JPH08134894A - Stabilization of soft ground - Google Patents

Abstract

PURPOSE: To greatly and economically reduce the manufacturing cost of piles without necessity of costly sand and gravel. CONSTITUTION: A cylindrical casing 2 having a large diameter is pushed into the ground by a rotary press-in and pull-out device 1 to penetrate the casing 2 to a specified depth of the ground. The soil in the casing 2 is excavated by a hammer grab 3 or the like and discharged onto the ground surface. Thereafter, a granular mixture S which is composed of the excavated soil and a cement solidifying material agitated and mixed together on the ground surface, is fed in the easing 2. Thereafter, the granular mixture S of the contents of easing pulled out by the rotary press-in and pull-out device 1 is charged in the ground again. The granular mixture S charged in the ground absorbs the water in the ground and forms soil improvement piles.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for improving soft ground, and more particularly to a method for forming a large-diameter ground improving pile on soft ground by using an apparatus for a whole casing method.

[0002]

2. Description of the Related Art The entire casing construction method is to dig a large-diameter casing having a diameter of 1 to 2 m into a ground by using a hammering grab or the like while pushing it into the ground while rotating it by a rotary press-in / pull-out device installed on the ground. While excavating the excavated soil to the ground and putting fresh concrete into the discharged casing, the casing is rotated by the rotary press-in / pull-out device and pulled out to form a concrete pile in the ground. , Sufficient bearing capacity can be obtained even on soft ground.

[0003]

However, the biggest difficulty of the above-mentioned conventional whole casing construction method is that a large amount of ready-mixed concrete is used, so that the construction cost is very high. Especially, sand and gravel, which are the main materials of ready-mixed concrete, are very expensive, and it is almost impossible to procure them in Japan.
Most of them are currently procured from foreign countries, and even foreign-made ones are quite expensive.

As a ground improvement pile using a cement-based solidifying material, a cement-based solidifying material is kneaded in a paste form, poured into the ground, and directly mixed with soil in the ground by stirring and mixing. Some soil cement piles are formed, but this soil cement pile mixes the cement-based solidifying material and the earth and sand in the ground with stirring, so it is judged whether both are sufficiently and uniformly stirred and mixed. It is impossible to do so, there is a possibility that it will cause variations in the supporting force, and the up and down movement and rotation of the stirring rod for stirring and mixing must be performed with considerable frequency. The work was extremely complicated.

An object of the present invention is to solve the above problems.

[0006]

In the construction method according to claim 1 of the present invention, a large-diameter cylindrical casing 2 is pushed into the ground by the casing rotary press-fitting / pulling-out device 1, and the casing 2 is grounded. After penetrating to a predetermined depth, excavating the soil in the casing 2 with an excavator 3 such as a hammer mug, discharging the excavated soil to the ground, and then mixing and stirring the excavated soil with a cement-based solidifying material or cement powder on the ground. The mixed powder or granules S formed by the above is put into the inside of the casing 2, and then the casing 2 is pulled out by the casing rotary press-fitting / pulling-out device 1 to discharge the mixed powder or granules S inside the casing 2 into the ground, The mixed powder granules S discharged into the ground absorb moisture in the ground to form the ground improvement pile P.

In the construction method according to the second aspect of the present invention, the vibroflot 11 which is attached to the tip of the rod 10 and which can be moved up and down by the up-and-down moving means is provided inside the casing 2 into which the mixed powder S is put. While vibrating and moving up and down, the mixed powder granules S are mixed and stirred to be inserted into the bottom of the casing 2 and pulled up, and then the casing 2 is pulled out by the rotary press-fitting / pulling-out device 1, so that the mixed powder granules S inside the casing 1 are pulled out. Is to be discharged into the ground.

In the construction method according to claim 3, while the casing 2 is pulled out by the rotary press-fitting / pulling-out device 1,
It is characterized in that the mixed powder and granules S are stirred and mixed to form the ground improvement pile P in the ground while vibrating and vertically moving the vibroflot 11 again.

In the construction method according to the fourth aspect, a butterfly-shaped opening / closing plate 18 is provided at the lower part of the vibro flot 11 so as to open laterally by earth pressure and close downwardly by its own weight. It is characterized in that the butterfly-shaped opening / closing plate 18 is opened / closed according to the vertical movement of the vibro flot 11 by the vertical movement means.

