JP2016044426A - Timbering structure of circular vertical shaft, and construction method for circular vertical shaft - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a timbering structure of a circular vertical shaft, which enables the circular vertical shaft to be simply and inexpensively constructed without being restricted by surrounding environments, and a construction method for the circular vertical shaft.SOLUTION: A timbering structure 2 of a circular vertical shaft includes: circular timbering 3 that is arranged inside an earth retaining wall 10; a plurality of jacks 4, 4,... that are interposed between the earth retaining wall 10 and the circular timbering 3; and jack control means 5 for actuating the plurality of jacks 4, 4,.... A construction method for the circular vertical shaft utilizes the timbering structure 2.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a support structure for a circular shaft and a construction method for the circular shaft.

In steel sheet pile shafts, if deformation occurs in the steel sheet pile due to earth pressure or the like, there is a risk of displacement such as subsidence in the surrounding ground.
Therefore, in steel sheet pile vertical shafts, deformation of the steel sheet piles may be restricted by arranging support works such as erections.

  For example, in the steel sheet pile vertical shaft of Patent Document 1, the support members are installed at predetermined intervals with respect to the depth direction of the shaft, and the support member is horizontally placed on the support member so that the pressing force of the support member This limits the deformation of the steel sheet pile.

  When the shaft is circular, in order to prevent the displacement that occurs on the retaining wall (steel sheet pile) of the shaft, it is desirable to apply a pressing force evenly to the retaining wall, but equally to the retaining wall. It was difficult to apply a pressing force. In addition, if a horizontal member is disposed in the circular shaft, there is a risk of hindering the carrying in and out of materials and equipment.

  Therefore, when constructing a circular shaft in a place where there is a risk of ground subsidence, the method of upgrading the retaining wall specification of the shaft, the method of installing an anchor toward the surrounding ground, or the surrounding ground On the other hand, the displacement of the retaining wall was minimized by the method of ground improvement.

Japanese Patent Laid-Open No. 10-183623

Upgrading the specifications of the retaining wall increases the cost and labor.
Moreover, the method of constructing an anchor toward the surrounding ground of the shaft and the method of improving the ground on the surrounding ground of the shaft cannot be adopted when the adjacent boundary line is adjacent to the shaft.

  From such a viewpoint, it is an object of the present invention to propose a support structure for a circular shaft and a method for constructing the circular shaft, which can easily and inexpensively construct a circular shaft without being limited to the surrounding environment. To do.

  In order to solve the above-mentioned problem, a support structure for a circular shaft according to the present invention includes a circular support disposed inside a retaining wall, and a plurality of support structures interposed between the retaining wall and the circular supporting structure. A jack and a jack control means for operating the plurality of jacks are provided.

In such a circular shaft support structure, when a plurality of jacks are actuated, the retaining wall is pressed against the surrounding ground. That is, according to the present invention, since the retaining wall can be preloaded, it is possible to suppress loosening of the ground on the back of the retaining wall and suppress displacement of the surrounding ground without upgrading the specifications of the retaining wall. it can.
It is economical if the specifications of the retaining wall can be kept low. Further, since the loosening of the ground can be suppressed only by installing and operating the jack, it is simpler and less expensive than the conventional support structure.

  When the retaining wall is formed with irregularities on the inner surface by a steel sheet pile built in a circular shape in plan view, the circular support is disposed so as to abut on the convex portion of the retaining wall, The plurality of jacks may be disposed in the recesses of the retaining wall. If it does in this way, even if it removes a jack, since the state where the circular support work contacted the retaining wall is maintained, stability of the retaining wall can be maintained by circular support work.

  The construction method of the circular shaft of the present invention includes a step of press-fitting a steel sheet pile into the ground so as to have a circular shape in plan view, a step of excavating the ground surrounded by the steel sheet pile, and an inner space of the steel sheet pile And a step of interposing a plurality of jacks in a gap between the circular support and the steel sheet pile, and a step of applying a pressing force to the steel sheet pile using the plurality of jacks. It is characterized by comprising.

When a pressing force is applied to the steel sheet pile using a plurality of jacks, the steel sheet pile is pressed against the surrounding ground, so that it is possible to prevent the surrounding ground from loosening due to excavation inside the steel sheet pile. In addition, what is necessary is just to set suitably the installation number and arrangement | positioning of a jack according to the magnitude | size, ground conditions, etc. of a circular shaft.
Therefore, according to the present invention, it is not necessary to upgrade the specifications of the retaining wall, and a circular shaft can be constructed easily and inexpensively as compared with the conventional construction method.

