JP2005307470A - Foundation reinforcing method for existing bridge pier constructed by well construction method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To easily reinforce a foundation of an existing bridge pier constructed by a well construction method, while maintaining its existing conditions, so as to be resistant to strong horizontal jolts (impact) occurring in case of an earthquake or the like. <P>SOLUTION: The foundation of the existing bridge pier is constructed in the following manner. First an assembled well having a plurality of stages connected to each other is formed by aligning reinforced concrete cylindrical wells with each other and successively embedding the same in the ground, then a bottom concrete portion 4 is formed by hardening concrete in a lower open cylinder port of the assembled well, and thereafter sand is packed and compacted in the assembled well, followed by forming an upper concrete portion 6 by hardening the concrete in an upper open cylinder port of the assembled well so as to confine the sand. According to a foundation reinforcing method for the existing bridge pier 7, a chemical such as a cement hardener is injected into the assembled well to harden the sand, and thus the foundation of the bridge pier 7 is reinforced. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for reinforcing a foundation of a pier constructed by a so-called well method adopted from the postwar period until around 1975.

  Since the Great Hanshin Earthquake, reinforcement work for existing piers such as highways and bridges has been carried out from the viewpoint of the importance of earthquake countermeasures. However, the reinforcement work is exclusively for the piers on the ground, and nothing has been done on the foundations in the ground. In particular, the foundations of piers constructed between the end of the war and around 1975 are problematic because they are constructed by the so-called well method.

Here, this well construction method will be briefly described below with reference to FIGS.
In FIG. 2, (1) the hole 1A is dug. (2) The well 2A is made in the hole 1A for the first digging. This first-stage well 2A is a reinforced concrete cylindrical body that is formed by assembling a formwork in a hole 1A for the first digging and pouring concrete into it, and has claws 3 on the lower surface. (3) The hole 1B is dug again in the first stage well 2A.

  FIG. 3 shows a state in which the first well 2A is lowered (dropped) into the second digging hole 1B by its own weight and the claw 3 by digging the second digging hole 1B. In FIG. 3, (4) a second-stage well 2B is formed in the first-drilled hole 1A that is vacated above the first-stage well 2A. The second-stage well 2B is formed of a reinforced concrete cylindrical body in which a rebar is poured into the knitted concrete so as to be connected to the rebar exposed on the upper surface of the first-stage well 2A by forming a formwork. (5) The hole 1C is dug again in the first stage well 2A.

  FIG. 4 shows a state in which the double wells 2A and 2B stacked in alignment are lowered (dropped) to the third digging hole 1C by its own weight and the claws 3 by digging the third digging hole 1C. Is shown. In FIG. 4, (6) a third-stage well 2C is made in the same manner as the second-stage well 2B in the first digging hole 1A vacated above the second-stage well 2B; Then, digging the hole 1D for the fourth digging is a repetition of the above, and the description is omitted.

  FIG. 5 shows a state in which the last eight-stage well 2H is stacked in a continuous state by omitting the middle by the method described above. In this simultaneous state, the eight wells 2A to 2H are the stacked wells stacked in a state of being aligned. In FIG. 5, (7) the bottom base concrete part 4 hardened with concrete is formed in the lower open cylinder port of the continuous well. (8) Sand 5 is packed inside the continuous wells and pressed.

In FIG. 6, (9) an upper concrete portion 6 solidified with concrete is formed at the upper open cylinder port of the continuous well so as to confine the sand 5 in the continuous well.
Since the foundation by the well method is thus completed, the pier 7 is constructed on the upper concrete portion 6 of the foundation portion as shown in FIG.

  When the foundation part of the existing pier constructed by the well method as described above is subjected to strong lateral shaking (impact) due to an earthquake or the like, the joints of the continuous wells are shifted as shown in FIG. Since all or a part of the piers are eccentric from each other, and this eccentric state is not visible at all from the ground, the upper pier 7 can be tilted or tilted as it is, or simply by the next shaking. The foundation part collapses and the pier 7 falls, and there is a problem that the bridge pier 7 falls when the foundation part that cannot be seen in the ground collapses no matter how much the portion of the pier 7 visible on the ground is reinforced. The present invention aims to provide a method for solving such a problem in a simple manner.

