JP2009179964A - Underground structure reinforcing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an underground structure reinforcing method which relatively easily allows restoration of a reinforced portion of an underground structure even if a large earthquake beyond assumption has occurred and restoration work of the reinforced portion is necessary, and brings about a reinforced state of the structure before occurrence of the earthquake. <P>SOLUTION: According to the underground structure reinforcing method, excavation of the ground is carried out along side walls 1b, 2b of respective buildings 1, 2, and a joint portion 4, building underground portions 1a, 2a sandwiching the joint portion, and an upper area of an underground connection structure 3 are exposed, followed by mounting load bearing members 8a, 8b that can bear a tensile load of a predetermined value or more on a side surface of the building underground portion and the underground connection structure, in a manner striding the joint portion. Then a deformation absorbing material 7 capable of absorbing earthquake vibration is connected to the load bearing member on the side of the building underground portion and the load bearing member on the side of the underground connection structure, and thus the load on the joint portion is reduced. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an underground structure reinforcing method for a nuclear power plant, and more particularly to an underground structure reinforcing method for reinforcing a connecting portion between an underground portion of an adjacent building and an underground connecting structure connected therebetween.

  Generally in nuclear power plants, reactor buildings with high seismic importance are built directly on the bedrock using a direct foundation format and have a robust structural design that can withstand large earthquake loads. Therefore, the reactor building itself is not greatly deformed or fluctuated because it has a structure that can sufficiently withstand even if a large earthquake occurs and a large ground load is applied.

  On the other hand, the turbine building, control building, reactor auxiliary building, etc. installed around the reactor building are constructed in a pile foundation type where the pile is penetrated into soft ground and the tip is driven into the support base. Some have a structural design that is less earthquake-resistant than the reactor building. If a large earthquake occurs, the building may be deformed or fluctuated due to the ground load.

In such a state, if the reactor building and the surrounding buildings are connected by an underground connection structure, a difference in the behavior of the structure due to ground load occurs during an earthquake, etc., and the relative deformation between the structures causes a difference between the buildings. There is a possibility that damage may occur where the connecting part is weak. That is, the reactor building and the turbine building or the auxiliary reactor building are constructed adjacent to each other, and in the basement of these buildings, in the event of an earthquake, the vibration properties include the differences in the basic form. Because it depends on the weight and rigidity, the natural period and phase do not match each other, and relative deformation occurs between the underground connected structures.Therefore, the adjacent buildings are connected so that these damages do not occur. In an underground connection structure, such as an inter-building trench, a certain degree of relative deformation can be absorbed by providing a joint portion that is structurally cut. However, conventionally, there has been a concern that a large earth pressure acts on the underground connection structure due to relative deformation, and the underground connection structure is damaged.

  On the other hand, as a conventional countermeasure, there is a proposal to replace the vicinity of the ground surface with a deformation absorption region in the soft ground in which the underground connection structure is embedded (see, for example, Patent Document 1). The outline of this proposal is to provide a deformation absorption area of the structure in the buried ground area of the underground connection structure between adjacent buildings so that the structure and the structure vibrate inherently at their respective periods and phases. As a result, even if relative deformation occurs between the two underground parts, the relative deformation is absorbed in the deformation absorption region, and earth pressure due to the relative deformation does not act between the building and the underground connected structure. It is to do.

In the deformation absorption area between structures, a cushioning material such as expanded polystyrene having a high deformation absorption capacity is used. The soft ground, which is the ground area, is dug down, and then the cushioned foam such as polystyrene is excavated in the excavated space. A material is filled to form a deformation absorption region.
JP-A-11-323960

  In existing nuclear power plants, large earthquakes will occur in the future, and relative deformation between structures due to uneven settlement of the ground and earth pressure during earthquakes due to ground shaking will occur, and a large load will be applied to underground connected structures. This may cause damage to the structure.

  The reactor building and the surrounding buildings such as the turbine building are structurally cut off, but because important piping is connected between the structures, it is not possible to connect them with underground connecting structures such as trenches between buildings. Structures are connected. In a portion where the edge between the structures is cut structurally, a flexible joint portion such as an M-type water-stopping joint is provided so that a certain degree of relative deformation can be absorbed.

