JPH11247200A - Caisson settlement method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily and vertically settle a caisson even in the case where the hard and soft condition of target ground is improper by reclaiming a previously sludge wall body on a caisson settling part, supporting the caisson by a force support device, and settling the caisson in the sludge wall body while the settlement amount of the caisson is controlled. SOLUTION: The existing earth of the settlement part of a caisson wall body is made sludge in the same degree as the thickness of a wall body for target ground 1 to form sludge wall body 2. Thereafter, a caisson wall body 4 is formed on the ground, and supported by a force support device 5 such as a plurality of jacks. Next, the caisson wall body 4 is settled in the sludge wall body 2 while the settlement amount of the caisson wall body 4 is uniformly controlled by the force support device 5. At this time, the caisson wall body 4 is not affected by the hard and soft condition of the target ground 1 and the discordance of the center of gravity and a reaction position of a caisson, can be vertically and easily settled in the sludge wall body 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The invention of this application relates to a caisson laying method. More specifically, the invention of this application relates to a new caisson laying method which is useful for caisson laying when the ground is too hard or soft and the hard and soft conditions are inappropriate, or when laying a caisson having an asymmetrical planar shape. Things.

[0002]

2. Description of the Related Art Conventionally, a caisson laying method has been often used in foundation works of building structures and construction of underground structures. This method is a method of constructing a caisson on the sinking design position, excavating the inside of the caisson and the cutting edge, and sinking the caisson in the ground. A balance between a certain squatting force and a squatting resistance force that resists the squatting is considered.

[0003] However, the caisson subsidence method has been evaluated as an excellent method in terms of economy and water stoppage as a foundation method or a method of constructing a basement. There are many restrictions on the plane shape of caisson, and it is not a general-purpose method in practice. For example, the restriction due to the hard and soft conditions of the target ground is that in a well-sealed sandy gravel or hard ground such as a dirt clay layer, settlement resistance is large and subsidence by its own weight alone is difficult. On soft ground such as clay layers or humus layers, settlement resistance is less than the weight of the caisson, resulting in excessive settlement, which in any case will hinder caisson construction. .

In order to cope with such a problem, in the case of a hard ground, measures such as increasing the wall thickness of the caisson more than necessary or increasing the settlement force by applying a load are taken. However, the effort, time, and cost for doing so is prohibitive. On the other hand, in the case of soft ground, the weight of the caisson is greater than the settlement resistance.For example, by improving the ground such as the chemicopile method or chemical injection method, the strength of the ground is increased and the settlement resistance is increased. Yes, but in this case,
There is a problem that it takes time and increases the cost.

[0005] In addition, the actual target ground often has a hard ground layer and a soft ground layer alternately, and in such a case, it is very difficult to apply the caisson laying method. In addition, there is a problem that the plane shape of the caisson is restricted. It is necessary for caisson to settle down exactly vertically after constructing the wall with concrete on the ground part in advance, but if the center of gravity of the caisson's sinking force does not match the resultant position of the settlement resistance, The caisson does not sink vertically well.

The inconsistency between the position of the center of gravity of the settlement force of the caisson and the resultant position of the settlement resistance occurs when the plane shape of the caisson is not a square or a rectangle close to a square. For this reason, it is said that the plane shape of the caisson is preferably a rectangle close to a square, and it is difficult to sink vertically when the plane shape is not the target or when the ratio of the short side to the long side is 4 or more. In this case, the caisson laying method was not applicable.

[0007] The invention of this application has been made in view of the above-mentioned problems of the prior art. Even when the condition of the target ground is inappropriate or the plane shape of the caisson is asymmetric, the caisson can be easily formed. Can be sunk vertically,
The task is to provide a new caisson laying method.

[0008]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides, as a first invention, a caisson burial method for laying a caisson in the ground, and A caisson characterized by constructing an ointment wall in advance, supporting the caisson with a supporting device, and submerging the caisson in the ozonized wall while controlling the amount of caisson settlement by the supporting device. Provide subsidence method.

Further, in the present application, regarding the above-mentioned caisson laying method, as a second invention, water or muddy water and, if necessary, a foam material and / or a superabsorbent polymer are also added to the caisson laying portion. As a third invention, there is provided a caisson squatting method for mixing and stirring to form an ointment wall, and as a third invention, a caisson sizing method for mixing and mixing soil and / or clay with water or muddy water.

