JP5021049B2 - Reaction device for bottom plate and method for constructing bottom plate - Google Patents

Description

The present invention relates to a reaction device for a bottom board of a caisson box and a construction method of the bottom board .

  Among the caisson works currently being constructed, excavation under the blade edge is sometimes difficult as a problem in the construction of the open caisson method (including the open caisson as well as the press-fitting caisson). In particular, excavation under the cutting edge becomes even more difficult on hard soils based on clay soil.

As a countermeasure, for example, in Japanese Patent Application Laid-Open No. 2000-319897 (Patent Document 1), a rail guide is fixed to the inner circumference in the vicinity of the caisson's edge, and the carriage is turned along the rail. Proposals have been made to provide a rotary excavator body such as an auger screw that excavates the ground near the blade opening. In this case, the reaction force accompanying excavation is received by the caisson via the excavator and further the rail.
JP 2000-319897 A

  On the other hand, in the open caisson method, it is difficult to bond the reinforcing material (rebar, steel frame, etc.) in the bottom board to the caisson box underwater when placing the underwater concrete after the caisson is set up. For this reason, usually, the bottom plate often has an unreinforced structure without a reinforcing material. In this case, it is necessary to place a large amount of underwater concrete in order to counter the elevation pressure acting on the bottom plate, and there is a problem that the increase in the bottom plate thickness causes a decrease in space volume, an increase in excavation depth, and the like.

The present invention aims to solve the above problems .

In order to achieve the above object, the present invention provides a reaction force device for a bottom board, which is provided at the bottom of a caisson box buried in the ground and reinforced with a reinforcing material, and includes a caisson box and a bottom board . A female member provided on either side, a male member provided on the other side, insertable into the female member and having a stepped portion, and a retaining mechanism for restricting the male member inserted into the female member from coming off A retaining mechanism is swingably attached to the female member, restricts the male member from coming out of the female member by engaging with the stepped portion of the male member, and is engaged with the stepped portion of the male member. It has an engaging member that is always elastically biased in the mating direction, and is characterized in that the unitized reinforcing material is coupled to a male member or a female member provided on the bottom plate .

Further, the present invention is a method for constructing a bottom plate reinforced with a reinforcing material, wherein a female member is provided in one of the caisson box and the reinforcing material in a unit, and the female member is provided on the other side. A male member that can be inserted and has a stepped portion is provided, the female member is restricted from being pulled out of the female member by engaging with the stepped portion of the male member, and is engaged with the stepped portion of the male member. A male member in which an engaging member that is always elastically biased in the mating direction is provided so as to be swingable, and after the caisson box is set, the unitized reinforcing material is provided in the reinforcing material inside the caisson box. Alternatively, the male member is inserted together with the female member, the male member is inserted into the female member while the male member is spread, and the engaging member is engaged with the stepped portion of the male member. To construct the bottom board.

If it is the above invention, it will become possible to receive the reaction force (elevation pressure) which arises in the baseboard which becomes a reaction force generation side with a caisson box with a simple structure. Further, since the male member can be inserted into the female member, in a reinforcing material in which a unit, a male member or a female member attached to the reinforcing member by making the hanging inside the caisson box making body, the male member female member The reinforcing material can be installed at a specified position by inserting it into the cable . Furthermore, since the male member inserted into the female member has a retaining mechanism for restricting the male member from being pulled out, the male member may come out of the female member after the male member is inserted into the female member regardless of the direction of reaction force. Absent. Therefore, it is possible to set it at a predetermined position and to couple it to the caisson box simply by suspending the reinforcing material . In addition, after the set, the stopper prevents the reinforcement from being pulled upward, so that a high resistance can be obtained against the elevation pressure acting on the bottom plate, thereby making the bottom plate reinforced. Is possible.

According to the present invention as described above, in addition to the insertable male member against the female member, the recess-projection engaging, by providing a stopper mechanism for restricting the exit of the male member inserted into the female member, the reaction force The caisson box can receive reaction forces in any direction generated on the generation side (including cases where the reaction force is parallel to the insertion direction of the male member). Therefore, the reinforcing material of the bottom plate can be integrated with the caisson box to ensure high bottom plate strength , and the construction cost can be suppressed.

  Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 1A is a cross-sectional view showing an example in which the reaction force device is applied to the open caisson method as a reference example, and FIG. 1B is an enlarged cross-sectional view of a portion X in FIG.

  The caisson box 1 as a structure has an arbitrarily-shaped cylindrical shape with both ends opened, and a tapered surface 1a is formed at the blade edge as shown in FIG. The caisson box 1 is submerged in the ground by a combination of excavation of the internal ground and the pressure input of the jack 3 anchored in the ground. The internal ground is excavated by excavating the central portion with various excavating means (not shown) such as clamshell buckets and excavating directly below the blade edge with an excavator 5 installed on the wall surface of the caisson box 1. Is called.

  On the inner periphery of the blade edge of the caisson box 1, a guide rail 9 is installed in a circular shape via a reaction force device 7 described later. On the guide rail 9, the roller 5 a 1 of the cart 5 a of the excavator 5 rolls, so that the cart 5 a is movable while being supported by the guide rail 9. The cart 5a is guided by the guide rail 9 and moves around the inner wall of the box 1 by being driven by the output of a motor (not shown) or by being pulled from the ground side via a wire (not shown). Of course, the shape of the guide rail 9 is not limited to the illustrated example, and various shapes can be selected.

  An excavator main body 5b having an excavating part 5b1 such as an auger cutter so as to be swingable is attached to the carriage 5a. As the excavator body 5b, excavators having various configurations can be used in addition to the auger cutter, and for example, backhoes, water jets, and the like can also be used. Since excavation by the excavator 5 is normally performed in water, the excavator 5 needs to have sufficient water pressure resistance.

  As shown in FIG. 1B, the reaction force device 7 of the present invention includes a female member 71 and a male member 72 that can be inserted into and removed from the female member 71 in the vertical direction. In the present embodiment, a perforated member having a plurality of holes 71 a is illustrated as the female member 71, and a pin that can be inserted into and removed from the hole 71 a is illustrated as the male member 71. A part of the perforated member 71 is fixed by being embedded in the caisson box 1, and the pin 72 is fixed to the back surface of the guide rail 9 via an appropriate bracket 73.

  The shape of the perforated member 71 is not particularly limited as long as the perforated member 71 can be securely fixed to the caisson box 1 and the hole 71 a with the axis oriented in the vertical direction is formed inside the box 1. In FIG. 2 (A), as an example, holes 71a are formed in a plurality of locations (two locations in the drawing) of the plate member with anchors, and the anchor portions are embedded in the box 1 and the plate portions are boxed. The structure protruded inside the body 1 is illustrated.

  The perforated member 71 is installed at a plurality of locations on the inner wall of the box 1 over substantially the entire circumference, whereby a plurality of holes 71 a are arranged along the entire inner wall of the box 1. By arranging the perforated members 17 not only in the circumferential direction of the box 1 but also in the height direction of the box 1, a plurality of holes 71 a may be formed in the height direction. In FIG. 2A, the perforated member 71 that is continuously installed is illustrated without providing a gap between the adjacent perforated members 71, but a gap may be provided between the adjacent perforated members 71.

  The pin 72 has a cylindrical shape with a tip formed in a tapered shape so as to enhance the insertability into the hole 71a, and is fixed to the bracket 73 with its central axis directed in the vertical direction. The outer diameter dimension of the pin 72 is a dimension that can be smoothly inserted into and removed from the hole 71 a of the perforated member 71. As shown in FIG. 2A, the rail 9 is divided into a plurality of segments 9a, and a pin 72 is attached to each rail segment 9a via a bracket 73. The number of pins 72 attached to each rail segment 9a is preferably two or more.

  FIG. 2B shows another embodiment of the perforated member 71. The perforated member 71 is formed by bending one end of a steel bar into a ring shape to form a hole 71a and forming the anchor embedded in the box 1 at the other end. Similarly, the perforated members 71 are also installed at a plurality of locations in the circumferential direction of the caisson box 1 and further at a plurality of locations in the height direction as necessary. The perforated member 71 shown in FIG. 2B can be used in combination with the perforated member 71 shown in FIG.

