Reinforced earth structure, and earth structure reinforcing method

Abstract

To solve problems associated with conventional technology, that is, to provide a "reinforced earth structure" that can be constructed more easily than conventional technology, and to provide a construction method of the reinforced earth structure.SOLUTION: A reinforced earth structure is an earth structure whose surface side is flooded, and comprises a main body, a permeability improving body, and a covering body. The permeability improving body is made of a material containing cement and aggregate, and has higher permeability than the main body. The covering body is a bag material filled with stone material inside. The permeability improving body is formed on a part of a backside slope including a bottom of the slope, and the covering body is installed on the backside slope and a top surface. A series of covering bodies are installed in a transverse direction of the main body, and the deformable covering bodies are installed so as to follow a shape of the backside slope.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to technology related to earth structures such as levees, seawalls, and embankments in rivers, coasts, reservoirs, etc., and more specifically to a "reinforced earth structure" that is reinforced using a "covering body" made of a bag material filled with stone and a "permeability improver" that has a higher permeability coefficient than the earth structure itself, and a method for reinforcing an earth structure using the covering body and the permeability improver. [Background technology]

[0002] It has been pointed out that the construction infrastructure (hereafter referred to as "construction infrastructure"), which was intensively developed during the period of high economic growth, is already showing signs of considerable deterioration. In 2014, the Council for Social Capital Development compiled a "Recommendation for Full-Scale Implementation of Measures to Counteract Road Deterioration," which cited the example of the Sasago Tunnel incident in 2012, sounding the alarm that "in the near future, this will lead to fatal incidents, such as bridge collapses, affecting human lives and social infrastructure," and strongly advocated the importance of maintaining and managing construction infrastructure. Against this backdrop, the national government promulgated a ministerial ordinance amending part of the Road Act Enforcement Regulations, formulating periodic inspection guidelines that outline specific construction infrastructure inspection methods, areas to look for in major abnormalities, and photographs of case studies.

[0003] Typical examples of construction infrastructure include structures such as dams and bridges, as well as coastal levees, river levees, seawalls, etc. Japan's total coastline is approximately 35,000 km, making it the sixth longest in the world, and naturally coastal levees are constructed in coastal conservation areas and other areas where they are needed. Not only are they functional, but they are also extremely important construction infrastructure due to their vast length.

[0004] Coastal levees are generally planned and constructed in accordance with the Coast Act (Act No. 101 of May 12, 1956). This Act was enacted in 1956 in response to Typhoon No. 13 in September 1953, which caused devastating damage mainly in Aichi Prefecture. This means that many coastal levees have been in use for a considerable amount of time since their construction; as of 2010, approximately 40% were said to be over 50 years old. For this reason, inspections to assess the deterioration of coastal levees are becoming increasingly important.

[0005] Levees and seawalls (hereinafter collectively referred to as "earth structures") on rivers, coasts, etc. are generally constructed by filling up the earth, and their cross section (a cross section perpendicular to the extension direction of the levee body) is roughly trapezoidal, with slopes formed on both the side outside the levee where the river or sea is located (hereinafter referred to as the "front side") and the side inside the levee (hereinafter referred to as the "back side").

[0006] Because the earth structure is an embankment, there are always concerns about phenomena such as scouring, particularly near the toe of the slope (bottom of the slope) on the front side, scouring on the back side due to overflow water, piping on the back side of the earth structure, and deterioration of the strength of the embankment body (i.e., the embankment body) due to seepage water (hereinafter referred to as "seepage failure").Moreover, since many earth structures have been completed a considerable amount of time, it is thought that many have already been scoured, piping has occurred, or seepage failure is progressing.

[0007] Furthermore, depending on the local conditions, earth structures may be constructed on soft layers, such as permeable ground made of sand or sandy soil, or ground containing a liquefiable layer. In such cases, there is a risk that the foundation ground will liquefy during an earthquake, causing the earth structure itself to become unstable.

