JP3213240B2 - Support pile reinforcement structure of existing structure and its reinforcement 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 support pile for supporting an existing structure such as a highway, a highway bridge, or a high-rise building constructed on soft ground such as sandy ground where liquefaction is likely to occur. The present invention relates to a reinforcing structure and a reinforcing method thereof.

[0002]

2. Description of the Related Art Conventionally, when a structure such as an expressway is constructed on soft ground such as sandy ground, the structure is prevented from tilting or subsidence due to liquefaction of the soft ground caused by an earthquake. As shown in FIG. 10, as shown in FIG. 10, a plurality of support piles 23 reaching the support ground 24 are cast in the soft ground 21, and the structure 22 is supported on these support piles 23. That is being done. However, soft ground
When liquefaction of 21 occurs, a water pressure difference occurs in the ground and soil particles flow, and there is a risk that the supporting pressure 23 may be damaged by the flow pressure, especially when the soft ground layer is inclined. The liquefied soil particles flow in the direction and a large shearing force acts on the support pile 23, and the support pile 23 is combined with the load from the structure 22.
23 buckles and breaks as shown in FIG. 11, and the structure 22 tilts or sinks.

[0003] As a method of improving soft ground such as sandy ground which is liable to liquefaction, sand compaction method by compacting by applying vibration, drainage method by drain column, and method of solidification by injection of hardening material Although it is known, any of the above construction methods are performed for the purpose of improving the ground, and after improving the soft ground using these construction methods, constructing a structure on the ground However, it is difficult to completely improve the ground immediately below where the supporting piles are cast in the ground where the structure has already been constructed.

[0004] For this reason, the present applicant has disclosed in Japanese Patent Publication No.
As described in Japanese Patent No. 340, a construction method of providing a ground fluidization preventing wall reaching the inside of the supporting ground from the surface side on the soft ground around the existing structure was developed.

[0005]

However, even if the soft ground immediately below the existing structure is surrounded by the ground flow prevention wall, the soft ground is entirely liquefied and pore water in the ground flows. Therefore, there is a possibility that the supporting force of the existing structure by the ground is drastically reduced and the load applied to the support pile increases, and the support pile tilts due to flow pressure of pore water or the like or vibration, and the existing structure may be tilted. The present invention has been made in view of the above-described problems, and strongly connects the support piles that are driven into the soft ground and support the existing structure, so that the liquid of the soft ground at the time of the earthquake is generated. The present invention provides a support pile reinforcement structure for an existing structure and a method for reinforcing the same, which aims to prevent buckling and tilting of the support pile despite the development.

[0006]

In order to achieve the above object, a support pile reinforcing structure for an existing structure according to the present invention is cast in soft ground such as sandy ground where liquefaction is likely to occur. Adjacent support piles that support objects are connected by a ground improvement reinforcing wall of a predetermined thickness that intersects these support piles.

In such a structure for reinforcing a support pile of an existing structure, the reinforcing wall may be provided obliquely with respect to the support pile as described in claim 2.
As described in the above, the reinforcing wall may be provided in an X-shape with respect to the support pile, or as described in claim 5, the reinforcing wall may be provided in the horizontal direction to connect the support piles. . The invention according to claim 4 has a structure in which a downwardly inclined end of the reinforcing wall connecting the support piles penetrates into the impermeable support ground.

A sixth aspect of the present invention relates to a method for reinforcing a support pile of an existing structure built on soft ground such as sandy ground where liquefaction is liable to occur. Insert the hardening material injection pipe into the soft ground between the adjacent support piles, spray the hardening material from this hardening material injection pipe in the direction of cutting the support pile, and pull out the hardening material injection pipe in the drawing direction. By moving, a reinforcing wall body of a predetermined thickness solidified by a hardening material is formed on the soft ground between adjacent pile bodies.

