JP6539566B2 - Construction method of cast-in-place concrete pile - Google Patents

Description

The present invention relates to a method of constructing cast-in-place concrete piles to be built in a ground having a cavity, and prevents cast-out of the pile body accompanying flow of the concrete to the cavity side and pours out cast-in-place concrete piles of uniform cross section. It was designed to be constructed.

  In general, cast-in-place concrete piles are constructed by placing a rebar cage in a pile hole excavated to a predetermined depth by an earth drilling method or the like and placing concrete.

  In addition, especially for the construction of cast-in-place concrete piles in ultra soft layer ground such as peat layer and buried ground, casing pipe (not shown) for hole wall protection in preparation for hole wall collapse etc. at the time of excavation and concrete placement. May be used.

  Furthermore, during concrete casting, the concrete flows to the hole wall side and the pile body is pumped out, or the concrete is not permeable to the earth and sand etc. along with the collapse of the hole wall, and a permeable net is formed on the outer periphery of the rebar cage. It is also done to set up.

  By the way, as a result of previous data and boring survey, hollows may appear in the ground, especially in the ground including limestone layers. In addition, there are also cases where air-barriers and underground burials excavated during wartime appear as hollows.

  Conventionally, when a cast-in-place concrete pile is constructed on the ground having such a cavity, a casing is partially installed as a concrete form in a portion passing through the cavity of the reinforcing steel cage erected in the pile hole, Alternatively, winding a wire or the like to reinforce the net so that concrete does not flow to the cavity side and is not pumped out.

Patent No. 3963921 JP, 2006-241919, A JP, 2005-264522, A

  However, there is also a method in which the casing is partially installed in a portion which penetrates the cavity of the reinforcing bar cage, but there is a problem that the handling is complicated and the cost is increased.

  On the other hand, in the method of reinforcing the net by winding the numbering wire from the upper side of the net around the reinforcing bar cage, the numbering wire is easily deformed and has poor restoring force (elastic force). It was not easy to keep the cross section in a uniform cross-sectional shape, and the restraint band in this case was poor in certainty.

The present invention has been made to solve the above problems, and in constructing cast-in-place concrete piles in a ground having a cavity, preventing the flow of concrete to the cavity side and the exudation accompanying the flow. It is an object of the present invention to provide a method of constructing a cast-in-place concrete pile in which a pile body of uniform cross section can be constructed.

The present invention relates to a permeable net installed in the outer periphery of the reinforcing bar and a reinforcing bar in the ground having a cavity, and a cast-in- place concrete pile formed through the cavity from concrete cast in the network. The pile hole is excavated while protecting the hole wall by the casing in the ground having a cavity, and a permeable net is formed on the outer periphery of the portion in contact with the hole wall of the rebar cage and the portion passing through the cavity. Are installed, and a plurality of flat bands made of flat steel are attached from the top of the net to the outer periphery of the part passing through the cavity of the reinforcing bar cage, and the reinforcing bar cage attached with the net and the constraining band is placed in the casing of the pile hole It is characterized by putting up, putting concrete in the net, and withdrawing the casing.

  In particular, when the pile body penetrates the cavity and the friction with the surrounding ground is insufficient, it is sufficient to increase the circumferential surface area of the pile body by increasing the length or the pile diameter of the pile body.

  A permeable net made of chemical fiber such as polyethylene is suitable for the net, and the net may be wound around the outer periphery of the reinforcing bar cage on the ground and installed together in a pile hole together with a reinforcing rod. In addition, by interposing a spacer and winding the net around the reinforcing bar cage, it is possible to secure a sufficient thickness of concrete for the reinforcing bar cage.

  The restraint band is suitably flat steel, and the thickness and width of the restraint band differ depending on the pile diameter and the installation interval of the restraint band etc. However, if the thickness is about 3 to 4.5 mm, processing is relatively easy. In order to have an appropriate restoring force (elastic force), it is desirable to be able to maintain the concrete cast in the net in a uniform cross-sectional shape.

  In addition, the restraint bands can be attached at intervals in the axial direction of the reinforcing bar cage, and the intervals can be made optimum in consideration of the depth of the cavity, the side pressure of the concrete placed in the net, and the like. In addition, as long as the constraining band can hold the concrete cast in the net in a uniform cross-sectional shape, it is possible to form and use a shaped steel such as a channel steel in a ring shape.

  Furthermore, the restraint band can be easily wound in a ring shape or a spiral or spiral form over the net from the top of the net around the reinforcing bar cage, and can be easily bound to the spacer by welding or a tie wire such as a wire. It can be attached.

