JP5075091B2 - Casting method for cast-in-place piles - Google Patents

Description

  This invention has the advantages of the earth drill method by constructing the pile body integrally with the improved ground by the ground drill method that does not use a stabilizing liquid in the improved ground, in particular, in the improved ground. , Improvement of workability of pile body, reduction of construction cost by reducing pile body diameter, improvement of pile body quality by non-use of stabilizing liquid, and earthquake resistance, horizontal resistance, etc. by pseudo increase of pile body diameter The present invention relates to a method for constructing cast-in-place piles that can be improved.

  One of the pile foundation methods for buildings is the cast-in-place pile method. This method includes an earth drill method, an all-casing method, and a reverse method. The cast-in-place pile construction method has the following advantages compared to the ready-made pile construction method in which a pile manufactured in a factory is driven into the ground in advance.

(1) Pile diameter and pile length can be selected freely.
(2) Pile construction with large diameter and depth is possible.

  The above earth drill method excavates the ground to the planned depth of the casing, lays the casing in the excavation hole, further excavates while injecting a stable liquid suitable for the soil into the excavation hole, after excavating to the planned depth, Reinforcing rods assembled on the ground are inserted into the excavation hole, and concrete is cast into the excavation hole and solidified, and has the following advantages.

(A) Low vibration and low noise.
(B) Equipment is simple, construction speed is fast and economical.
(C) Construction is possible even in a small site.

  When piles are constructed on soft ground by the above-mentioned earth drill method, the level of the stabilizing liquid injected into the drilling hole is increased or the depth of the casing is increased, thereby causing the collapse of the drilling hole wall. It was necessary to prevent and stabilize the ground.

  However, even if such measures are taken, the ground may not be sufficiently stabilized. In addition, even when excavating a drilling hole with a predetermined diameter, the surrounding soft ground pressed the drilling hole wall and narrowed the drilling hole. As a result, the drilling pile diameter was reduced and the design pile diameter was not satisfied. . Furthermore, there was a risk that the quality of the pile body would deteriorate due to the stabilizing liquid mixed into the cast concrete.

  For this reason, there has been a case where it has been necessary to change to a construction method using a ready-made pile, but it is desired to employ an earth drill construction method having the above-described advantages.

  However, even in soft ground, the drilling hole wall can be sufficiently protected, and there is no problem of reduction in the diameter of the excavated pile due to the surrounding soft ground pressing the drilling hole wall. There has not yet been proposed a method for constructing a pile by the earth drill method, which does not have a problem of deterioration in the quality of the pile main body due to mixing into the cast concrete.

  Therefore, the inventors of the present application can sufficiently protect the excavation hole wall even in soft ground, and there is no problem of reduction in the diameter of the excavation pile due to the surrounding soft ground pressing the excavation hole wall. Furthermore, in order to obtain a pile construction method by the earth drill method, there was no problem of deterioration of the pile body quality due to the mixing of the stabilizing liquid into the cast concrete. As a result, we have learned that all of the above problems can be solved by excavating in combination with ground improvement.

  This invention has been made on the basis of the above knowledge, and has an advantage of the earth drill method by constructing the pile body integrally with the improved ground in the improved ground by an earth drill method that does not use a stabilizing liquid. In addition, improvement of the workability of the pile body, reduction of construction costs by reducing the diameter of the pile body, improvement of the quality of the pile body by not using a stabilizing liquid, and earthquake resistance and horizontal resistance due to a pseudo increase in the diameter of the pile body It aims at providing the construction method of a cast-in-place pile which can aim at improvement.

  The present invention has been made on the basis of the above findings, and is characterized by the following.

In the invention according to claim 1, the improved ground is constructed in a cylindrical shape in the ground, and then a drilling hole is formed in the center of the improved ground without using a stabilizing liquid, The cast-in- place pile is inserted into the excavation hole into which the reinforcing bar is inserted, and a pile body is constructed integrally with the improved ground in the improved ground . The construction method is characterized in that a reinforcing bar is built in the improved ground, and thereafter, the pile main body is built inside the reinforcing bar .

  The invention according to claim 2 is characterized in that, in the construction method for cast-in-place piles according to claim 1, the improved ground is constructed to a depth at which the pile main body is constructed.

