JP4327639B2 - Construction method of cast-in-place concrete pile - Google Patents

Description

  The present invention relates to a method for producing cast-in-place concrete capable of efficiently building a cast-in-place concrete pile having good quality in which impurities such as slime are hardly mixed in a pile head or the like.

  Conventionally, in order to construct a cast-in-place concrete pile, a casing is embedded in the ground surface portion, and the ground below the casing is prevented from collapsing the hole wall with a stable liquid such as bentonite liquid through the casing. After digging to form a pile hole of a predetermined depth, and building a reinforcing bar in this pile hole, insert the tremy pipe into the center of the pile hole and through the treme pipe (hereinafter simply referred to as concrete) ), But the upper end of the cast concrete is mixed with impurities such as slime that reduce the strength of the pile. Pile head processing is performed by placing concrete and forming an extra portion of concrete on the pile head and removing this extra portion.

  Conventionally, such pile head treatment methods include a method of scraping off and removing the excess portion of concrete containing impurities such as slime after hardening of the cast concrete, or an uncured surplus immediately after casting of the concrete. A method of sucking and removing with a concrete or vacuum hose at the height is adopted.

On the other hand, in Patent Document 1, after placing concrete into the lower part of the top end face of the planned pile head in the pile hole, once the impurities such as slime on the concrete placed by the vacuum device are removed by suction, After that, colored concrete is placed up to the upper part of the top end of the planned pile, while checking the hue that colored the extra portion of the colored concrete mixed with impurities such as slime above the top end of the planned pile. It is described that it is removed by suction and then the top edge of the cast concrete is leveled.
JP 2003-64670 A

  However, in the former pile head processing method, in order to ensure the quality of the pile, since the surplus height is 1 m or more, the amount of turning is large, and it requires a lot of trouble and processing costs. In addition, a large-scale device and equipment are required to beat, and further, there is a problem that vibration and loud noise are generated at the time of scraping work and the environment is deteriorated. Therefore, the latter pile head treatment method is adopted, which can eliminate the pile head scraping work by sucking and removing the concrete of the surplus portion immediately after placing the concrete and leveling the top of the pile. However, in this method as well, since the surplus height is set to 1 m or more in order to ensure the quality of the pile, the amount of concrete to be removed by suction is large, and the processing cost for disposal as industrial waste is high. There is a problem.

  In addition, since it is impossible to confirm whether or not the concrete portion containing impurities such as bentonite liquid and slime has been completely removed, after the concrete is hardened, the core as a sample piece is extracted from a part of the pile head. At present, quality is confirmed by performing tests such as compressive strength. For this reason, it takes a lot of time and effort to perform a number of cast-in-place concrete piles from the extraction of the core to the test such as compressive strength, and it is impossible to move to the next work process until the test results are obtained. There was a problem.

  On the other hand, according to the above-mentioned patent document 1, since the surplus portion is removed by suction, the scraping work that generates vibration and loud noise can be omitted, but the work of removing the stable liquid and slime by suction, and coloring After placing concrete up to the upper part of the top end of the planned pile, it is necessary to remove impurities twice by sucking and removing colored concrete parts mixed with impurities such as slime in the colored concrete. In addition, there is a problem that the construction work of the pile becomes complicated and the work time becomes long. Also, in order to check the quality of the pile, the height of the piled concrete of the colored concrete is the same as the above pile head treatment method. 1m or more, and in addition, suction removal of the colored concrete in the excess portion and suction removal of impurities such as slime on the previously placed concrete Disposal cost may become high removal amount of concrete is a large amount.

  In addition, since the concrete is colored to check the quality, it requires material costs such as dyes for coloring and time until the dye is uniformly mixed with the concrete. In addition, when removing impurities such as slime on the concrete previously placed as described above by suction, the concrete placement is interrupted, and after removing the impurities by suction, colored concrete is cast. Therefore, it is difficult to ensure the quality of the pile, and there is a problem that it takes time to build the pile.

