JP3373429B2 - Ground improvement method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ground improvement method for stabilizing the ground.

[0002]

2. Description of the Related Art In tunnel construction by the shield construction method, vertical shafts are constructed for carrying in and transporting materials, excavating earth and sand and discharging groundwater, and ventilation.

This shaft is often left as a permanent structure even after the construction is completed, and is generally constructed of reinforced concrete. Then, an opening for starting and reaching the excavator is provided on the wall surface. As a method of providing such an opening, a method in which a wall surface is formed as a flapping opening, or a steel material is used for a part of the wall surface and the steel material is melted to form an opening is used.

When a vertical shaft is installed in this way, the soil on the ground around the side wall of the vertical shaft is disturbed, the opening for starting the shield is opened, and at the same time, the earth retaining and water blocking function is lost, and the ground is fluidized. Since there is a risk of inflow into the vertical shaft, the ground will be stabilized by using chemical injection method, column jet method, freezing method, etc. around the entrance to prevent inflow of spring water or earth and sand.

[0005]

However, since all the ground improvement bodies by the conventional method for stabilizing the ground using the chemical solution injection method, the column jet method, the freezing method, etc., have a small bending tensile strength, a wide range is improved. If it is not, the required performance cannot be satisfied, and as a result, the construction cost will rise.

The present invention eliminates the disadvantages of the conventional example and can easily and inexpensively improve the bending strength, so that the range of improvement can be reduced, and a ground improvement method which contributes to the reduction of construction cost is also provided. Especially.

[0007]

In order to achieve the above-mentioned object, the present invention firstly cuts the ground into a muddy state with a water jet to make it into a muddy state, and the filler to be injected therein flows out. A bag with a predetermined opening that can be inserted is inserted together with the rod in a contracted state, a filling material such as cement milk, mortar or concrete is filled into the bag through the rod to inflate it, and then it flows out from the bag. The filler is filled in the space between the bag and the ground, a column-shaped improved body having a core surrounded by the bag is constructed, and the column-shaped improved body is appropriately juxtaposed. Secondly, the filler is cement. The main point is to add fiber for reinforcement to milk, mortar or concrete.

Thirdly, the column-shaped improved body having the core body surrounded by the bag is arranged in parallel so that the filled portion of the filler outside the bag is polymerized, and fourthly, the core body surrounded by the bag. The column-shaped improved body having is characterized in that a portion in which these are arranged in parallel is combined with a ground-improved portion by another construction method.

According to the first aspect of the present invention, the column-shaped improved body having the core body surrounded by the bag is appropriately juxtaposed, and the fiber in the vertical direction of the bag serves as the main rebar and also in the circumferential direction. The fiber reliably functions as a reinforcing bar, and can exert a predetermined horizontal proof stress and deformation performance.

Further, since the bag has a predetermined opening through which the filler can flow out, it becomes possible to fill the filler such as mortar not only inside the bag but also between the bag and the ground ground by jet cutting. In this way, when filling the inside and outside of the bag with a filler such as mortar, since the bag is sandwiched between the mortar and sandwiches, the integrity of the bag and the filler such as mortar is improved, and it is also cylindrical. Since the gap between the expanded bag and the ground is surely filled with the filler such as mortar, the adhesion between the bag and the ground is enhanced, and the vertical proof strength and the horizontal proof strength are improved.

According to the present invention as set forth in claim 2, in addition to the above-mentioned action, the filler is made to contain fibers, so that the strength is increased, and the improved product having higher strength and more homogeneous than general improved products. Can be created.

According to the third aspect of the present invention, in addition to the above-mentioned action, water blocking performance can be improved by causing the filled portions of the filler outside the bag to be arranged in parallel so as to be polymerized.

According to the fourth aspect of the present invention, in the column-shaped improvement body of the present invention, a portion where the columns are arranged in parallel is combined with a ground improvement portion by another construction method to bend only a required portion. A versatile ground improvement can be obtained in which the yield strength is improved and the other parts are only waterproof. further,
It also functions as a ground improvement body for improving the water blocking property when cutting a wall body by an excavator such as a shield construction method for a shaft having a wall body using a resin-impregnated high-strength fiber rod or for reinforcing the wall body itself. As a result, it is possible to reduce the resin-impregnated high-strength rods and reduce the construction cost.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below with reference to the drawings. 1 to 4 are vertical sectional front views of respective steps showing one embodiment of the ground improvement method of the present invention, in which the outer peripheral portion of the starting opening of the starting shaft is stabilized by the shield method for tunnel construction. This starting shaft also includes a case where a wall body is formed by using a high strength fiber rod impregnated with resin.

In the figure, 1 is a retaining wall made of reinforced concrete which forms a starting shaft, 2 is a shield excavator installed in the shaft, and 1a is a starting opening which the shield excavator 2 is intended to start.