[0008] Reinforcement measures are implemented for earth structures that have suffered from significant scouring. Traditionally, the main method for reinforcing earth structures has been to form structures such as water-stopping ground improvement bodies or steel sheet piles on the surface of the slope (i.e., the outside of the embankment) on both the front and back sides. However, forming these ground improvement bodies requires space to place relatively large-scale construction machinery, such as deep mixing treatment using a three-point pile driver, which means that considering the length of the area involved, it requires considerable cost and construction time, making it difficult to put this into practice.

[0009] Furthermore, with the conventional construction method of forming watertight ground improvement bodies on both the front and back sides, although watertightness is improved, drainage function is significantly reduced, so once seawater or river water seeps into the embankment, the seepage water will remain inside the embankment, which can result in seepage failure.In particular, it is known that in the event of an earthquake, the seepage water inside the embankment can cause liquefaction of the embankment itself, which in turn can lead to prolonged deformation of the embankment.

[0010] Therefore, Patent Document 1 proposes an embankment reinforcement structure in which a drainage layer is provided on the rear slope of the embankment fill, the outer surface of this drainage layer is covered with a covering layer, and a permeable sheet is placed between the drainage layer and the rear slope.Patent Document 2 also proposes a technology to reinforce an earth structure by forming a "water-stopping improvement body" with a lower permeability coefficient than the earth structure itself on the front slope, and forming a "permeable improvement body" with a higher permeability coefficient than the earth structure itself on the rear slope. [Prior art documents] [Patent documents]

[0011] [Patent Document 1] Japanese Patent Application Laid-Open No. 2018-100506 [Patent Document 2] Japanese Patent Application Publication No. 2020-133311 Summary of the Invention [Problem to be solved by the invention]

[0012] Overflow erosion can occur on the slope or foot of the slope behind an earth structure, which can result in the collapse of the earth structure. If erosion can be suppressed in the early stages of overflow, the collapse of the earth structure can be prevented. Furthermore, even for structures that have been designed with appropriate countermeasures, if overflow continues for a long period of time, for example, the soil directly below the covering work that covers the slope may be washed away, or the covering work itself may peel off, resulting in the erosion of the earth structure and its collapse.

[0013] The technology disclosed in Patent Document 1 covers the outer surface of the drainage layer with a covering layer, but as mentioned above, it cannot prevent the soil directly below it from escaping, nor does it have any means to prevent the covering layer from peeling off. Furthermore, in order to install a drainage layer using mesh members, it is necessary to excavate the main body of the earth structure to form a horizontal, flat area, which must then be covered with a covering layer or a permeable sheet must be laid, so constructing the embankment reinforcement structure of Patent Document 1 requires a considerable amount of time and effort.

[0014] On the other hand, the technology disclosed in Patent Document 2 has the advantage of preventing water from seeping into the main body of the earth structure by protecting the front slope with a water-stopping improvement material, and quickly draining rainwater and other infiltrating the main body of the earth structure by forming a permeable improvement material on the back slope, thereby achieving a stable earth structure. However, the invention in Patent Document 2 is not suitable for preventing erosion of the crest and slope. For example, in the event of heavy rain, the river water level may exceed the levee height (crown height) and overflow. In this case, the overflowing water may erode the unreinforced crest and slope, resulting in the risk of extensive damage to the entire levee structure.

[0015] The object of the present invention is to solve the problems of the prior art, that is, to provide a "reinforced earth structure" that can be constructed more easily than the prior art, and a method for constructing the reinforced earth structure. [Means for solving the problem]

[0016] The present invention was made with a focus on the fact that earth structures are reinforced by using a covering body with stone filled inside the bag material and by installing a series of covering bodies in the transverse direction of the main body, and is an invention based on an unprecedented idea.