  The present invention has been made in view of such problems, and the object of the present invention is to minimize the amount of cast concrete to be removed by suction without providing a large amount of surplus parts, and to improve the strength, etc. It is in providing the construction method of the cast-in-place concrete pile which can construct the cast-in-place concrete pile excellent also in the quality of the stable and efficiently.

In order to achieve the above object, the cast-in-place concrete pile manufacturing method according to the present invention includes, as described in claim 1, a casing on the surface layer portion of the ground, and a lower end portion thereof below the top end surface of the planned pile. After being built until it is located, a pile hole is excavated while filling the lower ground from the inside of the casing to a predetermined depth with a stable liquid, and then concrete is put into the pile hole from the lower end of the casing in the planned pile. After laying up to the height position while reaching the top end surface part of the concrete, remove the concrete part mixed with stabilizing liquid and slime and impurities such as the slime on the concrete top end face of the cast concrete. The concrete is cast to reach a position higher than the top end surface to form a surplus part, and then the casing is raised to plan the top end surface of the cast concrete. Wherein the match the height of the top end face.

In the method for forming a cast-in-place concrete pile according to claim 1, the invention according to claim 2 removes the concrete part mixed with impurities such as slime until a large amount of concrete aggregate is visible at the top of the concrete. It is characterized by performing.

Furthermore, the invention which concerns on Claim 3 inserts the said vacuum hose in the clearance gap between the reinforcement bar which has built in the pile hole, and the inner peripheral wall surface of a casing, and removes the concrete part in which an impurity is mixed. It is characterized by.

  According to the first aspect of the invention, the casing is built until the lower end of the casing reaches a position deeper than the top end surface of the planned pile in the surface layer portion of the ground. After reaching the lower end of the casing, the ground will not collapse even if the stabilizing liquid such as bentonite in the pile hole is removed. Therefore, after the top of the cast concrete reaches the lower end of the casing Removing a portion of the concrete mixed with stable liquid, slime, and impurities such as slime on the top end surface of the cast concrete at an appropriate height position up to a predetermined height such as the vicinity of the top end surface of the planned pile in the casing. As a result, almost all impurities can be reliably removed.

  In this way, at the appropriate height position of the cast concrete up to the position of the top end face of the planned pile in the casing, the concrete portion in which the stable liquid, slime, and impurities such as the slime are mixed is removed once in the casing. Since it is eliminated by the work, impurities can be removed intensively in a short time and the amount of treatment can be reduced, so that the processing cost as industrial waste can be reduced and the effect of the removal work once. In addition, impurities such as slime and the concrete portion in which the impurities are mixed can be eliminated, so that piles can be built smoothly and efficiently, and piles excellent in quality such as strength can be created. In addition, the height position of the concrete top face exposed by removing impurities can be easily observed, and the height from the position to the top face of the planned pile can be confirmed. The concrete placement work up to can be performed accurately and efficiently.

Furthermore, after pouring to a height position between the concrete reaches the top end surface portion of the planned pile from the casing bottom end of the casing, impurities such as stabilizing solution and slime and the slime on the ball striking setting concrete top end face Remove the mixed concrete part, and then cast concrete until it reaches a position higher than the top edge of the planned pile to form a surplus part, and then raise the casing to produce the removal trace. In addition, since the concrete corresponding to the surplus portion is filled and filled in the gap corresponding to the thickness of the casing, the amount of the surplus portion to be placed upward from the top end surface of the planned pile can satisfy the volume of the extraction trace of the casing. Therefore, the top end face of the planned pile can be easily and accurately made with the minimum amount of concrete placed. It is possible to save the material cost it is possible to substantially coincide, the removal operation and disposal of extra pouring concrete in unnecessary or can be shortened reclamation work with less. Further, since the surplus portion is leveled without being cured, no turning work is required after turning, and a large machine for turning is not used, so that an environment free from noise and vibration can be realized.

