JP6640634B2 - Rock excavation method and swelling unit usable for the method - Google Patents

Description

  The present invention relates to a rock excavation method and a swelling unit usable for the method.

In the rock excavation work, for example, it is usual to use a breaker for rock excavation. This method is low in cost, but generates significant noise and vibration, and has a great influence on the surrounding environment of the excavation work site.
As a method of excavating with low noise and low vibration, there is a static crushing technique. This method generates heat due to a chemical reaction between water and chemicals in a hole in the rock, and utilizes the fact that water expands as water changes into water vapor. And excavates the rock.
In particular,
(1) A slurry obtained by kneading a static crushing agent based on hydration expansion with water is introduced into a hole formed in the material to be crushed, and if necessary, quicklime that promotes the hydration expansion is added. And let it stand and cause crushing (Patent Document 1), or
(2) A hole in which a water supply pipe is previously installed on the inner surface is provided in the material to be crushed, the expansive crushing agent is pushed into the hole using a jig, and water is supplied to the crushing agent using the water supply pipe to swell. To cause crushing (Patent Document 2)
It has been known.

Tokuhei 2-059258 64-47,895

"Swelling pressure characteristics of swellable water stopping agent", Shinya Inazumi, Tadashi Wakatsuki, Kenji Kato, Kenkatsu Kobayashi, Book name: "Materials" Vol. 61, No. 1, pp. 37-40, 2012. "Green tree using biodegradable nonwoven long pot", Shogo Ikemoto, Kanjiro Takemoto, Katsunori Kimura, Book name: "Journal of Japan Society for Green Technology" Vol. 38, no. 184-187, 2012. "Biodegradable water-absorbing polymer using microorganism-produced macromolecule. Crosslinked γ-glutamic acid of Bacillus natto has a water absorption rate of 5,000 times its own weight." No. 1, pp. 8-9, 2001.

The above-mentioned static crushing technology has a problem that it is difficult to adopt it at a large-scale digging site because a static crushing agent is expensive, so that the digging unit price per unit volume is very high compared to digging by a breaker. is there. In fact, there are few embodiments of this method.
In static crushing, the internal pressure generated in the hole is as large as 300 kg / cm ² or more. For this reason, there is an inconvenience that, for example, a phenomenon in which the medicine is ejected from the upper part of the hole to the ground occurs, which causes a problem in safety measures.

The applicant of the present invention has studied this problem diligently, and has obtained an idea of breaking the rock using the swelling action of the water-absorbing material.
That is, the water-absorbing material filled in the hole swells due to external water supply, and the swelling pressure causes the rock around the hole to split.
However, in this case, there is a problem of how to supply water to the water absorbing material filled in the hole. In the experiment conducted by the patent applicant, as shown in FIG. 12, when water is supplied through a water supply pipe simply protruding into the water-absorbing material, the flow of water is stopped when the water supply amount is only a few cc, and the water is entirely supplied to the water-absorbing material. It turned out not to go all the way. This is because the water-absorbing material in the vicinity of the outlet of the water supply pipe is gelled to form a lump Lu, which acts as a lid of the water supply pipe. This does not provide the swelling pressure required for rock splitting.

A first object of the present invention is to provide a low noise and low vibration rock excavation method using a water absorbing material.
A second object of the present invention is to provide a swelling unit that can easily execute the above rock excavation method.

The first method is a rock excavation method,
Excavating multiple vertical holes in the bedrock;
A step of constructing a swelling portion having a double structure surrounding the columnar water-permeable material by the annular water-absorbing material swellable by water absorption in the vertical hole;
A step of closing the upper side of the vertical hole with a closed portion having an exhaust hole and a water supply hole,
A step of injecting the water-permeable material through a water-supply pipe reaching the water-permeable material from the water- supply hole,
The water- absorbing material that has absorbed water swells from the boundary surface between the water-permeable material and the water-absorbing material, which is the peripheral surface of the water-permeable material, and the swelling pressure splits the rock around the vertical hole.

This means proposes a rock excavation method. In short, this method is to make a vertical hole 2 in the bedrock G, create a crushing mechanism including a swelling portion 6 in the vertical hole, and supply water to the swelling portion 6, The swelling pressure causes the rock part around the vertical hole 2 to split.
The invention of this means is a method of excavating rock, and uses a mechanism for crushing (hereinafter referred to as a "crushing mechanism") for the implementation. The crushing mechanism 4 comprises at least swelling part 6 and the closing portion 10, the swelling part 6 has a double structure in which the enclosed around the columnar water passage member C by the water absorbent material A circular, the closed portion It is configured to inject water into the water-permeable material C via a water-supply pipe that reaches the water-permeable material from the water supply hole .
That is, by allowing water to reach the annular water-absorbing material A via the water-permeable material C having a double structure, the water is evenly distributed to the water-absorbing material A.

The “water-absorbing material” is a material having a performance of swelling due to water absorption, and for example, a water-absorbing polymer can be used.
As the “water-permeable material”, a material that can pass water and is harder to compress than at least the water-absorbing material (has a small volume compression ratio) is used. Otherwise, the swelling pressure of the water-absorbing material is not sufficiently transmitted to the bedrock. The water-permeable material can be, for example, sand.
The shape of the water-absorbing material is called "annular", and the shape of the water-permeable material is "pillar-shaped", meaning those shapes occupying the double structure, meaning the general shape of the water-absorbing material / water-permeable material. is not. The water-absorbing material and the water-permeable material may be an amorphous material having fluidity.
"Double structure" means that the water-absorbing material and the water-permeable material overlap when viewed from the radial direction of the vertical hole. It is sufficient that this double structure is formed in a part of the vertical hole in the vertical direction.

