JP2014125803A - Caisson structure having pressure resisting slab, and construction method for the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pneumatic caisson method capable of suppressing or avoiding the influence of core displacement reaching a caisson even when the core displacement of a bearing pile occurs in the pneumatic caisson method, and a structure constructed by the method.SOLUTION: A caisson method for installing caissons by immersion includes the steps of: installing bearing piles in a ground for supporting the caisson prior to immersion of the caisson; immersing the caisson while excavating in a workroom in a pneumatic state partitioned by bottom slabs of the caisson; arranging first reinforcing-bars in the vicinity of the top face of the workroom and second reinforcing-bars in the vicinity of the underside of the workroom, respectively, so as to extend substantially in the horizontal direction; and placing concrete in the workroom to construct pressure-resisting slabs having the first and second reinforcing-bars and concrete and regulated by the inner surface of the workroom.

Description

  The present invention relates to a pneumatic caisson method and a caisson structure constructed by the method.

  Pneumatic caisson method is mainly a reinforced concrete caisson (box, frame) built on the ground, and an airtight work room is provided at the lower part of the caisson. This is a construction method in which caisson sinks into the ground while excavating and discharging soil in the work chamber, and part or all of it is buried in the ground. The caisson installed in this way is widely used as the foundation of buildings such as pumping stations and bridges, starting piles such as shield tunnels, and tunnel bodies of subways and underground roads.

  There are cases where the caisson is supported by a pile (so-called legged caisson) when the supporting force of the ground where the caisson is installed is insufficient. An example of conventional technology for supporting a pneumatic caisson with a cast-in-place pile is described in Patent Document 1. The technology described in Patent Document 1 is a concrete in which a cast-in-place pile is constructed on the ground where the caisson is installed, and then the caisson is sunk to an appropriate depth by a pneumatic caisson method, and the cast-in-place pile and the caisson are placed in the work chamber. Are combined.

  Another prior art example is described in Patent Document 2. The technology described in Patent Document 2 is a method of constructing a support pile prior to caisson deposition, and then constructing a caisson while excavating a pressurized working chamber partitioned by a bottom slab, In the pneumatic caisson method that integrates the caisson with cast concrete, steel is integrally attached to the ceiling of the work room as a synthetic member before the caisson is set, and the steel is removed from the ceiling of the work room after the caisson is set. It is something to arrange.

  As described in each of the above documents, in the case where the support pile is constructed prior to caisson settling, when the support position of the caisson by the support pile is deep underground, the support pile is originally supported for reasons such as construction. Misalignment (eccentricity) may occur from the position. Moreover, in many cases, whether or not the support pile is actually misaligned can be confirmed only after the caisson is submerged to a predetermined depth and the head of the pile is exposed on the excavation surface.

  When the support pile has misalignment, the support position of the caisson bottom slab by the support pile changes from the planned position. Then, it can be considered that the bending moment and the shearing force generated in the bottom slab of the caisson that is the upper structure also change. If such misalignment is large beyond design assumptions, reconfirm by restructuring whether the caisson bottom slab is strong enough to withstand changes in bending moments and shear forces. Need arises. In that case, when the caisson is submerged to the planned depth, the construction is stopped for reconfirmation work, resulting in a delay in the construction period and extra costs associated therewith. Moreover, even if it turns out that the strength of the caisson is insufficient at that stage, it is extremely difficult to re-lay the caisson bottom plate in order to increase the strength of the caisson that has already sunk. is there.

  Since the technique described in Patent Document 1 is only combined with concrete cast in place and caisson in the working chamber, the concrete itself has no effect on the change in bending moment as described above. The effect on the change in shearing force is limited. Therefore, the technique of Patent Document 1 cannot solve the above problem when it is found that the support pile is misaligned at the depth at which the caisson is scheduled to be laid.

  In the technique described in Patent Document 2, the steel material (3) is removed from the ceiling of the work room after the caisson (1) is set up, and the reinforcement is removed, as is apparent from FIG. The steel material (3) is only installed on the lower side of the working chamber. As shown in FIG. 4, after the concrete (5) is placed, the steel material (3) is a structural reinforcing bar. At best, it can only serve as the lower end muscle. Here, when the bending moment changes due to the misalignment of the support pile (2) as described above, the steel material (3) counters the increase in the bending moment that works to extend the lower surface side of the concrete (5). Although there is a possibility that a force can be exerted, no counter force can be exerted against an increase in bending moment that works to stretch the upper surface side of the concrete (5). Moreover, the said steel material (3) has no effect with respect to a shear force. For this reason, the above-described problems cannot be solved.

