JP2006299701A - Method of constructing precast concrete wall body by using self-hardening stabilizing liquid - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve various problems caused by increase in viscosity and specific gravity of a self-hardening stabilizing liquid, and to reuse the self-hardening stabilizing liquid which has overflowed due to erection of a precast concrete member. <P>SOLUTION: There is provided a method of constructing a precast concrete wall body by using the self-hardening stabilizing liquid. According to the method, the ground 2 is excavated while a hole wall is protected by using the self-hardening stabilizing liquid 1 to which a hardening retardant is added, to thereby form a trench-like excavated hole 3 in the ground. Then the precast concrete member 21 is lifted down into the excavated hole, and when the self-hardening stabilizing liquid 1 is hardened, the precast concrete wall body 4 is constructed in the ground 2. In the excavation step, a dispersing agent formed of a polyacrylate, a polymethacrylate, or a copolymer of them, and having a weight-average molecular weight Mw in the range of 10,000 to 14,000, is added to the self-hardening stabilizing liquid 1. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a construction method of a PC wall body using a self-hardening stabilizer applied when constructing a water blocking wall or a revetment using a precast member.

  By embedding precast concrete members (hereinafter referred to as PC members) typified by precast concrete plates in the ground to form PC wall bodies, the PC wall bodies can be used for various purposes such as water barriers, revetments, underground dams, etc. As a method of embedding PC members in the ground, a method of press-fitting PC members into the ground while excavating the ground with an auger, or a ground continuous wall is used. There is known a method in which a PC member is excavated in a trench shape, and thereafter, a PC member is built in an excavation hole filled with a stabilizing liquid.

  Here, when excavating the ground, in order to stabilize the hole wall of the excavation hole, usually a stabilizing liquid composed of mud water is used. Among such stabilizing liquids, a self-hardening stabilizing liquid is usually used during excavation. In the same way as the stable liquid, the collapse of the hole wall is prevented, and after drilling, the self-hardening stable liquid itself hardens and builds an underground wall with high water-stopping properties together with the PC wall. It is especially powerful in the layer.

Japanese Patent No. 3087961 JP-A-4-351691 JP-A-7-138666

  However, in constructing a PC wall body with a PC member while stabilizing the hole wall using a self-hardening stabilizer, the following problems have occurred.

  That is, during excavation, viscous soil is mixed in the self-hardening stabilizing liquid in the hole wall and the viscosity increases. As a result, the specific gravity increases, so that the buoyancy is obstructed when the PC member is suspended. The problem that it was not possible to secure the property or that the installation itself was difficult occurred.

  In addition, it takes time to suspend the excavation bucket due to the increase in viscosity, and a vicious cycle occurs in which the viscosity of the self-hardening stable liquid further increases during the elapsed time, and the self-hardening stable liquid with increased viscosity adheres to the excavated sediment. Therefore, it is necessary to replenish a new self-stabilizing stabilizer, and it is necessary to clean the self-stabilizing stabilizer adhering to the drilling bucket. There were a number of problems that changed and caused quality degradation.

  These problems are slightly improved by adding a retarder to the self-hardening stabilizer, but are far from a radical solution.

  In addition, if the PC member is suspended in the excavation hole filled with the self-hardening stabilizing liquid, the self-hardening stabilizing liquid corresponding to the volume of the PC member overflows. Although it is necessary to temporarily store, since the self-hardening stabilizer is literally self-hardening, it hardens in about several hours to half a day, and as a result, it is difficult to reuse it for the next day's construction. There was a problem that it was expensive to dispose of the overflowing self-hardening stabilizer.

  The present invention has been made in consideration of the above-mentioned circumstances, and solves various problems caused by the increase in viscosity and specific gravity of the self-hardening stabilizing liquid, and the self-hardening stabilizing liquid overflowed by installing the PC member. It aims at providing the construction method of the PC wall body using the reusable self-hardening stabilizer.

  In order to achieve the above object, the method for constructing a PC wall body using the self-hardening stabilizer according to the present invention provides pore wall protection with a self-hardening stabilizer containing a curing retarder as described in claim 1. By excavating the ground while planning, a trench-shaped excavation hole is formed in the ground, a PC member is suspended in the excavation hole, and a PC wall body is constructed in the ground by hardening of the self-hardening stabilizing liquid. In the method for constructing a PC wall body using a self-hardening stabilizer, a dispersant comprising a polyacrylate, a polymethacrylate or a copolymer thereof and having a weight average molecular weight Mw of 10,000 to 14,000 in the excavation step. Is added to the self-hardening stabilizer.