This application relates to the above-mentioned first to third inventions, and furthermore, as a fourth invention, a caisson laying method in which the thickness of the wall made of ooze is made larger than the thickness of the caisson wall, As a fifth invention, a caisson laying method in which a through hole penetrating from the top end to the cutting edge is provided in advance in the caisson, and after the caisson laying is completed, a solidifying material is injected from the through hole to solidify the caisson tip, According to the invention of the sixth aspect, a through hole penetrating from the top end to the cutting edge is provided in advance in the caisson, and after completion of the caisson laying, a water-stopping material is injected into the wall of the softened mud from the through hole and stirred. A caisson laying method for solidifying a portion of the caisson and solidifying the outer periphery of the caisson, and a caisson laying method for sinking a caisson having a heat insulating material attached to its outer wall as a seventh invention,
As another aspect of the present invention, there is also provided a caisson laying method for sinking a caisson having a wall against which buoyancy opposes in a horizontal direction outside a wall body.

Further, in this application, in the above caisson laying method, as a ninth invention, in order to form a wall made of ooze, when the target soil is a viscous soil, a superabsorbent polymer solution and air bubbles are used. A caisson laying method is also available that uses a mixed water solution of wood material or a mixed water solution of bentonite solution and foam material, or a mixed water solution of superabsorbent polymer solution and foam material when the target soil is sandy soil. I do.

With the above-described construction method, the caisson can be easily laid down even when the hard and soft conditions of the target ground where the conventional caisson laying method is difficult to apply or when the plane shape of the caisson is asymmetric. It is possible to do. Further, in the present invention, the vertical settlement can be remarkably improved as compared with the conventional caisson laying method.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
For example, construction can be performed according to the procedures illustrated in FIGS. 1 to 6 of the attached drawings. That is, first, as illustrated in FIG. 1, for example, the present soil at the sunk portion of the caisson wall is made into the same or a thicker thickness as the wall of the caisson wall with respect to the target ground (1), and Body (2)
To form The wall of the softened mud varies in shape depending on the structure to be built. In this case, the wall has a rectangular shape, and in FIG. 1, the completed portion (21) and the uncompleted portion (22) are shown. Are shown in a plan view.

As a method for softening the existing soil in the caisson-deposited portion, for example, a super-soiling machine (3) such as a soil mixing wall or a soil mixing pile typified by a drilling kneader or the like can be used. . In other words, the formation of the oozed wall is made of soil, clay, mud,
Mix and stir while discharging foam material, super absorbent polymer, etc.
The soil, clay, muddy water, foam material, superabsorbent polymer, etc. are uniformly kneaded to make ooze.

For example, in the case of soil having a large thixotropy, a muddy muddy water and a fine-grained foam material can be mixed at the same time as appropriate to obtain a softened muddy wall. The specific weight of the oozed wall is smaller than that of the in-situ soil. Normally 0.8 to specific gravity
It is better to adjust to about 1.3. The specific gravity of 1 or less can be easily achieved by increasing the mixing amount of the fine-grained foam material. It can also be obtained by mixing a lightweight material such as styrene beads instead of the foam material.

Thereafter, as shown in FIG. 2, for example, a caisson wall (4) is formed on the ground, and the caisson wall (4) is supported by a plurality of supporting devices (5) such as jacks. At this time, as a method of supporting the caisson wall (4) by the supporting device (5), for example, a column (1
0) may be positioned horizontally, and the supporting device (5) and the caisson wall (4) may be connected via the column (10).

Next, as illustrated in FIG. 3, for example, a caisson wall (4) is provided by a supporting device (5) such as a jack.
The caisson wall (4) is submerged in the ozonized wall (2) while controlling the amount of settlement of the wall uniformly. At this time, the caisson wall (4) is vertically and easily osmotic wall wall (4) without being affected by the hard / soft condition of the target ground (1) or by the mismatch between the center of gravity of the caisson and the reaction force position. 2) Can be sunk in.

Next, as shown in FIG. 4, for example, when the jack or the like is removed after the caisson is laid, if the ground is soft enough to cause the caisson to sink, the grout pipe (6) is connected to the grout pipe (6). The caisson is penetrated from the top end to the cutting edge, and a solidifying material (7) such as cement milk is injected from the front end of the grout pipe (6) to solidify the caisson front end and its surroundings. You can stop the self-sinking.

At this time, an earth anchor or the like may be provided to prevent the caisson from lifting up. Subsequently, as shown in FIG. 5, for example, after the caisson wall (4) is laid, the inside thereof is excavated (8).
Excavate using This excavator can be freely selected depending on the shape of the caisson and the properties of the ground.

