JP2007162377A - Construction method of underground water storage tank - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an underground water storage tank capable of being smoothly and surely constructed by settling a box body while maintaining a stabilized posture even if it is the extremely soft ground. <P>SOLUTION: Four piles (strut members) 9 penetrate the outside ground E of the box body 3 at intervals so as to surround the box body 3 to make them supported, and each of eight chain blocks (lifting and lowering implements) 12 is made to hold by the upper end of each pile 9, lower ends of eight wire ropes (rope-like members) 16 suspended by each chain block 12 is connected to the lower end outer circumference of the box body 3 through an auxiliary segment 13, and when the ground E inside of the box body 3 is excavated, the box body 3 is settled in the ground E by lowering each wire rope 16 by the chain block 12 in a tensile state. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a construction method of an underground water storage tank in which an underground water storage tank used as a fire prevention water storage tank, a water receiving tank, or the like is submerged in the ground by a submerged method.

Conventionally, a box formed in a cylindrical shape is dug into the ground by excavating the ground inside, and then a bottom plate is constructed at the bottom of the box, and a top plate is disposed at the top of the box A method of constructing an underground water tank by backfilling is generally known. And, in the case where the ground at the construction site of the underground water storage tank is soft ground where there is almost no earth bearing strength, a subsidence prevention body that obtains a reaction force from the ground is disposed on the ground on the outer peripheral side of the box, While holding a long bar member having a screw in the sinking prevention body with a nut, the lower end of the long bar member is connected to an auxiliary ring provided at the lower end of the box, and the ground inside the box is excavated. However, a construction method is known in which the box is submerged in the ground by loosening the nut and moving the holding position of the long bar member in the subsidence prevention body (for example, Patent Document 1). reference).
JP 2000-352085 A

  The construction method of the underground water tank is that the box is supported by the subsidence prevention body that obtains a reaction force from the ground even if the ground is soft, and is accurately set to a predetermined depth while stably controlling its posture. However, since the weight of the box is added to the ground at the outer peripheral portion of the box through the sinking prevention body, the ground value is N or zero. However, it sinks without being able to support the sinking prevention body, wraps around the inside of the box from the lower end of the box, and sinks the box in the ground while maintaining its posture stably. You may not be able to.

  The present invention has been made in view of the above circumstances, and it is possible to smoothly and surely construct an underground water tank by laying down a box while maintaining a stable posture even on extremely soft ground. It aims at providing the construction method of the underground water tank which can be done.

The present invention is characterized by the following points in order to solve the above problems.
That is, in the construction method of the underground water storage tank according to claim 1 of the present invention, the box formed in a cylindrical shape is arranged vertically on the ground, and the ground inside the box is excavated, It is a construction method of an underground water tank that sinks a box in the ground,
A plurality of support members are inserted into and supported by the ground outside the box so as to surround the box, and a plurality of elevator devices are held by the upper ends of the support members. Connecting the lower ends of the plurality of cord-like members suspended at the outer periphery of the lower end of the box, and lowering each cord-like member in a tensioned state by the elevator when excavating the ground, It is characterized by sinking in the ground.

  According to a second aspect of the present invention, there is provided a method for constructing an underground water storage tank, wherein a plurality of support members are stretched horizontally so as to surround the outer periphery of the box horizontally on the upper ends of adjacent ones of the support members. The plurality of lifting devices are arranged at equal intervals in the circumferential direction of the box through the members and are held by the support members.

  According to a third aspect of the present invention, there is provided a method for constructing an underground water tank, wherein an annular auxiliary segment is attached to a lower end of the box, and a lower end of each cord-like member is connected to the lower end of the box via the auxiliary segment. It is characterized by being connected to each.

According to the present invention, the following excellent effects can be obtained.
That is, according to the construction method of the underground water storage tank according to claim 1, the strut member is supported on the ground layer having the ground strength, and the box is subsidized by operating the elevator while supporting the box by the strut member. Therefore, even if the ground on which the box is to be installed is extremely soft, the box can be assembled and secured to a predetermined depth with a stable posture, smoothly and An underground water tank can be constructed without fail.

  Further, according to the construction method of the underground water storage tank according to claim 2, it is balanced so that the box is not tilted by the elevators arranged at equal intervals in the circumferential direction of the box by the support members surrounding the box. Since it can be supported well, the box can be assembled safely and easily, and the box can be smoothly sunk.

