Method for reinforcing existing embankment

Abstract

To provide a reinforcing construction method for an existing embankment capable of reducing cost, shortening a construction period and suppressing temporary construction cost low.SOLUTION: A method for reinforcing an existing embankment in which a flat surface (FS) is created on a top portion of the existing embankment constructed on an inclined foundation (OG: natural ground) and a building is constructed on the flat surface, the method comprising a step of installing a vertical reinforcing material (1), which is a structural member extending in a vertical direction and having a lower end portion reaching the natural ground of the existing embankment, at a valley side (side where slippage or collapse occurs) end portion of the flat surface, A place where the vertical reinforcing material (1) is installed is a region (a region close to a valley side) positioned on the valley side so that a collapse place (a region on the valley side from a slip surface SS) on a top part of the existing banking becomes small, and is a region (a region close to a building) constructible from the building (for example, a road) constructed on a flat surface.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a technique for reinforcing an existing embankment constructed on an inclined foundation (natural ground). [Background technology]

[0002] When reinforcing existing embankments constructed on a sloping foundation (natural ground), such as half-bank embankments, half-cut half-bank embankments, and valley filling embankments, in the prior art, as shown in Figure 23, ground anchors 21 are driven over the entire surface of the existing embankment EE to ensure the safety of the entire existing embankment EE. Alternatively, as shown in Figure 24, restraining piles 22 are installed from the middle to the lower part of the existing embankment EE, and ground anchors 21, natural ground reinforcement earthworks 23, and scaffolding 24 are installed on the entire slope. In Figures 23 and 24, symbol OG indicates the natural ground, symbol SS (dash line) indicates the slide surface, and symbol FS indicates the flat surface at the top of the existing embankment EE. In the prior art, ground anchors 21 are driven over the entire surface of the existing embankment EE as shown in Figure 23, or ground anchors 21 are driven over a wide area as shown in Figure 24 and restraining piles 22 are installed, thereby ensuring the safety of the entire existing embankment EE and preventing sliding or collapse of the existing embankment EE.

[0003] However, the conventional techniques shown in Figures 23 and 24 have the problem that the construction work is large-scale, costly, and takes a long time to complete, because they are designed to prevent sliding of the entire existing embankment. Furthermore, since measures must be taken over the entire existing embankment, large-scale temporary scaffolding and other structures will be required, which poses the problem of enormous temporary construction costs.

[0004] As another prior art, reinforced earthworks for excavating existing embankments at a steep slope have been proposed (see Patent Document 1). However, this conventional technology does not intend to solve the problems of high costs, long construction periods, and enormous temporary construction costs, because it involves implementing anti-slip measures for the entire existing embankment. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 2653731 Summary of the Invention [Problem to be solved by the invention]

[0006] The present invention has been proposed in consideration of the problems of the prior art described above, and aims to provide a reinforcement method for existing embankments that is inexpensive, enables a shortened construction period, and keeps temporary construction costs low. [Means for solving the problem]

[0007] As a result of various studies, the inventor noticed that roads, railways, houses and other buildings are mostly constructed on the flat top surface (FS) of existing embankments (EE) built on sloping foundations (OG: natural ground), and not on the entire surface of the existing embankment (EE).The inventor then discovered that even if the embankment collapses, as long as the flat top surface (FS) does not collapse, the damage caused by the collapse of the embankment will be relatively small. The present invention is a method for reinforcing existing embankments (EE) that was created based on this knowledge. A method for reinforcing an existing embankment (EE) in which a flat surface (FS) is constructed on top of the existing embankment (EE) built on a sloping foundation (OG: natural ground), and a structure is constructed on the flat surface (FS), The method includes a step of installing a vertical reinforcement (1) which is a structural member extending vertically at the end of the valley side (the side where a slide or collapse occurs) of the flat surface (FS) and whose lower end reaches the ground (OG) of the existing embankment (EE), The location where the longitudinal reinforcement (1) is to be installed is an area located on the valley side (area close to the valley side) so that the collapsed area (area on the valley side of the slide surface SS) at the top of the existing embankment (EE) is small, and also an area where construction can be performed from a structure (e.g., a road) constructed on the flat surface (FS) or near the structure, i.e., an area close to the structure. inIt is characterized by the fact that Here, the structures are, for example, roads (highways), railways, houses, and the like.