In the above-mentioned method for reinforcing a support pile, the invention according to claim 7 is a method for inserting a hardening material injection pipe obliquely from the ground surface on one side of an existing structure into soft ground between the supporting piles, By moving the injection pipe body in the drawing direction while injecting hardening material into the soft ground from the injection pipe body to the adjacent support pile, it is provided diagonally to the support pile and connects the support piles Characterized by forming a reinforcing wall body of a predetermined thickness, wherein in this method,
According to the invention described in claim 8, after the hardening material injection pipe is inserted from the soft ground to a depth immersed in the water-impermeable support ground, the hardening material is moved in the pulling-out direction while jetting the hardening material, thereby causing the lower inclined end. The portion forms a reinforcing wall penetrating into the supporting ground.

Further, in the above method for reinforcing a support pile, the invention according to claim 9 is characterized in that a shaft is excavated in the soft ground on one side of the existing structure and hardened in the soft ground between the support piles from within the shaft. The hardening material injection tube is inserted horizontally, and the hardening material is injected from the hardening material injection tube in a direction perpendicular to the insertion direction of the hardening material injection tube, and the hardening material injection tube is pulled out in the drawing direction. By moving, a reinforcing wall body of a predetermined thickness solidified by a hardening material is formed on the soft ground between adjacent pile bodies.

[0011]

[Function] The plurality of support piles supporting the existing structure are:
Reinforced walls provided in a direction crossing the support pile in the soft ground below the existing structure are integrally connected to each other,
It constitutes one structure. Therefore, even if soft ground such as sandy ground below the existing structure liquefies due to the seismic motion, and this liquefied layer flows and its flow pressure acts as a large lateral pressure on the support pile, the lateral pressure is transmitted through the reinforcing wall. Thus, there is no possibility that the support pile is buckled or broken, and the existing structure can be reliably supported.
Such a supporting force can be further increased by penetrating (penetrating) the end of the reinforcing wall into the impermeable supporting ground, and the supporting force is maintained despite the liquefaction of the soft ground. The existing structure can be stably supported by the pile. Further, fluidization of the liquefied layer and spouting of interstitial water onto the ground can also be suppressed by the reinforcing wall.

In order to provide the above-mentioned support pile reinforcing wall in the soft ground below the existing structure, the hardening material is provided from the soft ground on one side of the existing structure to the soft ground below the existing structure. Inserting the injection pipe, pulling back the injection pipe while spraying a liquid hardening material such as cement paste or mortar from the hardening material injection pipe in a direction intersecting the support pile, the liquid hardening material and earth and sand By mixing and hardening the hardening material, a reinforcing wall body made of a ground improvement body having a predetermined thickness portion penetrating a plurality of support piles is formed.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to the drawings, an embodiment of the present invention will be described with reference to the drawings. In FIG. 1, reference numeral 1 denotes a soft ground which is liable to liquefy, such as a sandy ground. An existing structure 2 such as is constructed, and the existing structure 2 is supported by upper end surfaces of a plurality of support piles 3 cast in the soft ground 1. The support pile 3 is vertically driven into the soft ground layer below the existing structure 2, and the lower end thereof is formed on the soft ground 1.
Is driven into and supported by the impermeable support ground 4 where liquefaction does not occur. Reference numeral 5 denotes a reinforcing wall having a predetermined thickness, which intersects the adjacent support piles 3 and 3 and connects the support piles 3 and 3 in the soft ground below the existing structure 2. And a liquid hardener made of cement paste or mortar.

In FIG. 1, the reinforcing wall 5 has a structure that is inclined obliquely downward from the vicinity of the ground surface on one side to the vicinity of the supporting ground on the other side below the existing structure 2. However, as shown in FIG. 2, the reinforcing wall 5 inclined obliquely downward from the ground surface on the other side to the ground near the supporting ground on the other side is formed in an X-shape on the reinforcing wall 5. As shown in FIG. 3, a vertical reinforcing wall 5a having a lower end reaching the supporting ground 4 is provided on the soft ground 1 on one side of the existing structure 2 as shown in FIG. A structure may be provided in which horizontal reinforcing wall members 5, 5 which intersect at right angles with the support piles 3, 3...
Further, as shown in FIG. 4, a structure in which the lower end of the inclined reinforcing wall 5 penetrates into the supporting ground 4 to support the reinforcing wall 5 on the supporting ground 4 may be adopted.