[0017] The "reinforced earth structure" of the present invention is an earth structure whose surface is flooded, and comprises a main body, a permeability improver, and a covering. Of these, the main body is formed with a backside slope and a top surface, and the permeability improver is formed from a material containing cement and aggregate and has higher permeability than the main body. The covering is a bag material filled with stone. The permeability improver is formed on a part of the backside slope, including the bottom of the slope, and the covering is installed on the backside slope and the top surface. A series of coverings is installed in the transverse direction of the main body, and the covering, which is made deformable by using a bag material, is installed so as to follow the shape of the backside slope and the top surface.

[0018] The reinforced earth structure of the present invention can also be constructed by connecting the covering body and the permeability improver with the lower end of the covering body butting against the upper end of the permeability improver.

[0019] The reinforced earth structure of the present invention can also be constructed by connecting the covering body and the permeability improver with a portion of the covering body overlapping the permeability improver. In this case, the covering body can be positioned so that a portion of the covering body is submerged under the permeability improver.

[0020] The reinforced earth structure of the present invention may also have a plate-shaped connecting plate disposed at the connection between the covering body and the permeability improver. This connecting plate is fixed with an anchor, thereby connecting the covering body and the permeability improver via the connecting plate.

[0021] The reinforced earth structure of the present invention can also have a sheet-like connecting sheet placed at the connection between the covering body and the water permeability improver. In this case, the connecting sheet and the covering body are fixed together by sewing with string material, and the connecting sheet and the water permeability improver are fixed together with adhesive or anchors.

[0022] The reinforced earth structure of the present invention can further include a top road. This top road is constructed by using a covering body placed on the top surface as a roadbed material, and paving is applied on top of the roadbed material.

[0023] The earth structure reinforcement method of the present invention is a method for reinforcing an existing earth structure whose front side is flooded, and includes a permeability improvement body forming step and a covering body forming step. In the permeability improvement body forming step, a permeability improvement body having higher permeability than the earth structure is formed on a portion of the backside slope of the earth structure, including the bottom of the slope, using a material containing cement and aggregate. In the covering body forming step, covering bodies, which are made of bag materials and filled with stone, are installed on the backside slope and top surface of the earth structure. In the covering body forming step, a series of covering bodies are installed in the transverse direction of the main body, and the covering bodies, which are made deformable by using bag materials, are installed so as to follow the shape of the backside slope. [Effects of the Invention]

[0024] The reinforced earth structure and the method for reinforcing an earth structure according to the present invention have the following effects. (1) By installing a covering on the slope and top surface of the back side of the main body, it is possible to suppress erosion caused by overflow water, particularly erosion of the top of the main body, the back side slope, and the back side slope toe. In addition, by installing a permeability improver on the back side slope of the main body, it is possible to promote the drainage of infiltrated water into the main body. As a result, it is possible to quickly restore stability to the main body after overflow. (2) By installing a covering body on the main body, a restraining effect is created on the top and backside slope of the main body (the effect of holding down the embankment), and the flow rate of infiltrated water and overflow water is reduced as they flow down inside the covering body, thereby suppressing erosion on the surface of the main body and the toe of the slope. (3) The drainage-promoting function of the permeable improvement body suppresses erosion at the bottom of the rear slope, and as a result, the progression of erosion throughout the entire main body can be suppressed. (4) A series of covering bodies are installed in the transverse direction of the main body, which prevents the covering bodies from peeling off even in the event of overflow for a long period of time. (5) The covering body is deformable because the bag material is made of a mesh material made of synthetic resin, so that it can be installed to follow the shape of the slope on the back side. (6) Prefabricated coverings can be easily installed using a crane, etc. In other words, they do not require special temporary facilities or high construction precision, so they can be installed quickly and at low cost. [Brief explanation of the drawings]

