JP5846150B2 - Construction method of river revetment structure - Google Patents

Description

The present invention is to renovate revetment dilapidated medium-sized or small river flowing city, to a protection method for constructing a shore to build a new one.

  In the post-war land improvement policy irrigation and drainage project, irrigation canals and drainage canals connected to surrounding rivers were developed to expand farmland. However, along with economic development, farmland around large cities has become disorderly and rapidly urbanized, and as a result, irrigation and drainage channels for agricultural work, and eventually rivers around urban areas, serve as drainage channels for urban rainwater and domestic wastewater. It is used without appropriate and sufficient repair and refurbishment.

The rivers, irrigation canals, and drainage canals around these urban areas are medium- or small-scale rivers or canals, and are hereinafter collectively referred to as rivers.
Many of these rivers have been aging decades after construction, but refurbishment has not progressed for various reasons such as local government financial difficulties. Moreover, with the passage of time from construction, there arises a problem that rigidity is reduced due to corrosion of steel materials such as steel sheet piles used for revetment, that is, the strength of revetment is reduced. Furthermore, there is a problem that earth pressure increases due to embankment when converting farmland into residential land, and the strength of the revetment is insufficient with respect to the surrounding earth pressure.

In view of this, a technique for reinforcing a decrease in strength or an insufficient strength of an existing revetment (hereinafter referred to as an existing revetment) has been studied.
For example, by installing cut beams at the heads of existing revetments built on both banks of the river and laying them on the river, the strength of the existing revetments on both banks will be increased and the strength maintained stably. Technology. However, since the cut beams built on the river are left behind after the renovation work is completed, there is a risk that the water flow will be hindered during flooding, and the water flow hindered by the cut beams will flood the city area beyond the existing revetment. There is. In addition, the water flow may be hindered by the increase in water pressure, causing the existing revetment to break.

Patent Document 1 discloses a technique for reinforcing an existing revetment by installing a decorative panel on the river side of the existing revetment and filling concrete in a gap between the decorative panel and the existing revetment. Patent Document 2 discloses a technique for reinforcing an existing revetment by installing a concrete retaining wall on the river side of the existing revetment.
In the techniques disclosed in these Patent Documents 1 and 2, since the river volume is reduced, it is necessary to dig up the river bed in order to prevent the flooding of the river. However, if only the construction section of the revetment is dug excessively, the slope with the downstream area cannot be secured, and there is a problem that the water flow of the river stays in the deep section of the river bed. In addition, since the earth pressure acting on the existing revetment increases until the decorative panel and the concrete retaining wall are installed, measures such as excavating the ground on the city side to reduce the earth pressure are required.

Patent Document 3 discloses a technique for constructing a steel sheet pile revetment while crushing and removing an existing revetment.
In the technique disclosed in Patent Document 3, it is necessary to provide earth retaining in order to prevent problems such as tilting or collapsing of a site of a nearby private house or a surrounding road. In addition, it is necessary to dam the river flow during the removal of the existing revetment.

As explained above, conventional technologies related to the renovation of existing revetments are
(A) It is difficult to maintain the river flow smoothly not only during the renovation of the existing revetment but also after the completion of the work, and it requires a great deal of labor and cost to prevent flooding and rupture.
(B) Since excavation and earth retaining are also performed on the ground in the city area, there is a problem that various activities must be performed over a wide area of the city area, which hinders the daily activities of neighboring residents. And to cope with these problems, it is necessary to reduce the construction cost and the construction period.
(C) There is a problem that it is difficult to take sufficient measures to improve the strength of newly constructed revetments.

JP-A-8-92936 JP 2010-196271 A JP 7-11645 A

The present invention aims to provide a method for constructing a revetment structure constructed by renovation of the existing seawall, it is possible to maintain a particularly high strength for a long time, moreover not inhibit the activity of the nearby residents not, and an object of the invention to provide a method for constructing a revetment structure that can be built while maintaining a flow of rivers smoothly.

The present inventor examined a technique for repairing an existing revetment,
(a) By placing a steel sheet pile wall behind the existing revetment, that is, adjacent to the city area, the required construction work in the city area can be carried out in the minimum area without hindering the activities of neighboring residents.
(b) After removing the existing revetment, installing a reinforced concrete wall on the river side of the steel sheet pile wall, and connecting the steel sheet pile and the reinforced concrete wall with a shear key can prevent the deformation of the revetment and increase the strength.
(c) During the renovation work, a beam is installed on the river. By removing the beam after the completion of the work, even if the river increases, the water flow can be maintained without interruption.
(d) Instead of cutting beams, the strength of the newly built revetment can be maintained for a long time by installing a riverbed at the bottom of the river and bringing it into contact with the reinforced concrete walls on both sides.
(e) It was made based on the knowledge that the river waterway can be divided into two in the direction of the water flow, and the river water flow can be maintained smoothly by carrying out the repair work alternately on each bank. is there.