The construction method according to claim 5 is characterized in that the hydraulic cylinder 9 is used as the vertical movement means.

The construction method according to claim 6 is characterized in that the cement-based solidifying material contains calcium oxide, silicon dioxide, aluminum oxide and sulfur trioxide as main components.

[0012]

According to the construction method of claim 1, the large-diameter cylindrical casing 2 is pushed into the ground by the rotary press-in / pull-out device 1 and penetrates to a predetermined depth, and the soil in the casing is excavated by a hammer tool or the like. The excavated soil that has been excavated and discharged to the ground is used as it is as earth and sand material for pile formation,
The mixed powder granules S formed by mixing and excavating the excavated soil and the cement-based solidifying material or cement powder on the ground are used for the casing 2
Since it is put into the inside of the pile, it does not require expensive sand and gravel as in the past, and it is extremely economical, and the pile construction cost can be greatly reduced.

After the mixed powder S is put into the casing 2 as described above, the casing 2 is pulled out by the rotary press-fitting / pulling device 1 to discharge the mixed powder S inside the casing 2 into the ground. However, since the mixed powder S discharged into the ground absorbs the water in the ground to form the ground improvement pile P, the water contained in the soft ground is absorbed by the mixed powder S. As a result, the density of the soft ground is increased, and the mixed powder S absorbs moisture in the ground to be hardened, whereby the mixed powder S swells and consolidates the soft ground. Consolidation can be effectively achieved.

According to the construction method of the second aspect, the vibroflot 11 is inserted into the inside of the casing 2 in which the mixed powder S has been charged while vibrating and moving up and down, and after being pulled up, this casing In order to discharge the mixed powder and granules inside the casing into the ground, the excavated soil and the cement-based solidifying material or cement powder are evenly mixed and stirred inside the casing 2 to obtain a homogeneous mixture. The granules S are formed, whereby a good ground improvement pile P can be created.

Further, according to the method of claim 3, the casing 2 is pulled out by the rotary press-fitting / pulling-out device 1, and
While vibrating and vertically moving the vibroflot 11 again, the mixed powder particles S in the ground are stirred and mixed to form the ground improvement pile P. Therefore, the mixed powder particles discharged into the ground by pulling out the casing 2 When the body S is mixed and stirred by the vibrating action of the vibro flot 11 and the vertical movement, the powder mixture S in the ground is promoted to absorb water from the surrounding ground and the expansion degree is increased. As a result, the surrounding ground is further consolidated and the ground strength is further increased.

According to the construction method of claim 4, when the vibroflot 11 is inserted into and pulled up from the mixed powder granules S, the butterfly-shaped opening / closing plate 18 mounted below the vibroflot 11 is During the downward movement of the vibro flotto 11 by the hydraulic cylinder 9, the pressure of the mixed powder and granules S opens laterally, and the downward movement in this open state causes the mixed powder and granules S to move. It is closed downward by its own weight and moves up smoothly without receiving the resistance of the powder mixture S.
By the way, this butterfly-shaped opening / closing plate 18 is
By opening and closing with the vertical movement of the mixed powder and granules S, the mixed powder and granules S inside the casing 2 are agitated and compacted, and the mixed powder and granules S discharged into the ground are compacted and compacted. A strong consolidation pile S is formed.

Further, according to the construction method of the fifth aspect, by using the hydraulic cylinder 9 as the vertically moving means, a sufficient driving force can be obtained, and the structure is compact and the mounting is easy.

Further, according to claim 6, when the cement-based solidifying material containing calcium oxide, silicon dioxide, aluminum oxide and sulfur trioxide as the main components is used, the experimental result shows that 240 kg of ordinary cement powder is used. The uniaxial compressive strength when adding / m ³ was 2 kgf / cm ² , whereas
It was found that this cement-based solidifying material has a uniaxial compressive strength of 6.4 kgf / cm ² when 240 kg / m ³ is added, and exhibits a strength three times that of cement powder. Therefore, according to this cement-based solidifying material, a very good supporting force as a pile can be exhibited.

