JP4248716B2 - Caisson top end construction method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a construction method for an upper end portion of a caisson whose upper end portion is located below the ground surface.
[0002]
[Prior art]
In the caisson method, as in the open caisson method, a tubular structure constructed of reinforced concrete is placed on the ground, the ground below the tubular structure is excavated, and the weight or load of the tubular structure is There is a method of sinking the cylindrical structure into the ground, and by repeatedly adding the cylindrical structure and excavating the ground, the cylindrical structure reaches the predetermined supporting ground, and then the bottom concrete and the top Construction of slab concrete and construction of foundation structure. The constructed foundation structure serves as the foundation of the ground structure and the main body of the underground structure.
In such a caisson method, since the cylindrical structure always reaches the ground surface, the cylindrical structure itself has a retaining wall that prevents the surrounding soil from flowing into the cylindrical structure. It has become.
[0003]
[Problems to be solved by the invention]
By the way, when building a structure in the basement, when the ground surface on the underground structure is used for a purpose of use unrelated to the underground structure, for example, as a park or residential land, a certain amount of It is necessary not to leave a structure or temporary material in the depth. Therefore, as described above, in the caisson method in which the cylindrical structure reaches the ground surface, in such a case, the cylindrical structure near the ground surface must be removed.
[0004]
However, in the above-described caisson method, the cylindrical structure has a strong structure because it serves as the foundation of the ground structure and the base of the underground structure. Therefore, there is a problem that it takes time to remove a part (upper part) of the cylindrical structure.
[0005]
Accordingly, an object of the present invention is to easily remove the structure above the top plate of the caisson and backfill in a caisson having a structure in which the upper end portion is located below the ground surface and the top plate is backfilled. The object is to provide a method for constructing the upper end of the caisson.
[0006]
[Means for Solving the Problems]
In order to solve the above problems, the present invention provides a caisson method including a step of excavating the caisson and sinking the caisson, so that the position of the upper end of the caisson installed below the ground surface is below the surface part. The caisson upper end portion in the caisson having a structure in which the top of the top plate provided on the upper end portion is backfilled, the caisson (1) upper end portion being submerged below the ground surface portion A temporary earth retaining wall (4) that is substantially the same as the caisson and can be divided into a plurality of pieces is provided on the caisson so as to reach the ground surface portion, and in the temporary earth retaining wall, After the top plate (8) is provided at the upper end of the caisson, the top plate is refilled and the temporary earth retaining wall above the top plate is divided and removed.
[0007]
Here, it is preferable that the temporary earth retaining wall is cut and cut into a plurality of vertical surfaces intersecting the earth retaining wall.
[0008]
As described above, according to the present invention , in the portion extending from the upper end portion of the caisson, which is sunk below the ground surface portion, to the ground surface portion, a temporary soil that is substantially the same cylindrical shape as the caisson and can be divided into a plurality of pieces. A retaining wall is provided, and after the caisson top plate is formed in the temporary earth retaining wall, the top plate is refilled and the temporary earth retaining wall is divided and removed. Therefore, the top plate can be provided at the upper end portion of the caisson submerged below the ground surface portion by retaining the portion from the upper end portion of the caisson to the ground surface portion with the temporary earth retaining wall. In addition, the temporary earth retaining wall is not subjected to weighting as when caisson is sunk, and is not used as a foundation or basement structure, and has sufficient strength to allow earth retaining. Since it is sufficient, the thickness can be made thinner than the caisson. Such a temporary earth retaining wall can be further divided into a plurality of parts, so that it can be easily pulled out after being backfilled and easily removed.
When the caisson is laid, a temporary earth retaining wall is created on the cylindrical structure in advance when the cylindrical structure that becomes the upper end of the caisson is submerged from the ground to the basement. Even if the upper end of the object is submerged below the ground surface, it is necessary to be able to retain the top of the cylindrical structure with the temporary retaining wall. In this case, it is necessary to sink the caisson deeper than the ground surface by applying a load to the caisson's own weight or the upper end of the caisson without applying a load to the temporary earth retaining wall.
[0009]
In the construction method of the caisson upper end portion according to the present invention, the temporary earth retaining wall is a lower part of the earth retaining wall that serves as a mold for the outer peripheral portion of the top plate when the concrete is placed and the top plate is provided. 5) and a retaining wall upper portion (6) provided on the lower part of the retaining wall, removable from the lower part of the retaining wall and detachable into a plurality of parts, and refilling the top plate In this case, the upper part of the separable earth retaining wall is divided and removed.
