JP4903016B2 - Improvement method of slime remaining in cast-in-place concrete pile. - Google Patents

Description

  The present invention relates to an improved construction method for slime remaining at a pile hole tip of a cast-in-place concrete pile.

  A cast-in-place concrete pile is a general term for a pile formed by inserting a reinforcing bar into a pile hole excavated in the ground and then placing concrete in the pile hole. As methods for forming cast-in-place concrete piles, the earth drill method, reverse circulation method, and deep foundation method have been developed. In these methods, excavation work is carried out by filling the hole with a stable liquid such as bentonite mud water in order to carry out excavated earth and sand, cool the excavator, prevent ejection of groundwater, etc., and prevent collapse of the hole wall. Therefore, after excavation of the pile hole, slime treatment remaining at the bottom of the pile hole is carried out, but it is difficult to completely remove the remaining slime. In this way, when concrete is placed with the slime remaining at the bottom of the pile hole, the support strength at the tip of the pile is reduced, the design support force is not obtained compared to the driven pile, and the structure sinks. A problem occurs.

In order to solve such a problem, Japanese Patent Laid-Open No. 10-131187 discloses a capsule filled with a solidified material after excavation of a pile hole, destroys the capsule by impact or the like, and the solidified material is piled up in the pile hole. A cast-in-place concrete pile slime treatment method is disclosed in which the slime and the solidified material remaining in the bottom of the pile hole are mixed by agitating blades and solidified by agitation.
JP-A-10-131187

  However, in the conventional slime treatment method of stirring and mixing the slime remaining in the bottom of the pile hole and the solidified material, a stirring member such as a stirring blade is required, and depending on the components of the slime, the solidified material may be stirred and mixed to be solidified. There arises a problem that sufficient support strength cannot be obtained.

  The present invention solves the problems of the conventional slime treatment method remaining in the pile hole, without using equipment such as a stirring blade, and despite the difference in the components of the slime remaining in the pile hole, the solidified material It aims at providing the slime improvement method which remains in the simple cast-in-place concrete pile which can obtain the bearing strength degree strength of a pile tip by pouring.

In order to solve the above-mentioned problem , the slime improvement method remaining on the cast-in-place concrete pile of the present invention inserts a reinforcing bar with a solidifying material injection pipe fixed into the pile hole excavated in the ground, and puts the concrete into the pile hole. Before or after pouring the concrete, the solidification material is injected from the solidification material injection pipe to the tip of the pile hole, the density of the solidification material to be injected is made larger than the density of the slime remaining at the tip of the pile hole, and the tip of the pile hole And the solidified material to be injected is replaced and solidified.

In addition, the slime improvement method remaining in the cast-in-place concrete pile of the present invention is to insert a reinforcing bar with a solidifying material injection pipe fixed into the pile hole excavated in the ground, before placing concrete in the pile hole or in the concrete. After casting, the solidifying material is injected from the solidifying material injection pipe to the tip of the pile hole, and when the slime remaining at the tip of the pile hole is sandy soil slime containing sand having a large particle size, the particle size of the solidifying material to be injected is set. Smaller than the particle size of the sand, leaving the sand in the slime, extruding the small particle of slime and water around the sand and replacing it with the solidified material, and solidifying the sand particles with the solidified material. It is characterized by making it.

Moreover, the slime improvement construction method remaining on the cast-in-place concrete pile of the present invention is characterized in that a slime discharge pipe is disposed on the reinforcing bar.

The slime improvement method remaining in the cast-in-place concrete pile of the present invention is characterized in that the solidified material to be injected into the tip of the pile hole is injected under pressure from the upper, lower or middle portion of the remaining portion of the slime at the tip of the pile hole. .

Moreover, the slime improvement method which remains in the cast-in-place concrete pile of this invention is characterized by making the homogel strength of the solidification material inject | poured into a pile-hole tip more than the supporting force degree of a pile.

In addition, the slime improvement method remaining in the cast-in-place concrete pile of the present invention suppresses the penetration of the solidified material into the surrounding ground into the solidified material injected into the tip of the pile hole, and also cracks that fracture and break the ground with the injection pressure. It is characterized in that a joint filling material for suppressing the inflow of the solidifying material is mixed.

