JP2019002271A - Earthquake disaster suppression method of existing steel pipe pile type pier and steel pipe pile type pier - Google Patents

Abstract

To provide an earthquake disaster suppression method of an existing steel pipe pile type pier which can inexpensively and easily suppress a disaster by earthquake of an existing steel pipe pile type pier, and a steel pipe pile type pier.SOLUTION: Provided is an earthquake disaster suppression method of an existing steel pipe pile type pier 1 which has a steel pipe pile 11 installed on a water area side of revetment and having a lower end installed in ground 15 in water, and a superstructure work 12 supported by the steel pipe pile 11. The earthquake disaster suppression method removes a part of the ground on the water area side.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a method for suppressing earthquake damage of an existing steel pipe pile type pier and a steel pipe pile type jetty. The present invention relates to a method for suppressing earthquake damage of an existing steel pipe pile type jetty and a steel pipe pile type jetty in which the earthquake damage is suppressed.

  As a structure for berthing a large ship, there is a structure consisting of a revetment constructed with steel sheet piles and a jetty installed on the water side of the revetment. In this structure, in order to reduce the construction cost of the revetment, for example, an embankment having an inclined surface may be provided on the waterside side of the revetment such as a steel sheet pile. And as a pier, there exists a steel pipe pile type pier which has a steel pipe pile and the superstructure supported by this steel pipe pile.

  When such a steel pipe pile type jetty is installed on the waterside side of the revetment having the above embankment, as shown in Non-Patent Document 1, a typical damage caused by an earthquake of a steel pipe pile type jetty is a steel pipe pile. This is due to the fact that the revetment with embankment behind the pier is deformed to the sea side (water side) due to the liquefaction of the surrounding ground, causing the steel pipe pile to undergo bending deformation such as buckling. Therefore, steel pipe pile piers that do not take measures against ground liquefaction due to such earthquakes, and steel pipe pile piers that require liquefaction countermeasures by reviewing the design earthquake after construction, etc., need to be seismically reinforced. There is. In addition, as in Non-Patent Document 1, the distance between the revetment and the steel pipe pile type pier is not limited to the case where the steel pipe pile is located in the embankment, but the distance between the revetment and the steel pipe pile type pier is relatively long. In the case where is separated, the steel pipe pile may be bent and deformed by the revetment having embankment at the time of earthquake.

  Here, as the seismic reinforcement of the existing steel pipe pile type jetty, it is common to perform ground improvement on the ground where the occurrence of liquefaction is a concern (see Non-Patent Document 2, etc.). However, in the ground improvement as in Non-Patent Document 2, it is necessary to perform a wide range of ground improvement depending on the conditions, which is a large-scale construction and is not easy, and the reinforcement cost increases.

  Note that Non-Patent Document 3 referred to in [Example] described later is also described here.

Shiozaki Goro et al .: Reproduction calculation of damage cases of straight pile type horizontal pier by two-dimensional effective stress analysis, JSCE Proceedings A1, Vol. 65, no. 1 pp. 881-891, 2009 Kazunari Okada et al .: (1-4) Evaluation example of injection solidification ground by various in-situ tests in large-scale ground improvement work in service berth, Proceedings of 10th Ground Improvement Symposium (October 2012), pp. 47-54 Goro Shiozaki: Study on seismic control of steel pile pile jetty using buckling restrained braces, JSCE Proceedings B3, Vol. 71, no. 2, pp. I_167-172, 2015

  The present invention has been made in view of the above-described problems, and is capable of easily and inexpensively suppressing damage caused by an earthquake of an existing steel pipe pile type pier, and a method for suppressing earthquake damage of an existing steel pipe pile type pier and a steel pipe pile type. The purpose is to provide a pier.

  As a result of studies to solve the above-mentioned problems, the present inventors consider firstly to suppress the damage of the steel pipe pile type jetty, and the terrestrial ground where there is no damage to the revetment itself and thus there is no important structure behind the revetment. By removing a part of the ground on the water area, which may push out the steel pipe pile to the water side, it is possible to suppress the damage caused by the earthquake of the steel pipe pile type pier easily and inexpensively. As a result, the present invention was completed.

  The present invention has been made on the basis of the above findings, and the gist is as follows.