  However, if a large earthquake occurs and the relative deformation exceeds the expected value between adjacent structures, or if there is a large earth pressure during an earthquake, the joints between the structures will be damaged, and important piping will be damaged. It is considered that a large damage is caused.

  As a measure for preventing the occurrence of the above-mentioned damage, it is conceivable to carry out the construction work for converting the deformation area into the soft ground shown in the above-mentioned publicly known literature. It is difficult to ensure the soundness of the structure due to large relative deformation and earth pressure during earthquakes only with countermeasures, and it is actually necessary to implement remodeling work by using a deformation absorption area, which requires a lot of cost and construction period. Become.

  In other words, when soft ground improvement work (consolidation improvement work or modification work for deformation absorption area), which is a conventional method, is performed, the amount of excavated material increases because of the wide ground improvement. Since an area is required, it will be a major remodeling work. In addition, even if the foundation improvement work at the lower part of the inter-building trench is performed, it is necessary to excavate deep underground, so a large excavating machine is necessary, and the foundation remodeling work after excavation will also be large Cost and construction period become enormous.

  In order to solve the problems of the known technical examples, there is a demand for a structure or method for ensuring the soundness of the inter-building underground connection structure with a small amount of excavated material.

  The present invention has been made in view of such circumstances, and it is possible to reinforce an underground connection structure by simply applying a simple reinforcement structure to an underground connection structure such as an inter-building trench in a nuclear power plant. It aims at providing a structure reinforcement construction method.

  In order to achieve the above-mentioned object, the present invention excavates the ground between adjacent buildings of a nuclear power plant, and reinforces the underground connection structure connected by a joint part capable of relative displacement between the building underground parts. An underground structure reinforcement method for adding material, wherein excavation of the ground is performed along a side wall of the building, and the joint portion, the building underground portion sandwiching the joint portion, and the upper portion of the underground connection structure are represented. Among these exposed parts, a load supporting member capable of supporting a tensile load of a certain level or more is attached to the side surface of the building basement part and the underground connection structure in an arrangement straddling the joint part, and these building basement parts By connecting a deformation absorbing material capable of absorbing seismic vibration between the load supporting member on the side and the load supporting member on the underground connection structure side, the load applied to the joint portion can be reduced. Providing underground construction Retrofit characterized by.

  In the present invention, the deformation absorbing material is a tensile material, and one end side of the tensile material is connected to the load support member on the building basement side, while the other end side of the tensile material is a load on the underground connected structure side. It is desirable to connect to a support member.

  Further, the load supporting member on the basement side of the building connecting one end side of the tension member is arranged on the larger diameter side than the outer periphery of the underground connecting structure, and a roller portion is provided on the load supporting member on the basement side of the building. It is desirable that the tension member can be bent in the circumferential direction of the roller, and the underground connection structure is supported to be swingable from the outer peripheral side.

  Furthermore, it is desirable that the tensile material and the load support member are accommodated in a sheath embedded in the soil.

  ADVANTAGE OF THE INVENTION According to this invention, in the underground structure reinforcement construction method of an existing nuclear power plant, the amount of excavated material can be made smaller than the conventional construction method. Further, according to the present invention, the excavation range, the amount of excavated material, and the construction range can be reduced as compared with the conventional method. As a result, the amount of the construction work can be reduced, and the construction cost can be reduced and the construction period can be shortened. In addition, the reliability of the reinforcement structure of the underground connection structure can be improved, and even if an earthquake that is larger than expected occurs and repair work is required, repair can be performed relatively easily and replacement of parts, etc. By doing this, the structure before the occurrence of a large earthquake can be restored in a short period of time.

  Hereinafter, an embodiment of the underground structure reinforcing method according to the present invention will be described with reference to FIGS. 1 to 3. FIG. 1 is a process diagram showing the procedure of the underground structure reinforcing method according to the present embodiment. 2 is a longitudinal sectional view showing a state in which the underground structure is reinforced by the process shown in FIG. 1, and FIG. 3 is a plan view of FIG.