JP 54-38608 A Japanese Patent No. 2782274

  Therefore, the object of the present invention is to suppress or avoid the influence of the misalignment reaching the caisson even in the case where the misalignment of the support pile supporting the caisson occurs in the pneumatic caisson method. It is an object of the present invention to provide a pneumatic caisson method and a caisson structure constructed by the method.

As a result of intensive studies in order to solve the above-mentioned problems, the present inventors have arrived at each aspect of the present invention as follows.
That is, the caisson method according to one aspect of the present invention is a caisson method in which a caisson is installed by sinking, and a caisson is installed in the ground before the caisson is set, and a support pile for supporting the caisson is installed. Sunk caisson while excavating a pressurized working chamber partitioned by a bottom slab, and in the working chamber, a first reinforcing bar near the upper surface of the working chamber, a second reinforcing bar near the lower surface, By placing the bars so as to extend in a substantially horizontal direction, and placing concrete in the work chamber, a pressure-resistant plate that has the first and second rebars and concrete and is defined by the inner surface of the work chamber is constructed. And a caisson method.

  According to the above construction method, the first and second reinforcing bars are arranged near the upper surface and the lower surface in the work chamber, respectively. Therefore, the pressure-resistant plate constructed by placing concrete in the work chamber can be a reinforced concrete structure having upper and lower reinforcement bars. Therefore, even if a situation occurs in which the bending moment changes from the planned bending moment (ie, the bending moment assumed when there is no misalignment) due to the misalignment of the support pile, With the pressure plate, it can withstand changes in bending moment. Therefore, even if the misalignment of the support pile is found when the caisson is sunk, etc., it can be handled with a pressure-resistant version, so the trouble of reconfirming whether the caisson has the strength to cope with misalignment can be saved. be able to. As a result, it is possible to avoid construction delays and cost increases due to reconfirmation of the caisson strength. Furthermore, if it is a pressure-resistant plate constructed by the above construction method, it is possible to resist the pile head bending moment generated during an earthquake.

The caisson method according to another aspect of the present invention further includes a step of measuring the degree of misalignment of the support pile.
The caisson method according to another aspect of the present invention further includes a step of changing at least one of the strength and the amount of bar arrangement of at least one of the first and second reinforcing bars in accordance with the degree of misalignment of the support pile. Have.
According to such a configuration, when the misalignment of the support pile is found, for example, when the caisson is sunk, depending on the degree of misalignment, the strength and the bar arrangement of at least one of the first and second reinforcing bars By changing at least one of the quantities, it is possible to construct a pressure plate having a strength that can withstand a change in bending moment. In this way, even when the caisson has already been sunk, it is possible to cope with changes in the bending moment by changing the strength of the pressure plate, so there is no need to change the sunk caisson.

The caisson method according to still another aspect of the present invention includes a step of disposing a shear reinforcement in the working chamber, and the strength and disposition amount of the shear reinforcement according to the degree of misalignment of the support pile. Change at least one.
By setting it as such a structure, since the pressure-resistant plate which has a shear reinforcement material can be constructed | assembled, the pressure-resistant plate can exhibit a bigger resistance force also with respect to a shear force. Furthermore, when the misalignment of the support pile is found when the caisson is sunk, at least one of the strength and the amount of the shear reinforcement can be changed according to the degree of misalignment of the support pile. Therefore, it is possible to construct a pressure-resistant plate having strength that can cope with a change in shearing force due to misalignment.

The caisson method according to still another aspect of the present invention further includes a step of changing the strength of the concrete according to the degree of misalignment of the support pile.
According to such a configuration, when the misalignment of the support pile is found when the caisson is sunk, the strength of the concrete to be placed in the working chamber is changed according to the degree of the misalignment of the support pile. Therefore, the pressure plate can be made to have a strength necessary to cope with a change in shearing force. If necessary, the pressure plate can have a necessary strength by the effects of both the concrete and the shear reinforcement.