  Moreover, according to the construction method of the underground water tank according to claim 3, since the box is connected to the rope-like member suspended from the elevator device via the auxiliary segment, the box itself is connected to the rope-like member. There is no need to provide a section, and it is possible to prevent an excessive load from acting on a specific segment of the box, and to mount the box on the auxiliary segment. Work can be performed more smoothly and reliably.

Next, a construction method of an underground water storage tank according to an embodiment of the present invention will be described with reference to the accompanying drawings.
First, the underground water tank 1 constructed by the underground water tank construction method according to an embodiment of the present invention will be described. As shown in FIG. 1, this underground water storage tank 1 is a cylinder in which a plurality of segments 2 formed in a circular arc shape are arranged in a circumferential direction and an axial direction, and adjacent segments are connected by bolts, nuts, or the like. And a bottom slab 5 having a water collecting pit 5a through a split stone, crushed stone 4a, discarded concrete 4b, etc. at the bottom of the box 3 (lower box 3a), A top plate 7 having a manhole 6 is provided above the box 3 (upper box 3b). The bottom slab 5 is overcoated with a waterproof mortar 5b.

Hereinafter, the construction method of the underground water tank 1 will be described with reference to FIGS.
First, a depth slightly larger than the diameter (outer diameter) of the box 3 of the underground water tank 1 and a predetermined depth (for example, a depth slightly shallower than the height of the lower box 3a) in the ground E where the underground water tank 1 is to be constructed. The circular pit 8 is excavated. Then, a plurality of (four in the illustrated example) columnar piles (post members) 9 arranged at equal intervals in the circumferential direction of the box 3 on the outside of the pit 8 using a pile driving machine Drive perpendicular to the ground E. In this case, the tip of the pile 9 is driven to the formation where the earth bearing strength is sufficiently obtained, and all the upper ends of the piles 9 are made to have the same height.
The pile 9 may be made of steel, reinforced concrete, or steel pipe filled with concrete, and the pit 8 is not limited to a circle but may be a rectangle or other shapes.

  Thereafter, two pairs of adjacent piles 9, 9, and in the example of FIG. 2, the piles 9, 9 positioned on the left side of the box 3 and the piles 9, 9 positioned on the right side are vertically The support members 10a, 10a made of H-shaped steel or the like directed in the vertical direction in FIG. Further, support members 10b and 10b made of H-shaped steel or the like are bridged in the lateral direction (left and right direction in FIG. 2) on the ends of the pair of support members 10a and 10a. Tighten the ends with a vise and fix them. Instead of fixing the supporting members 10a, 10a to the piles 9, 9 and fixing the end portions of the supporting members 10a, 10b with a vise, it can be performed by fastening means such as bolts and nuts.

  The bottom surface of each of the support members 10a and 10b assembled in a four-column pattern is provided with brackets at a plurality of positions (eight positions in the illustrated example) at equal intervals in the circumferential direction of the box 3. A chain block (elevator) 12 is held via 11. After this preparation is made, a steel segment formed in an arc plate shape with a U-shaped cross section on the ground E at the position where the box 3 in the pit 8 is to be set is not shown in detail. Are connected with bolts and nuts, and the annular auxiliary segment 13 having a diameter corresponding to the outer diameter of the box 3 is assembled. A cylindrical ring 14 into which the lower end portion of the box 3 can be fitted is fixed to the auxiliary segment 13 on the outer periphery of the upper end portion, and the chain block 12 is spaced at equal intervals in the circumferential direction on the outer periphery of the lower end. A plurality of (eight in the illustrated example) suspension fittings 15 are fixed in accordance with the number. A wire rope 16 having a predetermined length (a length necessary for sinking the box 3 to a predetermined depth) is fixed to each hanging bracket 15. Therefore, the wire gripping portions at the ascending positions of the chain blocks 12 are locked in a tensioned state in the middle of the wire ropes 16 fixed to the corresponding hanging brackets 15 of the auxiliary segments 13.

  Next, the arc-shaped segment 2 prepared in advance at the construction site is lifted by a heavy machine such as a truck crane and moved onto the auxiliary segment 13 through the inner space surrounded by the support members 10a and 10b. Then, the lower end of the segment 2 is placed along the inner surface of the ring 14 and the upper surface of the flange 13 a at the upper end of the auxiliary segment 13. Then, another segment 2 is placed next to the first placed segment 2, the joining surfaces in the circumferential direction of the segments 2 and 2 are brought into contact with each other, and the first of the bolts, nuts, etc. provided on the joining surface It connects by the fastening part 17a. The assembly work of the segments 2 is repeated, and the segments 2 are sequentially connected in the circumferential direction to complete the lower box 3a on the auxiliary segment 13 (see FIG. 3). At that time, if necessary, the lower box 3a is connected to the auxiliary segment 13 by a second fastening portion 17b such as a bolt and a nut.