[0008] Here, the multiple vertical reinforcement members (1) may be provided in a cross section at the same position in a direction perpendicular to the paper surface of Figure 1, or the positions of the multiple vertical reinforcement members (1) (for example, in a direction perpendicular to the paper surface of Figure 1) may be different within a range that does not cause the embankment to collapse. That is, in the present invention, it is preferable to install a plurality of (e.g., two) longitudinal reinforcements (1) in a cross section (e.g., cross sections at the same position in a direction perpendicular to the paper surface of Fig. 1) at the valley side end of the flat surface (FS). The plurality of longitudinal reinforcements (1) may be located at different positions in a direction perpendicular to the paper surface of Fig. 1, for example, as long as the collapse of the flat surface (FS) of the embankment (EE) can be prevented. The heads of the plurality of longitudinal reinforcements (1) may be connected to each other to form an integrated unit. The plurality of longitudinal reinforcements (1) may extend in the vertical direction so as to be parallel to one another, or one longitudinal reinforcement (1) may extend in the vertical direction, while the other longitudinal reinforcements (1-3) are inclined relative to the one longitudinal reinforcement (1), and it is preferable that the upper end of the one longitudinal reinforcement (1) and the upper end of the other longitudinal reinforcement (1-3) are connected.

[0009] In the present invention, it is also preferable that horizontal reinforcements (2) extending horizontally or in a direction inclined from the horizontal are installed in the regions between the vertical reinforcements (1). Here, the horizontal reinforcement (2) may not have its ground-side end reach the ground (OG), or only a portion of the horizontal reinforcement (2) may reach the ground (OG).

[0010] Alternatively, in the present invention, it is preferable to install a ground anchor (3) having a tendon (3A) extending horizontally or in a direction inclined relative to the horizontal direction with respect to the longitudinal reinforcement (1), and an anchor head (3B) provided at a height position of the upper end of the longitudinal reinforcement (1).

[0011] In addition, in the present invention, it is preferable to provide longitudinal reinforcement (1-2) not only at the valley side end of the flat surface (FS) but also at the central part of the flat surface (FS) (the central part between the natural ground side and the valley side: if the structure is a road, the part where the center line is located). Furthermore, in the present invention, it is preferable that a hole-out prevention wall 5 (FIGS. 13 and 14) is constructed at the upper end of the vertical reinforcement member (1). [Effects of the Invention]

[0012] The present invention, which has the above-mentioned configuration, aims to ensure the safety of structures existing on the top flat surface (FS) of the existing embankment (EE), and does not aim to ensure the safety of the entire existing embankment (EE). Therefore, according to the present invention, vertical reinforcement (1) is provided at the valley side end of the flat surface (FS) at the top of the existing embankment (EE), so that only the area on the natural ground OG side (the left side in Figure 1: the opposite side to the valley) (the area where the construction section is constructed) of the vertical reinforcement (1) is prevented from collapsing (or falling down) due to sliding. In other words, according to the present invention, although it is not possible to prevent the collapse (or sliding) of the entire existing embankment (EE), it is possible to prevent the collapse (slide) of the natural ground (OG) side (or the side away from the valley) of the longitudinal reinforcement (1), thereby ensuring the safety of structures (roads, railways, and other various structures) on top of the existing embankment.

[0013] Furthermore, since it is only necessary to install longitudinal reinforcement (1) at the valley-side end of the flat surface (FS) at the top of the existing embankment, the countermeasures are much smaller in scale than when implementing slide prevention measures on the entire existing slope, reducing costs and shortening the construction period. Also, compared to when implementing measures on the entire existing embankment (EE), the amount of temporary scaffolding required is small, and the temporary construction costs are much lower. Furthermore, if the only requirement is to install longitudinal reinforcement at the valley-side end of the flat surface (FS) at the top of the existing embankment, then, for example, if the flat surface (FS) is a road, construction can be carried out by occupying only one lane on the valley side with construction equipment, etc., while allowing vehicles to pass through the remaining lanes. Therefore, even if roads, railways, and other structures already exist on the flat surface (FS), construction can be carried out without impairing the function of the roads, railways, and other structures as social infrastructure. In addition, temporary scaffolding can be minimized and only the minimum necessary can be constructed (for example, reinforcing only an area of ​​about one slope). [Brief explanation of the drawings]