As shown in FIG. 1, a water jet is ejected horizontally from the tip, a rod 5 capable of cutting the ground with this water jet is inserted into the ground, and the water jet is used to appropriately set the range and height of the ground. Cut to make muddy water. In that case, mud water such as bentonite may be replaced.

When the rod 5 is inserted into the ground, the rod 5 itself may be provided with a drill bit so that it can be drilled. Alternatively, another rod drilling machine can be used for vertical drilling of about φ150 mm. A hole may be provided and the rod may be lowered into the hole. Further, the earth and sand cut with a water jet can be discharged upward as necessary.

Next, as shown in FIG. 2, the bag 6 is inserted together with the rod 7 in a closed state, and as shown in FIG.
A filling material 8 such as cement milk, mortar, or concrete is filled and spread inside the column, and a column-shaped improvement body 4 having a core body 3 surrounded by a bag 6 is constructed as shown in FIG. In this step, a bag 6 is attached to the rod 5 used for cutting shown in FIG. 1, and the rod 5 is filled with a filling material 8 in addition to the water jet.
It is also possible to fill the bag 6 with a filling material 8 such as mortar and spread it at the same time as cutting, as a multi-layer structure capable of injecting.

The shape of the bag 6 is cylindrical, and the mouth of the upper end is narrowed to have a small diameter. This mouth is φ150 mm to φ.
It is made of woven fabric with a small diameter of about 200 mm. Further, a predetermined opening 11 is formed so that the filler 8 can flow from the inside of the bag 6 to the outside of the bag 6 when the bag 6 is filled with the filler 8 such as cement milk, mortar or concrete. The ratio of the opening 11 to the bag 6 is the opening ratio n = 1.
0-30% is suitable.

The opening ratio n is determined in consideration of the relationship between the outflow property of the filler 8 such as cement milk, mortar or concrete flowing out of the bag 6 and the strength of the fiber reinforced pile. The material of the bag 6 will be described below. In a test for testing the effect of the present invention, a bag made of polyester of φ250 mm × length 300 mm,
In 4 cases of opening ratio n6%, 13%, 25%, 57%, if the ratio is 13% or more, the outflow property of the mortar is out of the bag, and the yield strength of the ground improvement body is the value calculated by RC theory. It was confirmed to have the above maximum yield strength. Note that the aperture ratio n is 4
Even if it is 0 to 50%, it is judged that there is no problem in terms of yield strength, but it is preferably 30% or less in consideration of the restraining effect as a bag, economy, and the like.

The material of the bag 6 is polyvinyl alcohol fiber, polyester fiber, polyamide fiber, polyethylene fiber, aramid fiber, PBO (polyparaphenylene benzobisoxazole) fiber, glass fiber, carbon fiber, High-strength fibers such as metal fibers were used as warp and weft threads to form bag-shaped fabrics.

Since the bag 6 is made of high-strength fiber as described above, the bag 6 can be provided with the same function as the reinforcing bars in the vertical direction and the circumferential direction, and the bag 6 is used as a mold. In this case, since the filling material 8 such as cement milk or mortar filled is replaced with muddy water, qu = 300 kgf
Higher strength of / cm ^{2 to} 500 kgf / cm ² is possible. However, the bag 6 can be broken by the cutter bit when the shield excavator 2 excavates.

The filler 8 such as cement milk, mortar or concrete may further be mixed with reinforcing fibers such as steel fiber, carbon fiber and glass fiber.

5 and 6 show the filling state of the filling material 8. The filling material 8 flows out from the opening 11 and not only inside the bag, but also between the bag and the ground ground by jet cutting. The filling material 8 can be filled.

The column-shaped improvement body 4 having the core body 3 surrounded by the bag 6 is provided by juxtaposing them with each other. At this time, as shown in FIG. By arranging them in parallel so that they are polymerized, the water stopping property can be enhanced.

7 and 8 show a second embodiment of the present invention. The polyvinyl alcohol fiber, polyester fiber, polyamide fiber, polyethylene fiber, aramid fiber, PBO (polyparaphenylene benzobis). A belt made of similar high-strength synthetic fiber or steel fiber in the longitudinal direction of a bag formed of a woven fabric of high-strength fiber such as oxazole) fiber, glass fiber, carbon fiber, metal fiber or the like of ordinary fiber 12 Was installed as a reinforcing material.

9 and 10 show a third embodiment of the present invention, in which the bag 6 is made of the polyvinyl alcohol fiber, polyester fiber, polyamide fiber, polyethylene fiber, aramid fiber, PBO ( Lateral belt made of high strength fiber such as polyparaphenylene benzobisoxazole) fiber, glass fiber, carbon fiber, metal fiber, etc.
13a and the vertical belt 13b are knitted in a lattice to form a bag.
At that time, the openings 11 are secured by opening the stitches of the lateral belt 13a and the longitudinal belt 13b.