  The invention according to claim 3 is characterized in that, in the construction method for cast-in-place piles according to claim 1, the improved ground is constructed only in the soft ground layer.

  Invention of Claim 4 makes the diameter dimension of the said pile main body the same in the longitudinal direction of the said pile main body in the construction method of a cast-in-place pile as described in any one of Claim 1 to 3. It has the characteristics.

  Invention of Claim 5 is the construction method of a cast-in-place pile as described in any one of Claim 1 to 3, If the radial dimension of the said pile main body is partially different in the longitudinal direction of the said pile main body. It has a characteristic in making it.

  According to the present invention, by constructing the pile main body integrally with the improved ground in the improved ground by an earth drill method that does not use a stabilizer, the low-vibration / low-noise operation, equipment that is an advantage of the ground drill method Is easy, fast and economical, and has the advantages of being able to work even in a small site. In addition, it improves the workability of the pile body, reduces the construction cost by reducing the pile body diameter, and does not use a stable liquid. It is possible to improve the quality of the main body, and improve the earthquake resistance, horizontal resistance, etc. due to the pseudo increase in the pile main body diameter.

  One embodiment of the method for constructing cast-in-place piles of the present invention will be described with reference to the drawings.

  FIG. 1 is a diagram showing a ground improvement process by a cast-in-place pile construction method according to the present invention, where (a) is a schematic plan view, (b) is a schematic cross-sectional view, and (c) is an improved ground. It is a schematic sectional drawing at the time of constructing a reinforcing bar rod. 2A and 2B are diagrams showing the excavation process by the cast-in-place pile construction method of the present invention, wherein FIG. 2A is a schematic plan view and FIG. 2B is a schematic cross-sectional view. Drawing 3 is a figure showing a pile main part construction process by a construction method of cast-in-place pile of this invention, (a) is a schematic plan view and (b) is a schematic sectional view.

  As shown in FIG. 1, the cast-in-place pile construction method of the present invention first constructs a cylindrical improved ground 2 on a soft ground 1. The columnar improved ground 2 is constructed by, for example, a teno column (registered trademark) method. The teno-column method is a method in which a cement-based solidified material is liquefied and poured into the soft ground 1, and the soft ground 1 and the solidified material liquid are stirred and mixed so that the columnar improved body, that is, the improved ground 2 is placed in the soft ground 1. To build.

  Hereinafter, the teno column method will be further described with reference to the drawings.

  FIG. 7 is a schematic view showing equipment for carrying out the teno column method.

  As shown in FIG. 7, the teno column construction equipment includes plant-side equipment including a water tank 5, a cement silo 6, a mixing plant 7 and a pump 8, and construction equipment-side equipment including a construction machine main body 9 and a stirring device 10. The ground is improved as follows.

  Water and cement are respectively sent from the water tank 5 and the cement silo 6 to the mixing plant 7, where water and cement are mixed to prepare a cement slurry. The cement slurry thus prepared is sent to the construction machine main body 9 by the pump 8. The cement slurry sent to the construction machine main body 9 is sent to a stirring device 10 having a stirring blade 11 attached to the tip. The stirring device 10 stirs the soft ground 1 to a predetermined depth by the stirring blade 11 while injecting cement slurry into the soft ground 1. Thereby, the stirring blade 11 passes and the columnar ground part stirred is in a state where the soft ground and the cement slurry are mixed. Then, if the stirring blade 11 is pulled up and the cement is solidified, a cylindrical improved ground 2 is constructed in the soft ground 1 as shown in FIG.

  When the improved ground 2 is constructed by the above method, the amount of cement slurry injected can be adjusted according to the degree of softness in the depth direction of the soft ground 1, or the cement slurry injection location can be adjusted. . For example, the strength of the outer peripheral portion of the improved ground 2 can be increased as compared with other portions by increasing the amount of cement slurry injected from the outer peripheral side of the stirring blade 11.

  When the cylindrical improved ground 2 is constructed on the soft ground 1 in this way, the excavation hole 3 is formed in the improved ground 2 as shown in FIG. 2, and then the excavation hole is obtained as shown in FIG. 3, the pile body 4 made of concrete 16 reinforced by the reinforcing bar 14 is constructed integrally with the improved ground 2. Although the pile main body 4 is constructed by the earth drill method, the pile main body 4 is constructed not in the soft ground but in the improved ground 2, so there is no need to use a casing or a stabilizing liquid. This point is different from the above-described earth drill method.

