JP4011209B2 - Construction method of shaft - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a shaft construction method by construction of earth retaining walls.
[0002]
[Prior art]
Examples of the shaft construction method include steel sheet pile method, SMW method, underground continuous wall method, caisson method and the like.
By the way, in the case of sandy soil and cohesive soil with deep ground and high groundwater in the shaft, phenomenon of swelling of the ground due to heaving, boiling, and pressurized water occurs on the bottom of excavation. For this reason, except for the caisson method, which does not require rooting, the length of the retaining wall is often long.
As a method for reducing the penetration depth, there are a groundwater level lowering method and a ground improvement method for the bottom.
[0003]
[Problems to be solved by the invention]
However, the groundwater level lowering method involves subsidence of the surrounding ground, so it is difficult to adopt it in urban areas, and the ground improvement method for the bottom has problems such as extremely high construction costs at large depths.
[0004]
Accordingly, an object of the present invention is to reduce the construction period and reduce the construction cost while reducing the groundwater level in the ground while reducing the length of the retaining wall in a deep shaft. Is to provide a construction method.
[0005]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, the invention according to claim 1 is a method for constructing a shaft after constructing a retaining wall in the soil, and comprising a retaining wall construction step and a shaft surrounded by the retaining wall An underwater excavation process for introducing water into the shaft and excavating the interior of the shaft, a permeable material injection process for supplying a permeable material to the bottom of the digging inside the shaft, a submersible pump installation process for installing a submersible pump in the permeable layer, Temporary concrete placement process for placing underwater concrete on the water permeable layer formed by material input, drainage process for draining the water inside the shaft, and temporary bottom slab concrete formed by temporary concrete placement and the inner surface of the shaft A concrete placement process in which the concrete is placed in the water, and in the drainage process, the submersible pump installed in the permeable layer is operated as necessary to drain the water in the permeable layer. It is set to.
[0006]
Here, the earth retaining wall is constructed by a general construction method such as a steel sheet pile method, an SMW method, or an underground continuous wall method.
As the water permeable material, crushed stone or sandy soil is generally used, and the water permeable layer formed thereby is also called a water collecting layer.
The drainage inside the shaft is performed by a submersible pump installed inside the shaft. If there is a risk that the lifting pressure on the temporary bottom slab concrete will cause the concrete to collapse due to the lowering of the internal water level, the lifting pressure is reduced by the submersible pump installed in the permeable layer.
It is desirable to place the bottom slab concrete after the concrete is placed on the inner surface of the shaft by reverse winding or forward winding.
[0007]
As described above, according to the first aspect of the present invention, when a shaft is constructed, water is introduced into the shaft surrounded by the retaining wall and the inside of the shaft is excavated underwater, and then the water is permeable to the bottom of the excavation inside the shaft. The material is poured to form a water permeable layer, and underwater concrete is cast on the water permeable layer to construct a temporary bottom slab concrete. Therefore, the construction period and cost as much as the ground improvement work are not required.
And compared with the ground improvement work, the solid connection state of the earth retaining wall and the temporary bottom slab concrete is obtained, and the fall of the groundwater level in the ground can be suppressed.
Furthermore, after constructing such a temporary bottom slab concrete, the construction of the shaft by construction of the retaining wall is completed by placing the concrete on the temporary bottom slab concrete and the inner surface of the shaft along with drainage inside the shaft. .
[0009]
In addition, according to the first aspect of the present invention, the submersible pump is installed in the permeable layer in parallel with or subsequent to the permeable material charging step, and is installed in the permeable layer under the temporary bottom slab concrete by the subsequent underwater concrete placement. Since the water is discharged by the submersible pump, effective drainage can be performed at the time of the next permanent concrete placement.
[0010]
Invention of Claim 2 is the construction method of the shaft of Claim 1, Comprising: It uses crushed stone and sandy soil as a water-permeable material, It is characterized by the above-mentioned.
[0011]
Thus, according to the invention described in claim 2, since crushed stone and sandy soil are used as the water-permeable material according to claim 1, formation of the water-permeable layer as the water collecting layer can be easily performed.
[0012]
The invention according to claim 3 is the construction method of the shaft according to claim 1 or 2, wherein, following the drainage process, there is provided a cleaning process such as deburring and green cutting of the interior of the shaft and the temporary bottom slab concrete surface. It is a feature.
[0013]
Thus, according to the invention described in claim 3, in the cleaning process following the draining process described in claim 1 or 2, the inside of the shaft and the temporary bottom slab concrete surface are cleaned to prepare for the next permanent concrete placement. It is done.
[0014]
Invention of Claim 4 is the construction method of the shaft of Claim 1, 2, or 3, Comprising: The drainage process was made parallel to the permanent concrete casting process, and the permanent bottom slab concrete reached the required strength After confirming this, drainage from the permeable layer is terminated.
[0015]
As described above, according to the invention described in claim 4, the drainage process described in claim 1, 2 or 3 is made parallel to the permanent concrete placing process, and the fact that the bottom slab concrete of the permanent structure has reached the required strength is confirmed. Since the drainage from the permeable layer is completed after confirmation, a shaft made of permanent bottom slab concrete having a predetermined strength without risk of collapse of the temporary bottom slab concrete due to lift pressure such as pressurized water can be constructed.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Below, the embodiment of the construction method of the shaft which concerns on this invention is described based on FIGS.