  That is, the present invention is a revetment structure for medium- or small-scale rivers, and is a reinforced concrete wall disposed on both sides of the river, and a steel sheet pile wall that is installed on the ground behind the reinforced concrete wall and functions as a retaining wall And a seawall that connects the steel sheet pile wall to the reinforced concrete wall to prevent deformation, and a riverbed that is installed at the bottom of the waterway and maintains the distance between the reinforced concrete walls on both banks.

  Further, the present invention provides a method for constructing a revetment structure for a medium or small river, after placing a steel sheet pile wall on the ground behind the existing revetment formed on both banks of the river, and then the head of the steel sheet pile wall. Installed a beam in the part and built it on the river, then removed the existing revetment, installed a reinforced concrete wall on the river side of the steel sheet pile wall, then connected the reinforced concrete wall and the steel sheet pile wall with a shear key, Furthermore, it is a construction method of a revetment structure in which a riverbed is installed in contact with a reinforced concrete wall at the bottom of a river, and then the beams are removed.

  In the construction method of the revetment structure according to the present invention, a beam is cut, a cut-off wall is installed at the center of the river, the river is divided into two in the direction of the water flow, the water flow is guided to only one side, and the other existing revetment is removed. The reinforced concrete wall is installed on the river side of the steel sheet pile wall, and then the reinforced concrete wall and the steel sheet pile wall are connected with the shear key alternately on both banks. It is preferable that the riverbed body is installed at the bottom of the river after the two walls are restrained and installed on both banks and after the cutoff wall is removed.

  ADVANTAGE OF THE INVENTION According to this invention, a renovation work can be performed without preventing a breakwater and a ground deformation, and without affecting a local inhabitant. Moreover, by dividing the river into two in the direction of the water flow, the existing revetment can be removed and a new revetment can be constructed for each bank while maintaining a smooth water flow. Therefore, it is effective for the renovation work of the existing revetment and has a remarkable industrial effect.

It is sectional drawing which shows the procedure of the construction method of the seawall structure which concerns on this invention. It is sectional drawing which shows the example of the revetment constructed by applying this invention. It is sectional drawing which shows the example of the conventional revetment.

FIG. 1 is a cross-sectional view showing the procedure of a method for constructing a seawall structure according to the present invention. Below, with reference to FIG. 1, when the existing revetment of the river which flows through an urban area becomes old, the method of constructing a new revetment structure is demonstrated.
As shown in FIG. 1 (a), private houses 1 are lined up on the city side of the existing revetment 3 constructed on both banks of the river 2.

  When repairing an old existing revetment 3, first, as shown in FIG. 1 (b), a steel sheet pile wall 4 is placed on the ground behind the existing revetment 3 on both banks (that is, on the city side). The steel sheet pile wall 4 plays a role of earth retaining, and by placing the steel sheet pile wall adjacent to the existing revetment 3, the work area in the urban area can be minimized. In placing the steel sheet pile wall 4, it is preferable to use a hydraulic press machine with less noise and vibration.

Moreover, it is preferable that the steel sheet pile wall 4 is driven into a formation (hereinafter referred to as a non-liquefied layer) in which no liquefaction phenomenon occurs due to an earthquake.
The steel sheet pile which comprises the steel sheet pile wall 4 is not specifically limited, The steel sheet pile conventionally known (for example, U-shaped steel sheet pile, hat-shaped steel sheet pile, combination steel sheet pile, steel pipe sheet pile etc.) is used. However, if the steel sheet pile to be used is too large, not only large equipment is required for placing but also noise and vibration are increased. Therefore, the dimensions of the steel sheet piles are appropriately set so that noise and vibration can be suppressed according to the situation at the construction site.

  Generally, since the road between the private houses 1 is relatively narrow, it is difficult to allow a large device (for example, a crane or the like) to enter. Therefore, it is preferable to transport the material using the existing revetment 3 (for example, laying rails). Even if the construction site is confined and the place where the crane can be installed is remote, construction can be performed by loading the material on the carriage and transporting it along the existing revetment 3.