Further, as a fourth embodiment, as shown in FIGS. 12 and 13, a column-shaped improvement body 4 having a core body 3 surrounded by a bag 6 is a ground improvement portion formed by another method. It can also be combined with 9. As an example of the ground improvement portion 9 by this other method, after drilling to a target depth with a boring machine, the improvement material (grout) is injected from the lower end of the rod at ultrahigh pressure to cut the ground and mix soil particles and grout at the same time. By the column jet method of forming a columnar solidified body by stirring or replacing.

Other methods such as a deep layer mixing treatment method of solidifying the deep layer portion by performing mechanical stirring and mixing, a chemical solution injection method, and the like can also be adopted as the construction of the ground improvement portion 9 by another method.

In this way, the core body 3 surrounded by the bag 6 of the present invention
It is also possible to increase the versatility of ground improvement by disposing the column-shaped improvement body 4 having the above-mentioned structure only at the position where bending and pulling occur, and using the other as the ground improvement portion 9 by another construction method.

In the embodiment described above, the ground improvement method of the present invention is described as a case where the outer peripheral portion of the starting opening of the starting shaft is stabilized by the shield method of tunnel construction. However, the present invention is not limited to this. It can be used for prevention and general ground improvement.

[0032]

As described above, according to the ground improvement method of the present invention, the bending strength can be easily and inexpensively improved, so that the improvement range can be reduced and the construction cost can be reduced. . In particular, by using a high-strength fibrous bag having a predetermined opening, cement milk, mortar, etc. can be filled not only inside the bag but also in the space between the bag and the ground. Since the integrity and the adhesion between the bag and the ground are enhanced, it is possible to improve the supporting force, the horizontal proof stress, and the deformation performance.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional front view showing a first step of a first embodiment of a ground improvement method of the present invention.

FIG. 2 is a vertical cross-sectional front view showing a second step of the first embodiment of the ground improvement method of the present invention.

FIG. 3 is a vertical sectional front view showing a third step of the first embodiment of the ground improvement method of the present invention.

FIG. 4 is a vertical sectional front view showing a fourth step of the first embodiment of the ground improvement method of the present invention.

FIG. 5 is a vertical cross-sectional front view of the essential parts of the first embodiment of the ground improvement method of the present invention.

6 is a cross-sectional view taken along the line AA of FIG.

FIG. 7 is a vertical sectional front view showing a second embodiment of the ground improvement method of the present invention.

8 is a cross-sectional view taken along the line AA of FIG.

FIG. 9 is a vertical sectional front view showing a third embodiment of the ground improvement method of the present invention.

10 is a cross-sectional view taken along the line AA of FIG.

FIG. 11 is a cross-sectional plan view showing a parallel example of column-shaped improved bodies by the ground improvement method of the present invention.

FIG. 12 is a vertical cross-sectional front view showing a fourth embodiment of the ground improvement method of the present invention.

13 is a cross-sectional view taken along the line AA of FIG.

[Explanation of symbols]

1 ... Tsurudome 1a ... Starting opening 2 ... Shield excavator 3 ... Core body 4 ... Column-shaped improved body 5 ... Rod 6 ... Bag 7 ... Rod 8 ... Filler 9 ... Ground improvement part by other construction methods 11 ... Opening 12 ... Belt 13a ... horizontal belt 13b ... vertical belt

─────────────────────────────────────────────────── --- Continuation of front page (56) References JP-A-7-18658 (JP, A) JP-A-4-85411 (JP, A) JP-A 64-10820 (JP, A) JP-A 57- 24718 (JP, A) JP-A-8-177039 (JP, A) JP-A-6-228942 (JP, A) JP-A-6-257135 (JP, A) JP-A-7-189240 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) E02D 3/12 102 E21D 9/06 301

Claims (4)

(57) [Claims] 1. A ground is cut into a muddy state by a water jet to make it into a muddy state, and a bag having a predetermined opening through which the filler to be injected into the inside can flow out is inserted together with the rod in a contracted state. , A rod filled with cement milk, mortar, concrete or other filling material into the bag to inflate, and the filling material flowing out of the bag is filled in the space between the bag and the ground and surrounded by the bag. A ground improvement method characterized by constructing a column-shaped improved body having a body, and appropriately arranging the column-shaped improved body in parallel. 2. The ground improvement method according to claim 1, wherein the filler is cement milk, mortar, concrete or the like further mixed with reinforcing fibers. 3. The ground improvement method according to claim 1, wherein the column-shaped improvement body having a core body surrounded by a bag is arranged in parallel so as to polymerize a filled portion of the filler outside the bag. 4. The ground improvement according to any one of claims 1 to 3, wherein a column-shaped improvement body having a core body surrounded by a bag is combined with a ground improvement portion by another construction method in a portion where the columns are arranged in parallel. Construction method.