[1] A method for suppressing earthquake damage of an existing steel pipe pile type jetty having a steel pipe pile installed on the waterside side of the revetment and having a lower end installed in the underwater ground and an upper work supported by the steel pipe pile. ,
A method for suppressing earthquake damage to an existing steel pile pier characterized by removing part of the ground on the water side.

  [2] The existing steel pipe pile type pier according to [1], wherein the removal range of the ground is adjusted according to the distance between the revetment and the steel pipe pile, the water depth, and the strength of the ground. Earthquake damage control method.

  [3] The earthquake damage suppression method for an existing steel pipe pile type jetty according to [1] or [2], wherein the ground on which the steel pipe pile is installed has a liquefied layer.

[4] A steel pipe pile pier that is installed on the waterside side of the revetment and has a steel pipe pile with a lower end installed in the underwater ground and a superstructure supported by the steel pipe pile,
A steel pipe pile type jetty characterized in that a part of the ground in front of the revetment that pushes out the steel pipe pile to the water side is removed.

[5] A steel pipe pile-type pier installed on the water area side of the revetment and having a steel pipe pile with a lower end installed in the underwater ground and an upper work supported by the steel pipe pile,
The steel pipe pile type jetty characterized in that the land side ground of the steel pipe pile on the outermost side of the steel pipe piles has a ground height that does not deform the steel pipe pile on the outermost side.

  [6] The steel pipe pile type jetty according to [4] or [5], wherein the ground on which the steel pipe pile is installed has a liquefied layer.

  According to the present invention, it is possible to suppress damage caused by an earthquake of a steel pipe pile type jetty by an inexpensive and simple method of removing a part of the ground on the waterside side of the revetment where the steel pipe pile type jetty is installed. Play.

It is a schematic diagram which shows the structural example of the existing steel pipe pile type jetty targeted for earthquake damage suppression. It is a schematic diagram which shows the damage form at the time of the earthquake of the existing steel pipe pile type pier of the earthquake damage control object of this invention. It is a schematic diagram which shows the structural example of the existing steel pipe pile type jetty to which the earthquake damage suppression method of this invention is applied. It is a schematic diagram which shows the damage form at the time of the earthquake of the existing steel pipe pile type jetty to which the earthquake damage control method of this invention is applied. It is a schematic diagram which shows the structural example of the existing steel pipe pile type jetty to which the earthquake damage suppression method of this invention is applied. It is a figure which shows the waveform of the input earthquake motion in the Example of this invention. It is a residual deformation | transformation figure by the response analysis at the time of the earthquake of the existing steel pipe pile type pier of the earthquake damage suppression object of this invention. It is a residual deformation | transformation figure by the response analysis at the time of an earthquake of the existing steel pipe pile pier to which the earthquake damage suppression method of this invention is applied.

  The method for suppressing earthquake damage of an existing steel pipe pile type jetty according to the present invention includes an existing steel pipe pile installed on the waterside side of a revetment and having a lower end portion installed in the underwater ground and an upper work supported by the steel pipe pile. A method for suppressing earthquake damage to steel pipe pile piers, which removes a part of the ground on the waterside of the revetment. Specifically, the ground between the revetment and the existing steel pipe pile pier, or the existing steel pipe pile pier Part of the ground including the ground directly below is removed. In addition, when embankment is given on the original ground on the waterside side of the revetment, the embankment is also included in the ground on the waterside side of the revetment.

  About the seismic damage control method of such an existing steel pipe pile type pier of the present invention, here, as an example of removing all or part of the embankment applied on the original ground on the waterside side of the revetment, This will be described below with reference to FIGS. FIG. 1 is a schematic diagram showing an example of the structure of an existing steel pipe pile pier targeted for earthquake damage control. FIG. 2 is a schematic diagram showing a damaged form at the time of an earthquake of an existing steel pipe pile type pier targeted for earthquake damage suppression according to the present invention. FIG. 3 is a schematic diagram showing an example of the structure of an existing steel pipe pile type pier to which the method for suppressing earthquake damage according to the present invention is applied, and is an example in which the embankment portion is completely removed. FIG. 4 is a schematic diagram showing a damaged form at the time of an earthquake of an existing steel pipe pile type pier to which the earthquake damage suppressing method of the present invention is applied. FIG. 5 is a schematic view showing a structural example of an existing steel pipe pile type pier to which the earthquake damage suppressing method of the present invention is applied, and is an example in which a part of embankment is removed.