Confirming the quality of cast-in-place concrete piles is assured by performing suction removal of concrete parts mixed with impurities such as slime until a large amount of concrete aggregate is visible at the top of the concrete as described in claim 2. Can be done.

In addition, when the concrete placement work into the pile hole is performed with a tremey pipe inserted into the center of the pile hole, the concrete flow from the tremey pipe side to the hole wall surface of the pile hole at the top of the cast concrete Since concrete that flows toward the surface and mixed with impurities such as slime is concentrated on the hole wall surface side, the reinforcing bar in which the vacuum hose is built in the pile hole as described in claim 3 By inserting it into the gap between the ridge and the inner peripheral wall surface of the casing, the concrete in which impurities are mixed can be efficiently removed by suction.

  Next, specific embodiments of the present invention will be described with reference to the drawings. First, the construction procedure of the on-site concrete pile from the excavation of the pile hole to before the pile head processing will be briefly described based on FIG. As is well known in the art, after excavating the ground 1a as shown in FIG. 1 (a) using the excavating machine 10, the surface casing 2 is moved to its lower end as shown in FIG. 1 (b). Is built so as to reach a lower position deeper than the top end face 6 of the planned pile to prevent the collapse of the hole wall above the excavation hole. Next, the pile hole 1 is excavated to a predetermined depth as shown in FIG. 1C by the excavating machine 10 with the hole wall stabilizing liquid 13 such as bentonite liquid filled in the excavated hole. After excavation of the pile hole 1, primary processing of the slime settled on the bottom of the hole is performed, and then a reinforcing bar 3 is built in the pile hole 1 as shown in FIG.

  Next, as shown in FIG. 1 (e), while the tremy tube 4 is positioned at the center of the pile hole 1, it is suspended until the lower end of the opening reaches the bottom surface of the pile hole 1, and the secondary slime treatment is performed. After that, as shown in FIG. 1 (f), the concrete 5 is driven into the pile hole 1 from the ground through the tremy tube 4.

  The concrete 5 is placed while the lower end of the opening of the tremmy pipe 4 that supplies the concrete 5 into the pile hole 1 is always immersed in the concrete 5 that has been placed. The tremely pipe 4 is pulled upward while keeping the immersion depth of the concrete 5 from the casting top end surface 5a within a certain range (2 to 6 m) as the casting concrete 5 rises. If the immersion depth of the tremmy pipe 4 from the upper end surface 5a of the concrete 5 is too shallow, it will cause material separation of the concrete 5 and mixing of slime. If it is too deep, the outflow of the concrete 5 from the tremy pipe 4 will stop. 4 cannot be pulled up, so that the tremy tube 4 is pulled up according to the placement of the concrete 5 while holding the tremy tube 4 at a depth of 2 to 6 m as described above. In addition, although the liquid level of the stable liquid 13 supplied in the pile hole 1 rises with the placement of the concrete 5, the stable liquid 13 is pumped out by the submersible pump 9 and the water level is kept at a constant height. When the cast concrete 5 reaches the lower end of the casing 2, even if the stabilizing liquid is removed, the casing 2 performs a soil retaining action, so that the ground does not collapse.

  In this way, when the placement upper end surface 5a of the concrete 5 reaches the lower end portion of the casing 2, the placement of the placement concrete 5 is once stopped, and thereafter, as shown in FIGS. The submersible pump 9 that has been lowered to the height of the planned pile inside is started, all the stabilizing liquid 13 on the cast concrete 5 is discharged to the ground, and then, as shown in FIG. A vacuum device (vacuum wheel) 11 (shown in FIG. 1 (G)) disposed in a proper place on the ground to which the vacuum hose 12 is connected by means of a vacuum hose 12 inserted in the pile hole 1 in advance. When activated, impurities such as slime 14 on the cast concrete 5 and concrete part 15 (concrete surface part) mixed with slime are sucked and removed.