[0010]
As described above, according to the present invention , the temporary earth retaining wall is a lower part of the earth retaining wall that forms the outer peripheral portion of the top plate when the concrete is cast to form the top plate. By providing the upper part of the retaining wall upper part, which is detachable from the lower part of the retaining wall and can be divided into a plurality of parts, it is not necessary to newly provide a form plate for the top plate, and the cost can be reduced. Further, since the upper part of the retaining wall can be removed from the lower part of the retaining wall, it can be easily removed even after placing concrete in the lower part of the retaining wall.
[0011]
In the construction method of the caisson upper end , the present invention provides an annular beam (for example, ring beam 3) provided along the circumferential direction on the inner peripheral side of the temporary earth retaining wall, and the temporary earth retaining wall. The temporary earth retaining wall is supported by a support having a column (for example, an H beam 2) extending vertically along the inner periphery of the ring, and the annular beam is removed when the top plate is refilled. In addition, the column is cut at a position corresponding to the upper end of the top plate, and the column is removed.
[0012]
Thus, according to the present invention , the annular beam provided along the circumferential direction on the inner peripheral side of the temporary earth retaining wall, and the column extending vertically along the inner circumference of the temporary earth retaining wall. By supporting the temporary earth retaining wall with the supporting structure provided, the strength of the temporary earth retaining wall can be increased, so that the temporary earth retaining wall itself can be reduced in weight, for example, by reducing the thickness, It can be made easier to remove. Also, when the top plate is backfilled, the circular beam is removed, and the column is cut at a position corresponding to the upper end of the top plate, so that the column is easily removed after the top plate is backfilled. be able to.
[0013]
Further, in the construction method of the caisson upper end portion according to the present invention, the position of the column corresponding to the upper end portion of the top plate before the backfilling on the top plate when removing the column of the support work. At the time of cutting, the upper end portion of the column and the portion below the cutting position of the column are fastened with bolts (10) and backfilled on the top plate, and then the upper end portion side of the column From the above, the fastening of the bolt is released and the column is pulled out.
[0014]
Thus, according to the present invention , before performing backfilling on the top plate, the column is cut at a position corresponding to the upper end portion of the top plate, and the upper end portion of the column and the portion below the cutting position of the column And after the backfilling on the top plate is completed, the bolts are released from the upper end side of the column, and the column before the backfilling is exposed by pulling out the column. Can be easily cut, and can be held in an upright state even after cutting with a bolt. Further, by the divided parts of the temporary設土fastening wall upper pillars of shoring is bonded, if a state where each divided portion of the temporary earth retaining wall upper is joined to temporary earth retaining wall lower By fastening the column cutting portion with the above bolts, when the backfilling is performed, the divided portions of the upper part of the temporary earth retaining wall can be kept joined to the lower part of the temporary earth retaining wall, and the above bolt After releasing the fastening by, each divided portion of the upper part of the temporary earth retaining wall can be easily removed.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Below, the embodiment of the construction method of the caisson upper end part which concerns on this invention is described based on FIGS.
The underground structure constructed by applying the present invention is, for example, a resistance that has drainage pipes 23 and 23 connected from two tunnels 21 and 22 for a subway and has a passage from the ground. The resistance is composed of an open caisson 26. However, since the ground surface on the open caisson 26 is used for a purpose different from this underground structure, the underground structure composed of the open caisson 26 is set to a position below the ground surface, and the top of the open caisson 26 is backfilled. It is in the state.
In order to secure a passage to the ground, a resistance composed of the open caisson 24 reaching the ground is provided at a position away from the open caisson 26, and the open caisson 26 and the open caisson 24 are joined by the passage 25 in the basement. Has been. Thereby, the passage between the lower part of the open caisson 26 and the ground can be secured.