  Further, according to still another aspect of the present invention, a range in which the strength and the amount of reinforcing bars of the first reinforcing bar and the second reinforcing bar are changed, a range in which the strength and arrangement amount of the shear reinforcement are changed, and the strength of the concrete The range to change is determined according to the degree of misalignment of the support pile. By adopting such a configuration, when the misalignment of the support pile is found when the caisson is sunk, it is necessary to change the design of the reinforcing bar, shear reinforcement, and concrete according to the degree of misalignment. The range is clarified, and design changes and construction after changes can be easily performed.

Moreover, according to another situation of this invention, the range which arrange | positions a shear reinforcement is determined according to the degree of misalignment of a support pile.
Thereby, when the misalignment of the support pile is found, it is possible to determine the range in which the shear reinforcement material is disposed according to the degree of the misalignment of the support pile, and to arrange the shear reinforcement material only within the range. It can be efficient.

  Further, the caisson method according to still another aspect of the present invention is the amount of change and the range of change of the strength of the first reinforcing bar and the second reinforcing bar and the amount of bar arrangement required depending on the degree of misalignment of the support pile. The method further includes the step of obtaining in advance by simulation the amount and range of change of the strength and arrangement amount of the shear reinforcement, the amount and range of change of the concrete strength, and the range of arrangement of the shear reinforcement. Then, based on the amount of change, the range of change, and the range of arrangement determined by the simulation, the strength and arrangement of the first reinforcing bar and the second reinforcing bar, the amount of reinforcement, and the shear reinforcement according to the degree of misalignment of the support pile The strength and the amount of the material and the strength of the concrete are changed, and the range of those changes and the range of the shear reinforcement material are determined.

  According to such a configuration, the amount of misalignment of the support pile is assumed, and the strength of the first rebar and the second rebar and the amount of rebar arrangement necessary for each assumed misalignment amount are changed. The amount of change and range of change, the amount and range of change in the strength and distribution of shear reinforcement, the amount and range of change in concrete strength, and the range of placement of shear reinforcement are used for structural calculations. Each can be obtained in advance by simulation based on the above. Then, when the caisson has been installed, the misalignment amount is measured at the stage where the misalignment of the support pile is found, and according to the measured misalignment amount, the first rebar or Change the strength and placement of the second reinforcing bar, the strength and placement of the shear reinforcement, and the strength of the concrete, determine the range of those changes and the range of placement of the shear reinforcement, Can do. According to such a method, when the misalignment of the support pile is found, it is not necessary to perform the structural calculation again based on the state in which the design is changed according to the misalignment, and the design is performed based on the result of the simulation performed in advance. Can be changed and the construction can be continued smoothly. In other words, it is not necessary to feed back the state of misalignment of the support pile to the structural calculation and design stage. Therefore, even if the support pile is misaligned, the extension of the construction period can be minimized.

A caisson structure according to still another aspect of the present invention is a caisson installed by sinking, a support pile supporting the caisson, and a pressure-resistant plate made of reinforced concrete installed between the caisson and the support pile. And a pressure-resistant plate having both lower end bars and a caisson structure.
According to the caisson structure having such a configuration, even when the bending moment changes due to the misalignment of the support pile, the pressure resistant plate having both the upper and lower reinforcing bars can withstand changes in the bending moment. be able to. Furthermore, the pressure plate can also resist the pile head bending moment during an earthquake.

According to still another aspect of the present invention, in the caisson structure, the pressure plate further includes a shear reinforcing material.
According to the caisson structure having such a configuration, the pressure plate having the shear reinforcing material can exhibit a greater resistance to the shearing force and changes thereof.

FIG. 1 is a schematic view showing a state in which a support pile is installed prior to caisson settling in the caisson method according to an embodiment of the present invention. FIG. 2 is a partial cross-sectional view showing a state in which the bar arrangement is performed in the caisson work chamber in the caisson method according to the embodiment of the present invention. FIG. 3 is a partial cross-sectional view showing a main part of a caisson structure constructed by a caisson method according to an embodiment of the present invention. FIG. 4 is a horizontal sectional view illustrating the caisson and the support pile of FIG. 2 along a two-dot chain line IV-IV. FIG. 5 is a flowchart showing a procedure for determining and constructing a change amount and a change range of the reinforcing bar strength and bar arrangement amount according to an embodiment of the present invention. FIG. 6 is a partial cross-sectional view showing a main part of a caisson structure constructed by a caisson method according to a modification of one embodiment of the present invention.