  At this time, since the cast concrete 5 is performed by inserting the treme tube 4 into the center portion of the pile hole 1, the concrete 5 is transmitted along the treme tube 4 when it is cast by the tremi tube 4. In the top end of the concrete, the insertion portion of the tremely tube 4 is the most swelled and flows from the center of the swell toward the inner peripheral wall surface of the casing 2. The slime 14 also flows on the inclined end surface and gathers on the inner peripheral wall surface side of the casing 2 as an inclined end surface inclined obliquely downward toward the peripheral wall surface.

  Therefore, the vacuum hose 12 is inserted along the inner peripheral wall surface of the casing 2, that is, inserted into the gap between the reinforcing bar 3 built in the pile hole 1 and the casing 2. When the concrete part 15 mixed with impurities such as slime 14 and the slime is sucked and removed while moving in the circumferential direction along the peripheral wall surface, the concrete part 15 mixed with impurities such as slime 14 and slime is efficiently concentrated. As the suction and removal progresses, the sloping 14 on the top end surface 5a of the cast concrete 5 and the concrete portion 15 mixed with impurities such as the slime are formed on the inclined top end surface of the cast concrete 5. The upper wall flows from the center side of the casing 2 to the inner wall surface, and the inner wall surface without moving the vacuum hose 12 to the center of the casing 2 Only moved in along a state in the circumferential direction, all the slime 14 and concrete portion 15 which impurities are mixed, such as the slime on pouring concrete 5 can be reliably and efficiently sucked and removed.

  It should be noted that the removal of the stabilizing liquid 13 on the top end surface of the cast concrete 5 and the suction removal of the concrete portion 15 mixed with the slime 14 and impurities, which is performed subsequent to the pump removal of the stable liquid 13, are carried out. It is not necessary to carry out immediately when the top end surface 5a of the concrete reaches the lower end of the casing 2, and may be performed after the top end surface 5a of the cast concrete reaches the vicinity of the top end surface 6 of the planned pile in the casing 2. . In short, after placing concrete 5 to the height position between the lower end of casing 2 and the top end surface of the planned pile, suction removal of slime 14 and concrete part 15 mixed with impurities such as slime can be performed. Good.

  At this time, quality of the top end portion of the pile A formed by the cast concrete 5 is confirmed to be good or bad by visually observing the suction removal of the slime 14 and the concrete portion 15 mixed with impurities. That is, when the suction of the slime 14 on the top edge of the cast concrete 5 and the concrete portion 15 mixed with impurities such as the slime is started, the stabilizing liquid 13 remains. Although the color of the stabilizing liquid 13 is observed, when the stabilizing liquid 13 is removed by suction, the color of the concrete 5 is observed. However, this concrete 5 may be mixed with impurities such as slime. Therefore, by removing the top end portion of the cast concrete 5 by suction until the aggregate is observed in the concrete from the state in which the color of the cast concrete 5 on the top end surface is observed, the quality such as strength is improved. It confirms that an excellent pile top end is created. Furthermore, the height position of the top end surface of the concrete exposed by removing impurities can be easily observed, and the height from that position to the top end surface of the planned pile can be confirmed. The concrete can be placed accurately and efficiently.

  Thus, if the top end of the cast concrete 5 is removed by suction until aggregate is observed in the cast concrete 5, it is possible to create a pile top end having excellent quality such as strength as follows. It is clear from the experimental results shown. That is, prior to the above-mentioned cast-in-place concrete pile construction work, the quality such as compressive strength, Young's modulus, unit volume weight, etc. of the pile top end of the cast-in-place concrete pile created under the same conditions as the cast-in-place concrete pile to be built When experimentally confirmed, the results shown in Table 1 were obtained.