[0025] [Figure 1] A cross-sectional view of an earthen structure whose surface is flooded, such as a levee or seawall on a river or coast. [Figure 2] 1 is a cross-sectional view schematically showing the "reinforced earth structure" of the present invention. [Figure 3] A cross-sectional view schematically showing a permeable improvement body and a water-stop improvement body formed without being embedded in the ground. [Figure 4] FIG. 2 is a plan view schematically showing a plurality of covering bodies arranged in the longitudinal direction. [Figure 5] A cross-sectional view schematically showing a covering body arranged with a portion of its lower end overlapping a water-permeability improver. [Figure 6] FIG. 2 is a cross-sectional view schematically showing a covering body arranged so that a portion of the covering body is submerged below a water permeability improver. [Figure 7] FIG. 2 is a cross-sectional view schematically showing a covering body and a water-permeability improver connected via a connecting plate. [Figure 8] 1 is a construction flow diagram showing the main steps of the earth structure reinforcement method of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0026] BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of a reinforced earth structure and an earth structure reinforcing method according to the present invention will be described with reference to the accompanying drawings.

[0027] 1.Definition Before describing the embodiments of the present invention, definitions of terms used herein will be provided.

[0028] (Front and back) Figure 1 shows a cross-section of a typical earth structure Dm, such as a levee or seawall on a river or coast. A typical earth structure Dm is an embankment constructed over a fairly long distance along a river or coast (in the depth direction of the page in the figure), and as shown in this figure, its cross-sectional shape is often roughly trapezoidal. The earth structure Dm prevents flooding from the river or sea; in other words, it separates the area outside the embankment (the right side in the figure) where the river or sea is located from the opposite area inside the embankment (the left side in the figure). For convenience, the area outside the embankment will be referred to as the "front side" and the area inside the embankment will be referred to as the "back side." The longitudinal direction (extension direction) of the earth structure Dm will be referred to as the "longitudinal direction," and the horizontal direction perpendicular to the longitudinal direction will be referred to as the "transverse direction."

[0029] (Slope surface and top surface) As mentioned above, the cross-sectional shape of the earth structure Dm, the front side of which is flooded, is roughly trapezoidal, and slopes are formed on both sides (the left and right sides in the figure). For convenience, in order to distinguish between the two left and right slopes, the slope formed on the front side of the earth structure Dm will be referred to as the "front side slope Sf," and the slope formed on the back side of the earth structure Dm will be referred to as the "back side slope Sr." Similarly, the slope toe (also called the slope tip) at the bottom of the front side slope Sf will be referred to as the "front side slope toe Tf," and the slope toe at the bottom of the back side slope Sr will be referred to as the "back side slope toe Tr." Furthermore, the surface that corresponds to the so-called "upper base" of the trapezoid will be referred to as the "top surface St."

[0030] 2. Reinforced earth structures Next, the "reinforced earth structure" of the present invention will be described in detail with reference to the drawings. The earth structure reinforcing method of the present invention is, in other words, a method for constructing the reinforced earth structure of the present invention. Therefore, the reinforced earth structure of the present invention will be described first, followed by the earth structure reinforcing method of the present invention. For convenience, the reinforced earth structure will be described here as functioning as a river levee, but the reinforced earth structure of the present invention can also be used as an earth structure with functions other than river levee, such as a coastal levee, a seawall, a sabo dam, or a weir.

[0031] (Overall composition) Figure 2 is a cross-sectional view showing the "reinforced earth structure 100" of the present invention. As shown in this figure, the reinforced earth structure 100 is composed of a main body 110 located at the center of the cross section, a covering body 120, and a permeability improver 130, and can also be composed of a crown road 140, a water-stopping improver 150, and a front-side covering work 160. Of these, the main body 110 corresponds to the earth structure Dm shown in Figure 1, and is mainly formed by embankment.

[0032] The reinforced earth structure 100 of the present invention can be constructed as a new structure, or can be constructed by reinforcing an existing earth structure Dm. When constructing a new structure, the main body 110, covering body 120, permeability improver 130, etc. are installed to achieve the planned shape and dimensions. On the other hand, when reinforcing an existing earth structure Dm, the earth structure Dm is used as the main body 110, and then the covering body 120, permeability improver 130, etc. are installed. Below, each of the main elements that make up the reinforced earth structure 100 will be explained.