[0014] [Figure 1] FIG. 1 is an explanatory diagram of a first embodiment of the present invention. [Figure 2] FIG. 4 is an explanatory diagram showing a first modified example of the first embodiment. [Figure 3] FIG. 10 is an explanatory diagram showing a second modified example of the first embodiment. [Figure 4] FIG. 10 is an explanatory diagram showing a combination of a first modified example and a second modified example of the first embodiment. [Figure 5] FIG. 10 is an explanatory diagram of a second embodiment of the present invention. [Figure 6] FIG. 6 is a reference view taken along arrow A6 in FIG. 5. [Figure 7] FIG. 10 is an explanatory diagram of the effect of the horizontal reinforcement material. [Figure 8] 10 is an explanatory cross-sectional view illustrating the inconvenience that occurs when the portion of the horizontal reinforcement that protrudes into the valley side region beyond the vertical reinforcement is long. FIG. [Figure 9] FIG. 10 is an explanatory cross-sectional view of a modified example of the second embodiment. [Figure 10] FIG. 10 is a reference view taken along arrow A11 in FIG. 9. [Figure 11] FIG. 10 is an explanatory cross-sectional view of a third embodiment of the present invention. [Figure 12] FIG. 13 is an explanatory view of the action and effect of the packer in the third embodiment, taken along the arrow A13 in FIG. 11. [Figure 13] FIG. 10 is an explanatory cross-sectional view of a fourth embodiment of the present invention. [Figure 14] FIG. 10 is an explanatory cross-sectional view showing the function and effect of the hole-removal prevention wall in the fourth embodiment. [Figure 15] FIG. 10 is an explanatory cross-sectional view of a modified example of the fourth embodiment. [Figure 16] FIG. 10 is an explanatory cross-sectional view of a fifth embodiment of the present invention. [Figure 17] FIG. 10 is an explanatory plan view showing the surface of the embankment in the fifth embodiment. [Figure 18] FIG. 13 is an explanatory view showing a main part of a modified example of the fifth embodiment. [Figure 19] FIG. 10 is an explanatory cross-sectional view of a sixth embodiment of the present invention. [Figure 20] FIG. 13 is an explanatory cross-sectional view of a seventh embodiment of the present invention. [Figure 21] FIG. 13 is an explanatory cross-sectional view of an eighth embodiment of the present invention. [Figure 22] FIG. 13 is an explanatory cross-sectional view of a modified example of the eighth embodiment. [Figure 23] FIG. 1 is an explanatory cross-sectional view showing an example of a conventional technique. [Figure 24] FIG. 24 is an explanatory cross-sectional view of a conventional technique different from that shown in FIG. 23. DETAILED DESCRIPTION OF THE INVENTION

[0015] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings. First, a first embodiment of the present invention will be described with reference to FIGS. 1 to 4. FIG. Fig. 1, which shows the first embodiment, shows a cross section perpendicular to the plane of the paper on which it is drawn. In Fig. 1, an existing embankment EE is constructed on top of a sloping natural ground OG (basement), and a flat surface FS is constructed on top of the existing embankment EE. The natural ground OG and the existing embankment EE extend in a direction perpendicular to the plane of the paper on which it is drawn. The flat surface FS at the top of the existing embankment EE may have roads (highways), railways, houses, and other buildings. When reinforcing existing embankment EE, roads, railways, houses and other structures are mostly constructed on the flat surface FS at the top, and in the illustrated embodiment, even if the existing embankment EE collapses, the flat surface FS is prevented from collapsing, ensuring the safety of structures (roads, railways and other various structures) on the flat surface FS.