  As is clear from this table, if the concrete top end is removed by suction until the aggregate is observed in the concrete after the color of the cast concrete on the top end surface is observed, The quality of the specimen at the top of the pile was extremely excellent, indicating that the concrete mixed with slime and impurities was completely removed. Therefore, when the cast-in-place concrete pile is constructed, when removing the slime 14 and the concrete portion 15 mixed with impurities, the suction removal work is performed until aggregate is observed in the concrete, thereby reducing the slime and impurities. It can be confirmed that the mixed concrete is completely removed.

  As the suction port of the vacuum hose 12 for sucking and removing the slime 14 and the concrete portion 15 mixed with impurities such as the slime, as shown in FIG. Or a bent suction port 12b formed by bending the tip (lower end) at a right angle toward one side as shown in FIG. 8 (b). As a result of this formation, the top of the opening of the inclined suction port 12a and the bent suction port 12b is exposed upward from the top end surface of the concrete portion 15 mixed with impurities such as slime. At the same time, the concrete portion 15 mixed with impurities such as slime can be removed by suction, so that the operator can operate the vacuum hose 12 on the ground side without entering the casing 2, and the suction force By the rapid flow of air, the concrete portion 15 in which impurities such as slime are mixed can be surely and efficiently removed by suction.

  Thus, after removing the slime 14 and the concrete portion 15 mixed with impurities such as the slime in the cast concrete 5 by suction, the concrete 5 is cast again and 10 to 50 cm from the top end face 6 of the planned pile in the casing 2. A surplus portion 5 ′ (see FIG. 4A) having a height that reaches the height is formed. The height of the surplus portion 5 ′ varies depending on the diameter of the pile head of the planned pile, the thickness of the casing 2, and the length of the gap corresponding to the thickness of the casing caused by lifting the casing 2. In short, when the casing 2 is lifted after the formation of the surplus portion 5 'by the cast concrete, the concrete corresponding to the surplus portion 5' can be filled and filled into the gap generated in the lifted trace. Provide as much as possible (amount). In this case, when the surplus portion 5 'flows into and fills the gap, it is not preferable that the top end surface is significantly higher than the top end surface 6 of the planned pile, and therefore, the top end surface is the same or slightly lower. The height (amount) of the extra portion 5 'is set in.

  After the formation of the surplus portion 5 ′, as described above, the casing 2 is pulled up until the lower end reaches the top end surface 6 of the planned pile, and the concrete corresponding to the surplus portion 5 ′ flows into the gap generated by the lifting, Filled (see Fig. 4 (b)), the vacuum hose 12 sucks and removes the surplus portion 5 "remaining above the top end surface 6 of the planned pile, and the top end surface 5a of the cast concrete 5 is planned Align with the top face 6 of The second suction and removal operation by the vacuum hose 12 is for precisely matching the top end surface 5a of the cast concrete 5 with the top end surface 6 of the planned pile, thereby finishing the pile top end. After that, the pile head is finished by leveling the top end surface A1 of the pile head A of the pile thus created (see FIG. 5). In addition, when the surplus portion 5 ′ flows and fills into the gap by lifting the casing 2, and the top end face coincides with the top end face 6 of the planned pile, the suction hose removal with the vacuum hose 12 is natural. do not need.

  Here, after adopting the method of the present invention to remove the slime 14 on the top end surface 5a of the cast concrete 5 and the concrete portion 15 mixed with impurities such as the slime, the height of the surplus portion 5 ′ is the casing. In piles constructed by placing them so as to be 80 cm even after pulling up 2, the core specimen from the pile head to a depth of 80 cm below the top end surface at the center and outer periphery of the pile A sample having a diameter of 10 cm was sampled and subjected to a compressive strength test to confirm the range in which the quality was deteriorated and the difference in strength in the height direction. The results shown in FIG. 6 were obtained.

