JP4032711B2 - Foundation pile construction method and foundation pile constructed by this method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a foundation pile construction method and a foundation pile constructed thereby, and more particularly, to a technology for loading before the foundation pile supports a structure to be supported.
[0002]
[Prior art]
In the case of ground where it is difficult to obtain good support with a direct foundation such as soft ground, pile foundations that can transmit the weight of the upper structure to the lower ground accurately to ensure good support are often constructed. In designing this pile foundation, for example, the allowable bearing force is calculated by taking into consideration the vertical bearing force such as the bearing force borne by the pile tip surface and the bearing force borne by the circumferential friction of the pile for each pile. And according to this permissible bearing capacity, the number of piles required for one structure, arrangement pattern, etc. are determined. In this case, the limit value (extreme support force) of the vertical support force is set to a safety factor of 2 to 3 so that the settlement caused by the load after completion of the structure does not damage the structure. The value divided is often used in the design as the allowable bearing force. The pile thus designed is driven into the ground by a method such as hammering, vibration, press-fitting, or pre-boring, or is constructed in the ground by a cast-in-place method.
[0003]
[Problems to be solved by the invention]
However, since the load that the foundation pile always bears after completion of the structure is only about 1/3 of the ultimate bearing capacity, there are few situations where the load is actually transmitted to the tip of the foundation pile. In other words, the pile foundation that was originally designed was rarely fully exhibited, and the pile foundation with an excessively large design was constructed as it was. On the other hand, as shown in Japanese Patent Laid-Open No. 3-90706, a loading jack that takes the circumferential frictional force of the pile as a reaction force is provided at the tip of the foundation pile, and a curable pressure fluid is press-fitted into the foundation pile, thereby A method has also been devised in which the pile is loaded in the vertical direction in advance to increase the bearing capacity and optimize the design. However, in order to assume the actual construction situation, it is necessary to install the load jack described above at the bottom of the placement hole before placing the pile, which is difficult to apply to construction methods other than the cast-in-place method and the pre-boring method. There was room for improvement in that it took a lot of labor and cost to handle the.
[0004]
The present invention has been made in view of such circumstances, and realizes an economical and efficient design and construction by suppressing an excessive design, and a foundation pile construction method capable of expressing a good bearing force, and this It aims at providing the foundation pile constructed by the method.
[0005]
[Means for Solving the Problems]
The present invention has been made in order to achieve the above object, a first aspect of the present invention, by installing the jack device in the pile head of the implanted or constructed foundation pile in the ground plate, the foundation pile is supported to construct taking reaction force, the foundation pile to pair with loading a row cormorants group Ishizuekui construction method, the rod-shaped body which projects upward from the pile head is fixed to the pile head end face of said foundation pile Of the connector, a protruding portion from the end face of the pile head is housed in a sheath pipe and connected to the structure prior to operation of the jack device .
[0006]
The second invention is characterized in that, in the first invention, the foundation pile is loaded more than the load after completion of the structure .
[0007]
3rd invention is the foundation pile used for 1st or 2nd invention, Comprising: It is fixed to the pile head of a foundation pile, and it protrudes upwards from a pile head end surface, and the protrusion site | part from this pile head end surface is a shear. A rod-shaped body connector housed in a pipe and a jack device installed on the pile head are provided.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a diagram showing the construction status in the foundation pile construction method of the present invention, FIG. 2 is a diagram showing the structure near the pile head of the foundation pile of the present invention, (a) before jack loading, (b) Indicates the state after the jack is loaded. Hereinafter, the foundation pile construction method of the present invention and the foundation pile constructed by this method will be described in detail with reference to the drawings. As a situation in the present embodiment, for example, a situation can be assumed in which the pier frame 11 is constructed along with the construction work of the bridge 10, and under this situation, the construction of the pile foundation 30 is selected in accordance with the state of the ground 20. .
[0009]
As the construction procedure of the pile foundation, after determining the geological condition such as the position of the support layer and the groundwater level and the condition of the ground 20 such as the ground strength, it is determined whether the ready-made pile is to be penetrated or the cast-in-place pile is to be placed. (A) If the foundation pile 31 shown in the figure is a cast-in-place pile, for example, a pile driving hole is drilled in the ground 20 with a drilling heavy machine such as an earth drill, and a reinforcing bar is built in the pile driving hole. It is formed by casting concrete. On the other hand, it is a matter of course that a ready-made pile may be penetrated into the ground 20 by adopting a hitting method, a press-fitting method, a Nakabori method or the like. Hereinafter, it is assumed that the foundation pile is “constructed” on the ground 20 including a case where a cast-in-place pile is placed and a case where a ready-made pile is inserted.
[0010]
