JP2011241606A - Caisson sinking method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for forming a skeleton structure caisson, which can sink by own weight depending on excavation of ground under the inside of the caisson, on a ground and making the same to stably sink by the excavation, upon structuring an underground structure.SOLUTION: In a caisson sinking method, a suitable spacing is provided between a ground wall surface formed by the outermost peripheral part of a leading blade in a lower part of a caisson and an outer peripheral surface of the caisson (a caisson forming form, a caisson wall concrete surface, or a protective layer surface formed on the caisson wall concrete surface), and an aggregate layer is formed in the spacing to decrease friction when the caisson is sinking. Accordingly, the caisson sinks stably by its own weight.

Description

The present invention relates to a case where a caisson (surrounding wall) for an underground structure such as a basement or an underground water tank constructed on the ground is excavated on the ground surrounded by the caisson (surrounding wall) for an underground structure and is submerged under its own weight. This is related to the construction method of self-sink caisson for underground structures.

Conventionally, there is a so-called submersible construction method for constructing an underground structure consisting of a basement, an underground water tank, etc. in the basement. The submersible construction method is a method in which the caisson (surrounding wall) for underground structures built on the ground is submerged in the underground. The construction method involves submerging the underground structure in water and the inside surrounded by the caisson for the underground structure (surrounding wall). There is a method in which the caisson (surrounding wall) for underground structures is gradually submerged to the underground by its own weight while excavating the ground. The latter method is performed by an open type of caisson housing structure (peripheral frame shape having no bottom on the inside) in which a leading blade is provided at the lower part.

Many open-type caissons are provided with a caisson (surrounding wall) for an underground structure, and then a so-called submersible construction method in which the caisson is sunk underground. For this reason, the basement of an underground structure is constructed after the caisson (surrounding wall) for underground structures is sunk in the basement. In the construction where an open caisson is submerged by the submerged method, the caisson is produced on the ground. There are various advantages such as the burden of work is greatly reduced, the period is shortened, and the cost is reduced.

For example, in Patent Document 1, “The construction method of an underground structure according to the present invention is to place concrete on a concrete formwork on the ground surface to construct a concrete peripheral wall, and then remove the concrete formwork from the concrete peripheral wall. The excavation of the ground in the inner space of the concrete peripheral wall causes the concrete peripheral wall to sink, and the concrete peripheral wall without the concrete formwork sinks, so that the concrete peripheral wall is easy to handle. "
JP 2001-323435 A

However, the method of Patent Document 1 has a disadvantage in order to stably sink the caisson with its own weight. The ground is ground with a wedge-shaped cutting edge, and the wall surface of the ground is formed. However, the friction with the outer peripheral portion of the caisson is not constant and may cause uneven settlement. The present invention is to solve the problem that friction is not constant in order to prevent such unequal settlement and to stabilize caisson settlement.

In order to solve the above-mentioned problems, the present inventors have conducted intensive research and adopted the following method. That is, the caisson is composed of an outer mold and an inner mold to fill the concrete milk in the caisson that is composed of the outer peripheral wall frame for filling the concrete milk in the basement and forming the concrete wall on the ground. A leading edge with an inverted triangle shape with a sharp point on the lower side is provided over the entire circumference, and concrete is placed between the excavation surface formed by the leading edge, which is a vertical line passing through the outermost edge of the leading edge, and the outer frame panel and inner frame panel of the caisson. After forming, the distance between the outer surface of the outer frame panel of the caisson or the surface of the protective layer in which the outer surface of the outer frame panel is removed and a protective layer for protecting the surface such as waterproofing is formed on the concrete outer surface or the concrete outer surface. It is set to be 20mm to 200mm, and this space reduces the friction when caisson sinks. It is sufficient to form a. The aggregate layer is to prevent resistance when sinking between the excavation surface and the caisson, and the distance value at this time should be in the range of 20 mm to 200 mm. If it is 200 mm or more, the effect of reducing friction becomes too large.

This aggregate layer is fluid and has a caisson outer peripheral surface having a protective layer in which a protective layer is formed on the outer surface of the outer wall panel of the caisson or the outer surface of the concrete with the outer frame panel removed or on the outer surface of the concrete. The concrete outer surface or the outer frame panel of the caisson is removed after the concrete is formed between the outer frame panel of the caisson and the outer frame panel of the caisson and the inner frame panel. What is necessary is just to make it flow into the space | interval between the protective layer surface which formed the protective layer in the concrete outer surface. That is, aggregate flows into the gap between the excavation surface formed by the leading blade and the outer surface of the outer frame panel of the caisson, the outer surface of the concrete surface or the surface of the protective layer formed with the protective layer on the surface of the concrete according to its own weight subsidence. You can do it.

The diameter of the aggregate of the aggregate layer may be 20 mm or less, more preferably 5 mm or less. The thickness of the protective layer may be 0.1 mm to 100 mm, and the protective layer is preferably 0.1 mm to 0.5 mm in the case of a sprayed waterproof layer, and the attached waterproof layer is preferably 0.4 mm to 7 mm. It is. Moreover, in the case of a polystyrene foam, 20 mm-100 mm are suitable.