  First, with reference to FIG. 1, the procedure of the underground structure reinforcement construction method by this embodiment is demonstrated roughly. First, the ground between adjacent buildings of the nuclear power plant is excavated along the side wall of the building, and the upper part of the joint part, which is the connection between the building basement and the underground connection structure, is exposed (ground excavation). Step S1).

  In the state where the upper part of the building basement, the underground connection structure and the joint part are exposed, the fixing part for fixing the reinforcing material is set in each building basement and the underground connection structure (adhesion part setting process) S2).

  After the fixing portions are set, tensile materials are respectively set in these fixing portions (tensile material setting step S3), and then the tensile materials are tensioned (tensile material tensioning step S4). After tensioning the tensile material, each tensile material is accommodated in the sheath (sheath setting step S5). Finally, the ground is backfilled (ground backfilling step S6).

  Next, with reference to FIG. 2 and FIG. 3, the underground structure reinforcement construction method by this embodiment is demonstrated concretely in order of the said process.

  2 and 3, as an example, a building 1 such as a reactor building and a building 2 such as a turbine building and a reactor auxiliary building are constructed adjacent to the ground G, and the basement of each of these buildings 1 and 2 is built. The inter-building trench 3 is embedded as an underground connection structure between the portions 1a and 2a, and the side walls 1b and 2b of each of the building basement portions 1a and 2a and the end portions of the inter-building trench 3 are connected through the joint portion 4. The state is shown. As described above, the joint portion 4 has a structure capable of absorbing a certain amount of relative deformation, that is, a structure in which an edge is cut structurally. Thereby, the rigidity of the end part side and the center side of the inter-building trench 3 is relaxed via the joint part 4, and it has a configuration that can basically cope with an earthquake load or the like.

  In addition, the reinforcement structure of this embodiment with respect to the adjacent buildings 1 and 2 is the same, and in the following description, only the left side part of FIG. 2, FIG. 3 is attached | subjected and demonstrated.

[Ground excavation process S1]
First, the ground G is excavated along the side walls 1b and 2b of the buildings 1 and 2. That is, in the inter-building trench 3 from the surface of the ground G, the periphery of the joint portion 4 is excavated to a substantially intermediate height position in the vertical direction of the inter-building trench 3. This takes into consideration that the amount of excavated material is reduced as much as possible and that the reinforcing structure is set using a small space on the upper side of the underground connection structure 4. Thereby, the upper part of the building underground parts 1a and 1b and the inter-building trench 3 sandwiching the joint part 4 is exposed.

[Fixed part setting step S2]
Next, as a load supporting member that can support a tensile load of a certain level or more in an arrangement straddling the joint portion 4 with respect to the side surface of the building underground portion 1a and the upper half portion of the inter-building trench 3 among the exposed portions. The fixing portions 8a and 8b are set at a plurality of locations. These adhering portions 8a and 8b constitute a jig portion for fixing a PC steel rod or the like, which is the following tensile material 7, and have a tension fixing portion structure (a structure in which a wedge is caught by a support plate). ing. Specifically, a lock bolt or the like having a ring or a hook-shaped head is applied, and these are dispersed and fixed to the side surface of the building basement part 1 a and the upper half of the inter-building trench 3.

  As a fixing means for the fixing portions 8a and 8b, for example, a lock bolt or the like is fixed to the side surface of the building basement portion 1a and the trench 3 between the buildings by a driving anchor or the like. In addition, when it is necessary to increase the fixing strength in terms of design, a part of the building basement part 1a and the inter-building trench 3 are suspended, and anchor bolts are set in the suspended part, and concrete is filled. Attach the fixing portions 8a, 8b to.

  Further, the setting portions of the fixing portions 8a and 8b are distributed and arranged on the upper part of the inter-building trench 3 in order to prevent the inter-building trench 3 from sinking. As shown by the arrow in FIG. 2, this is because the basement floor portion 1a and the inter-building trench 3 are caused by the ground 6 being loosened by the horizontal ground load w2 as shown by the arrow in FIG. This is to prevent the inter-building trench 3 from sinking relative to the building basement portion 1a, or to behave in different phases, to cause relative deformation between structures.