[0016]
Here, before explaining the construction method of the upper end portion of the open caisson, a temporary structure provided at the upper end portion of the open caisson will be described. FIG. 1 is a side view of the upper end portion of an open caisson, and FIG. 2 is an enlarged view of a portion A in FIG. In the figure, 1 is a circular caisson, 2 is an H beam (column), 3 is a ring beam ( annular beam), and 4 is a temporary earth retaining wall. The temporary earth retaining wall 4 is composed of an earth retaining wall lower part 5 and an earth retaining wall upper part 6. The H beam 2 and the ring beam 3 serve to support the temporary earth retaining wall 4. The H beam 2 is partially embedded in the caisson 1 and protrudes upward from the upper end of the caisson 1 in parallel with the length direction (vertical direction) of the caisson 1. A plurality of H beams 2 are provided at the upper end of the caisson 1. Inside the H beam 2, annular ring beams 3 and 3 are installed along the circumferential direction. The ring beams 3 and 3 are provided above the H beam with an interval in the vertical direction.
[0017]
On the upper end of the caisson 1, a cylindrical earth retaining wall lower part 5 is provided along the circumference of the caisson 1 outside the H beams 2, 2,. The retaining wall lower portion 5 is made of, for example, concrete having a thickness of 200 mm. The earth retaining wall lower part 5 (earth retaining wall 4) is thinner than the caisson 1 (the caisson 1 has a thickness of 700 mm, for example) and is formed so as to be placed on the outer peripheral side of the upper end surface of the caisson 1. . Therefore, the inner peripheral side of the upper end surface of the caisson 1 is in an exposed state, and a load can be applied to the caisson 1 inside the earth retaining wall 4 when the caisson 1 is laid down.
[0018]
On the earth retaining wall lower part 5, the earth retaining wall upper part 6 is installed so as to be outside the H beams 2, 2... Like the earth retaining wall lower part 5 (see FIG. 3). The earth retaining wall upper part 6 has a cylindrical shape made of concrete having a thickness of 200 mm, like the earth retaining wall lower part, but can be divided vertically into 10 parts. That is, the retaining wall upper part 6 on the cylinder is constructed by arranging and joining ten arc-plate-like divided bodies along the circumference. In addition, each division | segmentation body used as the earth retaining wall upper part 6 is good also as what consists of precast concrete, and is good also as what constructs by placing concrete in the field in the divided | segmented state.
[0019]
Moreover, joining of division bodies can be performed by a known method, for example, it is good also as what joins using a well-known various coupling. Moreover, joining of the retaining wall lower part 5 and the retaining wall upper part 6 can also be performed by a known method. Moreover, it is also possible to perform the joining of the respective divided bodies of the retaining wall upper part 6 and the joining of the retaining wall lower part 5 and the retaining wall upper part 6 through the supporting work composed of the H beam 2 and the ring beam 3. good. That is, by joining each divided body of the retaining wall upper part 6 to the support work, joining of each divided body of the retaining wall upper part 6 and joining of the retaining wall lower part 5 and the retaining wall upper part 6 are performed. You may do it.
[0020]
Further, the earth retaining wall upper portion 6 is arranged so that the joint portion between the divided bodies comes behind the H beam 2 as shown in FIG. 4. Moreover, the removal from the earth retaining wall lower part 5 can also be performed now easily.
Here, when there is a restriction that a structure or the like should not be left at a certain depth from the ground surface, the length of the earth retaining wall upper part 6 is set to be equal to or longer than a depth determined by the restriction. For example, when a structure or the like should not be left from the ground surface to 2.5 m underground, the length of the retaining wall upper part 6 is set to 2.5 m or more.
[0021]
Next, the construction method of the caisson upper end part which has the above temporary structures is demonstrated.
Similar to the general open caisson method, the ground below the caisson 1 is excavated, and the caisson 1 is buried in the ground by its own weight or press-fitting.
Then, when constructing the cylindrical structure part which becomes the upper end part of the caisson 1, the supporting work composed of the H beam 2 and the ring beam 3 as described above, the temporary earth retaining wall lower part 5 and the temporary earth retaining wall upper part 6 A temporary earth retaining wall 4 is constructed.
Further, the caisson 1 is further submerged in the ground, and the caisson 1 is buried until the upper end of the earth retaining wall upper part 6 becomes almost equal to the ground surface. After the caisson 1 is completely embedded, the precast concrete 7 serving as the bottom of the form plate of the top plate is laid on the upper end portion of the caisson 1 so as to close the caisson 1, and the concrete is placed on the top plate 8 Form. At this time, the earth retaining wall lower part 5 becomes a formwork of the top plate 8 simultaneously with earth retaining. Further, the top end of the top plate 8 is placed so as to be below the joint between the retaining wall lower part 5 and the retaining wall upper part 6. In order to prevent water or the like from entering the caisson 1, a waterproof sheet 12 is sandwiched between contact surfaces of the top plate 8 and the H beams 2, 2,.
