JP2006070436A - Aseismatic reinforcing method for gravity type quaywall - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an aseismatic reinforcing method for a gravity type quaywall that can cut down a construction period/a construction cost required for repair work while considering environment without lowering the stability of the ground. <P>SOLUTION: The aseismatic reinforcing method for the gravity type quaywall for repairing and aseismatically reinforcing the existing gravity type quaywall constructed by installing a hollow caisson 13 surrounded by side wall parts and filling sand 14 in a hollow part of the caisson 13, comprises a process for inserting landslide preventing anchors 22 through the inside of the caisson 13 vertically downward from the top of the caisson 13 to drive the anchors 22 into the ground 11, 12. In addition, constitution comprising a process for substituting an inside filling material (such as seawater) 23 lighter in weight than sand, for a part of the sand 14 filled in the hollow part, can also be exemplified. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a seismic reinforcement technique for a gravity quay. Specifically, it relates to a seismic reinforcement method for a gravity quay that reinforces a gravity quay for the purpose of increasing earthquake resistance.

  Gravity-type quay is a type of retaining wall that is filled with sand and water in a concrete box (caisson) and stops the soil on the land side (back side) with its weight. This gravitational quay stops the back soil by the frictional force with the ground caused by gravity.

  The gravity quay is designed by a design method called seismic intensity method. In other words, the level of safety is maintained against earthquakes of a level that is a seismic motion with a high probability of occurring during the service period (relatively small and frequently occurring earthquake level; referred to as level 1) (that is, the structure is intact). Designed to withstand).

  By the way, the gravity type quay designed by the design method that can withstand level 1 is an earthquake of a level that is a seismic motion that has a high intensity but a low probability of occurring during the service period ) Is likely to be damaged.

  In fact, in the 1995 Hyogoken-Nanbu Earthquake, the gravitational quay in the Hanshin-Awaji area was damaged all over and the gravitational retaining wall moved to the sea side (front) by 2 to 3 meters (4 to 5 meters at larger locations). Oops. For this reason, the transportation route of goods from the ship was closed, and it became difficult to fulfill the function as a port. For this reason, even if the ground motion (level 2) exceeds the ground motion (level 1) assumed by the conventional design method, it will suffer to some extent, but it will not cause much damage to the surroundings due to large-scale deformation. Therefore, it is necessary to rationally design the system so that it can hold the intended function.

  Against this background, the Ministry of Land, Infrastructure, Transport and Tourism is promoting seismic reinforcement of the quay with the goal of developing a port that can be used as a logistics base even in the event of a Level 2 earthquake. In addition, the “Technical Standards and Explanations for Harbor Facilities” revised in April 1999 introduced the concept of seismic performance design, and technical standards corresponding to each of the level 1 and level 2 earthquake motions. It was stated that the seismic strengthening facility will be designed based on the above standards. In other words, the seismic intensity method with the seismic performance of “Ensuring soundness” for Level 1 earthquake motions, and the seismic intensity method with the seismic performance of “Maintaining functions” for Level 2 earthquake motions. Perform cross-sectional design by.

  Therefore, work is underway to repair existing harbor facilities constructed according to conventional design standards to seismic strengthened quays. For example, in the case of a gravitational quay, the existing quay can be retrofitted into a seismic reinforced quay, either (a) a method that advances the quay normal or (b) a method that does not change the normal It is done in

  In other words, (a) In the construction method in which the quay normal is put forward, a construction method such as constructing a new jetty on the front of the existing quay or integrating with the concrete placed on the front is carried out. ing. Moreover, (b) As a construction method which does not change the normal line, construction methods such as improvement of the backside earth and weight of the padding material for the purpose of reducing the backside earth pressure are performed.

However, the conventional refurbishment method has the following problems: (a) In the case of the method of projecting the quay normal, the load on the environment is large and the width of the channel is reduced, and the stability of the ground due to the increase in the weight of the levee body Have problems such as decline in sex. In addition, (b) In the case of a construction method that does not change the normal, there are problems such as the need for extensive ground improvement in the background, and problems such as a decrease in ground stability due to an increase in the weight of the filling material. Yes. Furthermore, these conventional refurbishment methods have a problem of high costs such as a large construction period and construction costs required for renovation work because they are constructed over a wide area and use many materials.

  The present invention has been made to solve the above technical problems, and its purpose is to consider the environment, not to lower the stability of the ground, and to reduce the construction period and construction cost required for the repair work. It is a technical problem to provide a seismic reinforcement method for gravity quay that can be suppressed.