[0033] (improved water permeability) The permeability improver 130 has the function of draining water that has seeped into the main body 110 to the outside when the river water level rises, and the function of preventing scouring that occurs during this drainage (particularly scouring near the rear slope toe Tr). For this reason, the permeability improver 130 is formed on a part of the rear slope Sr, including the rear slope toe Tr, and is formed so that its permeability is higher than that of the main body 110. Furthermore, it is preferable that the permeability improver 130 is formed mainly from a cement-based material so that it can also function as a reinforcing member during an earthquake, that is, so that it has considerable strength (shear strength and bending strength).

[0034] Specifically, the permeability improver 130 is formed from materials containing cement and aggregate, and can also be formed from materials containing mineral admixtures. For example, the permeability improver 130 can be formed by mixing a small amount of cement slurry and a thickener (mineral admixture) with highly permeable crushed stone or sand. In this case, a highly permeable permeability improver 130 can be obtained that has solidified while maintaining voids. It is recommended that the thickener used as the admixture be an admixture for underwater concrete.

[0035] As described above, the permeability improver 130 is formed on a portion of the backside slope Sr, including the backside slope bottom Tr. To form the permeability improver 130, a portion of the main body 110 is excavated, and the material for the permeability improver 130 is poured into the space. After curing, the material hardens and becomes the permeability improver 130. For example, the permeability improver 130 can be formed by installing a concrete solidification body. In this case, the solidification body can be installed using cast-in-place concrete or a precast concrete solidification body. However, since the permeability improver 130 requires appropriate permeability (drainage), it is preferable to use a solidification body made of porous concrete (hereinafter referred to as "porous concrete"). Furthermore, since the permeability improver 130 has a drainage function, it is preferable to use a concrete solidification body that does not separate underwater to prevent the cement (mortar) from flowing out during drainage.

[0036] As shown in Figure 2, the permeability improver 130 can be formed so that it is embedded to a certain extent in the ground. For example, in cases where there is a soft layer on the surface, it is formed so that it penetrates this soft layer and embeds itself in the supporting layer below. Alternatively, as shown in Figure 3, the permeability improver 130 can be formed without being embedded in the ground. In cases where there is a solid supporting layer close to the surface of the ground, the permeability improver 130 is formed so that it is placed on top of the ground in this way.

[0037] (covering body) The covering 120 is formed by filling "stone materials" such as boulders, broken granite, and crushed stone into "bag materials." The bag materials are typically made to be flexible, such as a mesh of woven synthetic resin ropes. Therefore, the covering 120, with the stone materials packed into the bag materials, can also be freely deformed. This allows the covering 120 to flexibly conform to the curved shape connecting the top surface St to the rear slope Sr, i.e., it can be installed to fit the shapes of the top surface St and the rear slope Sr. Furthermore, the stone materials and bag materials have higher permeability than the embankment body, so they do not impede drainage within the embankment body. While a roughly rectangular parallelepiped shape is desirable for the covering 120, this shape is not limited to this.

[0038] The bag material for the covering body 120 can be, for example, a "cellular gravel mat" manufactured by Nakada Sangyo Co., Ltd. This cellular gravel mat is made of recycled polyester fiber and is constructed as a Russell net, with a mesh strength (tensile strength) of 450 N or more. Furthermore, the cellular gravel mat has the property of stretching nearly 150-200% before breaking, and its excellent elasticity makes it highly flexible. Furthermore, by using fine gravel or crushed stone with a particle size of around 10 mm as the filling material, it can exhibit high permeability, suction prevention, and scouring prevention functions.

[0039] Since the covering body 120 is constructed of stone filled bags, when it is installed so as to cover the top surface St and the rear slope Sr, it can suppress erosion caused by overflow. In addition, it has a restraining effect on the top surface St and the rear slope Sr (the effect of holding down the embankment), and as the seepage water and overflow water flow down inside the covering body 120, it has the effect of reducing the flow rate, thereby suppressing erosion of the main body 110.

