JP3778069B2 - Construction method of foundation pile with seismic isolation effect - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for constructing a foundation pile provided with a seismic isolation effect.
[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 addition, when constructing such a pile foundation, the foundation pile should be preloaded in consideration of the load of the support structure, and if the load is unloaded afterwards, It is possible to appropriately suppress settlement caused by the load. In this case, when designing the foundation pile, it becomes possible to use a value close to the limit value of the vertical bearing capacity of the foundation pile (ultimate bearing capacity) as the allowable bearing capacity. An efficient design in which the number is reduced as compared with the prior art is realized.
[0003]
[Problems to be solved by the invention]
However, even if the foundation pile is capable of efficient design by reducing the amount of subsidence due to the prior loading as described above, the situation will change when designing for earthquakes. Because whether or not to perform loading measures in advance is not a major design factor, the number of foundation piles to be used, the pile length, etc. are determined based on the support capacity of the foundation pile and the strength of the foundation pile during an earthquake. It is. Therefore, even if measures are taken to load the foundation piles or equipment that implements such measures is installed on the foundation piles, the number of foundation piles and the length of the piles are controlled more effectively than before. It was difficult to do.
[0004]
The present invention has been made in view of the circumstances as described above, and realizes an economical and efficient design and construction by suppressing an excessive design even in a design that takes into account the time of an earthquake, and has a good seismic isolation force. It aims at providing the construction method of the foundation pile provided with the seismic isolation effect which can express .
[0005]
[Means for Solving the Problems]
In order to achieve the above object, a method for constructing a foundation pile having a seismic isolation effect according to claim 1 of the present invention is to insert a ready-made pile into the ground or to cast a cast-in-place pile. The base pile is constructed, and the doughnut-shaped hollow elastic body and the rod-shaped connector are arranged on the pile head of the foundation pile so that the rod-shaped connector passes through the center of the hollow elastic body. One end of the rod-like connector is fixed to the pile head of the foundation pile, the other end protrudes upward from the pile head, and the protruding portion of the rod-shaped connector protruding from the pile head is slidably accommodated in a sheath pipe, Constructing a support structure on the top of the pile, connecting the sheath tube to the support structure, and applying a reaction force to the foundation pile or the support structure to press-fit fluid into the hollow elastic body To load the foundation pile, and then It characterized thereby leaving the fluid in the inner space of the elastic body.
[0006]
Moreover, the construction method of the foundation pile provided with the seismic isolation effect according to claim 2 of the present invention is the construction method of the foundation pile provided with the seismic isolation effect according to claim 1, wherein the support structure includes An expansion control frame for guiding the expansion action of the hollow elastic body in the vertical direction is provided .
[0007]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a diagram showing a construction state of a foundation pile by a construction method of a foundation pile having a seismic isolation effect of the present invention, where (a) shows a state before loading, (b) shows a state after loading, and FIG. These are figures which show the structural example of the hollow elastic body with which a foundation pile is provided.
Hereinafter, the construction method of the foundation pile provided with the seismic isolation effect of the present invention will be described in detail with reference to the drawings.
The construction procedure of the foundation pile 10 is to determine whether the ground pile such as the position of the support layer and the groundwater level and the ground 20 such as the strength of the ground is to be inserted, or whether to place the ready-made pile or to cast the cast-in-place pile. .
If the foundation pile 10 shown to Fig.1 (a) is a cast-in-place pile, a pile driving hole will be drilled in the ground 20 using, for example, a heavy hole drilling machine such as an earth drill, and a reinforcing bar It is constructed by installing concrete and placing concrete. On the other hand, a striking method, a press-fitting method, a Nakabori method, or the like may be adopted, and the ready-made piles may be penetrated through the ground 20 to construct.
Hereinafter, the foundation pile 10 shall be “built” on the ground 20 including the case where a cast-in-place pile is placed and the case where a ready-made pile is penetrated.
[0008]
A doughnut-shaped rubber body (hollow elastic body) 30 and a shear connector (rod-shaped body connector) 40 are installed on the pile head of the foundation pile 10 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 10 is constructed on the ground 20, the installation may be performed before applying a load such as “more than the completed load of the supporting structure” to the foundation pile 10. As shown in FIG. 2, the doughnut-shaped rubber body 30 has, for example, a lower flange 31 in contact with and fixed to the end surface 12 of the pile head 11, and an upper flange 32 in contact with and fixed to the lower surface 71 of the support structure 70. It is a fulcrum of reaction force, and performs an operation of extending appropriately in the length direction of the foundation pile 10, that is, vertically downward. For this purpose, the rubber portion 33 is tightened and reinforced in a bellows shape with a reinforcing ring 34, and a pressure regulating valve 35, an introduction pipe 36, and the like that control the pressure flow of the fluid 50 serving as a driving force for the stretching operation are provided. Of course, the hollow elastic body is not limited only to those having such a form and mechanism, and various types can be adopted according to the construction conditions. Of course, the fluid 50 to be press-fitted into the inner space 31 is not limited to viscous fluid such as oil, and any fluid can be employed as long as it has a required function.