[0019]

EXAMPLES Examples will be described with reference to the drawings.
FIG. 1 shows a pile forming apparatus used for carrying out the construction method according to the present invention. In this figure, reference numeral 1 denotes a casing rotary press-fitting / pulling-out device for pushing or pulling out a large-diameter cylindrical casing 2 into the ground while rotating it, and 3 denotes, for example, a crane 4 and a lifting wire 5
It is a well-known hammer mug (excavator) that is hung up and down via a shaft. 6 is supported, for example, so as to be able to move up and down along the leader 7, and a lifting wire 8 is provided from the top of the leader 7.
The lifting body is suspended by the
A rod 10 is provided via a hydraulic cylinder 9 as a vertically moving means.
Are connected in series and the lower end of the rod 10 is equipped with a vibro flot 11.

The casing rotary press-fitting / pulling-out device 1 is a well-known device which has been conventionally used. For example, as shown in FIG. 2, a rotary drive shaft 13, a hydraulic motor 14, and a press-fitting device are mounted on a base frame 12 installed on the ground. It is equipped with a pull-out means 15, a chuck device 16 and the like. While the casing 2 is inserted into the rotary drive shaft 13 and gripped by the chuck device 16, the rotary drive shaft 13 is rotated by driving the hydraulic motor 14. The casing 2 is rotated and pushed into the ground or pulled out.

As shown in FIG. 3 (A), a hydraulic cylinder 9 is mounted on the lifting body 6, a hollow rod 10 is coaxially connected to the hydraulic cylinder 9, and a vibroflot is attached to the lower end of the rod 10. 11 is attached. The vibro flot 11 is well known, and although not shown, the eccentric shaft is rotated by an electric motor to generate horizontal vibration. Power cable 1 to this motor
7 is inserted into the hollow portion of the rod 9 and extends out from the upper end portion of the rod 9 as shown in FIG.
Wired to the side. The hydraulic cylinder 9 is used as the vertical movement means.
Alternatively, an air spring or the like that can move up and down by a predetermined stroke may be used, but the hydraulic cylinder 9 has the advantages of a compact structure and easy mounting.

Further, at the bottom of the vibro flot 11,
As shown in FIGS. 3 (A) and 3 (B), it is possible to equip a butterfly-shaped opening / closing plate 18 that opens laterally by earth pressure and closes downward by its own weight.
In this case, a short tubular support pipe 19 having a large diameter is attached to the vibro flot 11 via a plurality of attachment pieces 20, and a horizontal support shaft 21 is fixed in the lower end portion of the support pipe 19 in the diametrical direction thereof. The support shaft 21 has a pair of semicircular plates 18a, 18
A butterfly-shaped opening / closing plate 18 made of a is pivotally attached. This butterfly-shaped opening / closing plate 18 is normally closed so as to be folded downward by its own weight as shown by the solid line in FIG. 3A, and is rotated upward by receiving earth pressure from below as shown by the phantom line in FIG. It moves and is deployed in the lateral direction, and is abutted and supported by the lower end of the support tube 19 at the deployed position.

Next, the construction method of the present invention using the pile forming apparatus having the above-described structure will be described with reference to FIG. 4 and other drawings as needed. Incidentally, in FIG.
Indicates the order of construction.

First, as shown in and of FIG. 4, the large-diameter casing 2 is rotated and pushed into the soft ground by the casing rotary press-fitting / pulling-out device 1. In this case, the casing 2 uses a plurality of unit length,
The casings 2 are successively added to penetrate into the ground. Also, as shown in the figure, every time the casing 2 is penetrated to a certain depth, the ground soil inside the casing 2 is excavated by the hammer mug 3 and the excavated soil is discharged to the ground. In this way, the casing 2 is penetrated into the soft ground to a predetermined depth, and the ground soil inside the casing 2 is entirely discharged to the ground.

The excavated soil discharged from the inside of the casing 2 to the ground as described above is, for example, as shown in FIG. 6, a stirring tank (notch tank) 2 installed in advance near the work site.
2) and mix an appropriate amount of cement-based solidifying material or cement powder into the excavated soil carried into the stirring tank 22 and stir them, for example, as shown in FIG. Device 2 with device 23 attached
4 can be mixed by stirring. This stirring device 2
As shown in FIG. 5, 3 has a rotary claw 25 that is rapidly rotated in the normal and reverse directions by a hydraulic motor, and is replaced with a shovel of a hydraulic shovel to which the agitator 23 is attached. For example, Mitsui Co., Ltd. Stirrer manufactured by Miike Seisakusho (trade name, MT Twin Header) and stirrer manufactured by Maruzen Construction Co., Ltd. (product surface, stabilizer) have extremely good stirring efficiency, and it is recommended that they be used for implementing the present invention. It

As described above, when the excavated soil discharged from the inside of the casing 2 to the ground and, for example, the cement-based solidifying material are mixed with stirring, the cement-based solidifying material is calcium oxide, silicon dioxide, aluminum oxide and It is preferable to use a material containing sulfur oxide as a main component, and specifically, the following mixing ratios are suitable.