  The caisson box 1 is excavated and sunk using the pressure input of the jack 3 after the perforated member 71 is previously attached to the inner wall on the ground. When the cutting edge of the caisson box 1 hits the hard ground and excavation directly below the cutting edge is required, the excavator 5 is installed. In this installation, as shown in FIGS. 1A and 1B, first, the rail segment 9a is suspended by the wire 8, and the pin 72 of each segment 9a is inserted into the hole 71a of the perforated member 71. At this time, in order to smoothly insert the pin 72 into the hole 71a, a wire (guide wire) (not shown) is inserted into the hole 71a in advance and both ends thereof are pulled out to the ground, and one end of the guide wire is attached to the tip of the pin 72. In this state, it is desirable to lower the segment 9a by pulling the other end of the guide wire. In this manner, each segment 9a is suspended in sequence, and the pin 72 is inserted into the hole 71a of the perforated member 71, whereby the rail 9 continuous along the inner wall of the box 1 is formed. Thereafter, the excavator 5 including the carriage 5 a and the main body 5 b is suspended by the wire 6 and set on the rail 9, and excavation immediately below the blade edge is performed while moving on the rail 9. After installation, as shown in FIGS. 1A and 1B, the excavator 5 is suspended by the wire 6 and the rail segments 9a are suspended by the wire 8 at fixed positions in the height direction.

  During excavation immediately below the blade edge by the excavator 5, an oblique reaction force P acts on the excavator main body 5b according to the inclination angle of the excavation part 5b1 as shown by the arrow in FIG. Since the pin 72 is strongly pressed against the inner periphery of the hole 71a by the reaction force P in the oblique direction, the pin 72 does not come out of the hole 71a by the reaction force P, and the excavator 5 that is the reaction force generation source, and further the rail 9 is held in place in the height direction. After the excavation, the excavator 5 can be recovered by pulling the wire 6 upward with a crane or the like installed on the ground, and the pin 72 is opened by pulling the wire 8 upward with the crane or the like. The rail 9 can be recovered by escaping from 71a. In this way, when excavation directly below the blade edge is not necessary, not only the excavator 5 but also the rail 9 can be removed, so that no excavation failure is caused by the rail fixed to the inner wall as in the conventional construction method.

  Even if the caisson box 1 naturally sinks during excavation by the excavator 5, the height positions of the excavator 5 suspended by the wire 6 and the guide rail 9 suspended by the wire 8 do not change. Therefore, as the caisson box 1 naturally subsides, the pin 72 is allowed to naturally escape from the hole 71a, whereby the guide rail 9 and the excavator 5 can be separated from the caisson box 1. Therefore, damage to the guide rail 9 and the excavator 5 due to collision with the ground can be prevented. At the same time that the natural settlement is detected, the wires 6 and 8 may be wound up to pull the guide rail 8 and the excavator 5 upward.

FIG. 3 shows another configuration example of the reaction force device 7. In this configuration , the female member 71 and the male member 72 are extended along the inner wall, and a groove 71b along the inner wall is formed in a portion of the female member 71 protruding inside the box 1, and the male member 72 is provided with the female member 71. A protrusion 72b that can be inserted into and removed from the groove 71b is formed.

In this configuration example , the case where the frame body 11 is fixed to the male member 72 and guided by a guide rail (not shown) provided in the frame body 11 and the excavator 5 is moved around is illustrated. . The frame body 11 is configured as a multiple frame body in which the frame bodies are sequentially arranged on the inside thereof, and each frame body can be moved in different directions (for example, the outer frame can be moved in the circumferential direction, and the inner frame can be moved to the outer frame In contrast, the excavator 5 arranged in the innermost frame can be moved in the three-dimensional direction. In addition, the guide rail 9 may be fixed to the male member 72 similarly to the configuration example shown in FIGS. 1A and 1B without using the frame body 11.