[0040] As mentioned above, a typical earth structure Dm is constructed over a considerable length along a river or coast. This means that the covering bodies 120 are installed over a considerable length in the longitudinal direction. For this reason, as shown in FIG. 4, it is advisable to arrange multiple (six in the figure) covering bodies 120 side by side in the longitudinal direction. In this case, it is desirable to connect adjacent covering bodies 120. For example, they can be connected using ropes, using a zipper structure, or by weaving parts of the covering bodies 120 together. Note that FIG. 4 is a plan view showing multiple covering bodies 120 arranged in the longitudinal direction, but for convenience, some of them (on the right side in the figure) are shown in a state where the covering bodies 120 have not yet been installed.

[0041] On the other hand, in the transverse direction, a series of covering bodies 120 are installed. In other words, instead of connecting multiple covering bodies 120 as in the longitudinal direction, a single covering body 120 is installed. Specifically, one covering body 120 is placed on the upper surface of the generally horizontal top surface St, and then placed on the upper surface of the backside slope Sr in a bent (folded) manner. This prevents the covering body 120 from peeling off, even if it is subjected to overflow for a long period of time. The covering body 120 can be installed simply by placing it on the upper surfaces of the top surface St and the backside slope Sr, or the placed covering body 120 can be further fixed with anchors AC as shown in Figure 2.

[0042] The covering body 120 can be placed so that its lower end in the transverse direction, i.e., the end on the water permeability improver 130 side, is butted up against the upper end of the water permeability improver 130, as shown in Figures 2 and 3. In this case, it is advisable to connect the lower end of the covering body 120 and the upper end of the water permeability improver 130 by filling the boundary between them with clay or cement-based filler.

[0043] Alternatively, as shown in Figure 5, the covering body 120 can be placed with a portion of the lower end side of the covering body 120 overlapping the top of the water permeability improver 130. In this case, it is advisable to connect the covering body 120 and the water permeability improver 130 by sewing them together with an anchor AC or the like at the overlapping portion. To overlap a portion of the lower end side of the covering body 120 with the water permeability improver 130, it is also possible to place the covering body 120 so that a portion of it is hidden below the water permeability improver 130, as shown in Figure 6.

[0044] In either case, whether the covering body 120 and the water permeability improver 130 are butted together or a portion of the covering body 120 and the water permeability improver 130 are overlapped, the covering body 120 and the water permeability improver 130 can be connected via a connecting plate 170, as shown in Figure 7. This connecting plate 170 is a plate-shaped member that can be made, for example, by bending a steel plate. In this case, the connecting plate 170 is placed at the connection between the covering body 120 and the water permeability improver 130 and is fixed to the main body 110 and the water permeability improver 130 by sewing it with anchors AC or the like, thereby connecting the covering body 120 and the water permeability improver 130 via the connecting plate 170.

[0045] Furthermore, the covering body 120 and the water permeability improver 130 can be connected via a sheet-like member (hereinafter referred to as a "connecting sheet") instead of the connecting plate 170. In this case, the connecting sheet is placed at the connection between the covering body 120 and the water permeability improver 130, and the connecting sheet and the covering body 120 are fixed by sewing them together with string material, and the connecting sheet and the water permeability improver are fixed with adhesive or anchors. The bag material of the covering body 120 (for example, a cellular gravel mat) can also be used as the connecting sheet.

[0046] (Water-stopping improvement body and covering work) As shown in Figure 2 and other figures, a water-stopping improvement body 150 and a front-side covering work 160 can also be installed on the front-side slope Sf of the reinforced earth structure 100. These water-stopping improvement body 150 and front-side covering work 160 have the function of suppressing water infiltration into the main body 110 when the river water level rises, and have the function of preventing scouring (particularly scouring near the front-side slope toe Tf) when the river reaches high water levels. For this reason, the water-stopping improvement body 150 is formed on a portion of the front-side slope Sf, including the front-side slope toe Tf, and is formed so that its permeability is lower than that of the main body 110 (i.e., its water-stopping ability is higher). In addition, the water-stopping improvement body 150 should preferably be formed primarily from a cement-based material so that it can also function as a reinforcing member during earthquakes, i.e., so that it has sufficient strength (shear strength and bending strength).