[0016] In Fig. 1, a vertically extending structural member, that is, a vertically extending vertical reinforcement member 1, is installed at the end of the valley side of the flat surface FS (the right side in Fig. 1: the side where a slide or collapse occurs). That is, in the first embodiment, a vertically extending vertical reinforcement member 1 is installed at the end of the valley side of the flat surface FS. The lower end of the vertical reinforcement 1 reaches the ground OG of the existing embankment EE, and is installed so that it can resist horizontal forces that would act in the event of a collapse of the existing embankment EE. Although one vertical reinforcement 1 is shown in Figure 1, multiple vertical reinforcement 1 are installed in the direction perpendicular to the plane of the paper in Figure 1. The number of vertical reinforcement 1 installed, and the distance between adjacent vertical reinforcement 1 when multiple reinforcement are installed, are determined according to the conditions of the construction site. In other words, the spacing of the vertical reinforcement 1 in the direction perpendicular to the plane of the paper in Figure 1 is set so that the flat surface FS of the existing embankment EE does not collapse. The area around the vertical reinforcement 1 that penetrates the existing embankment EE and natural ground OG is filled with hardening material. Although not clearly shown in the figure, when constructing the vertical reinforcement 1, if a road has been constructed on the flat surface FS, one lane on the valley side of the road can be occupied with construction equipment, etc., and construction can be carried out in the illustrated embodiment, with temporary scaffolding being installed as little as possible and only the minimum necessary being constructed (reinforcing only the area of ​​about one slope step (symbol N1) in Figure 1).

[0017] The installation position of the longitudinal reinforcement 1 in Figure 1 must be close to the area to be collapsed (the valley side area) so that the collapsed area at the top of the existing embankment EE is small, and also close to the structure (e.g., road) constructed on the flat surface FS of the top of the existing embankment. If the embankment is located close to the area that will collapse (the area on the valley side), the collapsed area at the top of the embankment (the area on the valley side of the slide surface SS) will be smaller. Also, if the embankment is located close to the road, construction can be carried out from the road (for example, one lane on the valley side). In other words, the location where the longitudinal reinforcement 1 is installed is a location that is close enough to the area to be protected (for example, the road on top of the embankment) that construction is possible, and is close to the area that will collapse (the area on the valley side). As mentioned above, Figure 1 shows only one cross section perpendicular to the paper surface, but the existing embankment EE extends in a direction perpendicular to the paper surface of Figure 1, and the installation interval of the longitudinal reinforcement 1 in the direction perpendicular to the paper surface of Figure 1 (or the interval between cross sections (shown in Figure 1) in the direction perpendicular to the paper surface of Figure 1) is set to a dimension that will prevent the collapse of the flat surface (FS) of the existing embankment EE. This dimension can be calculated using existing strength calculation methods.

[0018] In Figure 1, by providing vertical reinforcement 1 at the end of the valley side (right side in Figure 1) of the flat surface FS, reinforcement measures are taken to prevent the area (area where roads, railways, and other buildings are located) on the natural ground side of the vertical reinforcement 1 (left side in Figure 1: opposite the valley side) from sliding and collapsing even if the existing embankment EE collapses. In other words, the illustrated embodiment does not affect whether the area on the valley side of the vertical reinforcement 1 in the existing embankment EE will slide and collapse. Even in the first embodiment of Figure 1, it is not intended to ensure the stability of the entire existing embankment EE. As mentioned above, the intention is only to stabilize the road (including railways and various buildings) on the flat surface FS at the top of the existing embankment EE. In FIG. 1, the slip surface before the installation of the longitudinal reinforcement 1 is indicated by SS (chain line), and the slip surface after the installation of the longitudinal reinforcement 1 is indicated by SS1 (dashed line).