Silicon dioxide 18.6 to 20.2% Aluminum oxide 6.2 to 4.6% Ferric oxide 1.8 to 2.5% Calcium oxide
59.6-63.1% Magnesium oxide About 1.8% Sulfur trioxide 7.
7 to 6.7% Insoluble balance 0.1 to 0.2%

As a commercially available cement-based solidifying material, the trade name Heart Keep P-430 (manufactured by Tokuyama Co., Ltd.) or the trade name Aso Solid Ace (manufactured by Aso Cement Co., Ltd.) is preferable.

The mixing ratio of the cement solidifying material and the excavated soil differs depending on the soil quality of the excavated soil. Generally, the compression strength of one sand compaction pile (uniaxial compression strength
kgf / cm ² ) is ± ² to 3 kg before and after the center of 7 kgf / cm ^2.
It is said that f / cm ² is necessary and sufficient, but in order to reach these strengths, as a result of experiments by the present inventor, the compounding ratios shown in the following Tables 1 to 3 are suitable. It has been found.

[0030] Remarks The above clay is 80% silt, 40% clay,
As the cement-based solidifying material having a sand content of 60% and a water content of 70%, Heart Keep P-430 (manufactured by Tokuyama Corporation) was used. The above compressive strength is the value after 7 days have passed since setting.

[0031] Remarks The above sandy silt contains 70% silt and 15 clay.
%, Sand content 85%, water content 70%, and other conditions are the same as those in Table 1.

[0032] Remarks The above sandy soil contains 15% silt and 15% clay,
The sand content is 85%, the water content is 70%, and the other conditions are the same as in Table 1.

Then, the excavated soil discharged from the inside of the casing 2 and the cement-based solidifying material are stirred and mixed on the ground by the device 24 as shown in FIG. The mixed powder granules S that have been mixed are formed.

Mixed powder S formed as described above
As shown in FIG. 4, a required amount is put into the inside of the casing 2 that has penetrated into the ground by using a hopper 26 and the like. After that, although not shown in the drawing, the casing 2 in which the mixed powder S has been charged is pulled out while being rotated by the rotary press-fitting / pulling-out device 1, and the mixed powder S inside the casing 2 is discharged into the ground. The mixed powder particles S discharged into the ground absorb moisture in the ground to form a ground improvement pile. This ground improvement pile is a pile formed by the construction method of claim 1 of the present invention.

Further, from the state of FIG. 4 in which a required amount of the mixed powder S is put into the casing 2 penetrated into the ground, the vibroflot 11 is attached to the tip as shown in FIG. Lifting body 6 with hanging rod 10
While descending along the leader 7 (see FIG. 1), the vibroflot 11 is vibrated and moved up and down, and is inserted into the mixed powder granules S charged in the casing 2 to the bottom of the casing 2. After the insertion, the lifting / lowering body 6 is lifted and the vibroflot 11 is similarly vibrated and vertically moved, and is pulled up from the mixed powder S inside the casing 2. In this way, the mixed powder granules S inside the casing 2 are vibrated and moved up and down in this manner.
By inserting into the inside and pulling out from it, the excavated soil and the cement-based solidifying material or the cement powder can be more uniformly mixed and stirred to form a higher-quality mixed powder S.

After that, the casing 2 penetrating into the ground is pulled out while being rotated by the casing rotation press-fitting and drawing apparatus 1 as shown in FIG. 4, and the mixed powder S in the casing 2 is discharged into the ground. To do. The mixed powder and granules S discharged into the ground absorb moisture in the ground to form a ground improvement pile P'as shown by in the figure. Further, as shown in and in the figure, , The elevating body 6 is lowered and raised again as described above, and the mixed powder granules S discharged into the ground are agitated and mixed while vibrating and vertically moving the vibroflot 11, The ground improvement pile P as shown in is performed. In this case, the vibroflot 11 may be inserted into the mixed powder or granular material S after the casing 2 is pulled out, or may be in the process of being pulled out.
Incidentally, the ground improvement pile P'according to the present invention
And the ground improvement pile P is a pile formed by the method of claim 3.