The reinforcing wall 5 has a plurality of supporting piles 3, 3 of which total lengths are arranged in the left-right direction.
3 and a reinforcing wall 5 of these support piles 3.
Are provided so as to penetrate between the upper and lower surfaces of the reinforcing wall 5 and to connect the support piles 3 adjacent in the front and rear direction in the width direction. That is, when the reinforcing wall 5 is viewed from above, as shown in FIG. 5, the reinforcing wall 5 is formed in a horizontally long rectangular shape, and the front, rear, left and right supporting the existing structure 2 in the reinforcing wall 5 is performed. The pile 3 is integrally connected in a penetrating state. In this case, the support pile 3 has a structure completely contained in the reinforcing wall body 5, but as shown in FIG. 5 may be connected in a penetrating state, that is, at least a part of the support pile 3 may be connected to the reinforcing wall 5 in a penetrating state.

The thickness of the reinforcing wall 5 is not particularly limited, and may be any thickness as long as the support piles 3 can be connected to each other to support each other. When the number of the support piles 3 arranged in the front-rear direction is large and the width of the reinforcing wall 5 is large,
The reinforcing wall 5 may be divided into several parts in the width direction. In short, the reinforcing wall 5 may be a structure in which the front, rear, left and right support piles 3 are integrally connected.

Next, a method of constructing the above-described reinforcing wall 5 on the soft ground 1 below the existing structure 2 supported by the support pile 3 will be described. FIG. 7 shows a construction method of the reinforcing wall body 5 obliquely intersecting the support pile 3, and a central portion between the support piles 3 adjacent to the front and back from one side of the existing structure 2. A long hardened material injection pipe 6 is inserted into the lower part of the existing structure 2 to the vicinity of the support ground 4 below the soft ground on the other side. This hardening material injection pipe 6
As shown in FIG. 8, a hardening material injection nozzle 7 which is opened in a direction perpendicular to the pipe axis is provided at the tip of the nozzle, and a pressure water jet nozzle 8 is provided around the nozzle 7. These nozzles 7 and 8 are respectively provided with a hardening material injection pipe 6.
Connected to the hardening material supply pipe 9 and the pressure water supply pipe 10
They are communicating. Furthermore, these supply pipes 9 and 10 are connected from the base end of the opening of the pipe 6 to a hardening material supply tank 11 and a water tank 12 installed on the ground on one side of the existing structure 2 via pumps 13 and 14, respectively. They are communicating. An air compressor 15 is connected to the pressure water supply pipe 10 via a pipe 16.

As a method for inserting the hardening material injection pipe 6 into the soft ground 1, for example, a boring machine is used to install an auger screw at the position where the hardening material injection pipe 6 is to be inserted into the soft ground. Press the cylindrical casing. At this time, earth and sand are discharged while drilling with an auger screw. After press-fitting one tubular casing, the next tubular casing is added and press-fitted, and the hardening material injection pipe 6
After a series of cylindrical casings are driven into the insertion planned position, the auger screw is removed, the hardened material injection pipe 6 is inserted into the cylindrical casing, and then the cylindrical casing is removed. Can be.