According to the present invention, when the outer wall is constructed and the weight is subsided by excavating the inner space of the outer wall, the distance between the outer wall of the caisson and the wall of the ground formed by the outermost wall of the leading blade is 20 mm. The thickness is set to 200 mm, an aggregate layer is formed in this portion, and the aggregate is supplied during subsidence, whereby the friction of caisson settlement is reduced and stable caisson subsidence is possible.

The best mode for carrying out the present invention will be described below in detail with reference to the drawings.

FIG. 1 shows an embodiment of the present invention, and is a cross-sectional view showing the relationship between a leading blade, a caisson wall, and the ground to sink. 1 is a leading blade, 2 is a caisson concrete wall, 3 is a caisson concrete inner surface, 4 is a caisson concrete outer surface, and 5 is a protective layer such as waterproofing. Reference numeral 6 denotes a ground which sinks when a caisson with a leading blade excavates the lower inner surface of the caisson, and 10 denotes the excavation surface. 7 is an aggregate (sand, etc.). The presence of this aggregate reduces the friction between the caisson outer peripheral surface (protective layer surface) and the excavation surface, and the caisson with the leading blade can be stably settled by excavation. Here, the diameter of the aggregate may be 20 mm or less, and is optimal if it is 5 mm or less.

Reference numeral 8 denotes a vertical line passing through the outermost peripheral portion of the leading blade, and the excavation surface 10 is formed when the leading blade sinks. Here, since the outermost periphery of the caisson is a protective layer, the width of the outer peripheral portion of the protective layer and the excavation surface, that is, the width of the aggregate layer 9 should be 20 mm to 200 mm in order for the caisson with the leading blade to sink stably. That's fine. Here, there are various protective layers. For example, 0.1 mm to 0.5 mm is suitable for the sprayed waterproof layer, 0.4 mm to 7 mm is suitable for the attached waterproof layer, and 20 mm to 100 mm is suitable for the polystyrene foam.

FIG. 2 shows another embodiment of the present invention, and is a cross-sectional view showing the relationship between the leading blade, the caisson wall, and the ground to sink. 1 is a leading blade, 2 is a caisson concrete wall, 3 is a caisson caisson concrete inner surface, 4 is a caisson concrete outer surface, and 12 is left without being removed even after the outer formwork panel is formed into a concrete caisson. Reference numeral 6 denotes a ground which sinks when a caisson with a leading blade excavates the lower inner surface of the caisson, and 10 denotes the excavation surface. 7 is an aggregate (sand, etc.). The presence of this aggregate reduces the friction between the caisson outer peripheral surface (protective layer surface) and the excavation surface, and the caisson with the leading blade can be stably settled by excavation. Here, the diameter of the aggregate may be 20 mm or less, and is optimal if it is 5 mm or less.

Reference numeral 8 denotes a vertical line passing through the outermost peripheral portion of the leading blade, and the excavation surface 10 is formed when the leading blade sinks. Here, since the outermost periphery of the caisson is the outside of the 12 outer formwork panels, the width of the outer periphery of the outer formwork panel and the excavation surface, that is, the width of the aggregate layer 9 stably sinks the caisson with the leading blade. For this purpose, it is sufficient to be 20 mm to 200 mm.

FIG. 3 shows another embodiment of the present invention, and is a cross-sectional view showing the relationship between the leading blade, the caisson wall, and the ground to sink. 1 is a leading edge, 2 is a caisson concrete wall, 3 is a caisson caisson concrete inner surface, and 4 is a caisson concrete outer surface. Reference numeral 6 denotes a ground which sinks when a caisson with a leading blade excavates the lower inner surface of the caisson, and 10 denotes the excavation surface. 7 is an aggregate (sand, etc.). The presence of this aggregate reduces the friction between the caisson outer peripheral surface (protective layer surface) and the excavation surface, and the caisson with the leading blade can be stably settled by excavation. Here, the diameter of the aggregate may be 20 mm or less, and is optimal if it is 5 mm or less.

Reference numeral 8 denotes a vertical line passing through the outermost peripheral portion of the leading blade, and the excavation surface 10 is formed when the leading blade sinks. Here, since the outermost periphery of the caisson is the outer surface of the caisson concrete of 4, the width of the outer surface of the caisson concrete and the width of the excavation surface, that is, the width of the aggregate layer of 9 starts from 20 mm in order for the caisson with the leading blade to sink stably. What is necessary is just 200 mm.

The preceding blade has the shape of the leading blade corresponding to the gravel layer, but an example in the case of sludge or the like is shown. That is, this is a case where the upper end of the portion rising from the sharp lower end of the leading blade is the outermost peripheral portion of the leading blade. FIG. 4 is a cross-sectional view showing the relationship between the leading blade, the caisson wall, and the ground to sink in that case. 1 is a leading blade, 2 is a caisson concrete wall, 3 is a caisson concrete inner surface, 4 is a caisson concrete outer surface, and 5 is a protective layer such as waterproofing. Reference numeral 6 denotes a ground which sinks when a caisson with a leading blade excavates the lower inner surface of the caisson, and 10 denotes the excavation surface. 7 is an aggregate (sand, etc.). The presence of this aggregate reduces the friction between the caisson outer peripheral surface (protective layer surface) and the excavation surface, and the caisson with the leading blade can be stably settled by excavation. Here, the diameter of the aggregate may be 20 mm or less, and is optimal if it is 5 mm or less.