  Further, the restraint band may be divided into a plurality of pieces in the circumferential direction, and a plurality of pieces may be connected to each other by a connection bolt or the like according to the diameter of the reinforcing bar cage to form one restraint band.

  Further, by providing a rib which is continuous on the surface of the restraint band in the circumferential direction of the restraint band to impart rigidity, it is possible to make the restraint band thinner and to achieve weight reduction, material saving, and the like.

  If the inner diameter of the casing is smaller than the outer diameter of the reinforcing bar cage, the net will be caught between the reinforcing bar cage and the casing when the casing is pulled out and it will be easier to compete, so it will be comparable to the outer diameter of the reinforcing bar cage. It is desirable that the one with a slightly larger inner diameter is used.

  On the other hand, if the clearance between the casing and the reinforcing bar cage is large, the reinforcing bar cage is inclined or deviated to one side in the casing, so a spacer is attached to the outer periphery of the reinforcing bar cage so that the reinforcing bar cage is located at the center in the casing. It is desirable to do.

  The spacer in this case is preferably formed to reduce friction with the casing. For example, it may be formed in a V-shape or a W-shape from a plate or a reinforcing bar, and all these spacers penetrate the mesh of the net and are attached to the main bars, and the main bars are easy by welding or binding wires Can be attached to Further, it may be attached at appropriate intervals in the circumferential direction and the axial direction (vertical direction) of the reinforcing bar cage.

  In addition, it may be formed in a ring shape in the circumferential direction of the reinforcing bar cage, as long as it can be attached to the outside of the net so as to secure sufficient covering of concrete with the reinforcing bar cage and the net. .

  In this case, for example, a plurality of rod-like members (reinforcing bar etc.) may be projected radially from the reinforcing bar cage side to the outside of the net through the net, and a ring-shaped spacer may be attached to the tip of the plurality of rod-like members.

  Also, similar to the restraint band, it may be divided into a plurality of pieces in the circumferential direction, and the plurality of pieces may be connected to each other by a connection port or the like according to the diameter of the reinforcing bar cage to form one spacer.

  The present invention can prevent a hole wall from collapsing due to drilling even in a ground having a cavity by digging a pile hole while protecting the hole wall by a casing, and a pile hole of a predetermined diameter and a predetermined depth can be obtained. It can be dug well.

  Also, by placing a water-permeable net around the reinforcing bar cage via a spacer, and installing a plurality of restraint bands from the top of the net at the part that penetrates the cavity, the hollow of concrete placed in the net It is possible to construct a cast-in-place concrete pile of uniform cross section while preventing side flow and stagnation.

  Also, the restraint band is formed of flat steel having a certain width, and in order to hold the concrete cast in the net by the surface, the net is in the vicinity of the restraint band due to the lateral pressure of the concrete cast in the net. There is nothing to break.

The cast-in-place concrete pile constructed by the construction method of cast-in-place concrete pile of the present invention is shown, FIG. 1 (a) is a longitudinal sectional view, and FIG. 1 (b) is an I--I cross-sectional view in FIG. FIG. 1 (c) is a cross-sectional view taken along the line of FIG. 1 (b). Fig.2 (a), (b), (c), (d) is a longitudinal cross-sectional view which shows the procedure of the construction method of the cast-in-place concrete pile of this invention. Fig.3 (a), (b), (c) is a longitudinal cross-sectional view which shows the procedure of the construction method of the cast-in-place concrete pile of this invention. The construction method of the cast-in-place concrete pile of this invention is shown, and it is a longitudinal cross-sectional view of the casing in a ground, and a reinforcement cage. 5 (a) is a cross-sectional view taken along the line HA in FIG. 4, and FIG. 5 (b) is a cross-sectional view taken along the line ii in FIG. 5 (a). 6 (a) is a cross-sectional view taken along the line Ho in FIG. 4, and FIG. 6 (b) is a cross-sectional view taken along the line He--he in FIG.

  1 to 6 illustrate a cast-in-place concrete pile constructed in a ground having a cavity and a construction method thereof.

  In FIG. 1 (a) to (c), cast-in-place concrete pile 1 is constructed through the hollow A in the ground having the hollow A, and the cast-in-place concrete pile 1 stands rebar cage 3 in the pile hole 2. It is formed into a column of uniform cross section except for the lower end portion by pouring concrete 4 around it, and the lower end portion is formed by expanding the diameter so as to widen the end (expanded diameter pile).