In the slime improvement method remaining in the cast-in-place concrete pile, the solidification rod is inserted into the pile hole excavated in the ground, and the solidification is performed before or after placing concrete in the pile hole. Inject solidification material from the material injection pipe to the tip of the pile hole, make the density of the solidification material to be injected larger than the density of the slime remaining at the tip of the pile hole, and the slime remaining at the tip of the pile hole and the solidification material to be injected By replacing and solidifying the structure, the slime is pushed upward, the replacement of the slime with the injected solidified material is promoted, and the supporting force of the pile tip can be secured by a simple method.
Insert a reinforcing rod with a solidification material injection pipe fixed into the pile hole excavated in the ground, and inject the solidification material from the solidification material injection pipe to the tip of the pile hole before or after placing concrete in the pile hole. When the slime remaining at the tip of the pile hole is sandy soil slime containing sand with a large particle size, the particle size of the solidified material to be injected is made smaller than the particle size of the sand, leaving the sand in the slime, The slime and water with a small particle size around the sand are replaced with the solidified material by extruding, and the sand particles are solidified with the solidified material, leaving the sand and only other slime with a small particle size. Since it extrudes and replaces it with the solidified material, it is possible to secure the supporting force of the pile tip.
By arranging the slime discharge pipe in the vicinity of the tip of the reinforcing bar, the slime pushed out by the injection of the injected solidifying material can be efficiently discharged, and the replacement of the slime with the injected solidified material can be promoted.
By pushing the solidified material injected into the pile hole tip under pressure from the upper, lower or middle part of the slime residue at the pile hole tip, the slime is pushed upward to promote the replacement of the slime with the injected solidified material. Can do.
With a configuration in which the homogel strength of the solidified material injected into the pile hole tip is equal to or higher than the support strength of the pile, the pile support strength can be obtained even if the solidified material is solidified alone.
A composition that mixes the solidified material injected into the tip of the pile hole with the filling material that suppresses the penetration of the solidified material into the surrounding ground, and suppresses the inflow of the solidified material into the cracks that split and break the ground with the injection pressure. Thus, the injection solidified material can be prevented from leaking to the surrounding ground, so that the waste of the injection solidified material can be prevented and the improvement efficiency can be increased.

  An embodiment of a slime improving method remaining in a cast-in-place concrete pile according to the present invention will be described with reference to the drawings. FIG. 1 is a schematic diagram of an embodiment of a slime improving method remaining in a cast-in-place concrete pile of the present invention.

  The pile hole 1 is formed in the ground by an earth drill method, a reverse circulation method, a deep foundation method, or the like. When forming the pile hole 1, excavation work is carried out by filling the hole with a stable liquid 2 such as bentonite mud water to carry out excavated earth and sand, cool the excavator, prevent ejection of groundwater, etc., and prevent collapse of the hole wall. is doing. On the bottom 3 of the pile hole 1 after the formation of the pile hole, a slime 4 in which fine particles of excavated soil are suspended in a stable liquid is precipitated. As a component of the slime 4, there are various types such as clay and sand according to the ground to be excavated. However, whatever the nature of the slime 4 is, if the concrete is placed in the pile hole without treating the slime 4 settled on the bottom 3 of the pile hole 1, the pile supporting force can be sufficiently obtained. Therefore, the structure will sink.

  Therefore, in the slime improvement method remaining on the cast-in-place concrete pile of the present invention, first, the reinforcing bar 6 with the solidifying material injection pipe 5 fixed to the pile hole 1 is inserted. The number of the solidification material injection pipes 5 is 1 to 3 and 4 according to the residual amount of the slime 4 at the bottom of the pile hole 1. The distal end portion 5 ′ of the solidifying material injection pipe 5 is arranged so as to be located at the sedimentation portion of the slime 4 at the bottom of the pile hole 1. The tip 5 ′ of the solidifying material injection pipe 5 is a single pipe or a strainer pipe depending on the properties of the slime 4. Before or after placing concrete in the pile hole 1, the solidification material is injected into the slime 4 that settles at the bottom of the pile hole 1 from the injection pump 7 installed on the ground surface. As the solidifying material, fine particle cement milk, underwater inseparable cement milk, underwater inseparable mortar, or the like is used.