  The present invention constitutes a continuous well connected in multiple stages in the ground by sequentially filling cylindrical wells made of reinforced concrete and aligning them in the ground, and forming a bottom base concrete part solidified with concrete at the lower open tube opening of this continuous well Then, in the foundation of the existing bridge pier, which is constructed by forming a concrete part of the upper base solidified with concrete at the upper open cylinder mouth of the continuous well so that it can be trapped after filling the inside of the continuous well with sand. Further, a chemical solution such as a cement hardener is injected into the simultaneous wells to harden the sand and reinforce the foundation of the pier.

  The present invention is a method of injecting a chemical solution such as a cement hardener into the interior of the continuous wells and curing the sand that has been compacted, so that if the continuous wells are already eccentric between each well, In addition, even if each well is not eccentric, all wells are hardened and reinforced as a single lump together with the sand inside, so there is a shift between each well due to the shaking after this reinforcement work. There is an effect that the pier can be prevented from falling down.

  This was realized by injecting chemicals such as cement hardener into the wells at the foundation of the existing pier by the well method to harden the sand.

Embodiment FIG. 1 is a schematic view showing a state where a reinforcing method of the present invention is applied to an existing pier constructed by a well method. In FIG. 1, the interior of the continuous well is in a state (indicated by cross-sectional hatching) in which a chemical solution 8 such as a cement hardener is injected under pressure and the sand 5 is hardened as indicated by arrows. Accordingly, in the state of being hardened by the chemical solution 8 in this way, the wells 2A to 2H in a state where the joints are shifted due to shaking such as an earthquake are hardened as a single lump as they are, so that each well is also caused by subsequent shaking. It is possible to prevent the pier 7 from falling or tilting without further shifting between 2A to 2H.

  The injected chemical solution 8 such as cement hardener may be moved to the whole interior of the continuous well (up to the position of the bottom concrete part 4) by pressure, or may be terminated only upward. What is necessary is just to adjust injection quantity etc. suitably. In any case, the same effect is obtained in that the sand 5 in the simultaneous wells is hardened and the foundation can be reinforced.

  The injection direction of the chemical solution 8 is indicated by the arrow in FIG. 1, but depending on the situation of the site where the pier 7 is constructed, it can be injected from the side or the like, and the injection location and injection method are limited at all. Not what you want. Also, any chemical solution 8 can be used as long as the sand 5 inside the simultaneous wells can be sufficiently cured.

  In the above-described embodiment, the simultaneous wells have been described as being reinforced with respect to the state where the joints are already shifted and decentered between the wells 2A to 2H. However, as the object of reinforcement, the foundation portion may not be visible. Of course, the same effect can be obtained by reinforcing the same wells in a state where the wells are not eccentric between the wells 2A to 2H.

  The present invention can be widely used to reinforce the foundations of existing piers constructed by the well method.

It is the schematic which shows the Example of this invention. It is the schematic which shows the construction state of the 1st stage well 2A for demonstrating the conventional well construction method. FIG. 3 is a schematic diagram showing a construction state of the second well 2B following FIG. 2. It is the schematic which shows the construction state of 2 C of wells of the 3rd step following FIG. It is the schematic which shows the state by which the simultaneous well was finally constructed following FIG. It is the schematic which shows the state by which the pier was constructed following FIG. It is the schematic which shows the state in which the foundation part of the existing pier is eccentric and the joint part shifted | deviated between each well.

Explanation of symbols

1A: 1st digging hole 1B: 2nd digging hole 1C: 3rd digging hole 1D: 4th digging hole 2A: 1st stage well 2B: 2nd stage well 2C: 3rd stage well 2F: 6th stage well 2G: 7th stage well 2H: 8th stage well 3: Claw 4: Bottom concrete part 5: Sand 6: Upper concrete part 7: Pier 8: Chemical solution

Claims (1)

A cylindrical well made of reinforced concrete is sequentially embedded while being aligned to form a continuous well connected in multiple stages in the ground, and a bottom concrete part hardened with concrete is formed at the lower open tube opening of this continuous well, and then this In the foundation of an existing bridge pier constructed by forming an upper concrete part hardened with concrete at the upper open cylinder mouth of the continuous well so that it is packed and pressed into the interior of the continuous well and then confined, A method for reinforcing a pier foundation comprising injecting a chemical solution such as a cement hardener into the interior of the pier to harden the sand to reinforce the foundation of the pier.

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