  Further, in the same manner as when the lower box 3a is assembled, the segments 2 are sequentially placed on the upper end of the lower box 3a, and the adjacent ones in the circumferential direction are connected by the fastening portion 17a. The upper box 3b is formed. In that case, the position of the joint surface between the segments 2 and 2 in the upper box 3b is the position of the segment 2 in the circumferential direction of the box 3 with respect to the position of the joint surface between the segments 2 and 2 in the lower box 3a. Shift half the length in the circumferential direction. Then, the segments 2 and 2 of the lower box 3a and the upper box 3b are connected to each other by a second fastening portion 17b such as a bolt and a nut provided on a joint surface in the axial direction (see FIG. 4). (See chain line part).

  As described above, when the connection of the upper box 3b is completed on the lower box 3a, the excavating machine such as a club bucket is used to excavate the ground E inside the lower box 3a. When each chain block 12 is operated equally and each wire rope 16 is lowered at the same amount and at the same speed, the box 3a sinks while maintaining its horizontal state by its own weight. When the chain block 12 lowers the wire rope 16 by a certain stroke, the operation of the chain block 12 is temporarily stopped and, for example, eight pieces suspended on the support members 10a and 10b are not shown. The wire ropes 16 are temporarily supported by the lifting tool while maintaining the tension state. Then, after removing the gripping portion of each chain block 12 from each wire rope 16 and raising it to the original position by a certain stroke, the wire rope 16 is again moved upward by the certain stroke while maintaining the tension state. Is gripped by the gripping portion of each chain block 12. Thereafter, the support of each wire rope 16 by each suspension tool is released, and each chain block 12 is operated to lower each wire rope 16 to sink the box 3.

  By repeating the lowering operation (feeding-out operation) of the wire rope 16 by the chain blocks 12 and the suspension tools, the box 3 in which the lower box 3a and the upper box 3b are integrated is lowered. Go. Then, when the box 3 sinks until the upper end of the upper box 3b reaches a predetermined depth from the surface of the ground E, the operation of the chain block 12 is stopped and the lower box 3a by the excavating machine is stopped. Stop excavation of the inner ground. After this, in the state where the earth and sand are present in the auxiliary segment 13, the bottom plate 5 is constructed on the bottom of the lower box 3a in the same manner as the conventional construction method, and at the upper end of the upper box 3b. The top plate 7 is installed.

After the installation work of the top plate 7 is completed, the upper end portion of the wire rope 16 is removed from the chain block 12, the chain block 12 is removed from the support members 10a and 10b, and the support members 10a and 10b are removed. Is removed from each support member 9 and removed. And each said support | pillar member 9 is embedded in the ground E, or it pulls out from the ground as needed and removes.
Finally, earth and sand are refilled in the pit 8 so that the upper end of the manhole 6 of the box 3 is substantially flush with the surface of the ground E as shown in FIG. Complete construction work to install inside. The auxiliary segment 13 and the wire rope 16 are embedded in the ground.

  As described above, the construction method of the underground water tank according to the embodiment described above has four piles (post members) on the ground E outside the box 3 so as to surround the box 3. ) 9 are penetrated and supported, and eight chain blocks (elevating equipment) 12 are held by the upper ends of the respective piles 9 and are suspended by the chain blocks 12. When the lower end of 16 is connected to the outer periphery of the lower end of the box 3, and when excavating the ground E inside the box 3, the chain block 12 lowers each wire rope 16 in a tension state, The box 3 is set in the ground E.

  Therefore, according to the construction method of the underground water storage tank according to the embodiment, the piles 9 are supported on the ground layer of the ground strength E, and the chain block is supported while the box 3 is supported by the piles 9. 12 can be sunk by operating, so even if the ground E on which the box 3 is to be installed is extremely soft, the box 3 is secured and assembled in a predetermined depth. The underground water tank 1 can be constructed smoothly and reliably.

  Moreover, according to the construction method of the underground water storage tank according to the embodiment, four support members are provided so as to horizontally surround the outer periphery of the box 3 at the upper ends of adjacent ones of the four piles 9. 10 a and 10 b are spanned, and the eight chain blocks 12 are arranged at equal intervals in the circumferential direction of the box 3 through the support members 10 a and 10 b and are held by the piles 9. Therefore, the box 3 can be supported in a balanced manner so as not to tilt by the chain blocks 12 arranged at equal intervals in the circumferential direction of the box 3 by the piles 9 surrounding the outer periphery of the box 3. 3 can be performed safely and easily, and the box 3 can be smoothly sunk. Moreover, since the four support members 9 are connected to each other by the support members 10a and 10b, the box 3 can be supported while maintaining its posture.