The second means has the first means,
Along with disposing the annular water absorbing material in contact with the bottom surface of the vertical hole and the inner peripheral surface of the lower portion of the vertical hole,
By filling the space from the inside of the water-absorbing material to the back surface of the closed portion with a water-permeable material having fluidity,
In the lower part of the longitudinal hole, so it placed on the bottom of the vertical hole, thereby constructing the double structure.

In this means, as shown in FIG. 1, the annular water-absorbing material A having a double structure is placed on the bottom surface of the vertical hole 2 so as to be in contact with the bottom surface of the vertical hole and the inner peripheral surface below the vertical hole. The inside of the water absorbing material A and the gap between the upper surface of the water absorbing material A and the lower surface of the closed portion are filled with a water-permeable material C having fluidity.
In this configuration, the upper end of the annular water-absorbing material A is a free end because it is in contact with the flowable water-permeable material, and the lower end of the water-permeable material C is in contact with the bottom surface of the vertical hole 2, and is fixed. End.
When the water-absorbing material A absorbs water and swells, the free end side of the water-absorbing material A is movable with respect to the inner surface of the vertical hole 2, so that there is room for stress to escape to the surroundings (see FIG. 5). Stress concentrates on the fixed end side of.

A third means is a transportable swelling unit for use by loading into a vertical hole in the rock,
A double structure formed around at least a part of the height direction and surrounding the columnar water-passing portion with an annular water-absorbing portion that can swell by water absorption;
A water supply pipe standing up from the inside of the water passage section ,
The water-passing portion has a volume compression ratio smaller than that of the water-absorbing portion, and is configured such that water can flow to the water-absorbing portion through the entire boundary surface between the water-passing portion and the water-absorbing portion, which is the peripheral surface of the water- passing portion. Have
The water absorption portion swells due to water absorption from the water passage portion side, and the inner surface of the vertical hole can be pressed.

This means proposes a swelling unit 20 for installation in a vertical hole in a rock G, as shown in FIGS. This swelling unit 20 is transportable and used for performing the rock excavation method described herein.
In this rock excavation method, the swelling portion is constructed by installing a swelling unit in which at least a water-absorbing material and a water-permeable material are fixedly connected in advance in the lower part of the vertical hole. Since the transportable swelling unit 20 is installed in the vertical hole 2, the operation is simple.

Fourth means includes a third means comprises a double cylinder which is connected to each other via the connecting piece and the inner cylinder and the outer cylinder, the space between their inner cylinder and the outer cylinder Comprising a container body covering the lower surface of the inner cylinder and the lower surface of the space in the inner cylinder with a breakable bottom lid,
The water passage section and turning on the water passing member in the inner cylindrical water absorption unit and turning on the water absorbent material between the inner tube and the outer tube are constituted respectively.

This means shows a preferred embodiment of the swelling unit 20. In this manner, swelling unit 20 has a double cylinder was connected to one another via a connecting piece 28 via a connecting piece between the inner cylinder and the outer cylinder, and, with them the tube and the outer tube A container body is provided, in which the lower surface of the space between them and the lower surface of the space in the inner cylinder are covered with a breakable bottom lid .
The water passage section and turning on the water flow material C into said inner cylinder, water absorbing unit and turning on the water absorbent material between the inner tube and the outer tube are constituted respectively.

According to the first aspect of the invention, since the rock is split by the swelling action of the water-absorbing material due to water absorption, the rock can be split with low noise and low vibration.
According to the invention according to the second means, the lower end of the double-structured water-absorbing material is a fixed end fixed to the bottom surface of the vertical hole, while the upper end of the water-absorbing material is connected to the water-permeable material having fluidity. Since the free ends are in contact with each other and can be displaced against the earth pressure, stress is concentrated on the lower ends of the vertical holes, and cracks are easily generated.
According to the invention according to the third means, the swelling unit is transportable and can be brought into the vertical hole from the outside, which is convenient.
According to the invention relating to the fourth means, the double cylinder of the container body is pulled out from the bottom cover and collected, so that it can be reused and is economical.

It is a longitudinal section of a crushing mechanism constructed in a vertical hole in the mode of the rock excavation method of the present invention. FIG. 2 is a cross-sectional view in the II-II direction of the crushing mechanism of FIG. 1. It is a figure which shows the process of the rock excavation method of this invention, The figure (A) shows the process of excavating the vertical hole in the rock, and the figure (B) shows the process of constructing the swollen part and the intermediate part in the vertical hole. (C) shows the step of closing the upper part of the vertical hole with the closing part, (D) shows the step of injecting water into the swollen part to split the rock, and (E) shows the part of the split rock Respectively are shown. It is a top view which shows the water injection process of FIG. 3 (D). FIG. 4 is a vertical sectional view showing a water injection step of FIG. 3 (D). FIG. 4D is a cross-sectional view showing a split state of the rock around the vertical hole in which the lower side in the water injection step of FIG. 3D is the excavation surface E side. 1A and 1B show a configuration of an embodiment of a swelling unit according to the present invention, wherein FIG. 1A is a longitudinal sectional view of the swelling unit, and FIG. 8 shows a state in which the swelling unit of FIG. 7 is installed in a vertical hole. FIG. 9 shows a state where the tubular main body is pulled out from the bottom lid of the swelling unit shown in FIG. 8. FIG. 7A shows a preferred embodiment of the swelling unit of FIG. 7, wherein FIG. 7A is a plan view of the swelling unit, and FIG. It is a figure which shows the relationship between the dripping time of water with respect to a water absorbing material, and swelling pressure. FIG. 5 is an explanatory diagram of an operation of a swollen portion constituted only of a water absorbing material as a comparative example of the present invention. It is a figure which shows the structure of the Example (experimental example) of this invention, The figure (A) is a top view of a swelling unit, and the figure (B) is a longitudinal cross-sectional view of a swelling unit. It is explanatory drawing for applying the thick wall theory to the same Example. It is explanatory drawing of the experiment performed with respect to the swelling part of a single structure as a premise of designing the swelling part of a double structure of this invention, and the same figure (A) is before putting a water supply pipe into the container containing a swelling part. (B) shows a state where a water supply pipe is put in a container, and FIG. (C) shows a state where water is injected through a water supply pipe. FIG. 14 is a diagram illustrating a configuration example of an experiment performed to confirm a swelling amount for each mixing ratio of a water-absorbing polymer and sand prior to the experiment in FIG. 13. It is the result of having performed the test shown in FIG.