[Tensile material setting step S3]
After fixing the fixing parts 8a and 8b to the building basement part 1a and the inter-building trench 3, the tensile material 7 extends over the fixing part 8a on the building basement part 1a side and the fixing part 8b on the inter-building trench 3 side. The end portions of the tensile members 7 are fastened. As the tension member 7, for example, a PC steel bar used in a building structure is applied. At the stage of the tension material setting step, the tension material 7 is in a pre-tensioned state (temporary setting) and given a certain looseness.

  Each tensile material 7 such as a PC steel bar functions as a deformation absorbing material capable of absorbing seismic vibration between the fixed portion 8a on the building basement 1a side and the fixed portion 8b on the inter-building trench 3 side, The load applied to the joint part 4 is reduced. When relative deformation occurs in the inter-building trench 3 and the building underground portions 1a and 2a, the deformation energy is absorbed.

  About the connection method of the tension | tensile_strength material 7 of the building basement part 1a and the inter-building trench 3, the system which hangs the inter-building trench 3 directly diagonally with the tension | tensile_strength material 7 from the building basement part 1a may be used.

  In addition, as shown in FIG. 2, when the inter-building trench 3 is relatively shallowly embedded from the ground surface F and it is impossible to hang the inter-building trench 3 directly diagonally, Use a hanging system. The roller member 5 is supported by a roller support member 9 that protrudes from the side surface of the building basement 1a and is rotatably supported along the axial direction of the tensile material 7. For example, the roller member 5 is horizontal from the side of the building basement 1a. The tension member 7 drawn out to the bottom is guided downward through the upper surface of the roller member 5, and the tip of the tension member 7 is fixed to the fixing portion 8 b of the inter-building trench 3 in a downward inclined state.

[Tensile tension process S4]
After temporarily setting the tensile material 7 to the fixing portions 8a and 8b, the tensile material 7 is attached to one end side or both ends in the length direction at the fixing portions 8a and 8b of the structures of the building underground portion 1a and the inter-building trench 3 Tension from the side.

  Moreover, as a connection method of the tension | tensile_strength material 7 with respect to the building underground part 1a and the inter-building trench 3, the system which hangs | hangs the inter-building trench 3 directly diagonally with the tensile material 7 from the building underground part 1a may be used. However, when the inter-building trench 3 is relatively shallowly embedded from the ground surface F and it is impossible to suspend the inter-building trench 3 directly obliquely, as described above, the system is suspended through the roller member 5. Tension with.

  Further, as shown in FIG. 3, the fixed portions 8a and 8b and the tensile material 7 are set at different positions in the horizontal direction in the building underground portion 1a and the inter-building trench 3 due to the horizontal ground load w2. However, it is effective to arrange the fixing portions 8a and 8b and the tensile material 7 on the side surfaces on both sides of the inter-building trench 3 to cause the inter-building trench 3 to be deformed relative to the building underground portion 1a.

[Sheath setting step S5]
After installation of the fixing portions 8a and 8b and the tension member 7 is completed and the tension member 7 is tensioned, the ground is backfilled. In that case, the adhering portions 8a and 8b and the tensile material 7 are buried in the soil. Therefore, when it is necessary to consider these corrosions in terms of design, a method is adopted in which the fixing portions 8a and 8b and the tension member 7 are respectively housed in a flexible sheath 12 as a corrosion prevention measure. By storing the tensile material 7 in the sheath 12, it becomes easier to perform subsequent maintenance and replacement work of the tensile material 7 as compared with the case where the tensile material 7 is directly embedded in the soil.

[Ground backfilling step S6]
After the sheath 12 is set, the ground G is backfilled as a final process. That is, after the installation of the fixing portions 8a and 8b and the tension material 7 is completed and the tension material 7 is tensioned, the ground is backfilled as a final process. Thereby, the underground structure reinforcement construction method is completed.