  Furthermore, according to the construction method of the underground water storage tank according to the embodiment, the annular auxiliary segment 13 is attached to the lower end of the box 3, and the lower end portion of each wire rope 16 is interposed through the auxiliary segment 13. Since the box 3 is connected to the wire rope 16 suspended from the chain block 12 via the auxiliary segment 13, the box 3 is directly connected to the box 3. It is not necessary to provide a connecting portion with the wire rope 16, and an excessive load can be prevented from acting on a specific one of the segments 2 constituting the box 3, and the box on the auxiliary segment 13. 3 can be assembled, the assembly work can be performed more easily and smoothly.

  In the construction method of the underground water storage tank according to the embodiment, four piles 9 are inserted into the ground E on the outer peripheral side of the box 3, and four support members 10 a are formed at the upper end of the pile 9. , 10b are assembled and fixed to a cross beam, and the box 3 is supported by the eight chain blocks 12 held by the wire rope 16, but the pile 9 is not limited to four, but three According to this, the number of the supporting members 10a and 10b and the assembled shape with respect to the pile 9 can be made into a polygonal shape other than the cross beam. The number of chain blocks 12 is not limited to eight, and may be any other number depending on the size of the load that can be supported per one of them, the weight of the box 3, and the like.

In addition, when the pile 9 is used with a strong strength, the number of the chain blocks 12 can penetrate the formation layer of the ground E having earth strength and can be firmly supported. The box 12 can be supported by holding the block 12. In this case, the support members 10a and 10b can be omitted.
Furthermore, as a support | pillar member which supports the said box 3, not only the said pile 9, but a columnar member of various cross-sectional shapes other than a steel sheet pile, H-section steel, etc. can be used. Moreover, as an elevator apparatus which suspends the said box 3 via the wire rope 16, not only the said chain block 12, but a cord-like member, such as the wire rope which the load is acting, is extended in a tension state, and is stopped. It is also possible to use a manual hoisting machine or other equipment that makes it possible.

In the underground water tank construction method according to the embodiment, the pit 8 having a predetermined depth is provided in the ground E so that the box 3 can be configured at a low position inside the pit 8. Although it is not necessary to use a heavy machine such as a large crane that lifts the segment 2 constituting the box 3 high, it can be omitted depending on the size of the underground water storage tank 1 and the situation at the construction site.
Although the example in the case of constructing the underground water storage tank 1 in which the box 3 is connected in two stages up and down is shown, the present invention is not limited to this, and the box 3 is connected up and down one stage or three or more stages. It can also be applied to the construction of underground water tanks.

It is the side view which showed a part of underground water tank constructed by applying the construction method of the underground water tank concerning one embodiment of the present invention in the section. It is a top view which shows the construction method of the underground water tank which concerns on one embodiment of this invention. It is sectional drawing which similarly shows the assembly | attachment state of the lower box of an underground water tank. It is sectional drawing which similarly shows the subsidence state of the lower box of an underground water tank, and the assembly | attachment state of an upper box.

Explanation of symbols

1 underground water tank 2 segment 3 box 5 bottom plate 7 top plate 8 pit 9 pile (post member)
10a, 10b Support member 12 Chain block (elevating equipment)
13 Auxiliary segment 16 Wire rope (cord-like member)
E Ground

Claims (3)

A method for constructing an underground water tank in which a box formed in a cylindrical shape is arranged vertically on the ground, and the box is submerged in the ground by excavating the ground inside the box,
A plurality of support members are inserted into and supported by the ground outside the box so as to surround the box, and a plurality of elevator devices are held by the upper ends of the support members. Connecting the lower ends of the plurality of cord-like members suspended at the outer periphery of the lower end of the box, and lowering each cord-like member in a tensioned state by the elevator when excavating the ground, A method for constructing an underground water tank, characterized in that the ground is submerged in the ground.   A plurality of support members are horizontally spanned around the outer periphery of the box at the upper ends of adjacent ones of the strut members, and the plurality of elevator devices are arranged in the circumferential direction of the box through the support members. The method for constructing an underground water tank according to claim 1, wherein the strut members are arranged at regular intervals and held by the support members. An annular auxiliary segment is attached to the lower end of the box, and the lower end of each cord-like member is connected to the outer periphery of the lower end of the box via the auxiliary segment. Construction method of underground water tank as described.

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