JP2022094798A - Excavation method - Google Patents

Abstract

To provide an excavation method capable of carrying out excavation while appropriately supporting an existing column over a long time.SOLUTION: The excavation method executes: an installation step of installing a replacement structure 4 capable of freely supporting an existing column 1 from a ground part shifted from directly below the existing column 1; and an excavation step of executing excavation within an excavation target range 2A directly below the existing column 1 after the installation step. The replacement structure 4 has a plurality of temporary installed columns 6 fixed to a ground 2, and a replacement frame 9 for connecting the column heads of the temporary installed columns 6 to the existing column 1, and is configured to bear a long load and a short load transmitted from the existing column 1.SELECTED DRAWING: Figure 4

Description

The present invention relates to an excavation method for excavating an excavation target area directly under an existing pillar.

In Patent Document 1, an oil jack 24 capable of supporting an existing pillar from the ground outside the excavation target range directly under the existing pillar (upper pillar 16a, 16b) is installed, and the excavation target range directly under the existing pillar is excavated. The excavation method is shown.

Japanese Unexamined Patent Publication No. 2007-909658

However, in such a configuration in which the oil jack 24 supports the existing pillar, the oil jack 24 cannot bear the short-term load generated by an earthquake or the like, so that the existing pillar may not be properly supported over the excavation period.

In view of this situation, a main object of the present invention is to provide an excavation method capable of excavating while appropriately supporting an existing column for a long period of time.

The first characteristic configuration of the present invention includes an installation step of installing a replacement structure capable of supporting the existing pillar from a ground portion deviating from the ground portion directly under the existing pillar, and an excavation target directly under the existing pillar after the installation step. Performing an excavation step of excavating an area, the replacement structure has a plurality of temporary columns fixed to the ground and a replacement frame connecting the stigma of the temporary columns and the existing columns. Therefore, the long-term load and the short-term load transmitted from the existing pillar can be freely borne.

According to this configuration, a plurality of temporary columns are fixed to the ground, and the stigma of the temporary columns and the existing columns are connected by a replacement frame to form a replacement structure, so that the replacement structure supports the existing columns. It is easy to increase the strength of the body. Therefore, it is easy to construct the replacement structure not only the long-term load of the existing column but also the short-term load of the existing beam freely. The replacement structure can properly support existing columns for a long period of time.

The second characteristic configuration of the present invention is that the temporary pillar is fixed to the ground outside the excavation target range in a plan view.

According to this configuration, by fixing the temporary column to the ground outside the excavation target range in a plan view, it becomes easy to form a large space on the lower side of the existing column, so that excavation work in the excavation target range becomes easy. ..

The third characteristic configuration of the present invention is that the replacement frame has a first steel frame portion in a horizontal posture for connecting the capital heads of the plurality of temporary columns.

According to this configuration, by providing the first steel frame in the replacement frame, a plurality of temporary columns can be firmly connected to each other, and the strength of the replacement frame can be increased.

The fourth characteristic configuration of the present invention is that the replacement frame has a second steel frame portion in a horizontal posture that connects the stigma of the temporary column and the column base of the existing column.

According to this configuration, by providing the replacement frame with the second steel frame, the temporary column and the existing column can be firmly connected, and the strength of the replacement frame can be increased.

The fifth characteristic configuration of the present invention is that the replacement frame has a third steel frame portion in an oblique posture that diagonally connects the stigma of the temporary column and the upper side of the column base portion of the existing column. be.

According to this feature, by providing the replacement frame with the third steel frame, it becomes easy to prevent the existing columns from tilting with respect to the column base portion, and the strength of the replacement frame can be increased.

Side view showing the columns and the ground Perspective view of the replacement structure of the first embodiment A side view showing a state in which the replacement structure of the first embodiment is installed. Side view showing the state of excavating the excavation target range of the first embodiment A side view showing a state in which the excavation target range of the first embodiment is reinforced. A side view showing a state in which the replacement structure of the first embodiment is removed. A side view showing a state in which the replacement structure of the second embodiment is installed. Side view showing the state of excavating the excavation target range of the second embodiment A side view showing a state in which the excavation target range of the second embodiment is reinforced. A side view showing a state in which the replacement structure of the second embodiment is removed.