After the hardening material injection pipe 6 is inserted into the soft ground 1 below the existing structure 2, the pump 13 is driven to drive the hardening material supply tank 11 into a liquid hardening material such as mortar or cement paste. Through the supply pipe 9 and the hardening material injection nozzle 7
In addition, the hardening material is injected into the ground, and the pump 14 and the air compressor 15 are driven so that the water in the water tank 12 is blown out from the pressure water blowing nozzle 8 through the supply pipe 10 together with the compressed air. A gap is formed in the ground due to the pressure of the pressurized water, and the gap is filled with the hardening material injected from the hardening material injection nozzle 7, so that the hardening material is not consumed by earth and sand without consuming energy. The curing agent can be injected over a wide range. When the hardening material is sprayed and injected into the ground, the finely divided earth and sand and the liquid hardening material are mixed and agitated by the jet of the pressure water, and then the hardened material is hardened to form a ground improvement body.

The hardening material injection pipe 6 is configured to reciprocate in a fan shape around the pipe axis, move in the length direction at a constant speed, and inject the hardening material into the ground while pulling back to the ground side. However, at this time, the hardening material injection nozzle 7 is intensively directed in the direction of cutting the support piles 3 adjacent to each other in the front and rear direction, so that the support piles 3 are vertically thin and horizontally adjacent. A reinforcing wall 5 composed of a wide range of the above-mentioned ground improvement body that can include 3, 3 is formed.

The hardening material injected from the hardening material injection nozzle 7 can be sufficiently improved on the ground on one half circumferential side of the support pile 3 facing the nozzle 7, but can be improved on the other half circumferential side. When the hardening material does not wrap around, the hardening material injection pipe 6 is inserted so that the hardening material injection nozzle 7 faces the other half circumferential surface of the support pile 3 as described above, and then the hardening material is injected. I just need.

Further, the support ground 4 below the soft ground on one side of the existing structure 2 is provided in the central ground between the support piles 3 adjacent to the front and rear from the ground on the other side of the existing structure 2. After inserting the long hardening material injection pipe 6 to the vicinity, the hardening material injection pipe 6 is pulled back by operating the hardening material injection pipe 6 as described above while spraying the hardening material and the pressure water from the nozzles 7 and 8. Accordingly, the reinforcing wall 5 crossing the reinforcing wall 5 in an X-shape can be constructed. Further, the hardening material injection pipe 6
If it is inserted until the tip of reaches into the support ground 4,
As a result, a reinforcing wall 5 having a downwardly inclined end penetrating into the support ground 4 is obtained.

FIG. 9 shows a method of constructing the horizontal reinforcing wall 5 which intersects the support pile 3 in a direction perpendicular to the supporting pile 3. First, a shaft 17 having a predetermined depth is excavated on one side of the existing structure 2. After that, the hardening material injection pipe 6 is inserted from the inside of the shaft 17 into the soft ground 1 at the center between the support piles 3 adjacent to each other in the front and rear to the portion penetrating the position of the support pile 3 on the other side. . The method of inserting the hardening material injection pipe 6 is as follows: After the cylindrical casing is press-fitted from the inside of the shaft 17, the auger screw is removed and the hardening material injection pipe 6 is inserted into the cylindrical casing,
This can be performed by extracting the cylindrical casing. The structure of the hardening material injection tube 6 and the piping structure to the ground side are the same as in the above embodiment.

After the hardening material injection pipe 6 is horizontally inserted into the soft ground 1 between the front and rear support piles 3 as described above,
A pump 13 installed on the ground is driven to supply a liquid hardening material such as mortar and cement paste in the hardening material supply tank 11 to a supply pipe 9.
The hardening material is injected from the hardening material injection nozzle 7 into the ground, and the pump 14 and the air compressor 15 are driven to cause the water in the water tank 12 to be jetted out from the pressure water jetting nozzle 8 through the supply pipe 10 together with the compressed air. Similarly, the hardening material injection pipe 6 is gradually retreated in the length direction at a constant speed while reciprocatingly rotating in a fan shape around the pipe axis, so that the support piles 3 adjacent between the front and rear are To form a horizontal reinforcing wall 5 composed of a ground improvement body in which the support piles 3 are connected.

