopped for a long period of time, so it does not become a flow path for underground water, which can prevent various damage and disasters from occurring. Our goal is to provide an underground filling material based on a completely new idea.

[Means for Solving the Problems] The present invention, which can achieve the above objects, is made by mixing a highly water-absorbing and swelling polymer material with mineral powder, It is an underground filling material that is filled with water absorption and expansion capacity, and expands by absorbing water to follow the time-varying voids to continue blocking the voids and water-stopping them.

Here, various known materials can be used as the highly water-absorbing and swelling polymer material, and as the mineral powder, in addition to sand, silt, clay, etc., bentonite etc. can be used. . By adjusting the mixing ratio of these, the type of polymer material and mineral powder, particle size, etc., depending on the purpose of use, the amount of water absorption, amount of swelling, water absorption and swelling time, etc.
It is possible to freely adjust properties and functions such as fluidity at the time of water absorption, water permeability, expansion pressure generated by expansion, and elasticity after expansion.

Note that the above-mentioned "voids" are not limited to cracks and gaps in the soil layer, but also include gaps between the soil and structures.

[Function] The soil filler according to the present invention absorbs water and expands to generate pressure, is impermeable to water, has elasticity, and has large deformation performance. Moreover, it has the unique property of being able to freely adjust the rate of water absorption and expansion. When such a filler is placed in the soil, it absorbs groundwater, expands, and closes the voids, and the pressure it generates compacts the surrounding soil layer, increasing its strength and at the same time increasing the strength of that soil layer. Water permeability can be reduced. This filling material has flexibility such as elasticity and fluidity to follow changes in the gap after filling, without making the filling portion and its surroundings a rigid body.

[Example] Hereinafter, the present invention will be explained in more detail based on the drawings. As mentioned above, the present invention is made by mixing a highly water-absorbing and swelling polymer material and mineral powder, and filling the soil voids in a state that has residual water-absorbing and swelling capacity.
This is an underground filler that absorbs water and expands to keep up with the pores that change over time, closing the pores and keeping water out.

Here, the highly water-absorbing and swelling polymer material may be any conventionally known starch-based, cellulose-based, polyvinyl alcohol-based, acrylic-based, etc., such as vinyl alcohol/acrylic acid polymer, starch/acrylic acid polymer. Alternatively, a mixture of these with various rubbers and resins can be used. The amount of water absorption expansion of this type of polymeric material is approximately 50 to 500 times the volumetric expansion rate. Although it is not impossible to use such a polymeric material alone as a civil engineering material, it is economically disadvantageous, and there are cases where it is difficult to make complete contact with the soil layer, and the so-called "compatibility" is not good. There are many.

Therefore, in the present invention, an appropriate proportion of mineral powder is mixed with the above-mentioned super water-absorbing and swelling polymer material. As the mineral powder, sand, silt, clay, and various other types are used.

The reason for using the above combination of materials is that it provides the following advantages.
First, the mineral powder can be responsible for the contact between the filler and the soil layer or structure, thereby solving the above-mentioned problem of "compatibility" with the soil layer. However, by changing the mixing amount of this mineral powder, the amount of expansion can be easily adjusted, and the pressure generated by the expansion can be applied to the walls of cracks or gaps where the polymer material fills. It becomes a pressure transmission medium that transmits uniformly, and can bring about a good filling effect.
By the way, in terms of soil engineering, an impermeable layer has a permeability coefficient of 10 ^-6 cm/1, which indicates the ease of movement of groundwater.
sec (water movement speed) or less, it is easy to configure a material with this level of water impermeability by selecting the particle size distribution and material of the mineral powder, and even in that case, the powder The gaps formed by the body form a large number of capillary-like structures through which water can be supplied to the super water-swelling polymeric material, and furthermore, this type of mineral powder can be It is also possible to procure it at the work site, which is very economically advantageous.

The soil filler according to the present invention is a material that fills voids in the soil, and can constantly close fluctuating voids and maintain water-stopping properties by temporally controlling its properties of absorbing water and expanding. It is. In reality, existing groundwater or supplied water is filled into the voids by injecting or inserting it into the voids in the soil, or pasting it on the wall or bottom of an underground structure in advance. absorbs and expands. This closes the voids and provides watertightness.
Further, depending on the constraint conditions, expansion pressure can be developed.
To this end, we need to adjust the type and condition of the material, or the blending ratio, as appropriate, taking into account changes in usage conditions and restraint conditions.
Adjust the deformation characteristics, strength characteristics, thermal characteristics, chemical (weathering, deterioration) characteristics, specific gravity, form (powder or lump state), etc., and also adjust the expansion-time characteristics by adjusting the modeling materials and additive adjustment materials, etc. That's what I do. When the filling material adjusted in this way according to usage conditions etc. is filled into the void as described above, it freely follows the changing void and maintains its blocking and water-stopping effects over a long period of time. It is possible to continue holding it.

The advantages of using mineral powder materials are as described above, but the case of using bentonite will be described as an example. Although bentonite is classified as clay, it has the property of swelling several times as much as itself and has excellent water impermeability, making it an excellent material to mix with this type of polymeric material. , the amount of expensive polymeric materials used can be reduced.