  1 to 6 show a rock excavation method according to a first embodiment of the present invention. This method involves drilling a vertical hole in the bedrock and constructing a rock crushing mechanism 4 in the vertical hole. For convenience of explanation, the structure of the crushing mechanism 4 will be described first.

  The crushing mechanism 4 includes a swelling portion 6, an intermediate portion 8, and a closing portion 10.

The swelling portion 6 has a double structure including a central columnar core portion 6a made of the water-permeable material C and an annular peripheral portion 6b made of the water-absorbing material A. The water supply pipe 16 is inserted.
The term "double structure" means that the two parts overlap when viewed from the radial direction of the swelling part 6, and water flows from the water supply pipe to the annular peripheral part (water absorbing material) via the core part (water passing material). Is supplied.
The reason for the double structure is that water is supplied from a large area through the boundary surface S between the core portion 6a and the annular peripheral portion 6b, so that all the water-absorbing material swells and the rock is surely split. That's why.
It is desirable that the core portion 6a and the annular peripheral portion 6b are concentric. This is to supply water equally to all the water absorbing materials.

  The core part 6a is a relay area for supplying water to the water absorbing material A of the annular peripheral part 6b. The properties required as the water-permeable material C are good water permeability and non-compressibility (at least the volume compressibility is smaller than the water-absorbing material). Further, any inexpensive material or fluid material is suitable. This is because it is economical and easy to construct. One suitable example of the water-permeable material C is a sand material, and soil other than clay may also be applicable.

The annular peripheral portion 6b has a role of causing the surrounding rock part to be split by the swelling pressure due to the water absorbing material A absorbing water and swelling.
In general, rock requires a large force to deform a certain amount, so the swelling pressure required to cause splitting is large, but the swelling width is small. In the drawings of the present application, the degree of swelling is emphasized, and swelling does not always occur at the illustrated level.
For example, since the tensile strength of granite is about 100 kg / cm ² , the width of the annular peripheral portion 6b and the swelling pressure of the material are determined so as to obtain such a tensile strength. This will be described in the section of [Example].
The water absorbing material A is preferably a fluid material, for example, a granular material. Suitable materials are water-absorbing polymers.
The water-absorbing polymer is an inexpensive material that is currently used for a water-absorbing material such as a disposable diaper, and is in the form of sand-like particles.
FIG. 11 shows an example of the time-swelling pressure characteristics when the water-absorbing polymer swells (Source: Non-Patent Document 1). Although the swelling pressure is affected by the thickness of the swelling layer, it is reported that a swelling pressure of about 10 MPa = 100 kg / cm ² occurs after 24 hours. The present applicant has separately conducted experiments and confirmed that rock can be crushed by the swelling pressure of the water-absorbing polymer.
It is not necessary to use 100% of the components of the water-absorbing material as a polymer, and an inexpensive auxiliary material having fluidity or water permeability (such as sand) may be mixed. In the case of rocks and bedrocks with high strength, it is necessary to increase the amount of polymer.However, if the amount is too large, the cost increases, so a preliminary test is performed to determine the appropriate amount of polymer for each excavation site, such as rock type and weathering conditions. You need to decide.

The intermediate portion 8 is formed by filling at least a gas-permeable and fluid filling material between the swelling portion 6 and the closing portion 10.
The main role of the intermediate portion 8 is to set the water level at a position higher than the swelling portion 6 so as to swell at all the depths of the swelling portion 6. In addition, when the closing portion 10 is cast with the early-strength cement, the component of the early-strength cement may penetrate downward by gravity. It also has a function as a barrier so that this penetration does not reach the swelling portion 6. It is preferable that the filling material has air permeability, and a function of exhausting air through an exhaust pipe 18 described later is ensured in accordance with the amount of water absorbed into the swelling portion 6.
The filling material is preferably of the same quality as the water-permeable material of the swollen portion 6 (sand in this embodiment).

  The closing portion 10 is a lid formed at the upper end of the vertical hole 2, and seals the swelling portion 6 and the intermediate portion 8 against an increase in internal pressure due to swelling of the swelling portion 6, thereby effectively reducing the swelling pressure. It has the function of transmitting to the surrounding rock mass. The closing part 10 has a water supply hole 12 and an exhaust hole 14. The closing part 10 may be formed of a high-strength cement.