  Next, as shown in FIG. 1 (c), a beam 5 is installed on the heads of the steel sheet pile walls 4 on both banks, and is installed on the river 2. Thereby, since the displacement of the head of the steel sheet pile wall 4 can be suppressed, it is possible to use a steel sheet pile having a significantly reduced required cross-sectional rigidity as compared with a self-supporting steel sheet pile wall. As a result, the newly built revetment can be made thinner, and as a result, a river can be secured.

  Here, if the heads of the steel sheet pile walls 4 are connected by coping or raising, the cut beams 5 can be installed with appropriate intervals, and the lining plate can be placed on the upper surface thereof. And since the lining board can be used as a gantry without obstructing the water flow of the river 2, it is effective when performing construction in a confined area. Or even if it uses the board | plate material which has moderate rigidity as the cutting beam 5, the river 2 top can be utilized as a gantry similarly.

In addition, when an old cut beam is installed on the head of the existing revetment 3, the cut beam is removed at this stage.
Next, as shown in FIG. 1 (d), the existing revetment 3 is removed. The removal method of the existing revetment 3 is not particularly limited. When the existing revetment 3 is composed of a steel sheet pile, it can be removed by grasping the head and pulling it out. If the steel sheet pile on the existing revetment 3 is aging, it may break along the way and it may be difficult to remove. However, a cutoff wall 6 is installed in the center of the river 2 so that the river 2 is in the direction of water flow. If it divides into two, it becomes possible to remove the old steel sheet pile. In other words, the steel sheet piles are alternately removed one by one by guiding the water flow to only one of the two divided in the water flow direction of the river 2 and removing the steel sheet pile constituting the existing revetment 3 after blocking the other water flow. It becomes possible.

Moreover, also when the existing revetment 3 is comprised with a reinforced concrete, similarly, it becomes possible to crush and remove a reinforced concrete alternately for each bank by dividing | segmenting the river 2 into 2 in a water flow direction.
The cutoff wall 6 may be installed before the cutting beam 5 is installed.
In this way, if the cutoff wall 6 is installed in the center of the river 2 and the river 2 is divided into two in the direction of the water flow, the construction of each shore can be performed alternately while maintaining the water flow of the river 2 smoothly. it can.

Since the cut-off wall 6 is removed after completion of the construction as will be described later, a steel sheet pile is preferable from the viewpoint of reducing the burden of the removal work. Sandbags may be used in the river 2 where the water level is low.
Furthermore, a reinforced concrete wall 7 is installed on the river side of the steel sheet pile wall 4 as shown in FIG. Here, the steel sheet pile wall 4 and the reinforced concrete wall 7 are brought into contact with each other, and a shear key such as a headed stud is provided on the steel sheet pile wall 4 so as to be integrated with the reinforced concrete wall 7 to form a composite wall. Thereby, since the effect that the steel sheet pile wall 4 as the earth retaining member reinforces the reinforced concrete wall 7 is expressed, the wall thickness can be reduced as compared with the reinforced concrete wall 7 alone. As a result, the newly built revetment can be made thinner, and as a result, a river can be secured.

The reinforced concrete wall 7 can shorten the work period by using a precast product. However, in that case, in order to integrate with the steel sheet pile wall 4, it is necessary to provide a space for inserting a shear key in the reinforced concrete wall 7 and to fill mortar or the like at the construction site.
Next, after installing reinforced concrete walls 7 on both banks of the river 2 as shown in FIG. 1 (f), the deadline wall 6 is removed as shown in FIG. The riverbed body 8 is installed at the site where the cutoff wall 6 was installed. Since the riverbed body 8 plays the role of a cut beam after removing the cut beam 5 constructed on the river 2 as will be described later, the side surface of the river bed body 8 abuts against the reinforced concrete walls 7 on both banks. Let In this way, the displacement of the reinforced concrete wall 7 can be suppressed.

Since the installation of the riverbed body 8 is underwater work, it is preferable to use a precast RC plate and fit between the reinforced concrete walls 7 at the bottom of the river 2. Alternatively, the reinforced concrete may be placed by simply blocking the water flow around the place where the riverbed body 8 is installed with a sandbag or the like. In that case, it is preferable to remove the sandbag after completion of the construction.
Finally, as shown in FIG. 1 (h), the cut beam 5 is removed. As a result, the steel sheet pile wall 4 is cantilevered because the head is not restrained, and a maximum bending moment is generated in the vicinity of the river bed. However, since it acts in the direction opposite to the bending moment generated in the steel sheet pile wall 4 while the cut beam 5 was installed, the bending moment generated by removing the cut beam 5 is canceled out. As a result, a margin is generated with respect to the stress acting on the steel sheet pile wall 4 and the reinforced concrete wall 7, and as a result, the strength of the revetment can be improved.