Along with the formation of the horizontal reinforcing wall 5, another reinforcing wall 5 is provided above or below the horizontal reinforcing wall 5 and supported by the upper and lower reinforcing walls 5, 5 as shown in FIG. The piles 3 and 3 can be mutually connected.
The shaft 17 is excavated sequentially to a desired depth according to the construction position of the horizontal reinforcing wall 5, and is buried back after the horizontal reinforcing wall 5 is constructed. In addition, shafts are excavated on both sides of the existing structure 2, and hardening material injection pipes 6, 6 are inserted into the soft ground 1 below the existing structure 2 in opposite directions from both sides, and the horizontal Reinforcement walls 5, 5 may be constructed. Further, the shaft 17 after the formation of the horizontal reinforcing wall 5 may be backfilled with excavated soil as described above, or may be filled with ground improvement soil or hardened material in which hardened material and excavated soil are mixed. A reinforcing wall 5a made of an improved body may be formed. It is also possible to leave the shaft 17 as it is and use it as a groundwater observation well.

The ground improvement means employed in the present invention is not limited to the above-described method. For example, liquid hardening may be performed in a state where the hardening material injection pipe 6 is inserted into the cylindrical casing without removing the cylindrical casing. If the material is blown out together with the compressed air, the earth and sand excavated by the pressurized water mixed with the air is discharged to the ground through the gap between the hardening material injection pipe 6 and the cylindrical casing by an air lift. It is possible to form the reinforcing wall body 5 consisting of only the reinforcing wall body.

[0027]

As described above, according to the structure for reinforcing a support pile of an existing structure according to the present invention, the existing structure is supported by being poured into soft ground such as sandy ground where liquefaction is likely to occur. Since the adjacent support piles are connected by a ground improvement reinforcing wall having a predetermined thickness intersecting with the support piles, a plurality of support piles are integrally connected to each other by the reinforcing wall to form one structure. Therefore, even if soft ground such as sandy ground below the existing structure is liquefied and flows by the seismic motion, the flow pressure is not concentrated on one supporting pile and the other ground is passed through the reinforcing wall. Can be supported by supporting piles,
Therefore, the supporting pile can be prevented from buckling or breaking due to the flow pressure, and the existing structure can be reliably supported.

Further, the reinforcing wall is extended in the soft ground below the existing structure in the plane direction, and the soft ground is vertically partitioned through the reinforcing wall.
Even if the pore water pressure in the soft ground rises, it is possible to suppress the spouting of pore water on the ground surface side, and it is also possible to exert the effect of preventing the flow of the liquefied layer. Further, by penetrating the end of the reinforcing wall into the supporting ground, the connection between the supporting piles can be further strengthened, and the existing structure can be connected to the supporting piles despite the liquefaction of the soft ground. It can be stably supported.

Further, the invention according to claims 6 to 9 is a method for reinforcing an existing structure supporting pile which is cast in soft ground such as sandy ground where liquefaction is liable to occur. The hardened material injection pipe is inserted from the ground on one side into the soft ground between the adjacent support piles, and the hardened material is injected from the hardened material injection pipe in the direction of cutting the support pile and the hardened material is injected. By moving the injection pipe in the pulling direction, a reinforcing wall of a predetermined thickness solidified by the hardening material is formed on the soft ground between the adjacent piles, so that it is directly below the existing structure. In this case, a reinforcing wall composed of a ground improvement body in which supporting piles are connected to each other can be efficiently installed in the soft ground without affecting the existing structure.

[Brief description of the drawings]

FIG. 1 is a simplified longitudinal front view of a state in which a reinforcing wall is formed in a diagonal direction in soft ground,

FIG. 2 is a simplified vertical sectional front view showing a state in which reinforcing walls are provided in a staggered manner;

FIG. 3 is a simplified vertical sectional front view showing a state in which a reinforcing wall is provided in a horizontal direction;

FIG. 4 is a simplified vertical sectional front view showing a state in which a downwardly inclined end of a reinforcing wall is driven into a supporting ground.

