Hangzhou Structure

Abstract

Provided is a pile structure formed by an underpeening method, which has been provided with measures against liquefaction. [Solution] The pile structure 1 is a pile structure formed by an underpeening method, and comprises a pile section 10 formed by connecting multiple pile units 11 and a backfill section 30. The pile section comprises a foundation pile section 21 and a reinforcing pile section 23 with protrusions around it. The backfill section surrounds the reinforcing pile section, and the specific gravity of the total volume defined by the outer contour of the pile section and the backfill section is greater than the specific gravity of liquefied mud water.

Description

[Technical field]

[0001] The present invention relates to a pile structure formed by an underpeening method. [Background technology]

[0002] When a house tilts due to the effects of an earthquake or other natural disaster, it is necessary to bury piles that support the house and correct the tilt. One method for correcting tilt is known as underpeening. In this underpeening method, a hole is dug under the floor of the house, and workers enter the hole, lift the house with a jack, and insert piles between the lifted house and the ground. The piles are then embedded in the ground by the weight of the house. Please refer to Patent Documents 1 and 2 as prior art documents disclosing techniques related to this invention. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2023-101249 A [Patent Document 2] JP 2007-169927 A Summary of the Invention [Problem to be solved by the invention]

[0004] Underpeening techniques can correct the tilt of a house, but the earthquake that caused the house to tilt may repeat after some time has passed, and earthquakes that occur after underpeening techniques are performed may be accompanied by larger shaking. If the ground supporting a house is sandy or contains a layer of sand, there is a risk that the ground supporting the house will liquefy.

[0005] Generally, piles are made by connecting multiple steel pipe pile units, so their apparent specific gravity is less than 1.0. Here, apparent specific gravity refers to the mass of the pile divided by the volume of the total volume defined by the pile's exterior. If the apparent specific gravity of the pile is less than the specific gravity of liquefied muddy water, the pile may rise up when liquefaction occurs and interfere with houses, lifting them up or damaging floors.

[0006] Therefore, it is desirable to take measures against liquefaction in advance when carrying out the underpeening method. Therefore, an object of this invention is to provide a pile structure formed by the underpeening method, which also has measures against liquefaction. [Means for solving the problem]

[0007] This invention has been made in view of the above problems, and its first aspect is defined as follows. A pile structure formed by an underpeening method, The pile section includes a pile unit and a backfill section formed by connecting a plurality of pile units. The pile portion includes a foundation pile portion and a reinforcing pile portion having a protrusion around the periphery, The backfill portion surrounds the reinforcement pile portion, A pile structure in which the specific gravity of the total volume defined by the outer periphery of the pile portion and the backfilled portion is greater than the specific gravity of liquefied mud water.

[0008] In the first phase pile structure defined in this manner, the specific gravity of the total volume defined by the outer periphery of the pile section and the backfilled section is greater than the specific gravity of liquefied mud water, so even if the ground supporting the house, i.e., the ground on which the pile structure is installed, liquefies, the pile structure itself will not float up. The specific gravity of the total volume portion can be adjusted solely by the volume and / or specific gravity of the backfill portion. Since protrusions are provided around the reinforcing pile portion, the protrusions bite into the backfilled portion surrounding the reinforcing pile portion, ensuring the integrity of the reinforcing pile portion and the backfilled portion.

[0009] It is preferable that the reinforcement pile portion with a protrusion is only the topmost pile unit (aspect 2). When the pile is embedded in the ground as a reaction force of jacking up, the resistance to embedment of the pile increases when the bottommost pile reaches a hard stratum, and at this stage the embedment work of the pile reaches the final stage. Therefore, by adopting a pile unit with a protrusion as the last connected pile unit (the pile unit that directly supports the house, the topmost pile unit), the underpeening work becomes smooth (aspect 3). This is because this pile unit is not embedded in the ground. In other words, it is not preferable to embed a pile unit with a protrusion in the ground because it takes time and effort. Furthermore, if the distance to the hard stratum is known, the pile units protruding from the hole can be identified, and therefore protrusions can be provided on all of the pile units protruding from the hole.