  A water supply pipe 16 is provided to reach the lower part of the core portion 6a from outside through the water supply hole 12. The water supply pipe 16 is connected to a water supply facility (not shown).

An exhaust pipe 18 that reaches the external intermediate portion 8 through the exhaust hole 14 is provided.
A plurality of outlets (water supply ports) can be provided in the length of the pipe portion of the water supply pipe 16 inserted into the core portion 6a. Thereby, the water-permeable material C can be surely wet in a short time.
By installing the exhaust pipe 18, air can be exhausted from the exhaust pipe by the amount of supplied water to saturate the core portion 6a of the swelling portion 6, and the saturated state of the core portion 6a can be reliably maintained, so that the annular periphery It becomes possible to continue supplying water to the water absorbing material A of the part 6b.

By arranging the exhaust pipe 18 in the intermediate portion 8 which is a single sand layer above the swelling portion 6 of the double structure, the water surface in the borehole 2 exists above the double structure of the water-absorbing polymer and the sand layer. Will be. By doing so, it is possible to reliably wet the lower end surface of the exhaust pipe, and to absorb water in the entire range in the depth direction of the water absorbing portion.
In addition, by closing the uppermost portion of the borehole 2 with early-strength cement and securely fixing the water-absorbing polymer layer in the borehole 2, swelling pressure is generated in the borehole 2 and rocks are broken.

Next, the outline of the rock excavation method of the present application will be described with reference to FIG. The detailed design will be described in the section of Examples.
Here, the method of the present invention was applied to bench excavation (a small amount of excavation was performed so that the rock slope became stair-like, a rock crusher was placed on the top of the stairs, and the hole length was equal to the height of the steps. A method is described in which a plurality of holes are drilled so that one row is parallel to the vertical plane, and crushing is performed row by row (as described later, the water injection start time does not necessarily have to be the same). I do.
The present invention can also be used for crushing large-volume concrete such as footings of building foundations.

(1) Step of Excavating Boring Holes As shown in FIG. 3 (A), a plurality of boring holes 2 are excavated in an in-situ bedrock G in a row.
In the conventional static crushing, the standard of the interval between the boring holes is about 50 cm, and the present invention can conform to this. However, the interval between the boring holes may be appropriately changed. The greater the depth D of the boring, the better the rock excavation efficiency, but the necessity of exceeding the boring interval of 50 cm is low. Therefore, as a preferred embodiment, the interval between the boring holes and the depth of the boring holes can be the same.
The excavated part has the shape of a bench, and the groundwater level of the bedrock is at least as low as the bottom of the bench at the surface of the bench. For this reason, the groundwater level at the excavation point of the boring hole, which is L away from the surface E of the bench shown in FIGS. 3 and 4, is sufficiently lowered, and the following process is performed in a state where the groundwater level is sufficiently low. .
Incidentally, even when a very small amount of water is present on the bottom surface in the borehole, the water-absorbing polymer in the peripheral portion 6b instantaneously absorbs water within a range of 2.5 mm as described later and has high water permeability. The core portion 6a instantly takes in sufficient water into the gap. Therefore, even if a small amount of water is present, the present invention is not hindered.
(2) Step of constructing swollen portion in vertical hole As shown in FIG. 3 (B), below the boring hole 2 , a core portion 6 a formed of water-permeable material C and an annular shape formed of water-absorbing material A The swollen portion 6 composed of the peripheral portion 6b is constructed.
As described above, it is preferable that the water-permeable material C is sand and the water-absorbing material A is a granular water-absorbing polymer. In this case, for example, a cylindrical partition is disposed in advance in the lower part of the boring hole 2. The swollen portion 6 can also be constructed by first filling the water absorbing material A between the partition and the inner surface of the boring hole, then filling the partition with sand, and finally pulling the partition upward.
A simpler procedure will be described in a second embodiment.
The height d of the annular peripheral portion 6b of the swelling portion 6 is preferably d> D / √3 with respect to the depth D of the boring hole.
(3) Step of Constructing Intermediate Part 8 in Vertical Hole As shown in FIG. 3B, the intermediate part 8 is constructed in a portion above the swollen part 6 in the vertical hole 2. When the intermediate portion 8 is formed of the same material (for example, sand) as the core portion 6a of the swelling portion 6, the same material may be continuously filled on the swelling portion 6 after the operation of filling the core portion 6a. .
(4) Step of closing the upper end of the vertical hole with a closing part As shown in FIG. 3 (C), a closing part 10 for closing the upper end of the boring hole 2 is provided. The closing portion 10 has a water supply hole 12 and an exhaust hole 14.
The closing part 10 can be formed by a high strength cement.
A water supply pipe 16 reaching the core portion 6a of the swelling portion 6 is inserted through the water supply hole 12 of the closing portion 10, and an exhaust pipe 18 reaching the intermediate portion 8 is inserted through the exhaust hole 14 of the closing portion 10. .
As a concrete construction procedure, first, the supply pipe 16 and the exhaust pipe 18 are inserted into the sand layer to a predetermined depth, and then a high-strength cement is poured into the upper end of the boring hole 2 and hardened.
(5) Step of injecting water into the water-permeable material through a water supply hole As shown in FIG. 3D, water is supplied from an external water supply facility (not shown) to a core portion 6 a of the swelling portion 6 via a water supply pipe 16. Is supplied.
4 and 5 show a water supply step in a plan view and a longitudinal sectional view.
It is desirable to supply water at least until the sand in the core portion 6a is saturated, and it is preferable to fill the water until a part of the water reaches the lower portion of the intermediate portion 8.
The water saturated with the sand of the core portion 6a reaches the water supply material of the annular peripheral portion 6b via the boundary surface S with the annular peripheral portion 6b. Since the boundary surface has a larger area than the opening of the water supply pipe, a locally swollen polymer mass is formed near the opening of the pipe as in the case where the water supply pipe is directly inserted into the water-absorbing polymer as described above. It is unlikely to cause any inconvenience, and the water spreads over almost the entire water absorbing material.
Thereby, the water absorbing material A swells sufficiently, and a sufficient swelling pressure is obtained. FIG. 5 illustrates the expansion of the water-absorbing material A by an imaginary line, which is exaggerated in the degree of expansion. Although the water-absorbing material A tends to expand in the vertical direction, since the upper end of the boring hole 2 is closed by the closing portion, the upward expansion pressure does not escape to the outside as it is.
This swelling pressure is transmitted to the rock part around the boring hole 2, and a crack F is formed between adjacent holes in the row of boring holes.
Occurs.
The rock portion G1 up to the excavation surface E is divided into blocks by the cracks from the surrounding rock by the cracks F and H. Therefore, the rock portion G1 can be easily moved by the small breaker 50 or a backhoe and removed from the rock. Since a small breaker or the like can be used, vibration and noise can be suppressed.
The upper end of the water-absorbing material A is a free end, but the lower end is a fixed end in contact with the bottom surface of the boring hole 2, so that stress concentrates on the corner 3 of the boring hole 2. Thereby, the rock can be efficiently split.