Hereinafter, a pneumatic caisson method according to an embodiment of the present invention and a caisson structure constructed by the method will be described with reference to the drawings.
The pneumatic caisson method of this embodiment is to sink a part or all of the caisson in the ground, and the caisson is supported by a support pile installed in the ground. In the construction method of the present embodiment, the support pile 2 is installed in the ground as shown in FIG. 1 prior to the caisson 1 (see FIG. 2). In this example, the support pile 2 is a cast-in-place pile, and the support pile 2 is constructed so that the upper end of the support pile 2 comes to a position where the caisson 1 is to be supported. Since the method of installing or constructing the support pile 2 is known, a detailed description is omitted. Note that the support pile 2 is not limited to a cast-in-place pile, and may be a ready-made pile such as an SC pile or a steel pipe pile.

  When the installation of the support pile 2 is completed, the caisson 1 is sunk as shown in FIG. The caisson 1 of this example is a reinforced concrete box (frame), which is constructed in advance on the ground. An airtight work chamber 11 is provided in the lower part of the caisson 1, and the caisson 1 is moved by digging the ground below the work room 11 while feeding compressed air from the ground into the work room 11 to prevent intrusion of groundwater. I will sink into the ground. Reference numeral 12 in FIG. 2 is a cutting edge of the caisson 1. In FIG. 2, illustrations of peripheral equipment and devices such as a man shaft, a material shaft, a submersible shovel, and an earth and sand bucket are omitted.

  FIG. 2 shows a state in which the caisson 1 has been sunk to the position where it is to be installed, that is, a state in which the caisson 1 has been sunk. In this state, the upper rebar 3 as a structural rebar is installed near the upper surface (that is, the lower surface of the bottom slab of the caisson 1) in the work chamber 11, and the structural rebar is disposed near the lower surface (that is, the excavation surface below the work chamber 11). The lower rebar 4 is installed. Thereafter, concrete is placed inside the work chamber 11 and solidified. Thus, the caisson structure according to the present embodiment is completed. In FIG. 2, the pile head rebar 21 is constructed so as to protrude from the inside of the support pile 2. However, the present invention is not limited to this, and the pile head of the support pile 2 is not protruded. May be constructed so as to protrude into the working chamber. Moreover, you may attach the pile head reinforcement 21 to the location in any one of the pile heads of the support pile 2 later. In particular, when an off-the-shelf pile such as an SC pile or a steel pipe pile is used as the support pile 2, in the case of an SC pile, the pile head rebar 21 may be partially embedded in the upper end of the pile head or welded to the outer periphery. Well, in the case of a steel pipe pile, it may be welded to its inner periphery or outer periphery.

  FIG. 3 shows a main part of the caisson structure according to the present embodiment. As described above, and as shown in FIG. 3, the concrete in which the upper rebar 3 installed near the upper surface of the work chamber 11 and the lower rebar 4 installed near the lower surface are placed in the work chamber 11. 5 covers and the concrete 5 solidifies in that state. As a result, the concrete 5 and the reinforcing bars 3 and 4 become a reinforced concrete structure defined by the inner surface of the work chamber 11. The reinforced concrete structure including the concrete 5 and the reinforcing bars 3 and 4 is constructed as a pressure-resistant version of the caisson structure according to the present embodiment, as will be described in detail later. Since the concrete 5 also covers the pile head of the support pile 2, the pressure plate and the support pile 2 are firmly integrated.

  The upper reinforcing bar 3 is arranged near the upper surface of the working chamber 11 so as to extend in a substantially horizontal direction, and the lower reinforcing bar 4 is arranged near the lower surface of the working chamber 11 so as to extend in a substantially horizontal direction. . In the example of FIG. 3, the upper reinforcing bar 3 and the lower reinforcing bar 4 are arranged in a grid pattern in the horizontal direction, and are arranged so as to cover all the support piles 2 and the range between them from above. . In FIGS. 2 and 3, illustration of assembly bars and assembly joints for assembling reinforcing bars is omitted. For example, in the example of FIG. 3, the upper rebar 3 and the lower rebar 4 are welded or assembled to the pile head rebar 21 of the support pile 2 so that the upper rebar 3 and the lower rebar 4 are in the air in the work chamber 11. May be held.