[0010] In order to further ensure the unity of the reinforcing pile portion and the backfilled portion, it is preferable that the load of the building is applied to both the pile portion and the backfilled portion (third aspect). This is because if the load of the house is applied only to the pile portion, the two are likely to become misaligned, even if the reinforcing pile portion is surrounded by the backfill portion.

[0011] A fourth aspect of the present invention is defined as follows. That is, in the pile structure defined in the first aspect, a part of the reinforcing pile portion is replaced with a jack used during the underpeening method. In this invention, the holes made when performing the underpeening method are filled with backfill material, so that the periphery of the reinforced pile is surrounded by the material of the backfill. When the embedment of the pile stops to a certain extent, it is considered that the bottom end of the pile has reached hard ground. At this point, it is the jack that actually supports the house. Therefore, we thought of filling the hole before the last pile unit is inserted under the house, that is, when the house is being supported by the jack.

[0012] The jack is equipped with a handle and other protrusions, and if it is surrounded by the backfill, it will not shift sideways. In other words, by providing the backfill, the last pile unit (the top pile unit) can be omitted. Therefore, the work of inserting the last pile unit can be omitted, and an inexpensive pile structure can be provided. Of course, the last pile unit and the jack can also be used together. [Brief description of the drawings]

[0013] [Figure 1] FIG. 1 is a schematic diagram showing a pile structure according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a schematic diagram showing the formation work of the pile structure of the embodiment. [Diagram 3] FIG. 3 is a schematic diagram showing a pile structure according to another embodiment of the present invention. [Figure 4] FIG. 4 is a schematic diagram showing a pile structure according to another embodiment of the present invention. [Diagram 5] FIG. 5 is a schematic diagram showing a pile structure according to another embodiment of the present invention. [Figure 6] FIG. 6 is a schematic diagram showing a pile structure according to another embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows a pile structure 1 according to an embodiment of the present invention. This pile structure 1 comprises a pile portion 10 and a backfill portion 30, and supports a house 3. The pile portion 10 is configured by axially connecting pile units 11 made of steel pipes, with the portion that is embedded in the ground 5 being the foundation pile portion 21 and the portion surrounded by the backfill portion 30 being the reinforcing pile portion 23.

[0015] The pile unit 11t occupying the uppermost stage in the reinforcing pile portion 23 has a peripheral wall provided with a projection 25. The shape and number of the projections 25 are not particularly limited as long as they protrude outward from the peripheral wall of the pile unit 11t, but it is preferable that they are evenly distributed in the peripheral direction on the peripheral wall of the pile unit 11t in order to ensure that the projections bite into the backfilled portion 30. In addition, it is preferable that the projection amount is 10 mm or more. In this example, the block-shaped protrusions 25 are arranged on the imaginary spiral line of the peripheral wall of the pile unit 11t, but disk-shaped protrusions may also be arranged at intervals in the axial direction.

[0016] The backfill portion 30 may be made of a cement material as a base material. The cement material may be mixed with gravel, sand, or other aggregates, provided that the specific gravity of the aggregates is greater than that of water. The specific gravity of the backfill portion 30 may be adjusted by the aggregates. The width and height of the backfill portion 30 can be designed as desired as long as it surrounds the reinforcing pile portion 23. The entire hole made during the underpeening work may be backfilled with backfill material, or a partition plate may be placed in the hole to form the backfill portion 30 of any shape and size.

[0017] The specific gravity of the total volume defined by the backfilled portion 30 and the outer periphery of the foundation pile portion 21 of the pile portion 10 protruding from the backfilled portion 30, i.e., the value obtained by dividing the total mass of the pile portion 10 and the backfilled portion 30 by the volume of the total volume, is greater than the specific gravity of liquefied mud water (approximately 1.1 to 1.3). The specific gravity of the total volume can be adjusted by the volume of the backfilled portion 30 and / or the specific gravity of the backfilled portion 30 itself.

[0018] The pile structure 1 shown in Fig. 1 can be obtained by carrying out the underpeening method shown in Fig. 2. Note that the same elements as those in Fig. 1 are given the same reference numerals and their explanation will be partially omitted. In Fig. 2(A), a house 3 is lifted up by a jack 50 in a hole 7 drilled under the house 3. On the other hand, a retainer 51 is attached to the peripheral wall of the pile unit 11u exposed in the hole 7, and a pair of temporary supports 53 are placed on the upper surface of the retainer 51 so as to sandwich the jack 50 therebetween. In this state, the weight of the house is applied to the pile portion 10 via the jack 50, so that the pile portion 10 as a whole is embedded into the ground 5.