  Moreover, the construction method of the PC wall body using the self-hardening stabilizer according to the present invention, as described in claim 2, excavates the ground while protecting the hole wall with the self-hardening stabilizer added with a retarder. By forming a trench-shaped excavation hole in the ground, a PC member is suspended in the excavation hole, and a self-hardening stabilizing liquid that builds a PC wall body in the ground by curing the self-hardening stabilizing liquid In the construction method of the used PC wall body, in the excavation step, polyacrylate, polymethacrylate or a copolymer thereof and sodium carbonate are used, and the polyacrylate, polymethacrylate or the like A dispersant having a weight average molecular weight Mw of 10000 to 14000 of the copolymer is added to the self-hardening stabilizer.

  Moreover, the construction method of the PC wall body using the self-hardening stabilizer according to the present invention is a monovalent salt of the polyacrylate, polymethacrylate, or a copolymer thereof.

  Further, in the method for constructing a PC wall body using the self-hardening stabilizing liquid according to the present invention, the self-hardening stabilizing liquid sucked from the excavation hole is stored in a storage tank and stored. The self-hardening stabilizer is reused for the next excavation process.

  The dispersant used in the method for constructing a PC wall body using the self-hardening stabilizer according to the present invention has the effect of remarkably dispersing fine particles of soil together with the dispersant according to claim 1 and the dispersant according to claim 2. In addition, since the dispersion action continues for a long time, the self-hardening stabilizer in the drilling hole maintains low viscosity and suppresses the increase in specific gravity even when viscous soil is mixed during drilling. Thus, various problems due to an increase in viscosity and an increase in specific gravity can be greatly improved, and the construction of the PC wall can be advanced efficiently.

  In addition, instead of the conventional bentonite etc., the dispersed fine particles of soil form a good quality mud cake with a small amount of filtrate (water permeability coefficient) on the hole wall, and stabilize the hole wall.

  The dispersant used in the invention according to claim 1 may be composed only of polyacrylate or polymethacrylate, or may be composed of a copolymer thereof. Moreover, you may use these copolymers together. Here, the weight average molecular weight Mw was set to 10000 to 14000 in the experiment, and if it is within such a range, it is possible to perform the function as muddy water only with fine particles of soil particles without using bentonite or the like. This is because it was confirmed. Incidentally, the weight average molecular weight Mw is obtained on the basis of polystyrene by gel permeation chromatography (GPC).

  The dispersant used in the invention according to claim 2 is composed of polyacrylate, polymethacrylate or a copolymer thereof, and sodium carbonate. The sodium carbonate is excessively polyacrylate or the like. To prevent the soil from adsorbing to the fine particles of the soil, and to save the amount of polyacrylate and the like. Sodium carbonate may be mixed in advance in polyacrylate or the like to form a single agent, or may be mixed on site.

  Such a dispersant may be a combination of polyacrylate or polymethacrylate and sodium carbonate, or a combination of polyacrylate and polymethacrylate copolymer and sodium carbonate. Two or more of these copolymers may be used in combination with sodium carbonate. Here, the weight average molecular weight Mw of the polyacrylate or the like may be set as appropriate. However, when this is particularly set to 10,000 to 14,000, only a fine fraction of soil particles can be used as a stable liquid without using bentonite or the like. It was confirmed by experiment that the function of can be performed remarkably. Incidentally, the weight average molecular weight Mw is obtained on the basis of polystyrene by gel permeation chromatography (GPC).

  In the inventions according to claims 1 and 2, if the weight average molecular weight Mw is in the above range, the fine particles of the soil particles can be remarkably dispersed, but the above-mentioned polyacrylate, polymethacrylate or If these copolymers are monovalent salts such as alkali metal salts and ammonium salts such as sodium salts, potassium salts, and lithium salts, the function as a stabilizer can be reliably obtained with a small addition amount. .

  Here, in the suspending step, the self-hardening stabilizing liquid sucked from the excavation hole is stored in a storage tank, and the stored self-hardening stabilizing liquid is reused in the next excavation step. Eliminates the need to dispose of the self-hardening stabilizer.

  Hereinafter, an embodiment of a construction method of a PC wall body using a self-hardening stabilizer according to the present invention will be described with reference to the accompanying drawings. Note that components that are substantially the same as those of the prior art are assigned the same reference numerals, and descriptions thereof are omitted.

  FIG. 1 is a flowchart showing a procedure for carrying out a PC wall construction method using a self-hardening stabilizer according to the present embodiment. As can be seen from the figure, in the construction method of the PC wall body using the self-hardening stabilizer according to this embodiment, first, as shown in FIG. 2, a self-hardening stabilizer to which a curing retarder and a dispersant are added. By excavating the ground 2 while protecting the hole wall at 1, a trench-shaped excavation hole 3 is formed in the ground (step 101).