  The solidified material injected into the slime 4 is not mixed with the slime 4 but injected to replace the precipitated slime 4. Therefore, when the property of the slime 4 is clayey, the density of the solidified material to be injected is made larger than the density of the slime 4, the solidified material injected into the slime 4 pushes the slime 4 upward, and the slime 4 is precipitated. The part is replaced with solidifying material. In order to discharge the slime 4 pushed upward, a slime discharge pipe 8 is installed in the reinforcing bar 6. In order to promote the replacement of the slime 4 with the solidified material, the viscosity, injection speed, injection pressure, etc. of the solidified material are adjusted. Since the solidified material to be replaced with the slime 4 at the bottom of the pile hole 1 is solidified by the solidified material alone, it is desirable that the homogel strength of the solidified material be equal to or higher than the pile supporting force. Moreover, in order to prevent the solidified material injected into the bottom of the pile hole 1 from penetrating into the soil around the bottom of the pile hole 1 and wasting waste, and improving the improvement efficiency, the fluidity is not hindered in the solidified material. It is preferable to mix joint fillers having a unit volume weight of the same level as or lower than that of the solidified material.

  When there is a large amount of sand having a large particle size in the slime 4, it is difficult to replace the entire slime 4 including the sand having a large particle size by the solidified material injected into the slime. Therefore, the cement milk of ultrafine cement is used as the solidifying material injected into the slime 4, and only the slime component having a small particle size and water existing around the sand component having a large particle size in the slime 4 are solidified. Push to replace. The extruded slime 4 having a small particle diameter is discharged through a slime discharge pipe 8. The solidified material is filled around the sand and the sand particles are consolidated. As the tip portion 5 ′ of the solidifying material injection pipe 5 when a large amount of sand having a large particle size is present in the slime 4, a strainer pipe is preferable to a single pipe.

(Example)
In order to verify the slime improvement method remaining in the cast-in-place concrete pile of the present invention, the following injection test was conducted.
2 (a) and 2 (b) show a test apparatus used for the test. The test device shown in FIG. 2 (a) creates a shape that mimics the shape of the tip of a pile hole in the soil in the case, and disposes a nonwoven fabric that suppresses the penetration of the injection material on the surface of the soil. A slime discharge pipe was installed at the bottom of the tube, and a strainer pipe was used as the injection pipe. The test apparatus shown in FIG. 2 (b) creates a shape that mimics the shape of the tip of the pile hole in the soil in the case, and disposes a nonwoven fabric that suppresses the penetration of the solidifying material on the surface of the soil. A slime discharge pipe was installed immediately above the slime residue part at the bottom of the tube, and a single pipe was used as the injection pipe.

  Tests were carried out by filling the test apparatus shown in FIGS. 2 (a) and 2 (b) with simulated slime using the slime composition material and the injection material parameters shown in Table 1 as cases 1 to 3.

  The test apparatus shown in FIG. 2A performs the test of the simulated slime and injection material of the parameters of case 1, and the test apparatus of FIG. 2B uses the simulated slime and injection material of the parameters of cases 2 and 3. The test was conducted. The injection rate was 5.0 liter / min. In the case 1, the injection volume was about 91 liters, which is the gap volume between the soil particles by osmotic injection, and in cases 2 and 3, the total volume of slime was about 155 liters aiming at total replacement. In the slime treatment state, after injecting a predetermined injection amount, the lid of the test apparatus was immediately disassembled and visually observed. In Case 1, specimens were collected at the positions shown in FIGS. 3A and 3B, and the uniaxial compressive strength was measured on the 28th day of the age in accordance with JIS A1108 “Compressive strength test method for mortar”.

(Test results)
1. Case 1
The cross-sectional condition after the injection was such that the injected material was slightly dissolved in the water in the gap on the upper surface. However, when the depth reached 30 cm, the injected material penetrated the entire surface, and at depths of 50 cm and 65 cm, the situation was observed where the injected material having a higher cement concentration than the upper portion penetrated between the soil particles. The external appearance of the specimen for strength test collected at the position shown in FIGS. 3 (a) and 3 (b) shows that in the cross section 1, the specimens 3 and 4 in the center are solidified, but the specimen is located outside the cross section. 1, 2, 5 and 6 were not solidified and were broken apart. However, in cross section 2, cross section 3 and cross section 4, all specimens were completely solidified and the surface was also stubborn. Table 2 shows the results of the uniaxial test.