[0019] As shown in FIG. 2(B), when the house 3 abuts against the temporary support 53 and is thus supported, the jack 50 is removed and the topmost pile unit 11 is inserted (see FIG. 2(C)). Thereafter, the retainer 51 and the temporary support 53 are removed, and a cement material is poured into the hole 7 and hardened to form the backfilled portion 30, thereby forming the pile structure 1 shown in FIG.

[0020] Fig. 3 shows a pile structure 60 according to another embodiment. In Fig. 3, the same elements as those shown in Fig. 1 and Fig. 2 are denoted by the same reference numerals, and the description thereof will be omitted. In this pile structure 60, the projections 25 are provided on the uppermost pile unit 11t and the pile unit 11u therebelow. When the length of the pile portion 10 is known in advance, the projections can be provided over a wide range of the reinforcing pile portion 23 surrounded by the backfilled portion 30.

[0021] Fig. 4 shows a pile structure 70 according to another embodiment. In Fig. 4, the same elements as those shown in Fig. 1 and Fig. 2 are denoted by the same reference numerals, and the description thereof will be omitted. In this pile structure 70, the uppermost pile unit 11 in FIG. Such a pile structure 70 is obtained as follows. In Fig. 2(A), the retainer 51 and the temporary support 53 are omitted, and only the jack 50 is placed on the pile unit 11u. The pile portion 10 is embedded in the ground 5 by the weight of the house 3, and with the house in contact with the ground, the hole 7 is backfilled with cement material with the jack 50 left in place.

[0022] Fig. 5 shows a pile structure 80 according to another embodiment. In Fig. 5, the same elements as those shown in Fig. 3 and Fig. 4 are denoted by the same reference numerals, and the description thereof will be omitted. In this pile structure 80, the uppermost pile unit 11t is replaced with a jack 50, and a projection 25 is provided on the pile unit 11u below it.

[0023] Fig. 6 shows a pile structure 90 according to another embodiment. In Fig. 6, the same elements as those shown in Fig. 1 and Fig. 2 are denoted by the same reference numerals, and the description thereof will be omitted. In this pile structure 90, the retainer 51 and the temporary support 53 are left in place in the structure of FIG. 1, and the temporary support 53 is arranged in parallel with the pile unit 11t. Such a pile structure 90 can be obtained by backfilling the hole 7 as shown in FIG. 2(C) with cement material.

[0024] Although the embodiment of the present invention has been described in detail above, the present invention is not limited to these descriptions. Various modifications that do not deviate from the scope of the claims and that are easily conceivable by a person skilled in the art are also included in the present invention. [Explanation of symbols]

[0025] 1,60,70,80,90 pile structure 3 houses 5 Ground 7 holes 10 Pile section 11 Pile Unit 11t Top pile unit 21 Foundation pile section 23 Reinforcement pile section 25 Protrusion 30 Backfilling section 50 Jack 51 Retainer 53 Temporary Support Stand

Claims

1. A pile structure formed by an underpeening method, A pile section and a backfill section are provided, each of which is formed by connecting a plurality of pile units, The pile portion includes a foundation pile portion and a reinforcing pile portion having a protrusion around the periphery, The backfill portion surrounds the reinforcement pile portion, A pile structure in which the specific gravity of the total volume defined by the outer periphery of the pile portion and the backfilled portion is greater than the specific gravity of liquefied mud water.

2. The pile structure according to claim 1 , wherein the projection is formed only on the topmost pile unit.

3. The pile structure according to claim 1 , wherein the load of a building to be supported is applied to the pile portion and the backfilled portion.

4. The pile structure according to claim 1 , wherein a part of the reinforced pile portion is replaced with a jack used in an underpeening method.

5. The pile structure according to claim 1 , wherein the protrusions of the reinforcing pile portion are evenly distributed in a circumferential direction on the peripheral wall of the pile unit.

6. The pile structure according to claim 1 , wherein a temporary support is arranged in parallel with the uppermost pile unit of the reinforcing pile section.

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