The present invention is a seismic reinforcement method for a gravity quay and has the following configuration in order to solve the above technical problem.
That is, the seismic reinforcement method of gravity quay of the present invention is
The landslide prevention anchor is provided with a step of passing through the caisson vertically downward from the top end of the caisson and placing it on the ground. According to this configuration, the sliding resistance force can be increased by introducing the anchor force vertically downward. The landslide prevention anchor can equalize the ground reaction force distribution by appropriately arranging the pitch and the number of the anchors. There are two types of anchors for preventing landslides, depending on the conditions.

  Moreover, in the seismic reinforcement method of gravity type quay of the present invention, a configuration including a step of replacing part of the sand packed in the hollow portion with a padding material that is lighter than the sand can be exemplified. According to this configuration, when the foundation ground is soft, the embankment sand is replaced with a filling material that is lighter than the sand, thereby reducing the weight of the dam body and reducing the ground reaction force, thereby reducing the bearing stability. Can be prevented. Furthermore, by using seawater as a filling material that is lighter than sand, the inertial force during an earthquake can be reduced.

  As described above, according to the present invention, (1) since the normal line of the quay is not changed, the load on the environment can be minimized, and there is no influence on the width of the channel. (2) By appropriately allocating the anchor force on the outside and inside of the port, the ground reaction force distribution can be made more uniform than before the refurbishment, so that the stability of the ground against the supporting force and the circular slip is improved. (3) If the foundation ground is soft, replace the filling sand with seawater to make the vertical force the same level as before repair and prevent an increase in ground reaction force. Moreover, it becomes possible to reduce the inertia force at the time of an earthquake by substituting with seawater, and also the stability at the time of an earthquake improves. (4) Since construction is possible within the range of caisson levee width, the hinterland can be used even during construction. (5) Since the seismic strengthening quay can be achieved only by installing an anchor, both the construction period and construction cost can be reduced compared with the conventional method.

  Therefore, the present invention can provide a seismic reinforcement method for a gravitational quay that can reduce the work period and construction cost required for the renovation work without lowering the stability of the ground in consideration of the environment.

  The best mode for carrying out the present invention will be exemplarily described in detail below with reference to the drawings. In addition, the seismic reinforcement method of gravity quay of the best form according to the present invention is to renovate existing gravity quay (see Fig. 2) at a harbor or fishing port to seismic reinforced quay and form as shown in Fig. 1 It is what is done.

[Overview of existing gravity quay]
First, the existing gravity quay will be described with reference to FIG.
The existing gravity quay is a revetment structure such as a mooring berth in a harbor or fishing port, and is intended to protect harbor facilities and hinterland from storm surges, tsunamis, and waves.

  As shown in FIG. 2, the existing gravity quay forms a foundation rubble portion 12 as a foundation by stacking rubble in a mound shape on the improved ground 11, and a hollow box-shaped caisson on the foundation rubble portion 12. 13 is placed.

  Then, after the caisson 13 is placed, the inside of the caisson 13 is filled with a filling material (in this embodiment, filling sand) 14, and the backstone 15 is placed on the back ground side of the caisson 13 from the basic rubble portion 12. Raise to the upper part of the caisson 13, and construct the superstructure on the upper part of the caisson 13 and the back stone 15. That is, the existing gravitational quay is filled with sand 14 in the caisson 13, and the soil (backside) on the land side (back ground side) due to the frictional force with the foundation rubble 12 (and the ground 11) generated by the gravity. Stone 15) is stopped.

  The superstructure is constructed with landfill 16 stacked on top of the caisson 13 and the backfill stone 15 and further with the upper concrete 17 covering the landfill 16.

[Explanation of seismic reinforcement method for gravity quay]
Next, the seismic reinforcement method for the gravity quay according to the present invention will be described. Here, the description will be made assuming that the existing gravity quay (see FIG. 2) is modified to the gravity quay shown in FIG.

  This seismic reinforcement method for gravity quay is carried out according to the construction procedures of (1) removal of superstructure, (2) anchor placement, (3) replacement of filling material, and (4) construction of superstructure.

  First, the superstructure is removed. The removal work of the superstructure is performed to facilitate the work of anchor placement and replacement of the filling material, which will be described later, and the superstructure can be removed only on the upper side of the caisson 13. Specifically, the upper concrete 17 and the landfill 16 which are superstructures are removed using a breaker and a backhoe.