Reference numeral 8 denotes a vertical line passing through the outermost peripheral portion of the leading blade, and the excavation surface 10 is formed when the leading blade sinks. Here, since the outermost periphery of the caisson is a protective layer, the width of the outer peripheral portion of the protective layer and the excavation surface, that is, the width of the aggregate layer 9 should be 20 mm to 200 mm in order for the caisson with the leading blade to sink stably. That's fine. Here, there are various protective layers. For example, 0.1 mm to 0.5 mm is suitable for the sprayed waterproof layer, 0.4 mm to 7 mm is suitable for the attached waterproof layer, and 20 mm to 100 mm is suitable for the polystyrene foam.

In addition, although the example in which the outermost periphery of the caisson is the protective layer surface is shown here (in the case of sludge, etc.), it is not limited to this, and it is the same as the case of the leading edge shape of the gravel layer. That is, when the outermost periphery of the caisson is outside the outer formwork panel or when the outermost periphery of the caisson is the outer surface of the caisson concrete, the width of the excavation surface and the outer formwork panel or the outer surface of the caisson concrete, that is, the bone The width of the material layer may be 20 mm to 200 mm in order for the leading edge caisson to sink stably.

FIG. 5 shows the mechanism in the case of FIG. 1. Since the caisson smoothly sinks due to excavation, if the aggregate (sand, etc.) is raised on the outer periphery of the caisson, the friction is reduced and the purpose is achieved. The state is shown in FIG. FIG. 5 shows the state of the sinking, and the leading blade at the position 11 sinks to the position 1. Here, 6 is the ground, 2 is the caisson wall, 5 is the caisson outer periphery protective layer, 10 is the excavation surface by the outermost periphery of the leading blade, and 7 is the aggregate layer. Friction is reduced by the presence of the seven aggregate layers, and the caisson sinks smoothly. Reference numeral 8 denotes a vertical line passing through the outermost periphery of the leading blade. The leading blade that was at position 11 represents the movement of sinking to the position of 1 as indicated by 13, and a new aggregate as indicated by 14 between the excavation surface formed by the leading edge outer periphery and the caisson outer periphery protective layer by the sinking. Even if it flows in and sinks, the friction is not particularly increased, and the caisson with the leading blade smoothly sinks by its own weight. The mechanism in the case of FIGS. 2 to 4 is the same.

Relationship between row blade and caisson wall and ground to sink when caisson outermost part is protective layer Relationship between row blade, caisson wall and ground to sink when caisson outermost part is outside outer formwork panel Relations between row blades, caisson walls and subsidence ground when caisson outermost part is caisson concrete outer surface Relationship between row blade, caisson wall and ground to sink when leading edge shape such as sludge and caisson outermost part is protective layer Mechanism that enables smooth settlement

1 Leading blade
2 Caisson concrete wall
3 Caisson concrete inner surface 4 Caisson concrete outer surface
5 Protective layer
6 ground
7 Aggregate (sand, etc.)
8 Vertical line passing through the outermost periphery of the leading blade
9 Width of aggregate layer (20mm ~ 200mm)
10 Excavation surface 11 Position before constant settlement of leading blade 12 Outer formwork panel 13 Movement of caisson and leading blade
14 Aggregate movement

Claims (4)

In the caisson that forms the outer wall of the basement on the ground and sinks its own weight by excavating the inner space of the outer wall, an inverted triangular leading blade is provided around the entire lower end portion of the caisson, and passes through the outermost edge of the leading blade. Excavation surface formed by a leading edge that is a vertical line and the outer surface of the caisson outer frame panel after the concrete is formed between the outer frame panel and the inner frame panel of the caisson or the outer surface of the concrete with the outer frame panel removed Alternatively, an interval between the outer peripheral surface of the caisson having a protective layer formed on the outer surface of the concrete and a caisson outer peripheral surface is set to be 20 mm to 200 mm, and an aggregate layer that reduces friction during caisson subsidence is formed in the gap. Caisson self-weight subsidence method characterized by formation The aggregate layer is an outer surface of the outer frame panel of the caisson or a concrete outer surface with the outer frame panel removed, or a caisson outer peripheral surface having a protective layer formed with a protective layer on the concrete outer surface and a drilling surface by a leading blade Between the excavation surface formed by the leading blade and the outer surface of the outer frame panel of the caisson, the outer surface of the concrete surface or the surface of the protective layer on which the protective layer is formed. The caisson self-weight subsidence construction method according to claim 1, wherein aggregate flows into the gap according to the self-weight subsidence. 3. The caisson self-weight subsidence method according to claim 1, wherein the aggregate layer has an aggregate diameter of 20 mm or less. 3. The caisson self-weight subsidence method according to claim 1, wherein the protective layer has a thickness of 0.1 mm to 100 mm.

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