[0019] Next, a first modification of the first embodiment will be described with reference to FIG. In Fig. 2 showing the first modified example, the first vertical reinforcement 1 is installed at the end of the valley side of the flat surface FS (the right side in Fig. 1, the side where sliding or collapse occurs) as shown in Fig. 1, and in addition, a second vertical reinforcement 1-1 is installed further towards the valley side of the first vertical reinforcement 1 in the same cross section (the same cross section in the direction perpendicular to the paper surface of Figs. 1 and 2) as where the first vertical reinforcement 1 is installed. A plurality of the first vertical reinforcement 1 and the second vertical reinforcement 1-1 (for example, 2 to 4) are installed in the same cross section in the direction perpendicular to the paper surface of Fig. 2. Here, the "same cross section as where the first vertical reinforcement 1 was installed" where the second vertical reinforcement 1-1 is installed should be set so that the spacing between the vertical reinforcements 1, 1-1 in the direction perpendicular to the paper surface of Figures 1 and 2 does not cause the flat surface FS to collapse. This spacing can be calculated, for example, using existing strength calculations. The reason for installing multiple longitudinal reinforcement members 1, 1-1 (two in Figure 2) as shown in Figure 2 is when it is considered that installing only one longitudinal reinforcement member 1 as shown in Figure 1 will not be enough to prevent the road on the flat surface FS from collapsing. Compared to installing only the first longitudinal reinforcement member 1, installing a second longitudinal reinforcement member 1-1 on the valley side of the flat surface FS provides greater strength to prevent collapse due to sliding, and can more reliably prevent the road from collapsing. The reason why the second vertical reinforcement 1-1 was installed closer to the valley than the first vertical reinforcement 1 was because it was anticipated that if it was installed closer to the natural ground than the first vertical reinforcement 1 (left side in Figure 2: opposite the valley), the shoulder of the road in the flat area FS would become narrower, making construction difficult. Although not explicitly shown, the ground EE extends in a direction perpendicular to the plane of the paper in Figure 2, so throughout the ground EE, multiple longitudinal reinforcement members 1 and multiple second longitudinal reinforcement members 1-1 are installed. Although not shown in the figure, the heads of the longitudinal reinforcement 1 and the longitudinal reinforcement 1-1 can be connected together. In addition, the heads of the longitudinal reinforcement 1 or 1-1 that are continuous in a direction perpendicular to the paper surface of the attached drawings can also be connected together. In Figure 2, two longitudinal reinforcements 1 and 1-1 are installed on the shoulder of a road with a flat surface FS, but it is expected that it will be difficult to install a third longitudinal reinforcement in the same cross section as Figure 2. Therefore, in the embodiment of Figure 2, it is expected that the multiple longitudinal reinforcements will be one longitudinal reinforcement 1 and a second longitudinal reinforcement 1-1. However, in FIG. 2, it is also possible to install only the longitudinal reinforcement 1 in another cross section in a direction perpendicular to the paper surface of FIG. 2, and to install two longitudinal reinforcements 1, 1-1 in yet another cross section. In Figure 2, the slip surface after the installation of the longitudinal reinforcement 1 and 1-1 is indicated by SS2. The other configurations and effects of the modified example of FIG. 2 are the same as those of the embodiment of FIG.

[0020] Next, a second modification of the first embodiment will be described with reference to FIG. In Fig. 3 showing the second modified example, in addition to the longitudinal reinforcement 1 at the end of the valley side of the road (of the flat surface FS) (the right side in Fig. 3, the side where sliding or collapse occurs), longitudinal reinforcement 1-2 is installed around the center line of the road (i.e., near the center of the flat surface FS). Because the natural ground EE extends in a direction perpendicular to the plane of the paper in Fig. 3, multiple longitudinal reinforcements 1 and 1-2 in Fig. 3 are installed throughout the natural ground, although this is not clearly shown in Fig. 3. By installing longitudinal reinforcement 1 and 1-2, collapse can be more effectively prevented, especially on the side of the ground closer to longitudinal reinforcement 1-2 (the left side in Figure 3, the side that is not on the valley side; in the case of a road, the side farther from the valley than the center line: the left side). If the area farther from the valley than the longitudinal reinforcement 1-2 (left side in Figure 3) has not collapsed, and the top flat surface FS of the existing embankment EE is a road, one-way traffic will be possible in the area farther from the valley than the center line, and the road will function as social infrastructure.Even if the top flat surface FS of the existing embankment EE is a railway, if the area farther from the valley than the longitudinal reinforcement 1-2 (left side in Figure 3) has not collapsed, the railway will be able to operate as a single track if it is a double track. The sliding surface in the embodiment of FIG. 3 is designated by the symbol SS3. Other configurations and effects of the second modified example of FIG. 3 are the same as those of the embodiment of FIGS.