  Hereinafter, another embodiment of the present invention will be described. In these descriptions, the description of the same configuration as in the first embodiment will be omitted.

  7 to 10 show a swelling unit 20 according to a second embodiment of the present invention.

  The swelling unit 20 is installed in the boring hole 2 and used for forming the swelling portion 6 in the rock excavation method of the first embodiment, instead of constructing the swelling portion 6 from the site at the site.

The swelling unit 20 is formed as a transportable container having at least a cylindrical main body 22 and a bottom cover 30.
The tubular main body 22 is formed by connecting a vertical inner tube 24 and an outer tube 26 with a vertical plate-like connecting plate 28. It is desirable that the lower end surfaces of the inner cylinder 24 and the outer cylinder 26 be formed flush. The outer diameter of the outer cylinder 26 is designed to be slightly smaller than the diameter of the boring hole 2.
The bottom cover 30 is detachably attached to the lower end surfaces of the inner cylinder 24 and the outer cylinder 26. The bottom cover 30 covers the lower surface of the space between the inner cylinder and the outer cylinder and the lower surface of the space in the inner cylinder. The bottom cover 30 can be formed of, for example, an aluminum wheel.
The inner tube 24 is filled with a water-permeable material C such as sand, and the gap between the inner tube 24 and the outer tube 26 is filled with a water-absorbing material A such as a water-absorbing polymer. It has a heavy structure.

  When used, the swelling unit 20 is installed in the lower part of the boring hole 2, a cylindrical jig J is installed in the water-permeable material part (see FIG. 9), and the water-permeable material part is vertically directed downward through the jig. When the cylindrical main body 22 is pulled upward in a state where the force is applied, the cylindrical main body 22 is separated from the bottom cover 30 and pulled up, and the water-absorbing material A and the water-permeable material C are together with the bottom cover 30 in the vertical hole 2. The swelled portion 6 of the first embodiment is formed remaining at the bottom. The bottom cover can be suitably separated by making the strength of the bottom cover itself higher than the adhesive strength between the bottom cover and the cylindrical main body.

As a preferred embodiment, in the illustrated example, the water-permeable material C in the inner cylinder 24 is filled by a predetermined height higher than the water-absorbing material A between the inner cylinder 24 and the outer cylinder 26, and When the tubular main body 22 is pulled out, the water-permeable material C of a predetermined height falls on the water-absorbing material A. Thereby, not only the swollen portion 6 but also the intermediate portion 8 can be formed at the same time, which is particularly preferable. However, a configuration in which the water-permeable material C and the water-absorbing material A are filled at the same height is also included in the technical range of the swelling unit 20 of the present invention.
Further, in the illustrated example, the lower part of the water supply pipe 16 is inserted into the water-permeable material in the cylindrical main body 22 to a depth equivalent to the core part, and the lower part of the exhaust pipe 18 is inserted to the depth equivalent to the intermediate part 8. In the case of this configuration, the swelling unit 20 is set at the lower part of the boring hole 2, and preferably the upper part of the water supply pipe 16 and the upper part of the exhaust pipe 18 are supported by support means (not shown) so that each pipe does not fall. When the cylindrical body 22 is supported and pulled out upward, the entire structure of the crushing mechanism 4 except for the cement portion of the closing portion 10 is completed at one time. After that, if the high-strength cement is poured into the upper end of the boring hole 2 and hardened, the construction of the crushing mechanism 4 is completed, which is convenient.