  The reinforcing steel cage 3 is piled with a plurality of main bars 3a arranged at regular intervals along the inner periphery of the pile hole 2 and a plurality of hoop bars 3b arranged in a ring shape on the outer periphery of the main metal 3aa. It is assembled in a cylindrical cage shape slightly smaller in diameter than the inner diameter of the hole 2.

  A plurality of spacers 5 and 6 are attached to the reinforcing bar cage 3 respectively, and a permeable net 7 is attached to the outer side thereof so as to wrap the outer periphery of the reinforcing bar cage 3. Restraint band 8 is attached.

  Spacers 5 and 6 are attached to ensure the required covering thickness of the concrete 4 between each of the main bars 3a and the hoop bars 3b constituting the reinforcing bar cage 3 and the net 7.

  The spacer 5 is a protrusion 5a protruding in an arc shape in the outer direction of the reinforcing bar cage 3 in a vertical plane, and fixing portions 5b and 5b protruding along the axial direction of the main reinforcement 3a from upper and lower end portions of the protrusion 5a. And are formed from. Further, the spacers 5 are arranged at regular intervals in the axial direction of the main bars 3a, and fixed by welding the fixing portions 5b, 5b at the upper and lower ends to the main bars 3a or by tying them with a binding wire. There is. In addition, when the space | interval between adjacent main bars 3a and 3a is narrow, you may attach the spacer 5 to the main bars 3a of every one or multiple.

  The spacer 6 is formed of a reinforcing bar or the like, installed in a ring or spiral along the outer periphery of the reinforcing bar cage 3 and fixed by welding to the projecting portion 5 a of the spacer 5 or by binding with a binding wire. ing.

  The permeable net 7 forms a pile having a predetermined diameter without the concrete 4 cast in the pile hole 2 leaking into the ground around the pile hole 2 or involving the earth and sand associated with the hole wall collapse. In particular, in the part in contact with the cavity A.

  The restraint band 8 is installed to prevent the concrete 4 cast in the net 7 from flowing to the cavity A side and causing the pile body to largely pump out to the flow A side. It is attached from the upper side of the net 7.

  In addition, the restraining band 8 is formed in a ring shape from flat steel, and is bound by welding or a binding wire or the like to the tip of each projecting portion 5 a of the plurality of spacers 5 adjacent in the circumferential direction of the reinforcing bar cage 3 It is fixed, and both ends are connected to each other by overlapping connection bolts (not shown).

  Further, the restraint band 8 is attached at regular intervals in the vertical direction of the reinforcing bar cage 3, and the width, thickness and installation interval etc. are optimum widths depending on the depth of the cavity A and the side pressure of the concrete 4 in the net 7, etc. Set to thickness and spacing.

  Furthermore, the restraint band 8 is formed of flat steel. The flat steel restraint band has a predetermined width and has a certain elastic force (restoring force), so the uncured concrete 4 cast in the net 7 flows to the cavity A side and is largely stagnant It is preferable from the viewpoint that it can be held in a cylindrical shape so as not to be ejected, and that the net 7 can be prevented from being torn by impact or side pressure when concrete 4 is placed in the net 7. In addition, while the net | network is easily broken by the side pressure of concrete, it is easy to deform | transform and it is hard to hold | maintain the concrete in a net | column in the column shape in the restraint band which consists of wire materials, such as a number wire.

  The restraint band 8 may be a shaped steel such as a channel steel as long as it holds the concrete in the net 7 in a plane, and the restraint band 8 is installed at regular intervals in the vertical direction of the reinforcing bar cage 3 However, it may be installed spirally in the vertical direction of the reinforcing bar cage 3.

  Next, the procedure of the construction method of the cast-in-place concrete pile of the present invention will be described (see FIGS. 2 to 6).

  (1) First, the pile hole 2 is excavated. The pile hole 2 is excavated by an excavator 10 such as a drilling bucket while protecting the hole wall by a casing 9. The casing 9 is press-fit into the ground while sequentially connecting short ones (2 to 3 m) by welding or the like as the depth of the pile hole 2 increases, and press-fits to the tip of the pile hole 2.

  If the inner diameter of the casing 9 is too small, the net 7 will be entrained between the reinforcing steel cage 3 and the casing 9 when the casing 9 is pulled out, and the inner diameter of the casing 9 will be the outer diameter of the reinforcing steel cage 3 A slightly larger one is desirable. Further, if the inner blade is attached to the end of the casing 9, there is a possibility that the net 7 may be broken when the casing 9 is pulled out, so the inner blade is not provided.