  The existing steel pipe pile type jetty 1 which is the object of earthquake damage suppression of the present invention, that is, the existing steel pipe pile type jetty 1 before performing the earthquake damage suppressing method of the present invention, is the steel pipe pile 11 and the superstructure 12 supported by the steel pipe pile 11. And installed in the sea 10. In FIG. 1, the steel pipe pile type jetty of a 4 row pile is illustrated, and the superstructure 12 can come and go with the land area by the transfer plate etc. which are not shown in figure. The lower end of the steel pipe pile 11 is installed on the ground 15 in the seawater. In FIG. 1, the steel pipe pile 11 reaches the hard support layer 17 located deeper than the liquefied layer 16 of the ground 15 from the vicinity of the sea surface. The liquefied layer 16 is a layer that may be liquefied by an earthquake. Although the example in which the steel pipe pile 11 reaches the support layer 17 is shown in FIG. 1, the present invention is not limited to this, and the steel pipe pile 11 may not reach the support layer 17. If the steel pipe pile 11 does not reach the support layer 17, for example, the steel pipe pile 11 may be supported by friction between the ground 15 and the surface of the steel pipe pile 11. The method of installing the lower end portion of the steel pipe pile 11 in the ground 15 is not particularly limited. For example, a method of driving the steel pipe pile, a method of statically pressing the steel pipe pile using a jack, etc., a predetermined while rotating the steel pipe pile And a method of piercing a steel pipe pile after digging a hole.

  Although the steel pipe pile 11 is not specifically limited, For example, a dimension (inside diameter) is 400-2600 mm, and plate | board thickness is about 6-30 mm. Further, the shape of the steel pipe pile 11 is not limited, and may be a cylindrical shape or a hollow polygonal prism shape.

  And the existing steel pipe pile type jetty 1 is installed in the water area side (sea 10 side) of the revetment which divides a water area and a land area. In this invention, this bank is a bank where the embankment 21 is provided in the water area side, and the embankment 21 has the inclined surface 22 which becomes low toward the water area side. In FIG. 1, the bank protection in which the embankment 21 is provided in the water area side of the steel sheet pile 25 installed in the ground 15 is illustrated as a bank protection.

  Here, as shown in FIG. 2, the revetment having the inclined surface 22 formed by the embankment 21 is deformed to the sea side (water side) when the surrounding ground 15 is liquefied, and is already installed. The steel pipe pile 11 of the steel pipe pile type jetty 1 will be pushed out to the sea side. In FIG. 2, the existing steel pipe pile type pier 1 and the revetment having the embankment 21 before performing the earthquake damage suppression method of the present invention indicated by the dotted line are deformed to the sea side by liquefaction due to the earthquake, and the steel pipe pile 11 is The structure extruded to the side is indicated by a solid line. Thereby, bending deformation, such as buckling, arises in the steel pipe pile 11, and the existing steel pipe pile type jetty 1 is damaged.

  Therefore, the existing steel pipe pile type pier 1 where measures such as liquefaction due to such an earthquake have not been taken, and the existing steel pipe pile type jetty 1 that required liquefaction measures due to a review of the design earthquake after construction, etc. It is necessary to suppress the damage caused by.

  Therefore, in the present invention, since there is the embankment 21 on the front side of the revetment, in order to prevent the displacement of the ground on the front side of the revetment due to deformation of the revetment from affecting further distances, the earthquake damage that the embankment 21 is removed is removed. Suppress. In the present invention, the primary consideration is to suppress the damage (destruction) of the existing steel pipe pile type pier 1, and the damage to the revetment itself and, as a result, the damage to the terrestrial ground where there are no important structures behind the revetment will be allowed. The steel pipe pile 11 is pushed out to the sea side, and all or part of the embankment 21 portion on the front side of the revetment is removed.