  According to the support structure of a circular shaft and the construction method of the circular shaft of the present invention, a circular shaft can be constructed easily and inexpensively without being limited by the surrounding environment.

It is a top view which shows typically the support structure of the circular shaft of this embodiment. (A) is an enlarged plan view which shows a part of support structure of FIG. 1, (b) is an enlarged plan view which shows the jack after the support structure is removed.

This embodiment demonstrates the support structure 2 for suppressing the displacement of the surrounding ground which arises at the time of construction of the circular shaft 1.
As shown in FIG. 1, the support structure 2 of the circular shaft 1 according to the present embodiment includes a circular support 3, a plurality of jacks 4, 4,...

The circular shaft 1 of the present embodiment has a retaining wall 10 that is circular in plan view. The retaining wall 10 is formed by continuously building a plurality of steel sheet piles so that the planar shape is circular.
The retaining wall 10 has irregularities on the inner surface due to the shape of the steel sheet pile. That is, grooves (concave portions 11) and ridges (convex portions 12) continuous in the vertical direction are alternately formed on the inner surface of the circular shaft 1 (see FIG. 2A).

  As shown in FIG. 2A, the circular support 3 is made of an H-shaped steel having a pair of flanges 31 and 31 and a web 32, and is disposed inside the earth retaining wall 10. One (outside) flange 31 of the circular support 3 is in contact with the convex portion of the earth retaining wall 10.

The circular support 3 is formed in a circular shape in plan view by combining a plurality of steel members (not shown).
In addition, the material which comprises the circular support 3 is not limited to H-section steel, For example, channel steel may be sufficient.

The jack 4 is interposed in the gap between the retaining wall 10 and the circular support 3. In this embodiment, the jack 4 is arrange | positioned in the recessed part 11 of the earth retaining wall 10, as shown to (a) of FIG.
In the present embodiment, a hydraulic jack is used as the jack 4. Note that the jack 4 is not necessarily hydraulic, and may be pneumatic, for example.

The jack 4 takes a reaction force from the circular support 2 and applies pressure to the earth retaining wall 10.
In the present embodiment, 23 jacks 4 are arranged, but the number of jacks 4 is not limited as long as it is possible to apply a uniform pressure to the retaining wall 10 in the circumferential direction. However, what is necessary is just to set suitably according to the magnitude | size, ground conditions, etc. of the circular shaft 1. For example, when the inner diameter of the circular shaft 1 is small, four jacks 4 may be arranged at equal intervals, and when the inner diameter of the circular shaft 1 is large, eight or more jacks 4 may be arranged. desirable.

  The jack control means 5 is a device that operates a plurality of jacks 4, 4,. The jack control means 5 of this embodiment is provided with the electric pump unit 51, the branch metal fitting 52, the hydraulic hose 53, and the branch hose 54, as shown in FIG.

The electric pump unit 51 adjusts the hydraulic pressure of the jack 4.
The electric pump unit 51 of the present embodiment is connected to each jack 4 via a hydraulic hose 53 and a branch fitting 52.
In the present embodiment, four hydraulic hoses 53 are extended from the electric pump unit 51 and connected to the branch fitting 52, respectively.

The branch fitting 52 is connected to a single hydraulic hose 53 and is connected to a plurality of branch hoses 54.
The branch hose 54 is connected to the jack 4.
In the present embodiment, four branch fittings 52 are used, but the number of branch fittings 52 is not limited.

Each branch fitting 52 is connected to five or six jacks 4 via a branch hose 54.
The pressure applied to the hydraulic hose 53 by the electric pump unit 51 is transmitted to each jack 4 via the branch fitting 52 and the branch hose 54.

Next, the construction method of the circular shaft of this embodiment is demonstrated.
The circular shaft construction method includes a sheet pile press-in process, an excavation process, a support process, a preload process, and a jack removal process.

The sheet pile press-fitting step is a step of forming a retaining wall 10 having a circular shape in plan view by press-fitting a plurality of steel sheet piles from the ground into the ground.
In the present embodiment, the steel sheet pile is press-fitted using a press-fitting machine until the lower end of the steel sheet pile reaches a predetermined depth (for example, a hardly water-permeable layer). In addition, the installation method in the ground of a steel sheet pile is not limited.

The excavation process is a process of excavating the ground (inside the retaining wall 10) surrounded by steel sheet piles.
The ground is excavated using a known excavator (for example, a backhoe) until a predetermined depth (depth at which a circular support can be installed) is reached.