[0022]
Next, a cover mortar 9 is placed on the top plate 8 as shown in FIG. 5A, and the H beams 2, 2... Are cut above the cover mortar 9. Similarly to the top plate 8, the cover mortar is also placed so as to be below the joint between the retaining wall lower part 5 and the retaining wall upper part 6.
When cutting the H beams 2, 2,..., Fasten the upper ends of the H beams 2, 2,... With the long bolts 10, 10,. (See FIG. 5B).
Further, after placing the concrete 11 on the cover mortar 9 (see FIG. 5 (c)), the ring beams 3, 3 are removed from the H beams 2, 2,... (See FIG. 5 (d)), and the top plate of the caisson. 8 The top is refilled with earth and sand 13 or the like (see FIG. 5E).
Then, the fastening of the bolts 10, 10... Is released from the upper end side of the H beams 2, 2... (See FIG. 5 (f)), and the H beams 2, 2. Thus, as shown in FIG. 6, the upper end portion of the open caisson can be constructed so as not to leave a structure or the like at a certain depth from the ground surface.
[0023]
Thus, according to the construction method of the caisson upper end part of the above embodiment, by carrying out the earth retaining with the earth retaining wall lower part 5 and the earth retaining wall upper part 6 from the upper end part of the caisson 1 to the ground surface, The top plate 8 can be easily driven on the upper end portion of the caisson 1 set below the ground surface. Moreover, since the retaining wall upper part 6 is thinner than the caisson 1 and can be divided into 10 parts, it can be easily removed after the top of the caisson 1 is backfilled. Since the earth retaining wall lower part 5 is not only earth retaining but also a mold frame of the outer peripheral portion of the top plate 8, it is not necessary to newly provide a mold frame, and the cost can be reduced.
Moreover, since the top plate 8 and the cover mortar 9 are driven below the joint between the retaining wall lower part 5 and the retaining wall upper part 6, the retaining wall upper part 6 can be easily pulled out.
The strength of the earth retaining wall lower part 5 and the earth retaining wall upper part 6 can be increased by supporting the earth retaining wall lower part 5 and the earth retaining wall upper part 6 with the H beams 2, 2. .
Further, before the back-filling on the top plate 8, the H beams 2, 2... Are cut with the H beams 2, 2. The parts below the cutting position of the beams 2, 2 ... are fastened with bolts 10, 10 ..., and after the back-filling on the top plate is completed, the fastening of the bolts 10, 10 ... is released, and the H beams 2, 2 ... By pulling out ..., the H beams 2, 2, ... can be kept upright even after cutting. Cutting and drawing operations can be easily performed.
[0024]
In the above embodiment, an open caisson is cited as an applied caisson. However, the present invention is not limited to this, and a caisson that is submerged under the ground surface by excavating the caisson. For example, it can be applied to a pneumatic caisson or a press-fitting caisson.
In addition, although the upper part of the retaining wall can be divided into ten parts, the present invention is not limited to this, and it is only necessary that the upper part of the retaining wall can be easily pulled out by dividing, and may be divided into any number of parts. .
The thickness of the earth retaining wall, the number of H beams and ring beams, and the like are arbitrary, and it is needless to say that other specific detailed structures can be appropriately changed.
[0025]
【The invention's effect】
As described above, according to the construction method of the caisson upper end portion according to the present invention , the caisson upper end portion submerged below the ground surface portion to the ground surface portion, on the caisson, in a cylindrical shape substantially similar to the caisson. By providing a temporary earth retaining wall that can be divided into a plurality of pieces, the temporary earth retaining wall can retain the part from the upper end portion of the caisson to the surface portion, and the upper end portion of the caisson set below the surface portion. A top plate can be provided. In addition, after forming the top plate of the caisson in the temporary earth retaining wall, by refilling the top plate, dividing the temporary earth retaining wall and removing it, the temporary earth retaining wall is thinner than the caisson, Furthermore, since it can be divided into a plurality of parts, it can be easily pulled out after backfilling and can be easily removed.