As a swelling unit that can be transported in a configuration other than the above, for example, a mesh tube that allows water to pass through substantially the entire inner cylinder, and an entire outer cylinder that is an inflatable elastic cylinder wall, and is provided with a water-permeable material in the inner cylinder. It is also conceivable that the supplied water is absorbed by the water-absorbing material through the mesh tube, and the swelling pressure of the water-absorbing material presses the surrounding rock portion through the outer tube.
The elastic cylinder can be, for example, a biodegradable nonwoven fabric as shown in Non-Patent Document 2. This eliminates the need to collect the swelling unit after rock failure.
FIG. 10 shows an example of a swelling unit using a nonwoven fabric. In this swelling unit, the inner tube 24, the outer tube 26, and the bottom cover 30 are formed of a nonwoven fabric. That is, the core portion 6a and the peripheral portion 6b are divided by a double cylindrical nonwoven fabric, and the bottom surface is closed by using the bottom cover 30 which is a nonwoven fabric. The top of the swelling unit is sealed with a seal portion 24a. Specifically, after inserting the water-absorbing polymer between the nonwoven fabric (inner cylinder 24) and the nonwoven fabric (outer cylinder 26), the cylindrical seal portion 24a extending from the upper end of the inner cylinder 24 is attached to the outer cylinder 26. It is configured to be sealed on the inner surface. In the figure, the symbol “K” indicates a joint between the nonwoven fabrics.
Incidentally, in the joining method of these nonwoven fabrics, adjacent sides are joined by known means to form a three-dimensional shape. As a known bonding means, for example, a method of performing lamination or thermal bonding with a water-soluble adhesive containing a biodegradable component, or a method of performing fusion such as heat fusion, high-frequency fusion, or ultrasonic fusion There is. Further, the intermediate portion 8 may be filled with sand after the unit is installed. Furthermore, by using a biodegradable water-absorbing polymer as shown in Non-Patent Document 3, it is not necessary to collect the water-absorbing polymer after rock breakage.
On the other hand, the configuration of the illustrated example is economical because the tubular main body can be reused by pulling it out and attaching a new bottom cover.

[Confirmation of crushing performance by swelling of water-absorbing polymer]
For the purpose of confirming that the rock can be broken by swelling of the water-absorbing polymer, an indoor rock breaking experiment was performed using a rock specimen having the size shown in FIG.
Rock name: Granite Specimen dimensions: 9cm (= w) x 9cm (= w) x 18cm (= h)
Boring hole radius: 2cm (= r)
Boring depth: 15cm
Polymer layer thickness: 0.5 cm (= t)
Polymer layer height: 9cm (= m)
Type of polymer: CP-1 (trademark) manufactured by Chemical Technos

A rock destruction experiment was performed with the structure described above. As shown in Table 1, the experimental parameters were the amount of polymer in the water-absorbing polymer layer, and the polymer layer was filled with a mixture of polymer and sand. Experiments were conducted on four types of polymers in which 100%, 50%, 25%, and 2% were mixed by mass ratio. The basis for setting these weight ratios will be described in the next paragraph.
Among them, in CASE-1 and CASE-2, a tensile crack occurred in 1 to 2 days, and the specimen was broken. In the experiment, since the thickness of the polymer layer was 0.5 cm and the height was 9 cm, the volume of the polymer layer was π × (2 ² −1.5 ² ) × 9 = 49 cm ³ .
The time from water injection to destruction requires 1-2 days. On the other hand, pouring water into the borehole may cause a time difference in operation. However, the time difference is sufficiently small for 1-2 days. Therefore, when performing bench excavation using a plurality of boring holes shown in FIG. 3, the time of water injection into each boring hole does not necessarily have to be the same.
In order to generate a swelling pressure, water more than saturating the 49 cm ³ polymer layer may be supplied to the polymer layer. In the experiment, since the upper portion of the borehole was closed with the high-strength cement, the volume expansion of the polymer layer was suppressed to almost zero, and as a result, a swelling pressure was generated. The amount of water necessary to obtain the swelling pressure is an amount that saturates 49 cm ³ as described above. If the volume of the sand layer in contact with the polymer layer in the double structure is π × 1.5 ² × 9 = 64 cm ³ , and the height of the single sand layer above the double structure is 4 cm, the volume is π × 2 ² × 2 = 50 cm ³ and there is water around the polymer layer that saturates the sand layer 64 + 50 = 114 cm ³ . By the way, this 114cm ³ is well above the 49cm ^3.
Further, once the crushing mechanism 4 is once saturated, the water level of the 50 cm ³ sand layer existing in the sand layer above the double structure is lowered, and sufficient swelling pressure is generated by moving water to the polymer layer. I do. That is, once the structure of the present invention is saturated, destruction can occur without additional water supply.
The internal pressure at the time of breaking is obtained as follows. That is, the cracks occurred in the cross section where the distance from the boring hole to the end of the test specimen was the shortest among the square test specimens whose plan views are shown in FIG.
In this case, it is considered that the thick cylinder theory can be applied (see FIG. 14). In the thick cylinder theory, the tangential tensile stress σ _θ generated on the borehole wall is obtained by the following equation. Here, P: internal pressure.
[Equation 1] σ _θ = (P · r ₀ ² ) / (r ₁ ² −r ₀ ² ) × (1+ (r ₁ ² / r ₀ ² ))
Here, since r ₀ = 2 cm and r ₁ = 4.5 cm,
^{_{σ θ = (P × 2 2}} ) / (4.5 2 -2 2) × (1+ (4.5 2/2 2)) = 1.49P
Since the tensile strength of granite is about 100 kg / cm ² , if σ _θ = 100 kg / cm ² , P = 100 / 1.49 = 67 kg / cm ² . In FIG. 11, it was described that the swelling pressure of the water-absorbing polymer was expected to be about 100 kg / cm ² , but it was also confirmed in an indoor rock breaking experiment conducted by the inventor that a swelling pressure close to this was generated.
Further, it was confirmed that the structure of the present invention can be used to break rock, that is, excavate, by utilizing the swelling property of the water-absorbing polymer.