  Next, anchor placement work is performed. The landslide prevention anchor 22 (see FIG. 1) is a friction anchor. The friction type anchor 22 transmits the anchor pulling force to the fixing ground by the frictional resistance between the anchor body peripheral surface and the fixing ground. The friction type anchor 22 includes an anchor body 22a, a tension portion 22b, and an anchor head portion 22c. Since high tension acts on the material of the anchor tension portion 22b, PC steel (PC steel rod, PC steel strand, etc.) is generally used for reasons such as reducing the relaxation of the steel.

  In the anchor placing operation, first, the anchor hole 21 is drilled, and the friction type anchor 22 is placed along the anchor hole 21.

  The anchor hole 21 is drilled to the ground (the foundation rubble portion 12, the foundation ground) by inserting the side wall portion of the caisson 13 vertically downward from the top end of the caisson 13.

  Next, the friction type anchor 22 is inserted into the anchor hole 21, and the anchor body 22a is driven on the foundation ground. In this way, the frictional anchor 22 is driven and the anchor force is introduced vertically downward to increase the sliding resistance of the levee body.

Next, replacement work for the filling material is performed. That is, the filling sand 14 is removed with a clam shell, and is replaced with a filling material that is lighter than the filling sand 14, for example, seawater 23. In particular, when the foundation ground is soft ground, driving the friction anchors 22 on the foundation ground may adversely affect the ground support force and arc slip. By replacing a part of the sand 14 with a lighter filling material (seawater 23) than the sand 14, the weight of the dam body is reduced and the ground reaction force is reduced.

  Next, superstructure construction work is performed. That is, the landfill 16 is piled up on the upper part of the caisson 13 and the back lining stone 15, and the landfill 16 is further covered with the upper concrete 17 to construct the superstructure.

  According to this embodiment, the sliding resistance force can be increased by introducing the anchor force vertically downward. The friction type anchor 22 can equalize the ground reaction force distribution by appropriately arranging and pitching. As for the arrangement of the friction type anchor 22, only the inner side of the port and the combination of the outer side and the inner side of the port are used depending on the conditions. In addition, when the foundation ground is soft, replacing the padded sand 14 with seawater 23 reduces the weight of the dam body (caisson, sand and water) 13 and reduces the ground reaction force, thereby improving the bearing capacity stability. A decrease can be prevented.

  That is, according to this embodiment, (1) since the quay normal is not changed, the load on the environment can be minimized, and there is no influence on the channel width. (2) By appropriately allocating the anchor force on the outside and inside of the port, the ground reaction force distribution can be made more uniform than before the refurbishment, so that the stability of the ground against the supporting force and the circular slip is improved. (3) If the foundation ground is soft, replace the padding sand with a padding material (seawater) that is lighter than this sand to make the vertical force the same level as before repair and prevent an increase in the ground reaction force. . Moreover, it becomes possible to reduce the inertia force at the time of an earthquake by substituting with a lighter filling material (seawater) than sand, and the stability at the time of an earthquake is further improved. (4) Since construction is possible within the range of caisson levee width, the hinterland can be used even during construction. (5) Since the seismic strengthening quay can be achieved only by installing an anchor, both the construction period and construction cost can be reduced compared with the conventional method.

  In this embodiment, the friction type anchor is used as the landslide prevention anchor. However, the landslide prevention anchor is not limited to the friction type anchor, and the embankment is formed by introducing the anchor force vertically downward. Any material may be used as long as it has a function of increasing the sliding resistance.

It is sectional drawing which shows the seismic reinforcement construction method of the gravity type quay of this invention. It is sectional drawing which shows the gravity-type quay before repair.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Improved ground 12 Foundation rubble part 13 Caisson 14 Filled sand 15 Backing stone 16 Landfill soil 17 Upper concrete 21 Anchor hole 22 Landslide prevention anchor (friction type anchor)
22a Anchor body 22b Tensile part 22c Anchor head 23 Seawater

Claims (3)

A seismic reinforcement method for a gravity quay where a hollow caisson surrounded by a side wall is installed and an existing gravity quay constructed by filling sand into the hollow part of the caisson is repaired and seismically reinforced,
An anti-seismic reinforcement method for a gravitational quay, comprising a step of inserting a landslide prevention anchor into the ground by vertically passing through the inside of the caisson from the top end of the caisson.   The method for seismic reinforcement of a gravity quay according to claim 1, further comprising a step of replacing a part of the sand packed in the hollow portion with a padding material that is lighter than the sand.   The seismic reinforcement method for a gravity quay according to claim 2, wherein the filling material lighter than sand is seawater.

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