  In this process, excavation of, for example, a length of 5 m and a width of 1 m is performed so as to be adjacent to the joint box 5 provided at the end of the PC wall body 4 that has been previously constructed and to extend to the PC wall body 4. Hole 3 is formed.

  What is necessary is just to use what is marketed, for example with the brand name of a geoliter (trademark), for example.

  On the other hand, the dispersant is composed of a sodium salt of polyacrylic acid and has a weight average molecular weight Mw of 10,000 to 14,000. Specifically, what is marketed under the trade name of Super Slurry can be used.

  Such a dispersant has an action of remarkably dispersing fine particles of soil and the dispersion action continues for a long time. Therefore, by excavating the self-hardening stabilizing liquid 1 in the excavation hole 3, the excavation hole is obtained. The self-hardening stabilizing liquid 1 in 3 has a low viscosity and suppresses an increase in specific gravity even when viscous soil is mixed during excavation.

  In addition, instead of the conventional bentonite etc., the dispersed fine particles of soil form a good quality mud cake with a small amount of filtrate (water permeability coefficient) on the hole wall, and stabilize the hole wall.

  Next, as shown by the arrow in FIG. 3, the joint box 5 is pushed down and pushed to the excavation side by the jacks 11 and 11, and the adhesion to the PC wall 4 is cut (step 102). When the adhesion to the PC wall 4 is completely broken, the joint box 5 is pulled out with a crane.

  Next, as shown in FIG. 4, a new PC member 21 is suspended in the excavation hole 3, and the temporary receiving hardware 22 attached to the top of the PC member is received by the guide walls 23, 23 to temporarily hold the PC member 21. Provisionally accept (step 103).

  In such suspension, the self-hardening stabilizer 1 maintains a low viscosity and a low specific gravity by the action of the dispersing agent described above, so that no hindrance due to buoyancy or viscous resistance occurs and the suspension can be suspended smoothly.

  Here, with the suspension of the PC member 21, the self-hardening stabilizing liquid 1 in the drilling hole 3 by the slurry pump 24 so that the amount of the self-hardening stabilizing liquid 1 corresponding to the volume of the PC member 21 does not overflow from the drilling hole 3. Is sucked and stored in the storage tank 25.

  The stored self-hardening stabilizing liquid 1 is mainly composed of the action of the dispersing agent described above, and the low viscosity and low specific gravity are maintained for several days in combination with the action of the curing retarder.

  Next, as shown in FIG. 5, a box-shaped PC wall suspension member 31 is attached to the top of the PC member 21 with long bolts 32, and the PC wall suspension member is suspended by hanging a crane wire. Then, the temporary support 22 is removed, and then the PC member 21 is suspended to a predetermined position (step 104).

  Here, an L-shaped docking plate 33 is provided on one side at the lower end of the PC member 21 and a docking pin 34 is provided on the other side, and the docking pin 34 of the PC member 21 previously installed is provided. The lower end of the PC member 21 is positioned by engaging the docking plate 33 of the PC member 21 being suspended.

  Next, as shown in FIG. 6, the upper end of the fishing line 61 tied to the lower end of the PC member 21 is tied to the measuring table 62 with a predetermined tension, and the fishing line 61 is collimated from two directions using a transit 63 to change the fishing line. The knot portion is adjusted so that 61 is vertical, and then the top of the PC member 21 is positioned with reference to the vertically stretched fishing line (step 105).

  Thus, by repeating steps 103 to 105, the PC member 21 is suspended in a wall shape as shown in FIG.

  Finally, the joint box 5 is suspended along the end portion of the PC wall 4 in which the PC members 21 are connected, and the joint box 5 is engaged by the docking pin and the docking plate in the same manner as the connection between the PC members 21. Is fixed to the PC wall 4 (step 106).

  The series of steps 101 to 106 are repeated until the PC wall 4 reaches a desired length while waiting for the self-hardening stabilizer 1 to harden. At this time, the self-hardening stabilizer stored in the storage tank 25 is used. 1 is used in the next excavation process.

  As described above, according to the construction method of the PC wall body using the self-hardening stabilizer according to the present embodiment, the dispersant described above has an action of remarkably dispersing the fine particles of the soil, and the dispersing action thereof. Therefore, the self-hardening stabilizing liquid 1 in the excavation hole 3 maintains a low viscosity and suppresses an increase in specific gravity even if viscous soil is mixed during excavation. Various problems due to the increase in specific gravity can be greatly improved, and the construction of the PC wall 4 can be efficiently advanced.