  Hereinafter, the earth drill method implemented in the present invention will be described in more detail with reference to the drawings.

  FIG. 4 is a diagram showing a process for constructing a cast-in-place pile on the improved ground by the earth drill method according to the present invention. FIG. 4A shows the rotary shaft of the excavator positioned at the center of the cylindrical improved ground. The schematic sectional drawing which shows a state, (b) is a schematic sectional drawing which shows the state which excavates the improved ground with the excavation blade attached to the rotating shaft of an excavator, (c) is the improvement in which the excavation hole was formed Schematic cross-sectional view showing the ground, (d) is a schematic cross-sectional view showing a state in which a reinforcing bar is inserted into the excavation hole, (e) is a concrete pile placed in the excavation hole in which the reinforcing bar is inserted It is a schematic sectional drawing which shows the state which constructed | assembled the main body.

  First, as shown in FIG. 4A, positioning is performed so that the rotary shaft (Kelly bar) 12 of the excavator (not shown) is on the center of the cylindrical improved ground 2. Next, as shown in FIG. 4 (b), the excavating blade 13 is attached to the tip of the rotating shaft 12, and the excavating blade 13 is rotated to excavate the improved ground 2. The excavation depth by the excavation blade 13 is set within the construction depth range of the improved ground 2. Next, as shown in FIG. 4 (c), when the excavation hole 3 is formed in the center of the improved ground 2, as shown in FIG. 4 (d), the rebar bar 14 assembled in advance on the ground is moved by the crane 15. It is suspended and inserted into the excavation hole 3. Then, as shown in FIG. 4 (e), if concrete 16 is placed in the excavation hole 3 into which the reinforcing bar 14 has been inserted and the concrete 16 is solidified, the center of the improved ground 2 will have FIG. As shown in FIG. 2, the columnar pile body 4 is constructed integrally with the improved ground 2.

  The improved ground 2 may be constructed over the entire pile body 4 as in the above example, but as shown in FIG. 5, it may be constructed only on the soft ground layer, thereby reducing the construction cost. Can be reduced.

  5 (a) shows a case where the soft ground layer is in the upper layer of the ground, and FIG. 5 (b) shows a case where the soft ground layer is in the center of the ground. Shows the relationship between depth and ground strength. The ground strength is higher as it goes to the right in the figure. As shown in FIG. 5 (b), the improved ground 2 can be easily formed in the center of the ground by changing the diameter of the stirring blade 11 in the case of the teno column method.

  Moreover, although the diameter dimension of the pile main body 4 is good also in the longitudinal direction of the pile main body 4 like the said example, as shown in FIG. 6, the diameter of the excavation hole 3 formed in the improved ground 2 is excavated. If the holes 3 are partially different in the longitudinal direction, that is, if the diameter dimensions of the pile body 4 are partially varied in the longitudinal direction of the pile body 4, the pile body 4 is more integrated with the improved ground 2. Built. In order to make the diameter of the excavation hole 3 partially different in the longitudinal direction of the excavation hole 3, excavation blades 13 having different diameters may be used.

  Further, as shown in FIG. 1 (c), if a cylindrical reinforcing bar 17 is constructed concentrically with the improved ground 2 in the improved ground 2, and the excavation hole 3 is formed inside the reinforcing bar 17, the pile body 4 The collapse of the wall of the excavation hole 3 during construction can be reliably prevented. The reinforcing bar 17 may be constructed over the entire length of the improved ground 2 if possible, but may be only the upper layer as shown. Further, if the upper part of the reinforcing bar 17 is protruded from the excavation hole 3 and the structure or footing constructed on the pile body 4 is integrated with the upper part of the reinforcing bar 17, smooth stress transmission can be achieved. In order to construct the reinforcing bar 17 in the improved ground 2, the reinforcing bar 17 may be dropped into the improved ground 2 by a vibration method using a vibrator when the improved ground 2 is not cured.

  As described above, according to the present invention, the following effects are brought about by constructing the pile body 4 integrally with the improved ground 2 in the improved ground 2 by an earth drill method that does not use a stabilizing liquid. It is.