  The pressure-resistant plate composed of the concrete 5 and the reinforcing bars 3 and 4 according to this embodiment is constructed as a reinforced concrete structure having the upper reinforcing bar 3 as an upper reinforcing bar and the lower reinforcing bar 4 as a lower reinforcing bar. Therefore, the pressure plate can exhibit a resistance against a bending moment generated inside. That is, the upper rebar 3 as the upper rebar can exert a resistance against the bending moment that acts to stretch the upper surface side of the pressure plate. On the other hand, the lower reinforcing bar 4 as the lower reinforcing bar can exert a resistance against the bending moment that acts to extend the lower surface side of the pressure-resistant plate.

  Therefore, even if the bending moment generated in the superstructure is changed from the planned bending moment (that is, the bending moment assumed when there is no misalignment) due to the misalignment of the support pile 2, the pressure plate Thus, the change can be countered, and further, the influence of the misalignment of the support pile 2 can be suppressed or avoided to the caisson 1 which is the upper structure. In particular, even if it is found for the first time when the caisson 1 is settled that the support pile 2 is misaligned, the method of this embodiment is effective by changing the bar arrangement of the pressure plate. It can correspond to. This will be described with reference to FIG.

FIG. 4 is a horizontal sectional view showing the caisson 1 and the support pile 2 of FIG. 2 along a two-dot chain line IV-IV. When the caisson 1 is sunk to the expected depth in this way, one support pile 2 indicated by “I” in the figure is shown in the horizontal direction (X direction) as indicated by the arrow a in FIG. )) Is assumed to be misaligned.
In that case, the space | interval of the support pile 2 of "I" and the support pile 2 shown by "U" on the opposite side to a shift | offset | difference direction will spread. Then, in the area between the support pile 2 of “I” and the support pile 2 of “U” and the periphery thereof, the bending moment changes relatively greatly, and the bending moment is locally planned (that is, It is conceivable that the bending moment is greater than that assumed when there is no misalignment. Therefore, the upper reinforcing bar 3 and the lower reinforcing bar 4 in the area indicated by b in the figure, which is the area between the supporting pile 2 of “I” and the supporting pile 2 of “U” and the surrounding area thereof, have higher strength. By using a high reinforcing bar (for example, a reinforcing bar with a large diameter) or increasing the amount of bar arrangement, the bending moment can be changed.

  Here, the region b is, for example, in the X direction, which is the direction in which the misalignment has occurred, with reference to the design span between the support piles 2 to the support pile 2 of “D” in the figure. Up to 3 spans (that is, the span between the support piles 2 with wide spacing and the total length of one span on each side in the spread direction), and perpendicular to the X and horizontal directions It can be an area having a length of one span in a certain Y direction. When a plurality of support piles 2 are misaligned, the entire region where the reinforcing bar strength or the amount of bar arrangement is changed is overlapped by overlapping a plurality of regions determined in the above manner for each support pile 2. Just decide.

  In this way, when the caisson 1 is sunk and the misalignment of the support pile 2 is found, the strength and the amount of reinforcement of the upper rebar 3 and the lower rebar 4 are changed, so that the strength to withstand the bending moment change can be obtained. It is possible to build a pressure plate with. Therefore, it is possible to suppress or avoid the influence of the misalignment of the support pile 2 up to the caisson 1. Therefore, as in the prior art, when the misalignment of the support pile is found after the caisson 1 is settled, whether the strength of the bottom slab of the caisson 1 can cope with the misalignment is determined again. There is no need to reconfirm by calculation. Further, when it is determined that the bottom plate of the caisson 1 does not have the strength that can cope with the misalignment, the work of increasing the strength of the caisson 1 (for example, the work of adding the bottom rebar 13 by rolling the bottom plate of the caisson 1) Etc.).