[0021] Next, a modified example that combines the first modified example of FIG. 2 and the second modified example of FIG. 3 will be described with reference to FIG. In Figure 4, longitudinal reinforcement members 1 and 1-1 are installed at the end of the valley side of the flat surface FS (the right side in Figure 4, the side where sliding or collapse occurs), and longitudinal reinforcement member 1-2 is installed around the center line of the road (i.e., near the center of the flat surface FS). Multiple longitudinal reinforcement members 1, 1-1, and 1-2 (for example, 2 to 4) are installed on the same cross section perpendicular to the plane of Figure 4. Although not shown in Figure 4, the heads of the longitudinal reinforcement 1 and the longitudinal reinforcement 1-1 can be connected. In addition, the heads of the longitudinal reinforcement 1 or 1-1 cast in a direction perpendicular to the paper surface can be connected. According to the reinforcement method shown in Figure 4, which is a combination of the first variant of Figure 2 and the second variant of Figure 3, the collapse of the top flat surface FS of the existing embankment EE is more reliably prevented than the reinforcement method of the first embodiment shown in Figure 1 and the reinforcement method of the second variant of the first embodiment shown in Figure 3. Furthermore, according to the reinforcement method shown in Fig. 4, the area closer to the natural ground than the vertical reinforcement 1-2 (the area on the left side in Fig. 4: the area farther from the valley) is more strongly protected and collapse is prevented than with the reinforcement method of the first embodiment shown in Fig. 1 and the reinforcement method of the first modified example of the first embodiment shown in Fig. 2. Therefore, if the structure on the flat surface FS is a road, "one-way traffic" will be possible, and if the structure on the flat surface FS is a double-track railway, it will be possible to operate it as a single track. The sliding surface in the embodiment of FIG. 4 is designated by the symbol SS4. Other configurations and effects of the modified example of FIG. 4 are the same as those of the embodiment of FIGS.

[0022] Here, the priority order for implementing the reinforcing method of the first embodiment shown in FIGS. 1 to 4 is FIG. 1 → FIG. 2 → FIG. 3 → FIG. As shown in Figure 1, the basic reinforcement method is to install vertical reinforcement 1 at the end of the valley side (right side in Figure 1) of the flat surface FS, and if the embodiment in Figure 1 is sufficient, then the embodiment in Figure 1 should be adopted. If the reinforcement method in Figure 1 is not strong enough to prevent the road on the flat surface FS at the top of the existing embankment from collapsing, the first modified example shown in Figure 2 can be adopted, in which a second longitudinal reinforcement 1-1 is installed on the valley side of the first longitudinal reinforcement 1. By installing the second longitudinal reinforcement 1-1 in this way, the required strength can be ensured. If it is desired to protect only the area of ​​the existing embankment EE far from the valley side, and for example to allow "one-way traffic" if the top flat surface FS is a road, or to allow operation as a single track if it is a double-track railway, it would be effective to adopt the reinforcement method shown in Figure 3 and also install vertical reinforcement 1-2 around the center line of the road (near the center of the flat surface FS). Furthermore, if the reinforcement method in Figure 1 is not strong enough to prevent the road on the flat surface FS at the top of the existing embankment from collapsing, and if it is necessary to protect only the area of ​​the existing embankment EE far from the valley side, for example, to allow "one-way traffic" if the flat surface FS is a road, or to allow operation as a single track if it is a double-track railway, then the reinforcement method shown in Figure 4 should be adopted.