(A) It has the advantages of the earth drill method, such as low vibration and low noise handling, simple equipment, fast construction speed, economics, and construction in a small site.
(B) Since there is no fear of collapse of the excavation hole 3, the workability of the pile body 4 is greatly improved.
(C) There is no fear that the diameter of the excavation hole 3 is reduced and the design pile diameter is not satisfied because the excavation hole wall is pressed by the surrounding ground.
(D) Since there is no need to use a stabilizing liquid, there is no fear that the stabilizing liquid will be mixed into the concrete and the quality of the pile body 4 will be deteriorated.
(E) Since the pile main body 4 is reinforced by the improved ground 2, the diameter of the pile main body 4 can be reduced, and as a result, the construction cost is reduced.
(F) Since the diameter of the pile body 4 is increased in a pseudo manner by the improved ground 2, it is possible to improve the earthquake resistance, the horizontal resistance, and the like.

BRIEF DESCRIPTION OF THE DRAWINGS It is a figure which shows the ground improvement process by the construction method of a cast-in-place pile of this invention, (a) is a schematic plan view, (b) is a schematic sectional drawing, (c) constructs a reinforcing bar in the improved ground It is a schematic sectional drawing at the time of doing. It is a figure which shows the excavation process by the construction method of a cast-in-place pile of this invention, (a) is a schematic plan view, (b) is a schematic sectional drawing. It is a figure which shows the pile main body construction process by the construction method of a cast-in-place pile of this invention, (a) is a schematic plan view, (b) is a schematic sectional drawing. It is a figure which shows the construction process of the cast-in-place pile to the improved ground by the earth drill method implemented by this invention, (a) is a schematic which shows the state which positioned the rotating shaft of the excavator in the center of the cylindrical improved ground Sectional drawing, (b) is a schematic sectional view showing a state in which the improved ground is excavated by the excavating blade attached to the rotary shaft of the excavator, and (c) is an outline showing the improved ground in which the excavation hole is formed. Cross-sectional view, (d) is a schematic cross-sectional view showing a state in which a reinforcing bar is inserted into the excavation hole, and (e) is a concrete body placed in the excavation hole in which the reinforcing bar is inserted to construct a pile body It is a schematic sectional drawing which shows a state. It is a schematic sectional drawing which shows the state where the improved ground was built only in the soft ground layer, and the excavation hole was formed, (a) is a case where a soft ground layer exists in the upper layer part of the ground, (b) is soft This is when the ground layer is in the center of the ground. It is a schematic sectional drawing which shows the state which made the diameter of the excavation hole formed in improved ground partially differ in the longitudinal direction of an excavation hole. It is the schematic which shows the construction equipment of a teno column construction method.

Explanation of symbols

1: Soft ground 2: Improved ground 3: Excavation hole 4: Pile main body 5: Water tank 6: Cement silo 7: Mixing plant 8: Pump 9: Construction machine main body 10: Agitation device 11: Agitation blade 12: Rotating shaft 13: Excavation Blade 14: Rebar rod 15: Crane 16: Concrete 17: Rebar rod

Claims (5)

The improved ground is built in a cylindrical shape in the ground, then a drill hole is formed in the center of the improved ground without using a stabilizing liquid, and then a reinforcing bar is inserted into the drill hole, and In the construction method of cast-in-place pile, in which concrete is placed in the excavation hole into which the reinforcing bar is inserted, and the pile body is built integrally with the improved ground in the improved ground ,
A cast-in-place pile construction method , wherein a reinforcing bar is built in the improved ground, and thereafter, the pile main body is built inside the reinforcing bar .   2. The cast-in-place pile construction method according to claim 1, wherein the improved ground is constructed to a depth at which the pile main body is constructed.   2. The cast-in-place pile construction method according to claim 1, wherein the improved ground is constructed only in a soft ground layer.   4. The cast-in-place pile construction method according to claim 1, wherein the pile body has the same diameter in the longitudinal direction of the pile body. 5.   4. The cast-in-place pile construction method according to any one of claims 1 to 3, characterized in that a diameter dimension of the pile body is partially varied in a longitudinal direction of the pile body.

Images