  (2) Next, the casing 9 is left in the pile hole 2 and only the excavator 10 is pulled out (FIG. 2 (c)). Then, the reinforcing steel cage 3 is erected in the casing 9 of the pile hole 2 (FIG. 2 (d)). A plurality of spacers 5 and spacers 6 are attached to the reinforcing steel cage 3 beforehand, a water-permeable net 7 is installed on the outer periphery thereof, and a restraining band 8 is attached to a portion located in the cavity A.

  In addition, the site work can be efficiently performed by attaching the spacer 5 and the spacer 6 when assembling the reinforcing steel cage 3 in a factory or the like. In addition, the net 7 is installed on the outer periphery of the reinforcing bar cage 3 on site, and is fixed to the protruding portion 5 a of the spacer 5 by binding with a binding wire or the like. Furthermore, in particular, it is desirable to install the net 7 in a double position in the portion located in the cavity A.

  In addition, it is desirable to attach a spacer 11 from the top of the net 7 to the outer periphery of the reinforcing bar cage 3 so that the reinforcing bar cage 3 is not inclined or deviated to one side in the casing 9 (FIG. 1 (a), (b)) .

  The spacers 11 may be attached to at least the upper and lower end portions of the reinforcing steel cage 3 and a plurality of intermediate portions (excluding the hollow A portion). The spacer 11 is preferably formed to reduce friction with the casing 9. For example, it may be V-shaped or W-shaped as viewed from the side from a plate or a reinforcing bar, and all these spacers penetrate the mesh of the net 7 and are attached to the main bar 3a, and the main bar 3a It can be easily attached by welding or binding wire. Also, the reinforcing bar cage 3 may be attached at appropriate intervals in the circumferential direction and in the axial direction (vertical direction).

  (3) Next, concrete 4 is placed around the reinforcing bar cage 3 in the net 7 using the tremy pipe 12 (see FIG. 3A). The tremy pipe 12 is erected at the center of the reinforcing steel cage 3 and its tip end is constantly inserted into the cast concrete 4 for a certain length to prevent mixing of air, separation of concrete and the like.

  Further, when the tip of the tremy pipe 12 is at the same position for a long time, the load of the concrete 4 is concentrated on the net 7, so the tip is raised as the bulk of the concrete 4 increases. In this case, using a short (about 2 to 3 m) detachably connected to the trimmy pipe 12, the bulk of the concrete 4 may be increased to be removed stepwise from the tip as the upper surface rises.

  (4) Then, when the concrete 4 is cast to the upper end of the pile hole 2, the casing 9 is gradually pulled out to complete the construction of the cast-in-place concrete pile 4 (see FIG. 3C).

  The present invention can construct cast-in-place concrete of uniform cross section in the ground having a cavity.

1 cast-in-place concrete pile
Reference Signs List 2 pile hole 3 reinforcement cage 4 concrete 5 spacer 6 spacer 7 permeable net 8 restraint band 9 casing
10 excavators
11 Spacer
12 Tremy tube

Claims (4)

  In a method of constructing a cast-in-place concrete pile formed through the hollow from a concrete placed in the net and a permeable net installed in the outer periphery of the reinforcing bar cage in the ground having the hollow The pile hole is excavated through the cavity while protecting the hole wall by the casing in the ground having the cavity, and a permeable net is formed around the portion in contact with the hole wall of the reinforcing steel cage and the portion penetrating the cavity. Are installed, and a plurality of flat bands made of flat steel are attached from the top of the net to the outer periphery of the part passing through the cavity of the reinforcing bar cage, and the reinforcing bar cage attached with the net and the constraining band is placed in the casing of the pile hole. A method of constructing a cast-in-place concrete pile, comprising putting up concrete, placing concrete in the net, and pulling out the casing.   In the construction method of the cast-in-place concrete pile according to claim 1, the water-permeable net is installed on the outer periphery of the reinforcing bar cage via a plurality of spacers, and the restraint band is fixed to the spacers. Construction method of cast-in-place concrete pile. The method of constructing a cast-in-place concrete pile according to claim 1 or 2, characterized in that a spacer holding a gap between the reinforcing bar cage and the casing is attached to the outer periphery of the reinforcing bar cage.   The method for constructing a cast-in-place concrete pile according to any one of claims 1 to 3, wherein the restraint band is attached in a ring shape or a spiral shape.

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