That is, according to the construction method which omits the steps of and shown in FIG. 4 and comprises the steps from to of the figure, the casing 2 is extracted into the ground by the rotary press-fitting / extracting device 1 as shown in FIG. The discharged mixed powder S forms a pile P ', and immediately after the formation (about 3
Hardening begins after a while), absorbs the interstitial water between soil particles in the surrounding ground and lowers the water content, and at the time of this water absorption expands by reacting with water, increasing the volume by 30-60% during pile formation. Let In this way, when the soil improvement pile expands, the surrounding soil is consolidated, and the soil strength is enhanced by this consolidation, and the once expanded soil improvement pile itself becomes a hardened body due to the hardening action, so it shrinks. Therefore, the ground improvement pile is
While being suspended in the ground, it consolidates the surrounding ground and further increases its strength.

In addition, according to the construction method in which the steps (1) to (4) described above are added, the casing 2
The mixed powder S discharged into the ground due to
By vibrating and vibrating the vibroflot 11 for mixing and stirring, the mixed powder S in the ground is mixed.
The water absorption effect from the surrounding ground is promoted, and the expansion degree is increased, whereby the surrounding ground is further consolidated and the ground strength is further increased, and the ground improvement pile P
Is pressed by the up-and-down movement of the vibro flot 11 to form a strong and consolidated pile.

Further, as shown in and of FIG. 4, in the mixed powder granules S discharged into the ground, the vibro flot 11
When inserting and pulling up, this vibro flot 11
The butterfly-shaped opening / closing plate 18 mounted on the bottom of the hydraulic cylinder 9
When the vibro flotto 11 is moved downwards by the pressure of the mixed powder S, the mixed powder S is opened in the lateral direction, and the mixed powder S is pushed downward to push the mixed powder S downward. It closes and moves up smoothly without receiving the resistance of the mixed powder S. Then, the butterfly-shaped opening / closing plate 18 opens and closes in accordance with the up-and-down movement of the vibroflot 11, so that the mixed powder and granules S discharged into the ground are agitated and compacted to thereby consolidate. A compact pile is formed. The butterfly-shaped opening / closing plate 16 also acts in the same manner in the step of FIG. 4, and the mixed powder granules S inside the casing 2 are agitated and compacted.

[0040]

According to the method of claim 1 of the present invention, the excavated soil excavated in the casing and discharged to the ground is used as it is as a soil material for pile formation. Since the mixed powder or granules formed by mixing and stirring the solidifying material or the cement powder on the ground are put into the inside of the casing, there is no need for expensive sand or gravel as in the past, and it is extremely economical. The pile construction cost can be significantly reduced.

Further, in the method of the present invention, the excavated soil inside the casing is discharged to the ground, and the excavated soil and the cement-based solidifying material or cement powder are agitated and mixed on the ground to form a mixed powder granule of both. Therefore, it is naturally possible to uniformly and sufficiently stir and mix, and there is no variation in the mixing of both. Further, although it is necessary to change the mixing ratio of the cement-based solidifying material or the cement powder depending on the earth and sand material, that is, the soil component contained in the excavated soil, this mixing ratio can be accurately ensured. Therefore, it is possible to form a ground improvement pile having uniform strength over the entire length.

Further, according to the method of the present invention, the casing is pulled out, the mixed powder and granules inside the casing are discharged into the ground, and the mixed powder and granules discharged into the ground remove moisture in the ground. As it is designed to absorb and form a soil improvement pile, the density of soft ground is increased, and the mixed powder and granules swell by absorbing moisture in the ground and hardening, and the soft ground is swelled. Is consolidated, which can effectively achieve the consolidation of soft ground.