First, FIG. 1 shows the construction method of a shaft by construction of a retaining wall as an example to which the present invention is applied, a schematic longitudinal sectional view showing a retaining wall construction process, and FIG. 2 shows a subsequent underwater excavation process. FIG. 3 is a schematic longitudinal sectional view showing a subsequent permeable material charging and submersible pump installation process, FIG. 4 is a schematic longitudinal sectional view showing a subsequent temporary concrete placing process, and FIG. 5 is a subsequent draining process and cleaning. FIG. 6 is a schematic vertical cross-sectional view showing a shaft completion state after completion of the continuous concrete pouring operation.
[0017]
In this embodiment, the shaft construction method according to the present invention includes (1) a retaining wall construction process, (2) an underwater excavation process, (3) a permeable material input and an underwater pump installation process, and (4) temporary concrete. This is the construction procedure of the placing process, (5) draining process and cleaning process, and (6) permanent concrete placing process.
[0018]
That is, in the (1) earth retaining wall construction process, as shown in FIG. 1, in the soil 1, the earth retaining wall 11 is moved to the final root bottom, for example, the steel sheet pile method, the SMW method, the underground continuous wall method. It is constructed by general construction methods such as. This earth retaining wall 11 becomes the peripheral wall of the shaft 12.
In the figure, 2 is an arbitrary formation.
[0019]
Subsequently, (2) in the underwater excavation step, as shown in FIG. 2, water 13 is introduced into the soil surrounded by the retaining wall 11, and the inside of the shaft 12 is excavated in the water. Such underwater excavation is performed up to a position where a penetration length that can ensure the safety of the retaining wall 11 is left.
Here, the introduction of the water 13 is performed using an appropriate water supply facility (not shown). Also, underwater excavation is performed using an appropriate excavating machine (not shown).
[0020]
Subsequently, in the step (3) of introducing the permeable material and installing the submersible pump, as shown in FIG. 3, permeable materials (drain materials) 14 and 14 such as crushed stone and sandy soil are formed on the bottom of the excavation in the water 13 inside the shaft 12. , 14,... And a plurality (three in the illustrated example) of submersible pumps 15, 15, 15 are installed to form a water collection layer (water-permeable layer) 16.
The submersible pumps 15, 15, 15 are connected to drain pipes 17, 17, 17 that lead to the ground surface along the inner surface of the retaining wall 11, as shown in the figure. Is connected.
[0021]
Then, in (4) the temporary concrete placing step, as shown in FIG. 4, underwater concrete is placed in the water 13 inside the shaft 12 to form a temporary bottom slab concrete 18 on the water collection layer 16.
[0022]
After that, in (5) draining process and cleaning process, (6) in the concrete placing process, as shown in FIG. 5, the submersible pump 31 provided in the shaft 12 is operated to drain the water 13 in the shaft 12. By draining from the drain pipe 31, the water 13 in the shaft 12 is reduced to the required depth.
Thus, after the inside of the shaft 12 is dried up according to the required depth, the wall surface is cleaned, and the inner wall concrete 21 is placed along the inner surface of the retaining wall 11 by reverse winding or forward winding. Moreover, the submersible pump 15 embed | buried in the water collection layer 16 is operated as needed.
Here, the reason why the submersible pump 15 in the water collecting layer 16 is operated is to reduce the lifting pressure applied to the temporary bottom slab concrete and prevent the temporary bottom slab concrete from collapsing with the decrease in the water level during the construction of the concrete. .
[0023]
(6) As shown in FIG. 6, the permanent concrete placing process is until the permanent bottom slab concrete 22 is placed on the temporary bottom concrete 18 and the permanent bottom slab concrete 22 has reached the required strength. If confirmed, the submersible pump 15 in the water collection layer 16 is stopped.
In addition, the strength confirmation of the permanent bottom slab concrete 22 is performed using an appropriate measuring instrument (not shown).
Thus, the shaft 12 is completed.
[0024]
As described above, the shaft construction method according to the present invention has the following characteristics.
(1) For the retaining wall 11, a general construction method such as a steel sheet pile method, an SMW method, or an underground continuous wall method can be applied.
(2) The internal excavation of the vertical shaft 12 is underwater excavation in order to compensate for the short defect of the penetration depth.
(3) After completion of underwater excavation, water-permeable materials 14, 14, 14,... And crushed stones, sandy soil, etc. and underwater pumps 15, 15, 15 are installed on the bottom of excavation in the retaining wall 11, and a water collecting layer ( A water permeable layer 16 is formed.
(4) In place of ground improvement work, underwater concrete is placed on the water collection layer 16 as a temporary bottom slab concrete 18. Further, the amount of collected water is reduced by making the connection between the earth retaining wall 11 and the temporary bottom slab concrete 18 dense.
