JP2010031564A - Basement pillar installation method and construction method for underground structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a basement pillar installation method, hardly causing shift of an installation position of a basement pillar in a process performed after erecting, and reducing cleaning work before concrete is placed. <P>SOLUTION: This basement pillar installation method includes: a process of inserting the basement pillar 1 having a precast concrete-made pillar part 1a and a steel core material 1b extended downward from the pillar part 1a in an excavated hole A formed in the ground, and burying the steel core material 1b in a pile top part of a foundation pile 2; a process of feeding hard granular material 3 in the periphery of the steel core material 1b; and a process of feeding back filling material 4 on the upside of the hard granular material 3. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an installation method for underground floor pillars and a construction method for underground structures.

  After installing the structural pillar that is the core of the pillar of the underground structure (including the basement floor of the building) in the ground, a top slab (advanced slab) is built on top of the structural pillar, and then the top slab A method (so-called reverse driving method) for constructing underground structures by excavating the lower side is known. In many cases, the structural pillar is made of a steel frame such as H-shaped steel.

  In the general reverse driving method, after excavating the ground to expose the structural pillar, the pillar is constructed by placing concrete around the structural pillar. There is also known a reverse casting method that simplifies the concrete placing work by using a unit (hereinafter referred to as “basement column”) replaced with a precast concrete member (see Patent Documents 1 to 3).

JP-A-62-86242 JP 63-67344 A JP-A-8-68057

  In the reverse driving method disclosed in Patent Documents 1 and 2, the subsequent steps are performed in a state where the periphery of the underground floor column is backfilled with excavated residual soil or the like. However, since the underground floor pillars of Patent Documents 1 and 2 have a top heavy structure, they may move from a predetermined installation position during floor excavation.

  In addition, in the underground floor pillars of Patent Documents 1 and 2, there is a portion where the steel frame is exposed (that is, a portion embedded in the foundation frame), so when placing concrete for the foundation frame Therefore, it is necessary to carefully clean up the backfill (excavated soil) that has adhered to the steel surface.

  From this point of view, the present invention is a method for installing a basement column including a precast concrete part, and is difficult to cause a shift in the installation position of the basement column in a process performed after the construction, and for a foundation frame. An object of the present invention is to provide a method of installing an underground floor pillar that can reduce the cleaning work performed before placing concrete, and further, a method for constructing underground structures including the method of installing this underground floor pillar. The issue is to provide.

  The basement column installation method according to the present invention is a method for inserting a basement column having a column part made of precast concrete and a steel core extending downward from the column part into an excavation hole formed in the ground. A step of burying the lower end portion of the steel core material in the pile head of the foundation pile, a step of introducing a hard granular material around the steel core material, and a backfill material on the upper side of the hard granular material And a step of installing the underground floor pillar.

  “Hard granular material” is a general term for granular hard materials (for example, crushed stone, slag, concrete pieces, etc.) that are not thawed or altered by drilling mud or groundwater.

  According to the present invention, since the steel core extending below the column part is rooted by the hard granular material, the installation position of the basement column is compared to the case where it is rooted by mere excavation residual soil It becomes difficult to slip. Further, according to the present invention, the steel core material is covered with the hard granular material that is difficult to be mud, so that it is difficult for mud or the like to adhere to the surface of the steel core material. It becomes possible to reduce the cleaning work of the steel core material performed before placing.

The underground structure construction method according to the present invention uses the above-described underground floor pillar installation method according to the present invention.
That is, the construction method of the underground structure according to the present invention includes a step of installing the underground floor pillar by the above-described method of installing the underground floor pillar according to the present invention, a top slab, and the top slab to the basement floor. A step of supporting by a pillar, a step of excavating the lower side of the top slab, a step of spreading the hard granular material on the floored surface of the foundation frame to form an underlayer, and on the underlayer Placing the concrete for the foundation frame and burying the steel core material exposed from the pile head in the foundation frame.

  According to the present invention, since the hard granular material thrown around the steel core material is spread and leveled on the floored surface, it is possible to omit or reduce the work of carrying in, for example, quarry stone.

  Note that the “underground structure” in the present invention includes not only a structure constructed entirely under the ground but also a structure constructed under the ground structure such as a basement floor of a building or the like.

  ADVANTAGE OF THE INVENTION According to this invention, it becomes difficult to generate | occur | produce a shift | offset | difference in the installation position of an underground floor pillar, and it becomes possible to reduce the cleaning operation performed before placing concrete for foundation frame.

  An example of the best mode for carrying out the present invention will be described in detail with reference to the accompanying drawings. In addition, although the case where a basement floor, such as a building, is constructed is illustrated in the following embodiments, the scope of application of the present invention is not limited.

  The underground structure construction method according to the present embodiment includes an underground floor pillar installation process (see FIGS. 1 and 2), a top slab construction process (see (a) of FIG. 3), and an underground intermediate floor construction process ( 3 (b) in FIG. 3) and a basic chassis construction step (see FIG. 4).

  The underground floor pillar installation process (the installation method of the underground floor pillar according to this embodiment) is a process of installing the underground floor pillar 1 in the ground as shown in FIGS.