[First Embodiment]
An embodiment of the excavation method of the first embodiment according to the present invention will be described with reference to the drawings.
The excavation method of the present embodiment is an excavation method used when excavating the ground 2 on which the existing pillar 1 is erected as shown in FIG. 1 and reinforcing the foundation structure 3 as shown in FIG. The existing pillar 1 constitutes a part of the building and is erected on the foundation structure 3 buried in the ground 2. The existing column 1 is composed of a steel frame, specifically H-shaped steel. The foundation structure 3 is made of reinforced concrete.

In the excavation method, as shown in FIG. 3, the installation process of installing the replacement structure 4 capable of supporting the existing pillar 1 from the ground portion 2B deviating from directly under the existing pillar 1 and the installation as shown in FIG. After the process, an excavation step of excavating the excavation target range 2A directly under the existing pillar 1 is executed. Then, after excavating by the excavation method, as shown in FIG. 5, a reinforcement step of constructing a new foundation structure (foundation slab) 18 in the excavation target range 2A and installation after the reinforcement step as shown in FIG. The removal process of removing the replacement structure 4 installed in the process is executed.

Next, the replacement structure 4 used in the excavation method, the excavation method, and the process to be executed thereafter will be described. In FIG. 1, the direction in the left-right direction is referred to as the first direction X, and in FIG. 1, it is the depth direction. The direction will be referred to as a second direction Y, and the direction orthogonal to the first direction X and the second direction Y will be referred to as a vertical direction Z.

As shown in FIG. 2, the replacement structure 4 has a plurality of temporary columns 6 fixed to the ground 2, and a replacement frame 9 for connecting the stigma 6A of the temporary columns 6 and the existing columns 1. Therefore, the long-term load and the short-term load transmitted from the existing pillar 1 can be freely borne. In the present embodiment, the replacement structure 4 has four temporary pillars 6, and the replacement frame 9 connects the four temporary pillars 6 and the two existing pillars 1 arranged in the second direction Y. The long-term load and the short-term load transmitted from the two existing pillars 1 arranged in the second direction Y can be freely borne. The replacement structure 4 is configured to freely bear a load equal to or greater than that of the existing basic structure 3.

The temporary pillars 6 have two first temporary pillars 7 on one side of the first direction X with respect to the two existing pillars 1 and two existing pillars 1 on the other side of the first direction X with respect to the two existing pillars 1. There are two second temporary pillars 8, and the two first temporary pillars 7 and the two second temporary pillars 8 are replaced in the replacement structure 4 at the same intervals as the two existing pillars 1. It is prepared.

The excavation target range 2A is a range including a range directly under the existing pillar 1 in the ground 2 and is a range to be excavated in the excavation process. Further, the excavation target range 2A is a range to be reinforced in the reinforcement process.
The temporary pillar 6 is fixed to the ground 2 outside the excavation target range 2A in a plan view. In the present embodiment, the first temporary pillar 7 is fixed to the ground 2 on one side of the first direction X with respect to the excavation target range 2A, and the second temporary pillar 8 is in the first direction with respect to the excavation target range 2A. It is fixed to the ground 2 on the other side of X. In this way, the temporary pillar 6 is fixed to the ground portion 2B deviating from the excavation target range 2A in the ground 2 in the first direction X.

<Replacement frame>
As shown in FIG. 2, the replacement frame 9 has a first steel frame portion 11 in a horizontal posture that connects the stigmas 6A of the plurality of temporary columns 6. Specifically, the replacement frame 9 connects one first steel frame portion 11 connecting the stigmas 6A of the two first temporary columns 7 and the stigmas 6A of the two second temporary columns 8 to each other. It has a total of two first steel frame portions 11 including one first steel frame portion 11 to be connected.

Further, the replacement frame 9 has a second steel frame portion 12 in a horizontal posture that connects the stigma 6A of the temporary column 6 and the column base portion 1B of the existing column 1. Specifically, the replacement frame 9 includes two second steel frame portions 12 connecting the stigma 6A of the first temporary column 7 and the stigma 1B of the existing column 1, and the stigma of the second temporary column 8. It has a total of four second steel frame portions 12 including two second steel frame portions 12 connecting 6A and the stigma 1B of the existing column 1.

Further, the replacement frame 9 has a third steel frame portion 13 in an oblique posture that diagonally connects the stigma 6A of the temporary column 6 and the upper side of the column base portion 1B of the existing column 1. Specifically, the replacement frame 9 includes two third steel frame portions 13 connecting the stigma 6A of the first temporary column 7 and the upper side of the column base 1B of the existing column 1, and the second temporary column 8. It has a total of four third steel frame portions 13 including two third steel frame portions 13 connecting the column head 6A of the column 1 and the upper side of the column base portion 1B of the existing column 1.