[Design of thickness of water absorbing material]
FIG. 15 shows an incident performed for the purpose of checking the range of the thickness in which the water absorbing material can absorb water.
As shown in FIG. 15A, the mold was filled with a polymer layer as a single layer, and water was absorbed through a water supply pipe under the condition that the polymer surface was a free surface.
The results are shown in FIG. At the moment when the water was supplied, the water level in the water supply pipe slightly decreased, and thereafter, the water level in the water supply pipe did not decrease for 5 minutes. The water supply pipe was taken out, and the diameter (d shown in FIG. 15C) of the gelled area around the water supply pipe was measured to be 14 mm. Since the outer diameter of the water supply pipe is 9 mm, the range in which the polymer layer instantaneously absorbs water can be evaluated as 2.5 mm (= (14-9) / 2 mm) from the water absorption surface.
If the layer thickness T of the water-absorbing material after installation shown in FIG. 1 is set to a large value, a large number of polymer layers that do not absorb water will remain, and wasteful polymers will be disposed, which is uneconomical. Due to the small Young's modulus, there is a possibility that the swelling pressure is absorbed and no breakage occurs. From the experimental results shown in FIG. 17 described later, it is known that the water-absorbing polymer swells 2.5 times. On the other hand, in the experiment shown in Table 1, the thickness of the water-absorbing polymer was tested at 5 mm to confirm that the rock was broken. From these facts, it is considered that the bedrock will break if the layer thickness T of the water-absorbing polymer after installation is in the range of 5 mm × 2.5 or less, that is, 12.5 mm or less.
Further, as shown in FIG. 11, it is known that when the thickness of the water-absorbing polymer layer is 2 mm to 3 mm, a sufficient swelling pressure can be obtained. Further, as described above, the range in which the polymer layer instantaneously absorbs water was 2.5 mm. Therefore, it is considered that the thickness of the polymer layer after installation is appropriately 2 mm or more.
From the above, it is preferable that the thickness T of the polymer layer after installation is in the range of 2 mm to 12.5 mm.

[Basis for setting weight ratio]
Prior to the execution of the indoor rock model test shown in Table 1, the swelling amount of a mixture of the water-absorbing polymer and sand was measured (see FIGS. 16 to 17). In the test, a sample having an initial height of 20 mm was placed on an acrylic cylinder, and water was absorbed from the lower surface to measure a change in sample height.
As a result, by increasing the mass ratio of the water-absorbing polymer to the sand to 50% or more, the sample swells sufficiently under the unconstrained condition and the volume swells to 2.5 times ((20 mm + 30 mm) / 20 mm). all right. Therefore, it was decided to conduct a laboratory test under the conditions of 50% and 100% of the water-absorbing polymer shown in Table 2. In addition, for comparison of test results, an indoor model test was performed under a total of four conditions of 25% and 2%.

[Design of the ratio of the depth of the vertical hole to the height of the swollen part and the thickness of the closed part]
Further, in the present invention, the height d of the polymer layer shown in FIG.
[Equation 2] d> D / √3
And the height p of the non-swelling portion obtained by adjusting the height of the middle portion to the closing height p ′ of the early-strength cement is [Equation 3] p <D / √3
It is characterized by the following.
The reason will be described below.
As shown in FIG. 7A, consider a case where a boring hole is excavated in an in-situ bedrock and a bench excavation is performed using the present invention. FIG. 4 is a plan view and FIG. 5 is a cross-sectional view. In the case of the conventional static crushing, the arrangement interval of the boring holes is a standard of 50 cm. It is thought that the greater the depth D of the boring, the better the rock excavation efficiency, but the need to exceed the boring interval of 50 cm is considered to be low. Therefore, the following description is based on the condition that the boring interval is equal to the depth of the boring hole. In practicing the present invention, the boring interval and the boring depth do not necessarily have to be equal.
As shown in FIG. 4, the cross section of the unit thickness 1 is focused on the rock around the boring hole. When swelling pressure w is generated by placing a polymer in a borehole, tensile stress concentration occurs at a corner at the lower end of the borehole shown in FIG. Assuming that the height of the polymer layer is d, the moment generated at the bottom corner of the boring is
M = load × distance = (w × d) × (d / 2) = (Wd ² ) / 2
Becomes
Moreover, the section modulus Z of the rectangular cross-section (the portion corresponding to the rock portion G ₁₎ shown in FIGS. 4 and 5, b = 1, h for unit thickness is 1 believe the same D as boring depth So
^{Z = (bh 2) / 6} = D 2/6
Becomes
Since the stress σ generated at the corner can be approximated by dividing the moment M by the section modulus Z,
^{σ = (wd 2/2)} / (D 2/6) = 3w × (d 2 / D 2) [Equation 3]
This load concentrates stress at the bottom corner of the boring. FIG. 14 illustrates the thick cylinder theory, but FIG. 14 illustrates the stress distribution in the rock around the boring hole when the stress concentration at the bottom corner of the boring is not considered.
The actual fracture causes a stress concentration at the corner 3 of the boring hole 2 shown in FIG. Therefore, as is apparent from [Equation 3], by setting (d ² / D ² )> ３, when the internal pressure W becomes equal to the tensile strength σt of the rock, the internal pressure near the corner of the lower end of the boring hole is reduced. Local destruction occurs due to a tensile stress greater than w. Once local fracture occurs, stress concentration occurs at the fracture surface tip, and as a result, a crack propagates in a direction parallel to the free surface of the bench as shown in FIG. 6E. At the same time, the rock on the free surface side of the bench undergoes rotational deformation as shown by the two-dot chain line in FIG. 5, so that the fracture surface H of the bending also advances from the lower end of the boring hole toward the free surface of the bench, As described above, efficient destruction can be performed. That is, if d> D / √3 is satisfied, excavation can be performed without providing a polymer layer near the upper end of the borehole.
When d is much larger than D / √3, stress concentration still occurs, and the polymer is used excessively.
The above-mentioned patent document discloses a structure in which a drug is loaded into most of the borehole in the depth direction and the surface of the borehole is closed with high-strength cement. Such a structure in which the drug is filled almost all over the borehole is theoretically overdesigned and uneconomical.
Therefore, in the present invention, the polymer is filled under the boring hole so that d> D / √3, and the upper portion is not filled with the polymer as shown in FIG. And the length p of the non-swelling region composed of the portion and the single sand layer portion is made as large as possible in the range of p <D / √3.
This enables more efficient and economical rock excavation than existing technologies. In addition, the blockage by the early-strength cement is originally intended to block (fix) the upper end portion of the boring hole to generate a swelling pressure due to the polymer.
Assuming that the radius of the boring hole is 3 cm, the thickness of the polymer layer is 0.5 cm, and the internal pressure generated by the polymer is 100 kg / cm ² , the closing height p ′ by the early-strength cement must satisfy the following expression. Here, μ is the bond strength between the early-strength cement and the rock, and μ is generally 10 kg / cm ² .
μ = Force acting on the lower end of blockage due to the early-strength cement (swelling pressure x cross-sectional area of polymer layer)
付 着 Adhesion area between early-strength cement and rock mass = (100 kg / cm ² × (3 cm × 3 cm-2.5 cm × 2.5 cm) × 3.14) ÷ (3 cm × 2 × 3.14 × p ')
= 10kg / cm ²
→ p '> 4.6cm
Another object of the present invention is to provide a structure in which the non-swelling layer is formed as large as possible in the range of p <D / ボ ー 3 above the boring hole, and the non-swelling region is actively provided with a high-strength cement or sand which is cheaper than a polymer. This allows for reasonable and economical drilling.