  In addition, as a method of changing the strength and the amount of bar arrangement of the upper reinforcing bar 3 and the lower reinforcing bar 4, depending on the amount of misalignment at the stage where the misalignment of the support pile 2 is found when the caisson 1 is subsidized. The necessary amount for changing the strength and the amount of bar arrangement of the upper reinforcing bar 3 and the lower reinforcing bar 4 may be calculated. For example, when the misalignment of the support pile 2 of “I” in FIG. 4 exceeds a predetermined amount (for example, 100 mm), the amount of reinforcing bar in the region b is changed as the amount of reinforcing bar strength or the amount of bar arrangement. The diameter can be set to a predetermined multiple (for example, 1.5 times), or the bar arrangement amount per unit area can be set to a predetermined multiple (for example, two times). When increasing the amount of reinforcing bars, the diameter of the reinforcing bars to be added is not necessarily the same as the diameter of the original reinforcing bars 3 and 4 as long as the required strength can be exhibited. Moreover, you may make it enlarge or reduce the area | region b (refer FIG. 4) which changes the intensity | strength and the amount of reinforcement of the upper reinforcing bar 3 and the lower reinforcing bar 4 according to the degree of misalignment. Moreover, the amount and range which change the intensity | strength and the amount of reinforcement of the upper reinforcement 3 and the lower reinforcement 4 may differ between the upper reinforcement 3 and the lower reinforcement 4 as needed.

  Or, as shown in the flowchart of FIG. 5, first, various amounts of misalignment are assumed, and the amount of change in the reinforcing bar strength and the amount of bar arrangement required for each misalignment amount, and the change are changed. Necessary ranges may be obtained in advance by simulation based on structure calculation (step S1). The amount and range of change of the reinforcing bar strength and the amount of reinforcement obtained here are created and retained as, for example, a reinforcement arrangement specification (for example, a tabular specification) associated with the amount of misalignment. It is desirable to keep it. Next, the amount of misalignment is measured at the stage where the misalignment of the support pile 2 is found, for example, when the caisson 1 is completely set (step S2). If possible, the amount of misalignment may be measured before the caisson 1 is completed.

  Next, in accordance with the measured amount of misalignment, the reinforcing bar strength and the amount of change in the reinforcing bar amount determined in step S1 and the range of the change (for example, based on the above bar arrangement changing specification), the reinforcing bar strength Then, the amount of change of the bar arrangement amount and the range of the change are determined, and the construction is performed (step 3). According to this method, there is no need to perform structural calculation again based on the state in which the bar arrangement is changed according to the misalignment of the support pile 2, and for example, the bar arrangement is changed based on the bar arrangement change specification at the construction site. Since it can be done, construction can be continued smoothly. That is, there is no need to feed back the misalignment of the support pile 2 to the structural calculation and design stage. Therefore, even if the support pile 2 is misaligned, the extension of the work period can be minimized.

(Modification)
Next, a modification of the above embodiment will be described with reference to FIG. In the pneumatic caisson method according to the modified example, the shear reinforcing material 6 is further disposed in the work chamber 11, and the pressure plate constructed by the method is the same as the pressure plate of the above embodiment. It will have. By carrying out like this, the pressure-resistant plate which consists of the concrete 5, the reinforcing bars 3, 4, and the shear reinforcement 6 can exhibit a bigger resistance force also with respect to a shear force. Therefore, even if a situation occurs in which the shearing force in the upper structure changes due to the misalignment of the support pile 2, it is possible to provide a pressure-resistant plate that can resist the change.
In the example of FIG. 6, a shear reinforcing bar as the shear reinforcement 6 is installed in the work chamber 11 in a substantially vertical direction. The shear reinforcing material 6 is not limited to this, and other steel materials such as carbon fiber, steel bar, and steel plate can be used. Further, the installation method is not limited to the one in which the shear reinforcement member 6 is installed in a substantially vertical direction as shown in FIG. 6, and the installation method can be appropriately selected, for example, in the oblique direction as long as the function as the shear reinforcement member can be exhibited.