Further, the replacement frame 9 has a fourth steel frame portion 14 that reinforces the structure surrounded by the first steel frame portion 11 and the second steel frame portion 12. Specifically, the replacement frame 9 is a fourth steel frame frame formed in an X shape in a plan view connecting the column base portions 6B of the two first temporary columns 7 and the two first steel frame portions 11. A fourth steel frame portion 14 formed in an X shape in a plan view connecting the portion 14, the column base portion 6B of the two second temporary columns 8 and the two first steel frame portions 11. It has a total of two sets of fourth steel frame portions 14.

Further, the replacement frame 9 has a fifth steel frame portion 15 that reinforces the structure surrounded by the temporary pillar 6 and the first steel frame portion 11. Specifically, the replacement frame 9 includes two fifth steel frame portions 15 connecting the column bases 6B of the two first temporary columns 7 and the first steel frame portion 11, and two second temporary columns. It has a total of four fifth steel frame portions 15 including two fifth steel frame portions 15 connecting the column base portion 6B of the column 8 and the first steel frame portion 11.

<Installation process>
The installation process is a process of installing a replacement structure 4 that can freely support the existing pillar 1. In the installation process, as shown in FIG. 3, a first temporary pillar foundation structure 16 is constructed on the ground 2, and a replacement structure 4 is installed on the first temporary pillar foundation structure 16. That is, first, the ground portion 2B deviating from the excavation target range 2A in the ground 2 in the first direction X and adjacent to the excavation target range 2A is excavated and the foundation structure 16 for the first temporary column is placed. .. Next, the temporary column 6 of the replacement structure 4 is connected to the foundation structure 16 for the first temporary column by using a member such as an anchor bolt, and the replacement frame 9 of the replacement structure 4 is connected to the temporary column 6 and the temporary column 6. The replacement structure 4 is installed by connecting to the existing pillar 1.

For example, as shown on the right side of the excavation target range 2A in FIG. 3, concrete is poured only in the vicinity of the temporary pillar 6 in order to use it as a foundation for erection of the temporary pillar 6 of the replacement structure 4. 1 The foundation structure 16 for temporary columns may be constructed, and as shown on the left side of the excavation target range 2A in FIG. 3, the temporary columns 6 are used as the foundation of a building (not shown) having the existing columns 1. The first foundation structure 17 which also functions as the foundation structure 16 for the first temporary column may be constructed by placing concrete over a wide range including the vicinity of the above.

<Excavation process>
The excavation process is a process of excavating the excavation target range 2A. In the excavation process, as shown in FIG. 4, the excavation target range 2A is excavated to dig up the earth and sand and rocks in the excavation target range 2A, and the foundation structure 3 placed in the excavation target range 2A is removed. By excavating the excavation target range 2A in this way, the load transmitted from the existing pillar 1 is borne by the replacement structure 4, and the excavation is performed while appropriately bearing the load in the replacement structure 4. can do.

<Reinforcement process>
The reinforcement step is a step of placing concrete in the excavation target range 2A to construct a new foundation structure (hereinafter referred to as a second foundation structure) 18 that functions as a foundation of a building. In the reinforcement process, as shown in FIG. 5, concrete is placed in the excavation target range 2A excavated in the excavation process to construct the second foundation structure 18, and the existing column 1 is used with members such as anchor bolts. It is connected to the second foundation structure 18. Since the second foundation structure 18 is constructed in the excavation target range 2A adjacent to the first foundation structure 17, the second foundation structure 18 and the first foundation structure 17 function as the foundation of the building. Is integrated.

<Removal process>
The removal step is a step of removing the replacement structure 4. In the removal step, as shown in FIG. 6, the replacement frame 9 is removed from the existing pillar 1 and the temporary pillar 6, and the temporary pillar 6 is removed from the foundation structure 16 for the first temporary pillar, and the replacement structure 4 is removed. .. By removing the replacement structure 4 in this way, the load transmitted from the existing pillar 1 is borne by the second foundation structure 18.

[Second Embodiment]
In the second embodiment, the configuration of the replacement structure 4 and the location of supporting the replacement structure 4 in the ground 2 are different from those in the first embodiment. In the second embodiment, the differences from the first embodiment will be mainly described, and the description of the same configuration may be omitted.