  As shown in FIG. 1A, the basement column 1 includes a precast concrete column portion 1a and a steel core 1b extending downward from the column portion 1a. The column part 1a consists of reinforced concrete, and the steel core material 1b consists of steel frames (for example, H-section steel). The upper part of the steel core 1b is embedded in the column part 1a. There is no restriction | limiting in the structure of the pillar part 1a, For example, the pillar part 1a may be comprised with a single precast member, or even if it connects the some precast member in the up-down direction, and comprises the pillar part 1a. Good.

  The underground floor pillar installation process of the present embodiment includes a drilling process, a reinforcing bar punch insertion process, an underground floor pillar insertion process (see FIG. 1A), and a pile concrete placing process (see FIG. 1B). ), A lower backfilling step (see FIG. 2A), an upper backfilling step (see FIG. 2B), and the like.

  The drilling step is a step of forming an excavation hole A (see FIG. 1A) that reaches the support ground (not shown), and the reinforcing rod insertion step is a reinforcing rod 2a for the foundation pile 2 (in FIG. 1). (See (a)). A casing (not shown) for preventing the hole wall from collapsing is inserted into the upper end of the excavation hole A.

  The underground floor pillar insertion process is a process of building the underground floor pillar 1 into the excavation hole A as shown in FIG. When the basement column 1 is built, for example, the basement column 1 connected to a Yatco (extension jig) Y is suspended in the excavation hole A by a crane (not shown) and the lower end of the steel core 1b. May be placed on the upper surface of the holding base K while the bracket B is attached to the side surface of the Yattoko Y while inserting the upper end of the reinforcing bar 2a. The horizontal position of the basement column 1 is adjusted using a jack (not shown) attached to the holding frame K. Specifically, for example, the horizontal position of the basement column 1 may be adjusted by arranging jacks at four locations on the front, rear, left, and right sides of the Y-cots Y and appropriately expanding and contracting a pair of jacks facing each other with the Y-cots Y interposed therebetween. . Moreover, the height position of the underground floor pillar 1 is adjusted using a jack (not shown) interposed between the holding base K and the bracket B. Incidentally, the upper end of the column part 1a is made to coincide with the lower end of the large beam 5a (see FIG. 3A) that supports the top slab 5, and the lower end of the column part 1a is the top of the foundation frame 9 (see FIG. 4B). Position slightly below the edge.

  The concrete placing process for piles is a process for placing concrete for foundation piles 2 as shown in FIG. When placing concrete, a tremy tube (not shown) inserted between the underground floor column 1 and the hole wall of the excavation hole A is used. After passing through the concrete placing process for piles, the lower end portion of the steel core 1b is buried in the pile head of the foundation pile 2. When the concrete for the foundation pile 2 reaches a predetermined strength, the Yatco Y is removed, and the underground floor column 1 is fixed to a casing (not shown) provided at the upper end of the excavation hole A. In addition, after performing the concrete placing process for piles, an underground floor pillar insertion process may be performed.

  The lower backfilling step is a step of putting the hard granular material 3 around the steel core 1b as shown in FIG. The hard granular material 3 is made of a granular hard material (for example, crushed stone, slag, concrete pieces, etc. having a particle diameter of 20 mm to 40 mm) that is not thawed or altered by drilling mud or groundwater. Although there is no restriction | limiting in the range with which the hard granular material 3 is filled, Fill the hard granular material 3 around the site | part embed | buried in the base frame 9 (refer FIG.4 (b)) among the underground floor pillars 1. FIG. Is desirable. In the present embodiment, the space around the exposed portion of the steel core 1b (the portion located between the lower end surface of the column portion 1a and the upper end surface of the foundation pile 2) and the space around the lower end portion of the column portion 1a. Are filled with hard granular material 3.

  The upper backfilling step is a step of feeding the backfilling material 4 to the upper side of the hard granular material 3 as shown in FIG. There is no restriction | limiting in the kind etc. of the backfilling material 4, An appropriate material can be used. For example, the above-described hard granular material may be used as the backfill material 4, and the residual soil generated when the excavation hole A is drilled may be used as the backfill material 4. In addition, what is necessary is just to use the thing which dried or solidified as the backfill material 4 when residual soil is sludge.

  If the underground floor pillar installation process (the installation method of the underground floor pillar which concerns on this embodiment) including each process mentioned above is completed, as shown to (a) of FIG. 3, it will transfer to a top slab construction process.

  As shown in FIG. 3A, the top slab construction step is a step of constructing a top slab 5 to be a floor slab on the first floor of the building and supporting the top slab 5 on the underground floor columns 1 and 1. In the top slab construction process of the present embodiment, a process of excavating the ground to a predetermined depth inside the retaining walls W, W (primary excavation process), a process of arranging a formwork and reinforcing bars (not shown) for the top slab 5 The process includes placing concrete in the mold. In addition, the top slab 5 of this embodiment is integrally formed with the large beam 5a which connects the upper end parts of the adjacent underground story columns 1 and 1, and is supported by the underground story columns 1 and 1 via the large beam 5a. The top slab 5 serves as a work floor when performing processes after the top slab construction process.