(5) The inside of the shaft 12 is dry-up according to the required depth, and the reversely or forwardly wound inner wall concrete 21 is placed. At this time, the submersible pump 15 in the water collection layer 16 is operated as necessary.
[0025]
The main effects obtained by the shaft construction method according to the present invention are as follows.
(1) Since the length of the retaining wall 11 can be shortened, the construction period can be shortened and the construction cost can be reduced.
(2) Since underwater concrete is placed instead of ground improvement work, the construction period and construction cost are not as high as those for ground improvement work.
(3) Since the solid connection with the retaining wall 11 is possible as compared with the ground improvement work, the decrease in the groundwater level in the ground can be reduced.
[0026]
In the above embodiment, the water-permeable material and the submersible pump are installed in the same process. However, the present invention is not limited to this, and the water-permeable material may be installed after the water-permeable material is introduced. .
In addition, drainage and cleaning methods are arbitrary, and it is needless to say that other detailed structures can be appropriately changed.
[0027]
【The invention's effect】
As described above, according to the shaft construction method according to the first aspect of the present invention, in the deep shaft, the underwater excavation and underwater concrete placement inside the shaft are performed while shortening the length of the retaining wall. Therefore, the construction period can be shortened and the construction cost can be reduced, and the groundwater level in the ground can be lowered by obtaining a more solid connection between the retaining wall and the temporary bottom slab concrete than the ground improvement work. Can be small.
[0028]
Moreover, according to the construction method of the shaft according to the invention of claim 1, the submersible pump installed in the permeable layer under the temporary bottom slab concrete by draining with the submersible pump installed in the shaft and as needed is installed. By operating and draining the water in the permeable layer, there is an advantage that the drainage can be effectively performed when the next concrete is placed.
[0029]
According to the shaft construction method according to the invention of claim 2, by using crushed stone or sandy soil as the water permeable material, in addition to the effect obtained by the invention of claim 1, the water permeable layer as the water collecting layer Can be formed easily.
[0030]
According to the shaft construction method according to the invention described in claim 3, by cleaning the inside of the shaft and the temporary bottom slab concrete, in addition to the effect obtained by the invention according to claim 1 or 2, The advantage that it can prepare for installation is acquired.
[0031]
According to the shaft construction method according to the invention of claim 4, it is confirmed that the bottom slab concrete of the main structure has reached the required strength, and drainage from the permeable layer is terminated, whereby claim 1, 2, or 3 In addition to the effects obtained by the described invention, there is an advantage that it is possible to build a shaft made of permanent bottom slab concrete having a predetermined strength without risk of collapse due to lifting pressure such as pressurized water.
[Brief description of the drawings]
FIG. 1 is a schematic longitudinal sectional view showing a retaining wall construction process, showing a shaft construction method by construction of retaining walls as an example to which the present invention is applied.
2 is a schematic longitudinal sectional view showing an underwater excavation process following the retaining wall construction process of FIG. 1; FIG.
3 is a schematic longitudinal sectional view showing a permeable material charging step and a submersible pump installation step subsequent to the submerged excavation step of FIG. 2. FIG.
4 is a schematic longitudinal sectional view showing a temporary concrete placing process following the water-permeable material charging and submersible pump installing process of FIG. 3; FIG.
5 is a schematic longitudinal sectional view showing a draining process, a cleaning process, and a permanent concrete placing process following the temporary concrete placing process of FIG. 4;
FIG. 6 is a schematic longitudinal sectional view showing a shaft completion state after completion of permanent concrete pouring following FIG. 5;
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Underground 2 Arbitrary stratum 11 Earth retaining wall 12 Vertical shaft 13 Water 14 Water permeable material 15 Submersible pump 16 Water permeable layer 17 Drain pipe 18 Temporary bottom slab concrete 21 Main wall concrete 22 Main bottom slab concrete 31 Submersible pump 32 Drain pipe

Claims (4)

  It is a method of building a shaft after building a retaining wall in the soil. The retaining wall building process and underwater excavation in which water is introduced into the shaft surrounded by the retaining wall to excavate the shaft. The process, the permeable material injection process for introducing the permeable material to the bottom of the excavation inside the shaft, the submersible pump installation process for installing the submersible pump in the permeable layer, and placing the underwater concrete on the permeable layer formed by the introduction of the permeable material Temporary concrete placing process, draining process for draining the water inside the shaft, and permanent concrete placing process for placing the concrete on the temporary bottom slab concrete and the inner surface of the shaft formed by the temporary concrete placement A construction method of a shaft, characterized in that, in the drainage process, a submersible pump installed in the permeable layer is operated as necessary to drain the water in the permeable layer.   The method for constructing a shaft according to claim 1, wherein crushed stone or sandy soil is used as the water permeable material.   The shaft construction method according to claim 1 or 2, characterized in that, following the drainage step, a cleaning step such as chipping or green cutting of the inside of the shaft and the temporary bottom slab concrete surface is provided.   It is characterized by paralleling the drainage process to the permanent concrete casting process, and after draining the permanent bottom slab concrete, confirming that the bottom slab concrete has reached the required strength and ending drainage from the permeable layer. The shaft construction method according to claim 1, 2, or 3.

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