  The revetment constructed by the procedure described above has excellent strength, and since the steel sheet pile wall 4 is covered with the reinforced concrete wall 7, it is difficult to corrode and can maintain its strength for a long time. In addition, it is not necessary for large equipment to enter the city area, and the work area in the city area can be minimized, so that construction can be performed without hindering the daily activities of neighboring residents.

  Since it is necessary to construct revetments on both banks in rivers, the river 2 is divided into two in the direction of the water flow, and the construction of each shore is alternately performed, so that the water flow of the river 2 can be maintained smoothly even during construction. Is possible. And since the cut beam 5 and the cutoff wall 6 are removed, the water flow after construction completion can also be maintained smoothly.

Since the existing revetment 3 of reinforced concrete (three-sided concrete of cast-in-place concrete) shown in FIG. 3 was provided on the sand ground, it was liquefied by the earthquake, and the whole was tilted and cracks occurred in the reinforced concrete. Therefore, by applying the present invention, a renovation work was carried out on the revetment provided with a steel sheet pile wall and a reinforced concrete wall with a wide overall river width shown in FIG.
The existing revetment 3 in FIG. 3 is sand ground and is liquefied by an earthquake. The pore water pressure increased due to the liquefaction of the ground, and soil pressure and water pressure larger than usual were applied to the bottom and side walls of the existing revetment 3. For this reason, the existing revetment 3 is lifted and cracks in the concrete due to deformation of the side wall portions are generated. Refurbishment was made because it was no longer used as a waterway because the river slope changed due to floating and water leaked due to cracks in the concrete. Since there is no space for installing a new waterway in the vicinity, it was necessary to construct a new waterway at the position of the existing waterway as shown in FIG.

  A steel sheet pile wall 4 (hat-shaped steel sheet pile 25H) was placed behind the existing revetment 3 (that is, the city area side) and driven to the non-liquefaction layer 9. Next, after installing a beam (not shown) on the head of the steel sheet pile wall 4, a steel sheet pile (hat-shaped steel sheet pile 25H) was installed as a cutoff wall (not shown) to divide the water flow into two parts. First, the existing revetment 3 on one bank is removed, and then a reinforced concrete wall 7 (a stud with a head) is installed on the river side of the steel sheet pile wall 4 and integrated with the steel sheet pile wall 4 through a shear key to form a composite wall. .

Thus, after removing the existing revetment 3 and installing the reinforced concrete wall 7 for each bank, the cut-off wall was removed and the riverbed body 8 was installed. In addition, since the damage by the earthquake was not recognized in the floor board of the existing revetment 3, the part was used as the riverbed body 8. Finally, the beam was removed and the steel sheet pile wall 4 was subjected to coping.
In this way, it was possible to expand the river volume while minimizing the increase in the overall width of the river, and to suppress deformation of the revetment. In addition, by incorporating the steel sheet pile wall into the non-liquefied layer, the movement of earth and sand below the river was suppressed even when liquefaction occurred, and subsidence and inclination of the ground could be suppressed.

  In addition, the construction site was in contact with the land boundary on one side and the road with heavy traffic, but it was possible to carry out the construction without hindrance.

DESCRIPTION OF SYMBOLS 1 Private house 2 River 3 Existing revetment 4 Steel sheet pile wall 5 Cut beam 6 Cut wall 7 Reinforced concrete wall 8 River bed 9 Non-liquefaction layer

Claims (1)

In the method of constructing a revetment structure for medium or small rivers, a steel sheet pile wall is placed on the ground behind the existing revetment formed on both sides of the river, and then cut to the head of the steel sheet pile wall. A beam is installed on the river , a cut-off wall is installed at the center of the river, and the river is divided into two in the direction of water flow. Then, the water flow is guided to only one side, and the other existing revetment is removed. the reinforced concrete wall is placed on the river side of the steel sheet pile wall Te, followed by alternating the work of connecting the steel sheet pile wall and the reinforced concrete wall with shear keys the both sides, the reinforced concrete wall and the steel sheet pile wall Are installed on both banks while being restrained from each other, and after removing the cutoff wall , a riverbed body is installed at the bottom of the river.

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