[0047] The water-stopping improvement body 150 can be formed by carrying out ground improvement work on a portion of the main body 110. In this case, it is preferable to improve a portion of the main body 110 with a cement-based solidification material using a mechanical mixing method, a high-pressure jet mixing method, or a chemical injection method. Furthermore, like the water-permeability improvement body 130, the water-stopping improvement body 150 can be formed so that it is embedded in the ground to a certain extent, or it can be formed without being embedded in the ground at all. Meanwhile, the front covering work 160 can be made of conventionally used concrete blocks or the like.

[0048] (Top road) The top road 140 is a road such as a roadway or sidewalk constructed on the top surface St. Typically, an asphalt-paved road is primarily composed of a roadbed (lower roadbed and upper roadbed) and an asphalt mixture (base and surface layers). Crushed stone may also be used as the roadbed material. The reinforced earth structure 100 of the present invention has a portion of the covering body 120 placed on its top surface St, and this covering body 120 is constructed by filling a bag with stone. In other words, the roadbed is already formed on the top surface St, and the top road 140 can be constructed by laying an asphalt mixture on top of it. In this way, the top road 140 is constructed by laying pavement on the top surface of the covering body 120. In addition to the top road 140 made of asphalt, the top road 140 can also be made of concrete.

[0049] 3. Earth structure reinforcement method Next, the earth structure reinforcing method of the present invention will be explained with reference to Figure 8. The earth structure reinforcing method of the present invention is, so to speak, a method for constructing the reinforced earth structure 100 explained so far, and therefore we will avoid any overlapping explanation with the contents explained for the reinforced earth structure 100 and will only explain the contents unique to the earth structure reinforcing method of the present invention. In other words, the contents not described here are the same as those described in "2. Reinforced Earth Structure", including the explanation in "1. Definition".

[0050] Figure 8 is a construction flow diagram showing the main steps of the earth structure reinforcement method of the present invention. First, preparatory work is carried out, such as surveying the locations where the covering body 120 and the permeability improver 130 will be formed, bringing in the necessary equipment and placing it in the designated locations, and confirming the construction procedure for that day.

[0051] Once preparations are complete, the permeability improver 130 is formed on a portion of the rear slope Sr of the existing earth structure Dm (main body 110) (Step 201 in Figure 8). Specifically, the permeability improver 130 is formed by pouring the material for the permeability improver 130 into the space excavated in a portion of the main body 110. For example, the permeability improver 130 can be formed by installing a concrete solidification body. In this case, the solidification body can be installed using cast-in-place concrete or a precast concrete solidification body. However, since the permeability improver 130 requires appropriate permeability (drainage), it is preferable to use a solidification body made of porous concrete (hereinafter referred to as "porous concrete"). Furthermore, since the permeability improver 130 has drainage function, it is preferable to use a concrete solidification body that does not separate underwater to prevent the cement (mortar) from flowing out during drainage.

[0052] Once the permeability improver 130 is formed, a series of covering bodies 120 are installed to cover the top surface St and the underside slope surface Sr (Step 202 in Figure 8). However, in cases where the covering bodies 120 are arranged so that part of them is submerged below the permeability improver 130 as shown in Figure 6, it is preferable to install the covering bodies 120 first (Step 202 in Figure 8) and then form the permeability improver 130 (Step 201 in Figure 8). Once the permeability improver 130 is formed and the covering bodies 120 are installed, and multiple covering bodies 120 are arranged in a line in the longitudinal direction, adjacent covering bodies 120 are connected to each other (Step 203 in Figure 8).