As a result of the strength test shown in Table 2, it was confirmed that the cross sections 2 to 4 had a high strength in the range of 9.91 to 19.2 N / mm ² . As a result, except for the upper part, it is determined that the injecting material penetrates between the soil particles, and the sandy soil slime is improved by the injecting material.

2. Case 2
In case 2, it is confirmed that the injection material leaks from the slime discharge pipe when the injection amount reaches about 10 liters, and thereafter, only the injection material leaks from the slime discharge pipe until the injection is finished. The situation continued. As for the cross-sectional shape after the injection, the injection material and the slime were not mixed but existed completely on the upper surface. The same condition was obtained at depths of 10 cm and 20 cm, and no injection material was present at a depth of 40 cm or more. As a result, although the injection material was discharged downward from the injection port of the single pipe, it is considered that the upward flow path was formed by the influence of density and viscosity, and the injection material was leaked from the slime discharge pipe.

3. Case 3
Similar to Case 2, up to a depth of 20 cm from the upper surface, the injection material was present only in the flow path toward the slime discharge pipe. However, at a depth of 40 cm, it was confirmed that the slime was almost replaced by the injection material. Furthermore, at a depth of 65 cm, it was observed that the slime was completely replaced by the injection material with a slight amount of slime adhering to the inner wall. Based on these results, in order to improve the clay clay slime by the slime improvement method remaining in the cast-in-place concrete pile of the present invention, it is necessary to use an injection material having a density higher than that of the slime. It is considered necessary to set the viscosity of the injection material so that no path is formed.

  These tests revealed that the slime remaining at the tip of the pile hole can be easily improved by selecting the injection material and the injection method according to the particle size composition of the slime.

It is a figure which shows embodiment of this invention. (A) (b) It is a figure which shows the test apparatus for demonstrating the effect of this invention. (A) (b) It is a figure which shows one collection of the test body which shows the effect of this invention.

Explanation of symbols

  1: Pile hole, 2: Stabilizing liquid, 3: Bottom part of pile hole, 4: Slime, 5: Solidified material injection pipe, 5 ′: Tip of solidified material injection pipe, 6: Rebar rod, 7: Injection pump, 8 : Slime discharge pipe

Claims (6)

Insert a reinforcing rod with a solidification material injection pipe fixed into the pile hole excavated in the ground, and inject the solidification material from the solidification material injection pipe to the tip of the pile hole before or after placing concrete in the pile hole. And the density of the solidified material to be injected is larger than the density of the slime remaining at the tip of the pile hole, and the slime remaining at the tip of the pile hole is replaced with the solidified material to be injected and solidified. Improvement method of slime remaining on concrete piles. Insert a reinforcing rod with a solidification material injection pipe fixed into the pile hole excavated in the ground, and inject the solidification material from the solidification material injection pipe to the tip of the pile hole before or after placing concrete in the pile hole. When the slime remaining at the tip of the pile hole is sandy soil slime containing sand with a large particle size, the particle size of the solidified material to be injected is made smaller than the particle size of the sand, leaving the sand in the slime, A slime improvement method that remains in cast-in-place concrete piles, characterized in that slime and water with a small particle size existing around sand are replaced with extruded solidified material, and the particles of sand are consolidated with solidified material. The slime improvement pipe | tube which remains on the cast-in-place concrete pile of Claim 1 or 2 characterized by arrange | positioning a slime discharge pipe to the said reinforcing bar. The cast-in-place concrete pile according to any one of claims 1 to 3 , wherein the solidified material to be injected into the tip of the pile hole is injected under pressure from the upper part, the lower part, or the middle part of the slime remaining part at the tip of the pile hole. Improvement method of slime remaining in the sea. The slime improvement method which remains in the cast-in-place concrete pile according to any one of claims 1 to 4 , wherein the homogel strength of the solidified material injected into the pile hole tip is equal to or higher than the support capacity of the pile. Incorporate joint filling material that suppresses the penetration of the solidified material into the surrounding ground into the solidified material injected into the tip of the pile hole, and suppresses the flow of the solidified material into the cracks that split and break the ground with the injection pressure. The slime improvement construction method which remains in the cast-in-place concrete pile of any one of Claims 1-5 characterized by these.

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