  4 (A) and 4 (B), the frame 11 is arranged between one opposing inner wall of the caisson box 1, and the reaction force device 7 is interposed between both ends and the other opposing inner wall. This is an example in which the frame 11 is attached to the box 1. A guide rail (not shown) is disposed in the frame body 11, and the excavator 5 is movable in the circumferential direction along the box body wall by being guided by the guide rail. Similarly to the above, the excavator 5 may be movable in the three-dimensional direction by configuring the frame 11 with a multiple frame.

In the configuration example shown in FIGS. 4A and 4B, instead of the reaction force device 7 or in combination with the reaction force device 7, a jack or the like is provided between both ends of the frame 11 and the wall of the box facing the frame 11. If the pressure bearing means is arranged, the frame body 11 can hold a higher support reaction force. Therefore, even when a rock or the like appears just below the blade edge, it can be excavated by the excavator 5. It becomes.

FIGS. 5A and 5B show the structure of the reaction force device according to the present invention, and FIG. 5B is an enlarged cross-sectional view of a Y portion in FIG.

  As shown in FIG. 5 (B), the reaction force device 7 ′ can only insert the pin 72 into the hole 71 a of the perforated member 71, and its escape is restricted by the retaining mechanism 19. Different from the reaction force device 7 shown in FIGS. The retaining mechanism 19 is a mechanism for retaining the pin by engaging a member provided on one of the perforated member 71 and the pin 72 with the other member. In the illustrated example, the step 72 a is provided on the pin 72. And a structure in which the engaging member 19a engaged with the stepped portion 72a from above is attached to the perforated member 71 is illustrated. The engaging member 19a can swing between a broken line position and a solid line position, and is always urged in a closing direction (solid line position) by an elastic member (not shown). Accordingly, when the pin 72 is inserted into the hole 71a of the perforated member 71 from above, the engaging member 19a is pushed and expanded to the position of the broken line by the tapered surface of the tip of the pin 72, and at the same time the stepped portion 72a passes through the engaging member 19a. The joint member 19a closes elastically and engages with the stepped portion 72a in the vertical direction. Therefore, an upward reaction force acting on the pin 72 can be received by the caisson box 1.

  In this way, the engaging member 19a is installed on the perforated member 71 side and engaged with the pin 72, and a member having the same function as the engaging member 19a is installed on the pin 72 side. And the pin 72 can be engaged with each other in the pulling direction.

  As shown in FIG. 5A, the reaction force device 7 'can be used as a reaction force receiver for the reinforcing member 17 in the bottom plate 1d when the bottom plate 1d of the caisson box 1 is constructed. The reinforcing member 17 is a unit in which a large number of reinforcing bars 17b (which may be steel frames) are assembled as shown in FIG. 5B, and pins 72 are attached to end plates 17a at both ends via brackets 73. The reinforcing member 17 is suspended inside the caisson box 1 in the same manner as described above, the pin 72 is inserted into the hole 71a, and the pin 72 is locked by the retaining mechanism 19, and then the underwater concrete is placed. The bottom board 1d is constructed. Note that the reinforcing material 17 can be stacked in a plurality of stages in the height direction.

  After the construction of the bottom plate 1c, the reinforcing member 17 receives the back pressure and becomes the reaction force generating side, but this upward reaction force is received by the box 1 through the reaction force device 7 '. Accordingly, it is possible to apply a countering force against the elevation pressure to the reinforcing member 17, and thereby it is possible to construct the bottom board 1 c having a sufficient strength even with a small amount of concrete. Therefore, the amount of underwater concrete can be greatly reduced, and the construction cost of the open caisson method can be greatly reduced in combination with the reduction of the excavation depth.

  When the reinforcing member 17 is used for the long-span caisson box 1, as shown in FIG. 6, a jack 21 having an anchor in the ground is installed at an intermediate portion of the reinforcing member 17. desirable.

FIG. 7 shows a construction method for suppressing the initial natural settlement of the caisson box 1 as a reference example , and is particularly suitable for the setting work on the super soft ground. The caisson box 1 in this construction method has a double structure comprising an inner box 1b and an outer box 1c, and the inner space of the inner box 1b is closed by a lid 23. A jack 25 is installed on the lid 23, and its anchor is attached to the box 1 via a reaction force device 7 'shown in FIG.