The supporting process is a process of arranging the circular supporting work 3 and the jack 4.
The circular support 3 is disposed so as to contact the convex portion 12 of the retaining wall 10. Prior to installing the circular support 3, a bracket (not shown) is fixed to the earth retaining wall 10.
The circular support 3 is disposed in a state of being placed on the bracket. Brackets are installed as necessary. Further, in the supporting step, it is not always necessary to bring the circular supporting work 3 into contact with the retaining wall 10.

Along with the installation of the circular support 3, a plurality of jacks 4, 4,... Are interposed in the gap between the circular support 3 and the retaining wall 10. In the present embodiment, the jack 4 is installed in the recess 11 of the retaining wall 10.
The jack 4 is connected to the jack control means 5.

The preload process is a process in which a pressing force is applied to the earth retaining wall 10 using a plurality of jacks 4, 4,.
When the electric pump unit 51 is operated, the jack 4 is extended, and the pressing force of the earth retaining wall 10 is applied.

The plurality of jacks 4, 4,... Are simultaneously operated by a single system of jack control means 5, so that when the electric pump unit 51 is operated, the pressing force is equally applied to the earth retaining wall 10. An axial compression force mainly acts on the circular support 3.
At this time, the pressure of the jack 4 is appropriately adjusted according to the depth position (presumed earth pressure).

The jack removing step is a step of removing the jack 4.
When a predetermined pressing force is applied to the retaining wall 10 by the jack 4, a steel plate or the like is formed in the gap formed between the circular support 3 and the convex portion 12 of the retaining wall 10 as shown in FIG. An interstitial material 6 is interposed.
Next, the jack 4 is removed from the recess 11. In addition, the material which comprises the filling material 6 is not limited.

  After the jack removal step, the circular shaft 1 having a predetermined depth is formed by repeating the excavation step, the support step, the preload step, and the jack removal step.

According to the support structure 2 and the circular shaft construction method of the present embodiment, the pressure can be evenly applied to the circumferential direction of the circular shaft 1 by simultaneously operating the plurality of jacks 4, 4,. . By doing so, the retaining wall 10 can be pressed against the surrounding ground, and the looseness of the ground on the back of the retaining wall 10 can be suppressed.
That is, by preloading the retaining wall 10, the displacement of the surrounding ground can be suppressed without upgrading the specifications of the retaining wall 10.

  Moreover, since the loosening of the ground is suppressed by preloading the retaining wall 10, it can be constructed even when the circular shaft 1 is formed in the vicinity of the adjacent land boundary.

Further, since the loosening of the ground can be suppressed only by installing and operating the jack 4, it is simpler and less expensive than the conventional support structure.
Since the jack 4 can be diverted, it is economical.

Since the jack 4 is installed in the recess 11 of the retaining wall 10 (steel sheet pile), the circular support 3 can be brought into contact with (or close to) the retaining wall 10.
In this way, after preloading the retaining wall 10 with the jack 4, the filler 6 can be easily installed between the circular support 3 and the retaining wall 10, so that the replacement is facilitated, Even when the jack 4 is removed, the state where the circular support 3 is in contact with the retaining wall 10 is maintained, so that the stability of the retaining wall can be maintained.

  The embodiment of the present invention has been described above. However, the present invention is not limited to the above-described embodiment, and the above-described components can be appropriately changed without departing from the spirit of the present invention.

Although the said embodiment demonstrated the case where a retaining wall was formed using a steel sheet pile, the formation method of a retaining wall is not limited. For example, you may employ | adopt the formation method of earth retaining walls, such as circular earth retaining by the mortar column pile method.
In addition, the retaining wall does not necessarily have irregularities on the inner surface.
The jack control means does not necessarily have to operate a plurality of jacks simultaneously.

DESCRIPTION OF SYMBOLS 1 Circular shaft 10 Retaining wall 11 Concave part 12 Convex part 2 Support structure 3 Circular support 4 Jack 5 Jack control means 6 Steel plate

Claims (3)

A circular support installed inside the retaining wall;
A plurality of jacks interposed in a gap between the retaining wall and the circular support;
A support structure for a circular shaft, comprising: jack control means for operating the plurality of jacks. The retaining wall is formed with an unevenness on the inner surface by a steel sheet pile built in a circular shape in plan view,
The circular support is disposed so as to contact the convex portion of the retaining wall,
2. The support structure for a circular shaft according to claim 1, wherein the plurality of jacks are disposed in a concave portion of the earth retaining wall. A process of press-fitting a steel sheet pile into the ground so as to have a circular shape in plan view;
Excavating the ground surrounded by the steel sheet pile,
Arranging a circular support in the inner space of the steel sheet pile, and interposing a plurality of jacks in the gap between the circular support work and the steel sheet pile;
And a step of applying a pressing force to the steel sheet pile using the plurality of jacks.

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