According to the second aspect of the present invention, the vibro flot is inserted into the casing into which the mixed powder and granules have been charged while vibrating and moving up and down, and after pulling up, the casing is pulled out to remove the casing. In order to discharge the mixed powder and granules inside into the ground, the excavated soil and the cement-based solidifying material or cement powder are mixed and stirred more uniformly inside the casing to form a homogeneous mixed powder and granules. ,
Thereby, a good ground improvement pile can be constructed.

According to the method of claim 3, the casing is pulled out, and the mixed powder particles in the ground are agitated and mixed while the vibro flot is vibrated and moved up and down again to form the ground improvement pile. Therefore, the mixed powder and granules discharged into the ground by pulling out the casing 2 are mixed and agitated by the vibration of the vibro flot and up and down, and the mixed powder and granules in the ground are promoted to absorb water from the surrounding ground. , The degree of expansion is increased, whereby the surrounding ground is further consolidated and the ground strength is further increased.

Further, according to the method of claim 4, the butterfly-shaped opening / closing plate is opened / closed in accordance with the up-and-down movement of the vibro flot, whereby the powder mixture S in the casing 2 is agitated and compacted. In addition, the mixed powder and granules discharged into the ground are compacted and compacted, thereby forming a strong compaction pile.

Further, according to the construction method of the fifth aspect, by using the hydraulic cylinder as the vertically moving means, a sufficient driving force can be obtained, and the structure is compact and the mounting is easy.

Further, according to the construction method of claim 6, it is possible to obtain a ground improvement pile having a semi-permanently strong supporting force.

[Brief description of drawings]

FIG. 1 is a side view showing a pile forming apparatus for carrying out a construction method of the present invention.

FIG. 2 is a perspective view showing a casing rotation press-fitting / pulling-out device.

FIG. 3 (A) is a side view showing an elevating body and a rod suspended from the elevating body, and FIG. 3 (B) is an enlarged perspective view of a vibro flot.

FIG. 4 is an explanatory diagram showing a construction sequence of the method of the present invention.

FIG. 5 is a perspective view showing an example of a stirrer used in the method of the present invention.

FIG. 6 is a perspective view showing an example of use of the stirring device of FIG. 1 Casing Rotation Press-in / pull-out device 2 Casing 3 Hammer grab (excavator) 6 Lifter 9 Hydraulic cylinder (vertical moving means) 10 Rod 11 Vibroflot 18 Butterfly-shaped open / close plate S Mixed powder granules P 'Ground improvement pile P Ground improvement pile

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display location E21B 11/04

Claims (6)

[Claims] 1. A casing rotary press-in / pull-out device is used to push a large-diameter cylindrical casing into the ground, and the casing is penetrated to a predetermined depth in the ground. After discharging the excavated soil to the ground, the mixed powder granules formed by mixing and stirring the excavated soil and the cement-based solidifying material or cement powder on the ground are put into the inside of the casing, and then this casing is replaced with the casing. It was pulled out by a rotary press-in / pull-out device to discharge the mixed powder and granules inside the casing into the ground, and the mixed powder and granules discharged into this ground absorbed moisture in the ground to form a ground improvement pile. Improvement method for soft ground. 2. The mixed powder and granules are vibrated and vertically moved by vibrating a vibro flot attached to the tip of a rod and vertically movable by a vertically moving means inside the casing into which the mixed powder and granules are charged. 2. Improvement of soft ground according to claim 1, wherein the mixed powder and granules in the casing are discharged into the ground by mixing and stirring and inserting the casing up to the bottom of the casing and pulling up the casing by the rotary press-in / pull-out device. Construction method. 3. The rotary press-fitting / pulling-out device pulls out the casing, and again while vibrating and vertically moving the vibroflot, the mixed powder and granules are stirred and mixed to form a ground improvement pile in the ground. The method for improving soft ground according to claim 1, wherein 4. A bottom portion of the vibroflot is equipped with a butterfly-shaped opening / closing plate that opens laterally by earth pressure and closes downwardly by its own weight, and the vibroflot upper and lower parts are moved up and down by the vertical moving means. The method for improving soft ground according to claim 2 or 3, wherein the butterfly-shaped opening / closing plate is opened / closed according to the movement. 5. The method for improving soft ground according to claim 1, wherein a hydraulic cylinder is used as the vertical moving means. 6. The method for improving soft ground according to claim 1, wherein the cement-based solidifying material contains calcium oxide, silicon dioxide, aluminum oxide and sulfur trioxide as main components.