  In this method, oversinking control is performed by moving the lid 23 up and down by driving the jack 25 while excavating the ground in the space between the inner box 1b and the outer box 1c. A pin 72 shown in FIG. 5B is attached to the tip of the anchor 25a of the jack 25. The pin 72 is inserted into the hole 71a of the perforated member 71 attached to the inner box 1b, and the pin 72 is removed by the retaining mechanism 19. By restricting the slipping off, the support reaction force of the jack 25 can be received by the caisson box 1 via the reaction force device 7 '.

  In this case, after the caisson box 1 sinks to a predetermined depth, the lid body 23 and the jack 25 are removed and the bottom base concrete work is performed, but even in that case, as in the case shown in FIG. The reaction force device 7 ′ remaining in the box 1 b can be reused as a reaction force receiver for the reinforcing member 17. Thereby, reinforcement of bottom board 1d is attained and construction cost can be controlled through reduction of the amount of underwater concrete used.

  The present invention is not limited to the open caisson described above, but can be applied as a reaction force device for any structure embedded in the ground.

  In addition, the reaction force devices 7 and 7 ′ described above are not only the reaction force generated by the excavator 5, the reinforcing material 17, and the jack 25, but also the reaction force generated by other members and devices arranged in the box 1. You can also receive. For example, the reaction force device 7 ′ shown in FIG. 5B can receive the reaction force of the geological surveying machine. In this case, since the geological surveying machine is installed closer to the excavated ground, this is connected to the caisson. Compared to the case where the box is installed on the ground side opening, a more accurate measurement value can be obtained.

(A) The figure is sectional drawing which shows the caisson setting process using a reaction force apparatus , (B) figure is sectional drawing which expanded the X section in (A) figure. FIG. 1A is a plan view of FIG. 1B viewed from above, and FIG. 1B is a plan view showing another configuration example of the female member 71. FIG. (A) The figure is a perspective view which shows the other structural example of a reaction force apparatus, (B) The figure is a longitudinal cross-sectional view which shows the set-up process which uses the said reaction force apparatus, (C) The figure is in (B) figure It is a cc line sectional view. (A) The figure is a longitudinal cross-sectional view which shows the other example of the excavation process just under a blade edge, (B) The figure is the top view. (A) The figure is a longitudinal cross-sectional view of the caisson laid by using the reaction force device of the present invention, and (B) is an enlarged cross-sectional view of the Y part in (A). (A) A figure is a longitudinal cross-sectional view of the caisson sunk using the reaction force apparatus of this invention. (A) is a longitudinal cross-sectional view which shows the other example of the setting process using the reaction force apparatus of this invention.

1 Caisson box (structure)
3 Jack 7 Reaction force device 17 Reinforcement material 19 Retaining mechanism 23 Lid body 25 Jack 71 Perforated member (female member)
71a hole 72 pin (male member)
73 Bracket

Claims (2)

It is a reaction force device for a bottom panel provided at the bottom of a caisson box buried in the ground and reinforced with a reinforcing material,
A female member provided on any one of the caisson box and the unitized reinforcing member , a male member provided on the other, insertable into the female member, and having a stepped portion, and a female member And a retaining mechanism for restricting the male member inserted in the
A retaining mechanism is swingably attached to the female member, restricts the male member from coming out of the female member by engaging with the male member step, and is always in the direction of engagement with the male member step. A reaction device for a bottom board, characterized by having an engaging member elastically biased. A method of constructing a bottom plate reinforced with a reinforcing material,
Provided with a either one female member of the caisson a box body and unitized said reinforcing member, on the other, can be inserted with respect to the female member, and a male member having a stepped portion is provided,
An engaging member that restricts the male member from coming out of the female member by engaging with the female member stepped portion and is always elastically biased in the engaging direction with the male member stepped portion. Provided so that it can swing,
After the caisson box is laid, the unitized reinforcing material is placed inside the caisson box together with the male member or the female member provided on the reinforcing material, and the male member is moved to the female while the engaging member is spread with the male member. After inserting into the member and engaging the engaging member with the step of the male member,
A method for constructing a bottom plate, comprising constructing a bottom plate by placing underwater concrete in a caisson box.

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