Finally, as shown in FIG. 6, for example, a bottom concrete (9) and a foundation pile are cast. When a basement is constructed by the caisson laying method of the present invention, dew condensation in the basement becomes a problem. In such a case, a heat insulating material having an appropriate thickness such as a polystyrene foam plate or a polyurethane plate is attached to the outer wall portion of the caisson wall (4), and the heat insulating material is settled to prevent dew condensation inside the caisson. be able to.

In the conventional caisson laying method, when such a heat insulating material is attached to the outer wall portion of the caisson and then the caisson is laid, the heat insulating material is broken by friction between the heat insulating material and the surrounding soil. However, such a construction method could not be adopted, but in the caisson laying method of the present invention, since the soil around the caisson is softened, the heat insulating material does not break.

In the present invention, not only the heat insulating material but also, for example, a buoyancy countermeasure wall can be protruded in the horizontal direction outside the caisson wall body (4) and settled down. Further, in FIG. 4, the solidification material is injected, mixed, stirred, and solidified during the softening, so that the water-stop layer can be easily formed. In the caisson laying method of the present invention,
Since the excavation of the caisson's soil is performed once after the caisson is laid, the construction can be performed efficiently, and the thickness of the caisson's side wall can always be the optimal thickness for strength, increasing the sinking force. Therefore, there is an additional advantage that the thickness does not need to be greater than the thickness required for strength.

Further, in the present invention, for example, FIG.
As exemplified in (A), a screw jack (51) can be used as an example of a supporting device, and a method of supporting the caisson wall (4) by the screw jack (51) is, for example, a column such as H steel. (10) is positioned horizontally, and its support (10) and the operating part (52) of the screw jack are fixed with bolts, and the support and caisson wall are fixed via a PC rod (11) or the like. May be.

Then, as illustrated in FIG. 7 (B), by operating the screw jack (51), the column (10) is lowered, and the caisson wall (4) is turned into the pulverized wall (2). Can be sunk in. Hereinafter, the present invention will be described in more detail with reference to Examples.

[0025]

EXAMPLE 1 The caisson laying method of the present invention was actually used for construction in Tsukuba City, Ibaraki Prefecture. The shape of the caisson was rectangular, its effective dimensions were 4.1 x 12.0 m, the sinking depth was 3.2 m and the wall thickness was 0.25 m.

The ground was the Kanto loam layer (0 to 2.7 m) and the aquifer sand layer (2.7 to 3.2 m). First of all, a column of an ozonized wall having a diameter of 0.60 m was formed around a caisson using a soil cement pile machine. Later, the caisson wall was supported by multiple jacks. The jack was a screw jack having a type of J4A, a procedure of 20 t / piece, a power of 4 kW / unit, and a speed of 20 to 50 mm / min.

The caisson wall was sunk by the jack while controlling the amount of settlement of the caisson wall evenly.
At this time, the caisson wall can be sunk vertically and easily into the ozonized wall without being affected by the hard and soft conditions of the target ground or by the mismatch between the center of gravity of the caisson and the reaction force position. Was. Embodiment 2 In the caisson laying method of the present invention, the target soil and muddy water
When mixing and agitating the foam material to form an ozonized wall, the properties of the ozonized wall, that is, whether the target soil does not separate and settle, and the hardness of the ozonized wall may cause problems in the sedimentation of caisson. A preliminary laboratory test was conducted to determine if any were found.

In the measuring cylinder, the current soil (target soil)
5.0 liters and 2.5 liters of a mixture of muddy water and foam material were mixed and stirred. A) The target soil did not separate or settle. Checked for suitability. As the present soil, two types of sandy soil and cohesive soil were used, and four types of mixed liquid were used for each soil as exemplified in Table 1.

[0029]

[Table 1]

In Table 1, the whip solution is a kind of superabsorbent polymer, and PALIC FA100 is used as a foam material.
Was used. The test results were as illustrated in Table 2. The meaning of "hard" in the table indicates that sedimentation or sedimentation occurred in the target soil, that is, in this case, the mixed solution that becomes the ozonized wall is not suitable for caisson settlement.

The terms “good”, “good”, and “somewhat good” mean that the target soil does not separate or settle, and that the target soil has a softness suitable for caisson settling. Is shown.

[0032]

[Table 2]

According to this experiment, when the target soil is a viscous soil, the wap liquid + bubble material or the bentonite liquid + bubble material is optimal, and when the target soil is sandy soil, the wap liquid + bubble material is used. The material was optimal. Example 3 Two sets of three grooves having a depth of 3.2 m were made into one set using a drilling and kneading machine having a diameter of 600 mm at the original position.