Such bentonite and vinyl alcohol
Figures 1 to 3 show the properties of the mixture of acrylic acid and EVA resin. FIG. 1 shows the time-expansion characteristics, where the horizontal axis is time (hr) and the vertical axis is volume change (times). Note that this Figure 1 shows the volume change in the unrestrained state, where curve A shows the change in volume for the vinyl alcohol/acrylic acid-EVA blend (2 mm square granules) alone, and curve B shows the change in volume for the above blend 1. This is the case where bentonite 9 (volume ratio) is blended. Figure 2 is a mixing ratio-pressure characteristic diagram, which shows the relationship between pressure and mixing ratio when the mixed material is expanded by water absorption in a container with twice the volume (after 100 hours). be. Figure 3 is a mixing ratio-viscosity characteristic diagram, showing the viscosity after water absorption for 100 hours after pressure release.

From these figures, it can be seen that the soil filler according to the present invention has water absorption and swelling properties, pressure development, fluidity, etc., and that these properties can be changed depending on the mixing ratio. These properties mainly depend on the selection of the material of the super water-absorbing and swelling polymer, the selection of its particle size to determine the expansion amount and expansion time, the selection of the material and particle size of the mineral powder to determine water permeability and viscosity, and furthermore, The amount of expansion, pressure developed, and viscosity are determined by selecting the mixing ratio of the two, and the desired properties can be freely produced depending on the purpose of use.

Next, a specific usage example of the soil filler according to the present invention will be explained. FIG. 4 shows an example in which filler material 3 is injected into cracks 2 occurring in soil layer 1. In this case, it should have the property of not shrinking even in unsaturated soil. The filler 3 absorbs water present in the surrounding area, expands, and fills the inside of the crack 2.

FIG. 5 shows an example of improvement of cohesive ground or sandy ground 3. As shown in Figure A, a columnar or strip-shaped hole 5 is formed in the ground to be improved, and a filler 3 is injected into it. The filler 3 absorbs moisture present in the surroundings or supplied moisture, and expands in the horizontal direction as shown by the white arrow in FIG. At this time, pressure is applied to the surrounding ground and the ground can be compacted. The ground is improved by the strength of the filler itself, compaction effect, and water-stopping performance.

Figures 6 and 7 show buried structures 6 in soil layer 1.
This is an example of filling the surrounding void with the filler 3. Particularly when the water is below the groundwater level, it is necessary to constantly close the pores to shut off water depending on the pore conditions. If the filler material 3 is placed on the side (see Figure 6) or the bottom (see Figure 7) of the structure when it is buried, it will absorb surrounding moisture and expand naturally when voids occur later, causing the voids to change. This can be blocked and water stopped at all times by following the flow. Based on the same idea, if the filling material 3 is sandwiched in a sheet form between the connecting parts of the underground structures 6 as shown in Fig. 8, it will always be closed even if the gap changes. It can be made waterproof.

As shown in Figure 9, the size of the voids in the soil often increases on the order of years and months when viewed over time. For example, as shown by curve A in the figure, this expansion occurs continuously and gradually due to the compaction of soil layers such as ground subsidence, and as shown by curve B, it is caused by human factors such as earthquakes and construction work. Although it may change in stages depending on the cause, if a filler like the one of the present invention is used, it is possible to design the amount of expansion to match the rate of change of the void, which gradually changes along curve A. If the constraint condition is loosened for some reason, as shown by curve B, it will expand to the extent that it has been loosened, and it will always close the void and stop water. It is also possible to do so.

[Effects of the Invention] Since the present invention is a soil filling material configured as described above, it can have flexibility such as elasticity and fluidity to follow the fluctuating deformation of the void after filling. Even if the voids change over time, the voids are always blocked and water is stopped, so they do not become channels for underground water, which can prevent various disasters from occurring, and once filled. Then, since it expands naturally, it is completely maintenance-free and has excellent effects, such as eliminating the need for cumbersome work such as inspecting the occurrence of voids and refilling with filler. It is something that can be played.

[Brief explanation of drawings]

Fig. 1 is a time-expansion characteristic diagram of the filler according to the present invention, Fig. 2 is a mixing ratio-pressure characteristic diagram thereof,
Figure 3 is a diagram of the mixing ratio vs. clay characteristics diagram, Figure 4 is an explanatory diagram showing the filling situation of filler into cracks in the soil, and Figures 5A and B are explanations of the case where the present invention is used for ground improvement. Figures 6 and 7 are explanatory diagrams of the case where it is used in voids around underground structures, and Figure 8 is an explanatory diagram of the case where it is applied to the connection part between structures.
FIG. 9 is an explanatory diagram showing the size of the gap with respect to time. 1...Soil layer, 2...Crack, 3...Filling material, 6...Buried structure.

Claims (1)

[Claims] 1. It is made by mixing a highly water-absorbing and swelling polymer material and mineral powder, and is filled into the soil voids with water absorption and expansion capacity, and absorbs water and expands to follow the time-varying voids, thereby blocking the voids. Soil filling material that continues to water.