  Specifically, for example, by removing all the embankment 21 in FIG. 1, as shown in FIG. As a result of such measures, as shown in FIG. 4, when the ground around the existing steel pipe pile type pier 1 is liquefied during an earthquake, the amount of collapse of the revetment itself to the sea increases, but the water area in front of the revetment Deformation on the side becomes local, and it is suppressed that the steel pipe pile 11 is pushed out to the sea side, and bending deformation such as buckling occurs in the steel pipe pile 11 and the existing steel pipe pile type jetty 1 is prevented from being destroyed. it can. In addition, in FIG. 4, the solid line shows the structure where the revetment from which the embankment 21 shown by the dotted line is removed is deformed to the sea side due to liquefaction due to the earthquake. FIG. 3 shows an example in which the whole embankment 21 is removed, but the embankment 21 may be removed by removing only a part of the embankment 21 and leaving the embankment 21 </ b> A as shown in FIG. 5. Thus, pushing out the steel pipe pile 11 to the sea side can be suppressed by removing an appropriate amount of all or part of the embankment 21.

  Such removal of all or part of the embankment 21 may be performed only by the work of removing the embankment 21, and since it is not necessary to use a ground improvement material, it is inexpensive and simple.

  The removal range of the embankment 21 is set to a minimum range in which the damage to the steel pipe piles is suppressed by performing an earthquake response analysis before performing the earthquake damage suppressing method of the present invention. Alternatively, the removal range of the embankment 21 is adjusted according to the distance between the revetment and the steel pipe pile, the water depth, and the strength of the ground.

  Moreover, the earthquake damage control method of the present invention is such that the distance (d) between the revetment and the steel pipe pile 11 before the earthquake damage control method of the present invention is 2.0 m or more, and the distance between the revetment and the steel pipe pile type pier is It is preferable to apply to long existing steel pipe pile type jetty 1. Conventionally, when the distance between the revetment and the steel pipe pile 11 is long, the deformation of the revetment caused by the liquefaction due to the earthquake is not so large, and even the revetment having the embankment 21 does not deform enough to deform the steel pipe pile 11. However, depending on the magnitude of the earthquake and the type of ground, the steel pipe pile 11 may be deformed even when the distance between the revetment and the steel pipe pile 11 is long. Therefore, about the existing steel pipe pile type jetty 1 where the distance of such a revetment and the steel pipe pile 11 is long, it is preferable to suppress an earthquake damage by the earthquake damage suppression method of this invention.

  The ground 15 in the seawater in which the steel pipe pile 11 is installed, that is, the seabed has a water depth of, for example, 5.0 m or more.

  As described above, in the present invention, since the damage to the revetment itself is allowed, the seismic resistance of the revetment is reduced by removing the embankment, but at least a part of the ground behind the revetment is replaced with lightweight soil, For example, by reinforcing the steel sheet pile 25 firmly or by using a combined steel sheet pile, it is not possible to suppress a decrease in the seismic resistance of the revetment.

  In FIG. 1, although all the steel pipe piles 11 which the existing steel pipe pile type pier 1 has shown the example arrange | positioned in the sea side rather than the embankment 21, the distance between a revetment and the existing steel pipe pile type pier 1 is short, and embankment is carried out. You may make it apply the earthquake-damage suppression method of this invention to the structure where the steel pipe pile 11 is located in 21. FIG.

  In addition, although the existing steel pipe pile type jetty 1 provided in the sea 10 was demonstrated above, the water area in which the existing steel pipe pile type jetty 1 is provided is not limited to the sea 10, A river etc. may be sufficient.

  Also, in the above, when embankment is applied on the original ground on the water side of the revetment, the embankment is removed, but the original ground on the water side of the revetment is excavated and the revetment is removed. The present invention can be similarly applied to the case where the current ground on the water area side is formed. In short, the point of the present invention is to remove the ground on the water area side, that is, the ground between the revetment and the existing steel pipe pile pier, and a part of the ground directly under the existing steel pipe pile pier.

  Furthermore, in the above description, the existing steel pipe pile type jetty has been described in mind, but the present invention can also be applied to the case where a new steel pipe pile type jetty is installed.

  And, from a different viewpoint, the present invention is a steel pipe pile type pier that is installed on the waterside side of the revetment and has a steel pipe pile having a lower end in the underwater ground and an upper work supported by the steel pipe pile. In addition, after the construction of the steel pipe pile type pier, a part of the ground on the water side has been removed for the purpose of earthquake resistance measures.

  In other words, the steel pipe pile-type pier is characterized in that a part of the ground in front of the revetment that pushes the steel pipe pile toward the water is removed. Or it is the steel pipe pile type jetty characterized by the land side ground of the steel pipe pile of the outermost side among the steel pipe piles being the ground height which does not deform | transform into the steel pipe pile of the outermost side.