[0053] Meanwhile, a water-stopping improvement body 150 and a front-side covering work 160 are installed on the front-side slope Sf of the existing earth structure Dm. Specifically, the water-stopping improvement body 150 is formed by carrying out ground improvement using a mechanical mixing method, a high-pressure jet mixing method, or a chemical injection method, and then the front-side covering work 160, such as concrete blocks, is installed on the front-side slope Sf using a crane or the like. Note that either the process relating to the back-side slope Sr or the process relating to the front-side slope Sf can be carried out first, or both processes can be carried out simultaneously (in parallel).

[0054] Once the covering body 120 is installed, pavement is laid on the top surface of the covering body 120 on the top surface St to construct the top road 140 (Step 204 in Figure 8). Once the covering body 120, permeability improver 130, top road 140, etc. have been formed over the entire planned area, cleanup is carried out and the work is completed. [Industrial Applicability]

[0055] The reinforced earth structure and the method for reinforcing an earth structure of the present invention can be used for earth structures where water accumulates on one side (front side), such as river levees, coastal levees, seawalls, erosion control dams, and weirs. The present invention can effectively reinforce coastal levees and river levees, which contributes to extending the life of construction infrastructure. Considering this, the present invention can be said to be an invention that can be used industrially and is also expected to make a great contribution to society. [Explanation of symbols]

[0056] 100 Reinforced Earth Structures 110 (Main body of reinforced earth structure) 120 (Reinforced Earth Structure) Covering 130 Permeable improvement body (for reinforced earth structures) 140 (Reinforced earth structure) top road 150 Water-stopping improvement body (for reinforced earth structures) 160 Surface covering (for reinforced earth structures) 170 (Reinforced earth structure) connecting plate AC Anchor Dm earth structure Sf Front side slope Sr Backside slope St top surface Tf front side glue butt Tr backside glue butt

Claims

1. An earthen structure whose surface is flooded, A main body portion having a back surface and a top surface formed thereon; a water-permeability improved body formed of a material containing cement and aggregate and having higher water permeability than the main body; A covering body in which stone material is filled inside the bag material, The water permeability improver is formed on a part of the backside surface including the bottom of the glue, The covering body is installed on the back slope surface and the top end surface, A series of the covering bodies is disposed in the transverse direction of the main body, The covering body, which is made deformable by using the deformable bag material, is installed so as to follow the shape of the back surface and the top surface. A reinforced earth structure characterized by:

2. The covering body and the water permeability improver are connected in a state where the lower end of the covering body and the upper end of the water permeability improver are butted against each other.

2. A reinforced earth structure according to claim 1.

3. The covering body and the water permeability improver are connected in a state where a part of the covering body is overlapped with the water permeability improver.

2. A reinforced earth structure according to claim 1.

4. A part of the covering body is disposed so as to be embedded below the water permeability improver.

4. A reinforced earth structure according to claim 3.

5. a plate-shaped connecting plate is placed at the connection between the covering body and the water permeability improver, and the connecting plate is fixed by an anchor; The covering body and the water permeability improver are connected via a front connecting plate.

2. A reinforced earth structure according to claim 1.

6. a sheet-like connecting sheet is disposed at the connection portion between the covering body and the water permeability improver, The connecting sheet and the covering body are fixed by sewing them together with a string material, The connecting sheet and the water permeability improver are fixed together by an adhesive or an anchor.

2. A reinforced earth structure according to claim 1.

7. The covering body arranged on the top surface is a roadbed material, and a top road is further provided in which pavement is applied to the top surface of the roadbed material.

2. A reinforced earth structure according to claim 1.

8. A method for reinforcing an existing earth structure whose surface is flooded, comprising: a permeability improvement body forming step in which a permeability improvement body having higher permeability than the earth structure is formed on a part of the rear slope surface including the bottom of the earth structure using a material containing cement and aggregate; a covering body forming process in which a covering body having stone material filled inside a bag material is installed on the rear slope surface and the top surface of the earth structure; In the covering body forming step, a series of covering bodies are installed in a transverse direction of the main body of the earth structure, In the covering body forming step, the covering body, which is made deformable by using the deformable bag material, is installed so as to follow the shape of the back surface and the top surface. A method for reinforcing an earth structure.

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