[0034] The mixed solution for constructing the oozing groove is A)
Superabsorbent polymer + bubble material, B) Bentonite + a bubble material, a mixture of them in current soil 1 m ³ per 0.4m
³ was mixed and stirred. In the case of the mixed solution of A), 1,500 kg of the Wap solution was used as the superabsorbent polymer, 3,300 kg of PALIC FA100 was used as the foam material, and these were mixed with 250 liters of water to prepare a mixed solution.

In the case of the mixed solution of B), # 250 bentonite, 0.400 kg, Palic F as a foam material
A100 and 3,300 kg were mixed with 250 liters of water to prepare a mixed solution. As for the present soil, the surface layer 1
m is a raised layer, and the rest of the depth is an untightened aquifered sand layer having an N value of <5, which can be said to be a soil layer in which hole walls are difficult to stabilize.

In the state 7 days after the excavation, collapse of the hole wall was not observed at all, and the hole wall was stable. In addition, when a deformed reinforcing bar (D-16) having a diameter of 16 mm was penetrated,
1.5 to 2 m was self-sinking, and after that, it penetrated only by pushing lightly. From this, it was found that the mixed solution used could be used in the method of the present invention.

[0037]

As described above, according to the present invention, the caisson can be easily laid down even when the target ground is too hard or too soft, or the caisson plane shape is asymmetric. It becomes possible.
Further, the construction of the basement is facilitated, and a low-cost and high-quality basement can be provided.

[Brief description of the drawings]

FIG. 1 is a diagram showing an oozing wall as a construction procedure according to the present invention (2).
3A and 3B are a vertical cross-sectional view and a plan view illustrating the formation of the first embodiment.

FIG. 2 is a longitudinal sectional view illustrating the formation of a caisson wall (4) on the ground as a construction procedure.

FIG. 3 is a longitudinal sectional view illustrating the subsidence of the caisson wall (4) into the ozonized wall (2).

FIG. 4 is a longitudinal sectional view illustrating the injection of a solidifying material.

FIG. 5 is a vertical cross-sectional view illustrating excavation.

FIG. 6 is a vertical cross-sectional view illustrating the placing of bottom concrete.

FIGS. 7A and 7B are schematic cross-sectional views showing an example in which a screw jack is used.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Target ground 2 Oozified wall 21 Construction completed part 22 Construction not completed part 3 Super mud soil construction machine 4 Caisson wall body 5 Support device 51 Screw jack 52 Screw jack operating part 6 Grout pipe 7 Solidified material 8 Excavator 9 Bottom Concrete 10 Prop 11 PC rod

Claims (9)

[Claims] In a caisson laying method for laying a caisson in the ground, a wall of softened mud is formed in advance in a caisson sunk portion of the ground, and the caisson is supported by a supporting device to support the sinking amount of the caisson. A caisson laying method characterized in that a caisson is sunk into its oozed wall while being controlled by a force device. 2. A softened muddy wall is prepared by mixing and stirring water or muddy water in advance in a caisson settling portion, if necessary, using a foam material and / or a superabsorbent polymer. Caisson laying method. 3. The caisson laying method according to claim 2, wherein soil and / or clay is mixed and stirred with water or muddy water. 4. The caisson laying method according to claim 1, wherein the thickness of the wall of the ointment is greater than the thickness of the caisson wall. 5. The caisson laying method according to any one of claims 1 to 4, wherein a through hole penetrating from the top end to the cutting edge is provided in the caisson in advance, and after the caisson laying is completed,
A caisson laying method characterized by injecting a solidifying material from the through holes to solidify the caisson tip. 6. The caisson laying method according to any one of claims 1 to 5, wherein a through hole penetrating from the top end to the cutting edge is provided in advance in the caisson, and after the caisson laying is completed,
A caisson laying method, wherein a water-stopping material is injected into the wall of the softened mud from the through hole and stirred to solidify the outer periphery of the caisson and to form a water-stop layer at the outer periphery. 7. The caisson laying method according to claim 1, wherein the caisson having a heat insulating material attached to an outer wall is sunk. 8. The caisson laying method according to claim 1, wherein a caisson having a buoyancy-protruding wall protruding horizontally in the outside of the wall is sunk. 9. The caisson laying method according to any one of claims 1 to 8, wherein, when the target soil is a viscous soil, a mixed water solution of a superabsorbent polymer liquid and a foam material, or a mixed water solution of a bentonite solution and a foam material. A caisson laying method characterized in that when the target soil is sandy soil, a mixed water solution of a superabsorbent polymer liquid and a foam material is mixed and stirred to form an ointment wall.