  In addition, when the misalignment of the support pile 2 is found, the strength and the disposition amount of the shear reinforcement 6 may be changed according to the degree of misalignment of the support pile 2. Accordingly, a range for changing them may be determined. Referring to the example of FIG. 4, when misalignment occurs in the support pile 2 of “I” (see arrow “a”), the range between the support pile 2 of “I” and the support pile 2 of “U” and its surroundings , There is a relatively large change in the shear force in the superstructure, and it is considered that the shear force is locally greater than what was planned (that is, the shear force assumed when there is no misalignment). . Therefore, by increasing the strength and arrangement amount of the shear reinforcement 6 in the range between the support pile 2 of “I” and the support pile 2 of “U” and the periphery (for example, in the region b), the pressure plate Can withstand changes in shear force. As a result, it is possible to suppress or avoid the influence of the misalignment of the support pile 2 reaching the caisson 1. The amount and range of change of the strength and arrangement amount of the shear reinforcement member 6 may also be determined and applied by the same method as described with reference to the flowchart of FIG.

  As yet another modification, when the pressure plate is designed so that the shear reinforcement 6 is not used if there is no misalignment of the support pile 2, the misalignment of the support pile 2 is larger than a predetermined amount. The shear reinforcement material 6 may be additionally installed at the stage where it has been found. In this case, the range in which the shear reinforcement material 6 is disposed may be determined according to the degree of misalignment of the support pile 2. In the example of FIG. 4, for example, the shear reinforcement material 6 is disposed only in the region b. You may make it install. In that case, by using a method similar to the method described with reference to the flowchart of FIG. 5, the range of arrangement of the shear reinforcement 6 required according to the degree of misalignment of the support pile 2 is obtained in advance by simulation, At the stage where the misalignment of the support pile 2 is found, the range in which the shear reinforcement material 6 is disposed may be determined based on the simulation result according to the degree of misalignment.

  As yet another modification, when the misalignment of the support pile 2 is found, the strength of the concrete placed in the work chamber 11 may be changed according to the degree of misalignment of the support pile 2. The concrete constituting the pressure plate can also exert a resistance against the shearing force generated in the pressure plate. Therefore, if the strength of the concrete of the pressure plate is changed according to the degree of misalignment of the support pile 2, the effect of the shear force can be obtained as an effect of the pressure plate concrete alone or as a result of cooperation with the shear reinforcement material 6. A pressure-resistant plate that can cope with changes can be obtained.

In this case, it is good also as determining the range which changes the intensity | strength of the concrete cast | placed in the working chamber 11 according to the degree of misalignment of the support pile 2. FIG. In the example of FIG. 4, for example, the strength of the concrete may be increased only in the region b.
Further, the amount of change in the strength of the concrete and the range of the change required in accordance with the degree of misalignment of the support pile 2 are obtained by simulation in advance by the same method as that described with reference to the flowchart of FIG. When the misalignment of the support pile 2 is found, the strength of the concrete may be changed based on the simulation result in accordance with the degree of misalignment, and the range of the change may be determined.

In addition, you may implement the above-mentioned embodiment and each modification in combination with each other within a possible range.
The present invention is not limited to the description of each aspect, the embodiment, and the modifications. Various modifications are also included in the present invention as long as those skilled in the art can easily conceive without departing from the scope of the claims.

1 Caisson 2 Support pile 3 Upper rebar (upper rebar)
4 Lower rebar (bottom bar)
5 Concrete 6 Shear reinforcement 11 Work room 12 Cutting edge 13 Bottom plate reinforcement 21 Pile head reinforcement

Claims (18)