  As is apparent from FIG. 6, it can be understood that the strength beyond the design reference strength is expressed not only below the pile top end but also in the extra portion. That is, it is shown that there is no concrete mixed with slime and impurities even in the extra portion 5 ′. Therefore, the surplus portion 5 ′ may be a height (amount) that can satisfy the clearance of the extracted trace of the casing 2 as described above.

  After building the concrete pile as described above, the crushed stone 7 reaches the upper end of the reinforcing bar 3 as shown in FIG. And the casing 2 is pulled out and removed as shown in FIG. 5B, and backfilling work such as earth and sand is performed up to the ground surface as shown in FIG. Thus, after all the pile building work is finished, before excavating around the pile and building the foundation of the building on the top of the pile, the top of the pile is subjected to high-pressure jet or chipping treatment, and occurs in the hardening stage of the cast concrete 5 Remove bleeding.

  In addition, in the above embodiment, the case where the tremy tube 4 for placing concrete 5 in the pile hole 1 was inserted in the center part of the pile cross section, that is, the center part of the pile hole 1 was described. However, the concrete 5 may be placed in a state where the insertion position of the tremy tube 4 is shifted to the one side wall surface side of the pile hole 1, and in this case, the concrete 5 is placed on the top end surface of the tremy tube 4. Flowing toward the other side wall surface side of the pile hole 1 while rising around the periphery, impurities such as slime also flow to the other side wall surface side together with the concrete, and concentrate in that portion. Therefore, by removing the vacuum hose 12 on the other side wall surface side without moving in the circumferential direction along the inner peripheral wall surface of the casing 2, it is possible to effectively remove and remove impurities such as slime. it can. Further, in the above embodiment, suction removal by vacuum is described as means for removing slime 14 and concrete 15, but the removal means is not limited thereto, and pumping means and scooping means by a bucket or the like may be adopted. .

The simplified longitudinal cross-sectional view which shows the construction procedure from excavation of a pile hole to concrete placement. The longitudinal cross-sectional view of the top end part in the state which has removed the stabilizer. The longitudinal cross-sectional view of the top end part in the state which removes impurities, such as slime, by suction. (A) is a longitudinal cross-sectional view showing a top end portion at the end of concrete pouring, and (b) is a vertical cross-sectional view showing a surplus portion lowered by raising the casing. The longitudinal cross-sectional view of the state which finished the pile head. The diagram which shows the intensity distribution state of the depth direction from a surplus part to a pile top end lower part. The simplified longitudinal cross-sectional view which shows the process after a pile creation. The simplified longitudinal cross-sectional view which shows the shape of the suction opening of a vacuum hose.

Explanation of symbols

1 Pile hole 2 Casing 4 Tremy pipe 5 Casting concrete
5a The top edge
5 'Extra portion 6 Top edge of the planned pile
12 Vacuum hose
13 Stabilizer
14 Slime

Claims (3)

After building the casing on the surface layer of the ground until its lower end is located below the top end face of the planned pile , drill the pile hole while filling the ground below the casing to the specified depth from the inside of the casing. Then, after placing concrete in the pile hole up to a height position between the bottom end of the casing and the top end surface of the planned pile in the casing, the stabilizing liquid and slime on the top end surface of the cast concrete are placed. And the concrete part mixed with impurities such as the slime is removed, and then the concrete is cast to reach a position higher than the top end face of the planned pile to form a surplus part, and then the casing is raised A cast- in-place concrete pile construction method characterized in that the top end surface of the cast concrete is matched with the height of the top end surface of the planned pile . The method for constructing a cast-in-place concrete pile according to claim 1, wherein the concrete part mixed with impurities such as slime is removed until a large amount of concrete aggregate is visible at the top of the concrete. Claim, characterized in that the removal of the insert into the gap concrete portions which impurities are mixed between the reinforcing bar cage and the inner peripheral wall surface of the casing that is built up a vacuum hose to the Kuiana 1 or claim 2 A method for constructing cast-in-place concrete piles as described in 1.

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