  According to this embodiment provided with the above process (S1-S6), when constructing the remodeling work of the underground connection structure in the existing nuclear power plant, by adopting the underground structure reinforcement construction method, The amount of material to be excavated can be reduced, and the reinforcement part is limited to the area around the joint part of the inter-building trench. Therefore, it is possible to perform reinforcement work even on the site between buildings where the construction area is narrow .

  When soft ground improvement work (consolidation improvement work or deformation absorption area remodeling work), which is a conventional construction method, is performed, the amount of excavated material increases because of the wide ground improvement, and there is a wide construction area. Because it is necessary, it will be a major remodeling work. In addition, even when the foundation improvement work at the lower part of the trench part between the buildings is carried out, it is necessary to dig deep underground, so a large excavation machine is required, and the foundation remodeling work after excavation becomes large. Therefore, the cost and the construction period become enormous.

  On the other hand, according to the present embodiment, even when a large earthquake more than expected occurs and repair work for the reinforced portion of the underground connection structure is required, repair can be performed relatively easily, especially for tensile materials. Instead, in the construction method that uses a deformation absorber, it is possible to restore the reinforced structure before the earthquake by simply replacing the part.

(Other embodiments)
As another embodiment of the present invention, it is possible to employ a deformation absorbing material having a deformation absorbing capacity instead of the tensile material 7. When a deformation absorber is applied, even if a large earthquake occurs and relative deformation occurs between the inter-building trench 3 and the building basement 1a, the deformation absorbing material absorbs the deformation energy. The damage of the joint part 4 can be avoided, and the breakage of important piping in the inter-building trench can also be prevented.

  As a deformation absorbing material used in place of the tensile material 7, a material having a toughness against deformation, such as a damper or a steel plate gutter structure used in a seismic isolation device for a building structure, should be adopted. Is desirable. However, the fixing portions 8a and 8b for setting the deformation absorbing material in each structure need to be rigidly coupled with a higher degree of fixing than the tension fixing portion structure of the tensile material 7.

  The object of the present invention can be applied not only to the inter-building trench 3 but also to the protruding portion of the building (not shown).

Process drawing which shows the construction procedure by one Embodiment of this invention. The side view which shows the construction method by one Embodiment of this invention. The top view of FIG.

Explanation of symbols

  1, 2 building, 1a, 2a building basement, 1b, 2b side wall, 3 building-to-building trench, 4 joint portion, 5 roller member, 7 tension material, 8a, 8b fixing portion, 9 Roller support member, 12 ... sheath, G ... ground, F ... ground surface, w1 ... upper ground load, w2 ... horizontal ground load.

Claims (4)

An underground structure reinforcement method for excavating the ground between adjacent buildings of a nuclear power plant and adding a reinforcing material to an underground connection structure connected by a joint part capable of relative displacement between the building underground parts, Excavation of the ground is performed along the side wall of the building, and the joint part, the basement part of the building sandwiching the joint part, and the upper part of the underground connection structure are exposed, and among the exposed parts, the basement of the building A load support member capable of supporting a tensile load of a certain level or more is attached to the side surface of the building and the underground connection structure so as to straddle the joint portion, and the load support member on the building underground side and the load on the underground connection structure side An underground structure reinforcing method characterized by reducing a load applied to the joint portion by connecting a deformation absorbing material capable of absorbing seismic vibration between the supporting member and the supporting member. The deformation absorbing material is a tensile material, and one end side of the tensile material is connected to the load support member on the basement side of the building, while the other end side of the tensile material is connected to the load support member on the underground connection structure side. The underground structure reinforcing method according to claim 1. The load supporting member on the basement side of the building connecting one end side of the tensile material is arranged on the larger diameter side than the outer periphery of the underground connection structure, and the load supporting member on the basement side of the building is arranged via a roller part. The underground structure reinforcing method according to claim 2, wherein the tension member is bendable in a circumferential direction of the roller, and the underground connection structure is supported to be swingable from an outer peripheral side thereof. The underground structure reinforcing method according to claim 2 or 3, wherein the tensile material and the load supporting member are accommodated in a sheath embedded in soil.

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