  That is, since low specific gravity is maintained during excavation, the PC member 21 can be smoothly suspended in the excavation hole 3 and verticality can be easily ensured. In addition, since the low viscosity is maintained, it does not take time to hang the excavation bucket, and there is no concern that the self-hardening stabilizing liquid is pulled up from the excavation hole 3 together with the excavated earth and sand. As a result, new self-hardening There is no need to replenish the stabilizer. Furthermore, there is no need to clean the excavation bucket, and as a result, there is no situation in which the amount of blended water of the self-hardening stabilizing liquid changes and the quality is deteriorated.

  Moreover, according to the construction method of the PC wall body using the self-hardening stabilizing liquid according to the present embodiment, the self-hardening stabilizing liquid 1 sucked from the excavation hole 3 is stored in the storage tank 25 in the hanging process, Since the stored self-hardening stabilizing liquid 1 is reused for the next excavation process, the self-hardening stabilizing liquid 1 can be used effectively, and it is not necessary to dispose of it.

  In this embodiment, the dispersant is made of a polyacrylate, polymethacrylate or a copolymer thereof, and a dispersant having a weight average molecular weight Mw of 10,000 to 14,000, particularly a sodium salt of polyacrylic acid. Although a dispersant having a weight average molecular weight Mw of 10,000 to 14,000 was used, a monovalent salt such as an alkali metal salt such as a potassium salt or a lithium salt or an ammonium salt may be used instead of the sodium salt.

  Further, in this embodiment, the dispersant is composed of polyacrylic acid sodium salt. However, in place of such polyacrylic acid sodium salt, polymethacrylic acid sodium salt or a copolymer thereof may be used as described in the embodiment. The effect of this can be obtained.

  Further, in this embodiment, as the dispersant, a dispersant made of polyacrylate, polymethacrylate or a copolymer thereof and having a weight average molecular weight Mw of 10,000 to 14,000 was used. , Polyacrylic acid salt, polymethacrylic acid salt or copolymer thereof, and sodium carbonate, and the weight average molecular weight Mw of the polyacrylic acid salt, polymethacrylic acid salt or copolymer thereof is 10,000 to 14,000. Used dispersants can be used.

  Even with such a dispersant, the same effects as described in the embodiment can be obtained, but the description thereof is omitted here.

The flowchart which showed the implementation procedure of the construction method of the PC wall body using the self-hardening stabilizer which concerns on this embodiment. It is the figure which showed the work procedure, (a) is a top view, (b) is sectional drawing which follows an AA line direction. It is the figure which showed the work procedure, (a) is a top view, (b) is sectional drawing which follows a BB line direction. It is the figure which showed the work procedure, (a) is a top view, (b) is sectional drawing which follows a CC line direction. It is the figure which showed the work procedure, (a) is a top view, (b) is sectional drawing which follows a DD line direction. It is the figure which showed the work procedure, (a) is a top view, (b) is sectional drawing which follows an EE line direction. It is the figure which showed the work procedure, (a) is a top view, (b) is sectional drawing which follows a FF line direction.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Self-hardening stabilizer 2 Ground 3 Excavation hole 4 PC wall body 21 PC member 25 Storage tank

Claims (4)

A trench-shaped excavation hole is formed in the ground by excavating the ground while protecting the hole wall with a self-hardening stabilizer added with a retarder, and a PC member is suspended in the excavation hole. In the construction method of the PC wall body using the self-hardening stabilizing liquid that constructs the PC wall body in the ground by hardening of the hard stabilizer liquid,
In the excavation step, a dispersing agent made of polyacrylate, polymethacrylate, or a copolymer thereof and having a weight average molecular weight Mw of 10,000 to 14,000 is added to the self-hardening stabilizer. A method for constructing a PC wall using a hard stabilizer. A trench-shaped excavation hole is formed in the ground by excavating the ground while protecting the hole wall with a self-hardening stabilizer added with a retarder, and a PC member is suspended in the excavation hole. In the construction method of the PC wall body using the self-hardening stabilizing liquid that constructs the PC wall body in the ground by hardening of the hard stabilizer liquid,
In the excavation step, polyacrylate, polymethacrylate or a copolymer thereof and sodium carbonate, and the weight average molecular weight Mw of the polyacrylate, polymethacrylate or the copolymer is A method for constructing a PC wall using a self-hardening stabilizer, wherein a dispersing agent of 10,000 to 14000 is added to the self-hardening stabilizer. The method for constructing a PC wall using the self-hardening stabilizer according to claim 1 or 2, wherein the polyacrylate, polymethacrylate or a copolymer thereof is a monovalent salt. The said self-hardening stabilizing liquid attracted | sucked from the said excavation hole is stored in a storage tank, and the stored self-hardening stabilizing liquid is reused for the next excavation process in the said suspension process. The construction method of PC wall body using the self-hardening stabilizer as described in any one.

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