  As shown in FIG. 3 (b), the underground intermediate floor construction process is a process of constructing an intermediate slab 6 that becomes a floor slab of the underground intermediate floor, a large beam 6a that connects the intermediate portions of the underground floor pillars 1 and 1, and the like. is there. In the underground intermediate floor construction process of the present embodiment, a process of excavating the ground below the top slab 5 to a position below the planned construction position of the intermediate slab 6 and the large beam 6a (secondary excavation process), It includes a step of placing a formwork and a reinforcing bar (not shown), a step of placing concrete in the formwork, and the like.

  In addition, when not building a basement intermediate floor, a basement intermediate floor construction process is abbreviate | omitted, and when building a some underground basement floor, a basement intermediate floor construction process should just be repeated. Further, the intermediate slab 6 and the large beam 6a may be constructed after constructing the underground frame 9 (see FIG. 4B).

  As shown in FIGS. 4A and 4B, the foundation chassis construction process is a process of constructing the foundation chassis 9 below the top slab 5. In addition, although illustration is abbreviate | omitted, the foundation frame 9 of this embodiment is equipped with the foundation beam which connects the upper end parts of the adjacent foundation piles 2 and 2, and the floor slab of the lowest floor.

  The foundation frame construction process of the present embodiment includes a flooring excavation process, a foundation layer forming process, a placing preparation process, a concrete placing process for foundation foundations, and the like.

  The flooring excavation step is a step of excavating the lower ground of the intermediate slab 6 to the lower side of the construction planned position of the foundation frame 9.

  The underlayer forming step is a step of forming the underlayer 7 by spreading the hard granular material 3 (see FIG. 3B), which has been introduced around the steel core 1b, on the floored surface. . When the amount of the hard granular material 3 is insufficient, the amount of cracked stone corresponding to the shortage is carried in.

  The placing preparation step is a step of placing the discarded concrete 8 on the foundation layer 7 and arranging the formwork and reinforcing bars for the foundation frame 9 on the hardened discarded concrete 8.

  As shown in FIG. 4 (b), the concrete placing process for the foundation frame is placed from the pile head of the foundation pile 2 by placing concrete for the foundation frame 9 on the discarded concrete 8 or in the formwork. This is a step of embedding the steel core 1b in the foundation housing 9. Prior to the concrete placing process for the foundation frame, cleaning is performed on the lower end of the column part 1a and the exposed portion of the steel core 1b (that is, the part embedded in the foundation frame 9). In the present embodiment, since the hard granular material 3 that is unlikely to be mud is filled around the lower end of the pillar portion 1a and the exposed portion of the steel core material 1b, the surface of the steel core material 1b or the like is mud. Therefore, the cleaning work is easier than in the case of backfilling with excavated residual soil that tends to be mud.

  The construction method of the underground structure according to the present embodiment includes the steps as described above, and the underground structure (underground floor) can be constructed through the above steps.

  According to the installation method of the underground floor pillar according to the present embodiment, the steel core 1b of the underground floor pillar 1 is rooted by the hard granular material 3, so that it is compared with a case where the steel core material 1b is rooted by simple excavation residual soil. The installation position of the underground floor pillar 1 becomes difficult to shift. Moreover, according to the construction method of the underground structure according to the present embodiment, since the hard granular material 3 thrown around the steel core 1b is spread on the floored surface, the work of carrying in, for example, quarrel stone Can be omitted or reduced.

(A) And (b) is typical sectional drawing for demonstrating the installation method of the underground floor pillar which concerns on one Embodiment of this invention, and the construction method of an underground structure. (A) And (b) is typical sectional drawing for demonstrating the process following (b) of FIG. (A) And (b) is typical sectional drawing for demonstrating the process following (b) of FIG. (A) And (b) is typical sectional drawing for demonstrating the process following (b) of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Basement column 1a Column part 1b Steel core material 2 Foundation pile 3 Hard granular material 4 Backfill 5 Top slab 6 Intermediate slab 7 Underlayer 8 Discarded concrete 9 Foundation frame A Drilling hole

Claims (2)

A basement column having a precast concrete column and a steel core extending downward from the column is inserted into an excavation hole formed in the ground, and the lower end of the steel core is used as a foundation. A process of burying in a pile head,
Introducing a hard granular material around the steel core;
And a step of introducing a backfill material to the upper side of the hard granular material. A basement column having a precast concrete column and a steel core extending downward from the column is inserted into an excavation hole formed in the ground, and the lower end of the steel core is used as a foundation. A process of burying in a pile head,
Introducing a hard granular material around the steel core;
Introducing a backfill material above the hard granular material;
Constructing a top slab and supporting the top slab on the basement pillar;
Drilling the underside of the top slab;
Laying and leveling the hard granular material on the flooring surface of the foundation housing to form an underlayer;
Constructing an underground structure characterized by including placing the concrete for the foundation frame on the foundation layer and burying the steel core material exposed from the pile head in the foundation frame Method.

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