[0026]
Moreover, according to the construction method of the caisson upper end part according to the present invention , the temporary earth retaining wall includes an earth retaining wall lower part which becomes a mold of an outer peripheral part of the top plate when the top plate is formed, and the earth retaining wall lower part. And an upper part of the retaining wall that is detachable from the lower part of the retaining wall and can be divided into a plurality of parts. As a result, it is not necessary to newly provide a form plate for the top plate, so that the cost can be reduced. Further, the upper part of the retaining wall can be easily removed even after the concrete is placed in the lower part of the retaining wall.
[0027]
Moreover, according to the construction method of the caisson upper end portion according to the present invention , an annular beam provided along the circumferential direction on the inner peripheral side of the temporary earth retaining wall, and a column extending up and down along the inner periphery The strength of the temporary earth retaining wall can be increased by providing the support work made of and supporting the temporary earth retaining wall. Thus, the temporary earth retaining wall can be reduced in weight, and the temporary earth retaining wall can be removed more easily. Also, when the top plate is backfilled, the circular beam is removed, and the column is cut at a position corresponding to the upper end of the top plate, so that the top plate can be easily removed after backfilling. Can do.
[0028]
Moreover, according to the construction method of the caisson upper end portion according to the present invention , before refilling the top plate, the column is cut at a position corresponding to the upper end portion of the top plate, and the upper end portion of the column and the column The part below the cutting position is fastened with bolts, and after the backfilling on the top plate is completed, the bolts are released and the pillars are pulled out. The pillar can be removed after cutting and backfilling. Moreover, since it can hold | maintain in the state stood with the volt | bolt after cut | disconnecting a pillar, for example, since the temporary earth retaining wall upper part state in which it was joined to the support work can be supported, earth retaining with a temporary earth retaining wall can be performed. it can.
[Brief description of the drawings]
FIG. 1 is a side view of an upper end portion of an open caisson as an example to which the present invention is applied.
FIG. 2 is an enlarged view of a portion A in the drawing at the upper end portion of the open caisson in FIG. 1;
3 is a top view of the upper end portion of the open caisson in FIG. 1. FIG.
4 is a partially enlarged view of a top view of the upper end portion of the open caisson in FIG. 3;
FIG. 5 is a schematic side view of the upper end portion of the open caisson showing the construction sequence of the upper end portion of the open caisson.
FIG. 6 is a schematic side view showing the state of the open caisson after completion of the construction of the upper end portion.
[Explanation of symbols]
1 Caisson 2 H beam 3 Ring beam 4 Temporary earth retaining wall 5 Earth retaining wall lower part 6 Earth retaining wall upper part 8 Top plate 10 Bolt

Claims (3)

By the caisson method that includes the step of excavating the caisson and sinking the caisson, the position of the upper end of the caisson installed below the ground surface is set below the ground surface and the top provided at the upper end It has a structure where the top of the plate is backfilled ,
A temporary earth retaining wall having a cylindrical shape substantially the same as the caisson and separable into a plurality of pieces is provided on the caisson so as to reach the ground surface from the upper end of the caisson that is submerged below the ground surface. ,
In the temporary earth retaining wall, said after providing the top plate to the caisson upper end, the construction method of the caisson upper end with backfill on the top plate to be removed by dividing the temporary earth retaining wall above the top plate Because
The temporary earth retaining wall is provided on the earth retaining wall lower part to be a formwork of the outer peripheral part of the top plate when the concrete is placed and the top plate is provided, and on the earth retaining wall lower part, the earth retaining wall It has a retaining wall upper part that is removable from the lower part and can be divided into a plurality of parts,
The caisson upper end construction method characterized in that when the top plate is backfilled, the separable earth retaining wall upper part is divided and removed . In construction methods caissons upper portion of claim 1 Symbol placement,
The temporary soil is a support structure comprising an annular beam provided along the circumferential direction on the inner peripheral side of the temporary earth retaining wall and a column extending vertically along the inner circumference of the temporary earth retaining wall. The retaining beam is supported, and the annular beam is removed when the top plate is refilled, and the column is cut at a position corresponding to the upper end portion of the top plate to remove the column. The caisson top end construction method. In construction methods caisson upper end of claim 2 Symbol placement,
When removing the column of the support, before performing backfilling on the top plate, the column is cut at a position corresponding to the upper end portion of the top plate, and at the time of cutting, the upper end portion of the column and the column are cut. Fasten the part below the position with bolts,
A caisson upper end construction method characterized by releasing the fastening of the bolt from the upper end side of the column and then pulling out the column after backfilling the top plate.

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