FIG. 5 is a simplified cross-sectional view of a reinforcing wall body connecting supporting piles,

FIG. 6 is a simplified cross-sectional view showing another embodiment of a reinforcing wall body in which supporting piles are connected to each other,

FIG. 7 is a simplified vertical sectional front view showing a method of constructing a reinforcing wall body in a diagonal direction in soft ground,

FIG. 8 is an enlarged longitudinal sectional view of a tip portion of the hardening material injection tube body,

FIG. 9 is a simplified longitudinal front view showing a method of constructing a reinforcing wall horizontally in soft ground,

FIG. 10 is a simplified longitudinal sectional front view showing a conventional existing structure support structure,

FIG. 11 is a simplified vertical sectional view showing a broken state of the support pile.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Soft ground 2 Existing structure 3 Support pile 4 Support ground 5 Reinforcement wall 6 Hardened material injection pipe

──────────────────────────────────────────────────続 き Continuation of front page (58) Field surveyed (Int.Cl. ⁷ , DB name) E02D 3/12 E02D 37/00

Claims (9)

(57) [Claims] 1. A ground improvement reinforcing wall having a predetermined thickness intersecting adjacent support piles, which are driven into soft ground such as sandy ground or the like where liquefaction is liable to occur and supporting existing structures, intersects with these support piles. A support pile reinforcement structure for an existing structure, which is connected by a body. 2. The support pile reinforcing structure for an existing structure according to claim 1, wherein the reinforcing wall body obtained by improving the ground having a predetermined thickness is provided obliquely with respect to the support pile. 3. The structure according to claim 1, wherein the reinforcing wall is provided in an X-shape. 4. The support pile reinforcing structure for an existing structure according to claim 2, wherein a downwardly inclined end of the reinforcing wall penetrates the support ground. 5. The support pile reinforcing structure for an existing structure according to claim 1, wherein the reinforcing wall is provided in a horizontal direction with respect to the vertical support pile. 6. A method for reinforcing an existing structure support pile installed in soft ground, such as sandy ground, where liquefaction is likely to occur,
The hardened material injection pipe is inserted from the ground on one side of the existing structure into the soft ground between the adjacent support piles, and the hardened material is injected from this hardened material injection pipe in the direction in which the support pile is cut into rings. A supporting pile for an existing structure, wherein a reinforcing wall body of a predetermined thickness solidified by a hardening material is formed on a soft ground between adjacent pile bodies by moving a hardening material injection pipe in a drawing direction together with the hardening material injection pipe body. Reinforcement method. 7. A hardening material injection pipe is inserted obliquely from the ground surface on one side of an existing structure into soft ground between support piles, and then softened from the hardening material injection pipe toward an adjacent support pile. By moving the injection pipe in the drawing direction while injecting the hardening material into the ground, it is possible to form a reinforcing wall body having a predetermined thickness provided diagonally with respect to the support piles and connecting the support piles. The method for reinforcing a support pile of an existing structure according to claim 6. 8. A hard material injection pipe body is inserted from a soft ground to a depth at which it is immersed in a water-impermeable support ground, and then is moved in a pulling-out direction while spraying the hard material, so that a downward inclined end portion is formed on the support ground. 8. The method according to claim 7, wherein a reinforcing wall is formed to penetrate the support structure. 9. A shaft is excavated in the soft ground on one side of the existing structure, and a hardening material injection pipe is horizontally inserted into the soft ground between the supporting shafts from the inside of the shaft, and the hardening material injection pipe is formed. By injecting the hardening material from the body in the direction perpendicular to the insertion direction of the hardening material injection pipe body and moving the hardening material injection pipe body in the pulling-out direction, the hardening is performed on the soft ground between the adjacent pile bodies. 7. The method according to claim 6, wherein a reinforcing wall body having a predetermined thickness solidified by a material is formed.