A hydraulic jack 40 and a shear connector 41 are installed on the pile head of the foundation pile 31 thus constructed in the ground 20. This installation may be performed according to the situation before and after foundation pile construction and before and after production of ready-made piles. In any case, after the foundation pile 31 is constructed on the ground 20, it is sufficient that the installation is made before adding “loading more than the completed load” in the present invention to the foundation pile 31. As shown in FIG. 2, the hydraulic jack (jack device) 40 has a base embedded and fixed to, for example, an end surface 33 of the pile head 32, and extends appropriately in the length direction of the foundation pile 31, that is, vertically downward. Perform the action. In addition, it is preferable to appropriately use means such as fixing reinforcing bars for improving the adhesion between the pile head 32 of the foundation pile 31 and the concrete on the lower surface of the pier frame 11. This fixing reinforcing bar is preferably used for fixing with at least one of the pile head 32 and the pier frame 11, but may not be used depending on the construction situation. The shear connector (rod-shaped body connector) 41 plays a role of transmitting a horizontal force to the foundation pile 31, and one end is fixed to the pile head 32 of the foundation pile 31, and the other end is above the pile head end surface 33. It is a rod-shaped body such as a steel rod that protrudes from the pile head end surface 33 and accommodates the protruding portion 42 in the sheath pipe 43.
[0011]
When the construction of the foundation pile 31 and the installation of the hydraulic jack 40 and the like at the pile head 32 are completed as described above, the protruding portion 42 that is housed in the sheath pipe 43 is used to construct the footing 12 in the pier frame 11. Connect with this. Or this connection process is abbreviate | omitted and the loading process by the said hydraulic jack 40 is started. In this loading process, the reaction force plate 40a of the hydraulic jack 40 abuts or is fixed to the footing 12, taking the reaction force bridge 10 a person the foundation pile 31 is supported (including pier building frame 11, etc.), the foundation pile 31 is loaded more than the post-completion load of the bridge 10 including the pier housing 11. As shown in FIG. 2, the bottom surface of the footing 12 and the bottom surface of the reaction force board 40 a of the hydraulic jack 40 coincide with the pile head end surface 33 of the foundation pile 31 in the state before the jack loading in FIG. On the other hand, in the state after jack loading of (b) figure, the pile head end surface 33 is pushed down from the lower surface of the footing 12, and the lower surface of the reaction force board 40a. That is, it can be said that the foundation pile 31 has penetrated more into the ground 20 by extending the hydraulic jack 40 vertically downward. At this time, the protruding portion 42 in the sheath pipe 43 slides in the sheath pipe 43 as the foundation pile 31 descends.
[0012]
FIG. 3 is a graph showing the relationship between the load applied to the pile and the amount of settlement, where (a) shows the case of the conventional method and (b) shows the case of the construction method of the present invention. According to the conventional construction method, as shown in FIG. 5A, the design load (corresponding to the allowable support force) is about 1/3 of the ultimate load that the foundation pile 31 can originally handle. On the other hand, in the present invention, in addition to the load of the built frame such as the footing 12 and the pier frame 11, a load higher than the post-completion load is loaded on the foundation pile 31 to prevent the settlement that will occur after the structure is completed in advance. It is possible to set the design load after it is generated. Therefore, a load value close to the ultimate load can be used as the design load. Of course, as a result, the amount of settlement after the structure (bridge 10) is completed is suppressed.
[0013]
【The invention's effect】
As explained in detail above, according to the foundation pile construction method of the present invention and the foundation pile constructed by this method, sufficient support force is provided in such a manner that the support ability of the foundation pile is provided to the limit. In addition to being able to perform construction that can be secured, there is an effect of suppressing excessive design even at the time of design prior to this construction. Moreover, the present invention can be applied not only to a method in which a pile driving hole such as a cast-in-place method or a pre-boring method is provided in advance, but also to a method in which an existing pile such as a batting method is inserted into the ground, and is surely applicable to a wide range of construction situations Can respond. In addition, since the jack device and the rod-shaped body connector that constitute the foundation pile of the present invention are provided on the pile head, it does not require much labor for construction, and the cost can be reduced.
[0014]
Thus, it is possible to provide an economical and efficient design and construction by suppressing an excessive design, and to provide a foundation pile construction method capable of expressing a good bearing force and a foundation pile constructed by this method.
[Brief description of the drawings]
FIG. 1 is a diagram showing a construction status in a foundation pile construction method of the present invention.
FIGS. 2A and 2B are diagrams showing a structure near a pile head of a foundation pile according to the present invention, in which FIG. 2A shows a state before jack loading, and FIG. 2B shows a state after jack loading.
FIG. 3 is a graph showing a relationship between a load applied to a pile and a subsidence amount, where (a) shows a conventional method and (b) shows a case of the construction method of the present invention.
[Explanation of symbols]
10 Structure (Bridge)
20 Ground 31 Foundation pile 32 Pile head 40 Jack device (hydraulic jack)

Claims (3)

By installing the jack device in the pile head of the implanted or constructed foundation pile in the ground plate, taking a reaction force to the structure to which the foundation pile is supported, intends row a load placement against to the foundation pile a group Ishizuekui construction methods,
Of the rod-shaped connector fixed to the pile head of the foundation pile and projecting upward from the end face of the pile head, the projecting part from the end face of the pile head is housed in a sheath tube and connected to the structure prior to the operation of the jack device. A foundation pile construction method characterized by: The foundation pile construction method according to claim 1, wherein the foundation pile is loaded more than a load after completion of the structure . It is the foundation pile used for the method of Claim 1 or 2, Comprising: It fixed to the pile head of the foundation pile, and it protruded upwards from the pile head end surface, and the protrusion site | part from this pile head end surface was stored in the Saya pipe. A foundation pile comprising a rod-shaped body connector and a jack device installed on the pile head.

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