[0009]
The stretching operation is performed by inflating the donut-shaped rubber body 30 by press-fitting a fluid 50 such as oil into the inner space 31 of the donut-shaped rubber body 30, and this expansion action is vertically lowered by the expansion control frame 60. To be done. This extending operation applies a load to the pile head 11 and the loading to the foundation pile 10 is realized. At this time, the loading amount can be controlled by knowing the expansion state of the donut-shaped rubber body 30 by the vertical position sensor 37 and controlling the press-fitting amount of the fluid 50 accordingly.
[0010]
Further, the shear connector (rod-shaped body connector) 40 plays a role of transmitting a horizontal force to the foundation pile 10, and one end is fixed to the pile head 11 of the foundation pile 10, and the other end is above the pile head end face 12. It is a rod-shaped body such as a steel rod that protrudes from the pile head end surface 12 and accommodates the protruding portion 41 in the sheath pipe 42.
[0011]
As described above, when the construction of the foundation pile 10 and the installation of the donut-shaped rubber body 30 and the like at the pile head 11 are completed, the protruding portion 41 that is housed in the sheath pipe 42 is moved along with the construction of the support structure 70. Connect to this. Or this connection process is abbreviate | omitted and the loading process by the said donut-shaped rubber body 30 is started. In this loading process, the upper flange 32 is brought into contact with or fixed to the lower surface 71 of the support structure 70, and a reaction force is applied to the ground 20 or the structure (support structure 70) supported by the foundation pile 10, For example, the foundation pile 10 is loaded more than the load after completion of the support structure 70. As shown in FIG. 1, the pile head end surface 12 is separated from the lower surface 71 of the support structure 70 and pushed downward in a state after loading from a state before loading. That is, it can be said that the foundation pile 10 has penetrated more into the ground 20 by extending the donut-shaped rubber body 30 vertically downward. At this time, the protruding portion 41 in the sheath pipe 42 slides in the sheath pipe 42 as the foundation pile 10 descends.
[0012]
If the loading measure to the foundation pile 10 is completed, the fluid 50 press-fitted into the inner space 31 of the donut-shaped rubber body 30 is left behind. Alternatively, the fluid 50 is adjusted as necessary. Thereby, the doughnut-shaped rubber body 30 in which the inner space 31 is filled with the fluid 50 such as oil appropriately absorbs the seismic energy acting on the foundation pile 10 at the time of the earthquake, and reduces the earthquake response of the entire support structure 70. It becomes possible to make it. Therefore, it becomes possible to reduce and estimate the influence at the time of an earthquake also at the time of the design of the foundation pile 10, and the pile length and the number of the foundation pile 10 used for a pile foundation work can be reduced conventionally. Efficient and low-cost design and construction is realized.
[0013]
【The invention's effect】
As explained in detail above, according to the construction method of the foundation pile having the seismic isolation effect of the present invention, the load at the time of earthquake acting on the foundation pile itself can be appropriately reduced by the excellent seismic isolation effect by the hollow elastic body. Therefore, it is possible to establish a reduction effect such as the number of foundation piles and the pile length that are realized by carrying out loading measures in advance, thereby realizing efficient design and construction.
Therefore, it is possible to provide a foundation pile capable of realizing an economical and efficient design and construction while suppressing an excessive design and capable of expressing a good seismic isolation force even in a design considering an earthquake.
Further, since the expansion action of the hollow elastic body can be guided in the vertical direction by the expansion control frame, it is possible to reliably load the pile head .
[0014]
Thus, it is possible to provide an economical and efficient design and construction by suppressing an excessive design even in a design that takes into account the time of an earthquake, and to provide a foundation pile capable of expressing a good seismic isolation force.
[Brief description of the drawings]
FIG. 1 is a diagram showing the construction status of a foundation pile having a seismic isolation effect according to the present invention, where (a) shows the situation before loading, and (b) shows the situation after loading.
FIG. 2 is a diagram showing a structural example of a hollow elastic body provided in a foundation pile having a seismic isolation effect according to the present invention.
[Explanation of symbols]
10 foundation pile 20 ground 30 hollow elastic body 31 pile head 50 fluid 70 structure (support structure)

Claims (2)

Build foundation piles by penetrating ready-made piles into the ground or by placing cast-in-place piles,
A donut-shaped hollow elastic body and a rod-shaped connector are arranged on the pile head of the foundation pile so that the rod-shaped connector passes through the center of the hollow elastic body, and one end of the rod-shaped connector is connected to the pile of the foundation pile. Fixed to the head, projecting the other end upward from the pile head ,
The protruding part of the rod-shaped connector protruded from the pile head is slidably stored in a sheath tube,
Build a support structure on top of the foundation pile, connect the sheath pipe to the support structure,
A reaction force is applied to the foundation pile or the support structure to press the fluid into the hollow elastic body, thereby loading the foundation pile, and then leaving the fluid in the hollow elastic body. A method for constructing a foundation pile having a seismic isolation effect, characterized by The method for constructing a foundation pile having a seismic isolation effect according to claim 1, wherein the support structure is provided with an expansion control frame that guides an expansion action of the hollow elastic body in a vertical direction .

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