  Although the embodiments of the present invention have been described above, the present invention is not limited to these embodiments at all, and it goes without saying that the present invention can be implemented in various modes without departing from the gist of the present invention.

2 ... vertical hole (borehole) 3 ... corners 4 ... crushing mechanism 6 ... Rise Jun portion 6a ... core portion 6b ... peripheral portion 8 ... intermediate portion 10 ... closing portion 12 ... feed water holes 14 ... exhaust hole 16 ... water supply pipe 18 ... Exhaust pipe 20 ... Swelling unit 22 ... Cylinder body 24 ... Inner cylinder 24a ... Seal part 26 ... Outer cylinder 28 ... Connecting plate 30 ... Bottom lid 50 ... Breaker A ... Water absorbing material C ... Water-permeable material E ... Excavation surface (bench Surface)
F: crack G: rock mass H: crack (crack / fracture surface)
J: jig K: bonding surface of nonwoven fabric L: distance from excavation surface to row of holes Lu: lump S: boundary surface T: layer thickness of water absorbing material

Claims (4)

Excavating multiple vertical holes in the bedrock;
A step of constructing a swelling portion having a double structure surrounding the columnar water-permeable material by the annular water-absorbing material swellable by water absorption in the vertical hole;
A step of closing the upper side of the vertical hole with a closed portion having an exhaust hole and a water supply hole,
A step of injecting the water-permeable material through a water-supply pipe reaching the water-permeable material from the water- supply hole,
A rock excavation method in which the water-absorbing material that has absorbed water swells from a boundary surface between the water-permeable material and the water-absorbing material, which is a peripheral surface of the water-permeable material, and the rock part around the vertical hole is split by the swelling pressure. Along with disposing the annular water absorbing material in contact with the bottom surface of the vertical hole and the inner peripheral surface of the lower portion of the vertical hole,
By filling the space from the inside of the water-absorbing material to the back surface of the closed portion with a water-permeable material having fluidity,
In the lower part of the longitudinal hole, so it placed on the bottom of the vertical hole, characterized in that to construct the double structure, rock drilling method according to claim 1. A transportable swelling unit for use by loading into a vertical hole in the rock,
A double structure formed around at least a part of the height direction and surrounding the columnar water-passing portion with an annular water-absorbing portion that can swell by water absorption;
A water supply pipe standing up from the inside of the water passage section ,
The water-passing portion has a volume compression ratio smaller than that of the water-absorbing portion, and is configured such that water can flow to the water-absorbing portion through the entire boundary surface between the water-passing portion and the water-absorbing portion, which is the peripheral surface of the water- passing portion. Have
A swelling unit in which the water absorption part swells due to water absorption from the water passage part side, and the inner surface of the vertical hole can be pressed. It has a double cylinder which is interconnected with the inner cylinder and the outer cylinder through the coupling piece, the lower surface and the lower surface of the space within the inner cylindrical space between their inner cylinder and the outer cylinder, break A container body covered with a possible bottom lid,
The water passage section and turning on the water passing member in the inner cylindrical water absorption unit and turning on the water absorbent material between the inner tube and the outer tube, and characterized by being constituted respectively The swelling unit according to claim 3,