A caisson method of installing caisson by sinking,
Prior to the caisson settling, installing a support pile on the ground to support the caisson;
Sinking the caisson while excavating a pressurized working chamber partitioned by the bottom plate of the caisson;
In the working chamber, arranging a first reinforcing bar in the vicinity of the upper surface of the working chamber and a second reinforcing bar in the vicinity of the lower surface so as to extend in a substantially horizontal direction,
Constructing a pressure plate having the first and second reinforcing bars and the concrete and defined by the inner surface of the working chamber by placing concrete in the working chamber. Caisson method.   The caisson method according to claim 1, further comprising a step of measuring a degree of misalignment of the support pile.   The method further comprises a first changing step of changing at least one of the strength and the amount of bar arrangement of at least one of the first and second reinforcing bars according to the degree of misalignment of the support pile. Item 3. The caisson method according to item 2. The method further includes the step of obtaining in advance by simulation the amount of change in the strength of the first and second reinforcing bars and the amount of bar arrangement required depending on the degree of misalignment of the support pile,
In the first change step, the first and second reinforcing bars are determined based on the degree of misalignment of the support pile, based on the amount of change in the strength and the amount of bar arrangement obtained by the simulation. The caisson method according to claim 3, wherein at least one of the strength and the amount of bar arrangement of at least one of the second reinforcing bars is changed.   The first changing step determines a range for changing at least one of the strength and the amount of bar arrangement of at least one of the first and second reinforcing bars according to the degree of misalignment of the support pile. The caisson method according to claim 3 or 4, characterized in that the caisson method. The method further includes a step of obtaining in advance by simulation a range of change in strength and bar arrangement amount of the first and second reinforcing bars that are required according to the degree of misalignment of the support pile,
In the first change step, the first and second rebars are determined according to the degree of misalignment of the support pile based on the range of change in the strength and the amount of bar arrangement of the first and second reinforcing bars obtained by the simulation. The caisson method according to claim 5, wherein a range in which at least one of the strength and the bar arrangement amount of at least one of the second reinforcing bars is changed is determined. Arranging a shear reinforcement in the working chamber;
7. The method according to claim 2, further comprising a second changing step of changing at least one of the strength and the amount of the shear reinforcement according to the degree of misalignment of the support pile. The caisson method according to claim 1. The method further includes a step of calculating in advance by simulation the amount of change in the strength and arrangement amount of the shear reinforcement necessary according to the degree of misalignment of the support pile,
In the second changing step, the strength and distribution of the shear reinforcement are determined according to the degree of misalignment of the support pile, based on the amount of change in the strength and arrangement amount of the shear reinforcement obtained by the simulation. The caisson method according to claim 7, wherein at least one of the installation amounts is changed.   The second changing step determines a range for changing at least one of the strength and the amount of the shear reinforcement according to the degree of misalignment of the support pile. 8. The caisson method according to 8. The method further includes a step of determining in advance by simulation a range of change in strength and arrangement amount of the shear reinforcement necessary according to the degree of misalignment of the support pile,
In the second changing step, the strength and distribution of the shear reinforcement material are determined in accordance with the degree of misalignment of the support pile based on the range of change in the strength and arrangement amount of the shear reinforcement material obtained by the simulation. The caisson method according to claim 9, wherein a range in which at least one of the installation amounts is changed is determined.   The said arrange | positioning step determines the range which arrange | positions the said shear reinforcement material according to the degree of misalignment of the said support pile, The Claim 1 characterized by the above-mentioned. Caisson method. The method further includes the step of obtaining in advance by simulation the range of the shear reinforcement material required according to the degree of misalignment of the support pile,
The step of arranging determines the range in which the shear reinforcement material is arranged according to the degree of misalignment of the support pile based on the range of the shear reinforcement material obtained by the simulation. The caisson method according to claim 11.   The caisson method according to any one of claims 2 to 12, further comprising a third changing step for changing the strength of the concrete according to the degree of misalignment of the support pile. The method further includes the step of obtaining in advance by simulation the amount of change in the strength of the concrete that is required depending on the degree of misalignment of the support pile,
The third changing step is characterized in that the strength of the concrete is changed according to the degree of misalignment of the support pile based on the amount of change in strength of the concrete obtained by the simulation. Item 14. The caisson method according to item 13.   The caisson method according to claim 13 or 14, wherein the third changing step determines a range in which the strength of the concrete is changed according to a degree of misalignment of the support pile. Further including a step of obtaining in advance a range of the strength change of the concrete required according to the degree of misalignment of the support pile by simulation,
The third changing step determines a range in which the strength of the concrete is changed according to a degree of misalignment of the support pile, based on a range of the strength change of the concrete obtained by the simulation. The caisson method according to claim 15, wherein the caisson method is used. Caisson installed by sinking,
A support pile supporting the caisson;
A caisson structure having a pressure resistant plate made of reinforced concrete installed between the caisson and the support pile, the pressure resistant plate having both upper and lower reinforcing bars.   The caisson structure according to claim 17, wherein the pressure plate further includes a shear reinforcement.

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