  In the following, for further understanding of the present invention, an explanation will be given using a study example based on seismic response analysis, but the present invention is not limited in any way.

  The target of the study is a steel pipe pile type pier (steel pipe pile diameter 700mm, plate thickness 9mm, 4 row piles (depth 6m pitch)) in the sea with a depth of -10m, and the revetment behind the steel pipe pile type pier is a steel pipe pile. The steel sheet pile revetment is arranged at a position 24 m from the most land side point of the superstructure of the type jetty, and the shortest distance between the steel sheet pile and the most steel pipe pile on the land side is 25.5 m. Furthermore, the sea side front of the steel sheet pile revetment is provided with an embankment having an inclined surface and a height of 4 m from the sea bottom. With respect to this configuration, the effect of the method for suppressing earthquake damage of a steel pipe pile type pier according to the present invention, in which the entire embankment is removed as a measure for suppressing earthquake damage of a steel pipe type pier, was verified. The water depth from -10 m to -20 m is a liquefied layer with an N value of 10, and the input seismic motion uses a waveform in which the maximum acceleration of the notification wave in the building field is 1.35 times as shown in FIG. . Detailed analysis conditions are the same as the method described in “3. Confirmation of effect by effective stress analysis” of Non-Patent Document 3.

  FIG. 7 shows a residual deformation diagram based on the seismic response analysis of the steel pipe pile pier targeted for earthquake damage suppression according to the present invention, that is, a residual deformation diagram based on the response analysis during the earthquake of the steel pipe pile type pier before removing the embankment. In FIG. 7, the left side is a water area and the right side is a land area. As shown in FIG. 7, since the embankment portion is pushed out to the sea side along with the deformation of the revetment to the sea side, it can be seen that the steel pipe pile on the land side of the steel pipe pile type pier is deformed.

  FIG. 8 shows a residual deformation diagram of an existing steel pipe pile pier applied with the earthquake damage control method of the present invention by an earthquake response analysis, that is, a residual deformation diagram of a steel pipe pile type pier when an embankment is removed. Show. In FIG. 8, the left side is a water area and the right side is a land area. As shown in Fig. 8, although the deformation of the revetment to the sea side is increasing, the deformation of the front of the revetment is local, and deformation occurs until the steel pipe pile on the land side of the steel pipe pile pier is deformed. You can see that it is not.

DESCRIPTION OF SYMBOLS 1 Existing steel pipe pile type pier 10 Sea 11 Steel pipe pile 12 Superstructure 15 Ground 16 Liquefaction layer 17 Support layer 21 Embankment 22 Inclined surface 25 Steel sheet pile 26 Land

Claims (6)

A method for suppressing earthquake damage of an existing steel pipe pile type jetty having a steel pipe pile installed on the waterside side of the revetment and having a lower end installed in the underwater ground and a superstructure supported by the steel pipe pile,
A method for suppressing earthquake damage to an existing steel pile pier characterized by removing part of the ground on the water side.   The earthquake damage suppression of the existing steel pipe pile type pier according to claim 1, wherein the removal range of the ground is adjusted according to the distance between the revetment and the steel pipe pile, the water depth, and the strength of the ground. Method.   The method for suppressing earthquake damage of an existing steel pipe pile type pier according to claim 1 or 2, wherein the ground on which the steel pipe pile is installed has a liquefied layer. A steel pipe pile-type pier that is installed on the waterside side of the revetment and has a steel pipe pile with a lower end installed in the underwater ground and a superstructure supported by the steel pipe pile,
A steel pipe pile type jetty characterized in that a part of the ground in front of the revetment that pushes out the steel pipe pile to the water side is removed. A steel pipe pile-type pier that is installed on the waterside side of the revetment and has a steel pipe pile with a lower end installed in the underwater ground and a superstructure supported by the steel pipe pile,
The steel pipe pile type jetty characterized in that the land side ground of the steel pipe pile on the outermost side of the steel pipe piles has a ground height that does not deform the steel pipe pile on the outermost side.   The steel pipe pile pier according to claim 4 or 5, wherein the ground on which the steel pipe pile is installed has a liquefied layer.

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