The excavation target range 2A is a range including a range directly under the existing pillar 1 in the ground 2 and is a range to be excavated in the excavation process. Further, the excavation target range 2A is a range for reinforcing the existing foundation structure 3 in the reinforcement step. In the present embodiment, the first temporary column 7 and the second temporary column 8 are fixed to the foundation structure 21 for the second temporary column surrounded by the excavation target range 2A in a plan view.

<Replacement frame>
As shown in FIG. 7, the replacement frame 9 includes a sixth steel frame portion (not shown) in a horizontal posture connecting the stigmas 6A of the temporary columns 6 arranged in the second direction Y, and the sixth steel frame. It has a seventh steel frame portion 20 in a horizontal posture that connects the intermediate portion and the stigma portion 1B of the existing column 1.

<Installation process>
In the installation process, as shown in FIG. 7, a portion of the ground 2 deviating from directly below the existing column 1 is excavated to the lower side of the lower end of the excavation target range 2A, and the excavated hole is used for the foundation structure for the second temporary column. After placing concrete for constructing the body 21, a temporary pillar 6 is inserted to fix the temporary pillar 6 to the ground 2. In the example shown in FIG. 7, the foundation structure 21 for the second temporary column is constructed below the lower end of the excavation target range 2A. Then, the replacement frame 9 is connected to the temporary pillar 6 and the existing pillar 1 to install the replacement structure 4.

<Excavation process>
In the excavation process, as shown in FIG. 8, the excavation target range 2A is excavated to excavate the earth and sand and rocks in the excavation target range 2A, and the foundation structure 3 in the excavation target range 2A is removed to remove the existing pillar 1. It is supported only by the replacement structure 4.
Further, in the present embodiment, in the excavation process, as shown on the left side of the excavation target range 2A in FIG. 8, the excavation target range is to be cast over a wide range as the foundation of the building having the existing pillar 1. The part adjacent to 2A is also excavated.

<Reinforcement process>
In the reinforcement step, as shown in FIG. 9, concrete is poured into the excavation target range 2A to construct the second foundation structure 18, and the existing pillar 1 is used as a member such as an anchor bolt to construct the second foundation structure 18. Connect to. Further, in the reinforcing process, concrete is also placed in the portion of the hole excavated in the excavation process where the foundation structure 21 for the second temporary column is not placed.

<Removal process>
In the removal step, as shown in FIG. 10, the replacement frame 9 is removed from the existing pillar 1 and the temporary pillar 6, and the portion of the temporary pillar 6 protruding upward from the excavation target range 2A is cut to form the temporary pillar 6. The replacement frame 9 is removed with a part left in the second foundation structure 18 and the foundation structure 21 for the second temporary column. By removing the replacement structure 4 in this way, the load transmitted from the existing pillar 1 is borne by the second foundation structure 18.

[Another Embodiment]
Other embodiments of the present invention will be described. It should be noted that the configurations of the respective embodiments described below are not limited to being applied independently, but can also be applied in combination with the configurations of other embodiments.

(1) In the first embodiment, the configuration in which the replacement frame 9 is provided with the first steel frame portion 11, the second steel frame portion 12, and the third steel frame portion 13 has been described as an example. However, it is not limited to such a configuration. For example, the replacement frame 9 may not include a part or all of the first steel frame portion 11, the second steel frame portion 12, and the third steel frame portion 13.

1 Existing column 1B Column base 2A Excavation target range 4 Replacement structure 6 Temporary column 6A Capital 9 Replacement frame 11 1st steel frame part 12 2nd steel frame part 13 3rd steel frame part

Claims (5)

An installation process of installing a replacement structure that can support the existing pillar from the ground portion directly under the existing pillar, and an excavation process of excavating the excavation target area directly under the existing pillar after the installation process are executed. death,
The replacement structure has a plurality of temporary columns fixed to the ground and a replacement frame connecting the stigma of the temporary columns and the existing columns, and a long-term load transmitted from the existing columns. And an excavation method that is configured to freely bear short-term loads. The excavation method according to claim 1, wherein the temporary pillar is fixed to the ground outside the excavation target range in a plan view. The excavation method according to claim 1 or 2, wherein the replacement frame has a first steel frame portion in a horizontal posture in which the stigmas of the plurality of temporary columns are connected to each other. The excavation method according to any one of claims 1 to 3, wherein the replacement frame has a second steel frame portion in a horizontal posture connecting the stigma of the temporary column and the column base portion of the existing column. According to any one of claims 1 to 4, the replacement frame has a third steel frame portion in an oblique posture that diagonally connects the stigma of the temporary column and the upper side of the column base portion of the existing column. The described excavation method.

Images