[0023] Next, a second embodiment of the present invention will be described with reference to FIGS. In the second embodiment shown in Fig. 5, in the existing embankment EE, multiple horizontal reinforcements 2 are installed in the area between adjacent vertical reinforcements 1. Here, "adjacent" means adjacent in the direction perpendicular to the paper surface of Fig. 5, and the vertical reinforcements 1 are adjacent as shown in Fig. 6. In Fig. 5, vertically extending longitudinal reinforcement 1 is installed at the end of the valley side of the flat surface FS (the right side in Fig. 5: the side where sliding or collapse occurs), as in the first embodiment. Although not clearly shown in Fig. 5, the embankment EE extends in a direction perpendicular to the plane of Fig. 5, and multiple longitudinal reinforcement 1 are also installed in the direction perpendicular to the plane of Fig. 5. In the region between the vertical reinforcements 1, which are installed in a direction perpendicular to the paper surface of Fig. 5, horizontal reinforcements 2 extending in a direction inclined from the horizontal (or in the horizontal direction) are installed. A plurality of horizontal reinforcements 2 (for example, 5 to 10) are installed along the length direction (vertical direction) of the vertical reinforcements 1. The vertical interval between the horizontal reinforcements 2 is, for example, 1.5 m or less, and preferably 0.5 to 1.5 m. The lower end of the horizontal reinforcement 2 (the left end in Fig. 5: the end on the natural ground OG side) does not reach the natural ground OG. On the other hand, the end on the valley side of the horizontal reinforcement 2 (the right side in Fig. 5) protrudes further into the valley than the vertical reinforcement 1. The horizontal reinforcement 2 can also be made of steel bars.

[0024] As shown in Figure 6, which is a view taken along arrow A6 in Figure 5, horizontal reinforcements 2 are installed in the area between vertical reinforcements 1 (which are installed in multiple directions perpendicular to the paper surface of Figure 5). In FIG. 6, a region R (only one region is shown in FIG. 6) indicated by a broken line around the horizontal reinforcement 2 is filled with a hardening material. In FIG. 6, the symbol SO indicates the soil between the longitudinal reinforcement members 1. The number of vertical reinforcements 1 and horizontal reinforcements 2 to be installed, the distance between adjacent vertical reinforcements 1 (in Figure 6), and the distance between adjacent horizontal reinforcements 2 above and below are determined on a case-by-case basis depending on the conditions of the construction site. The vertical spacing (pitch) of the horizontal reinforcements 2 is, for example, 1.5 m or less, and preferably 0.5 to 1.5 m.

[0025] In Figure 5, by installing horizontal reinforcement 2 in the area between vertical reinforcement 1, when a collapse (slide) occurs in the existing embankment EE, it is possible to prevent the soil existing between adjacent vertical reinforcement 1 (in the direction perpendicular to the page of Figure 5) (in Figure 6, the area between adjacent vertical reinforcement 1) from collapsing (becoming hollow). As will be described later, by providing the horizontal reinforcement 2, it is possible to prevent the sliding surface from reaching the flat portion FS, eliminate the need for edge breaks on the valley side of the vertical reinforcement 1, and support the load when sliding occurs on the vertical reinforcement 1 due to the valley side protrusion of the horizontal reinforcement 2. Here, the horizontal reinforcement 2 does not reach the natural ground OG, but it is effective enough to prevent soil from being lost between the vertical reinforcement 1. As shown in Figure 6, the hardening material is filled around the horizontal reinforcement 2, which also has the effect of preventing soil from leaking out from the area around the horizontal reinforcement 2. In Figures 1 to 5, the hardening material can also be filled around the vertical reinforcement 1. In Figure 5, the slip surface after the installation of vertical reinforcement 1 and horizontal reinforcement 2 is indicated by SS5.

[0026] FIG. 7 shows the effect of the horizontal reinforcement 2. In FIG. 7, a vertical reinforcement 1 shown by a broken line is installed at the valley side end of the flat surface FS, and a plurality of horizontal reinforcements 2 are installed in the vertical direction. In Figure 7, the dashed dotted line SS indicates the slide surface in the "soil between vertical reinforcement" when no horizontal reinforcement 2 is installed. As is clear from the slide surface SS, if no horizontal reinforcement 2 is installed, the slide surface SS in the "soil between vertical reinforcement 1" will reach the flat surface FS on which the facilities and structures to be protected (roads, railways, etc.) are constructed. On the other hand, if multiple horizontal reinforcements 2 are installed between vertical reinforcements 1 as shown in Figures 5 and 6, the slide surface SS5 (Figures 5 and 7) in the "soil between vertical reinforcements 1" in Figure 7 will move towards the valley (to the right in Figures 5 and 7) compared to the slide surface SS when no horizontal reinforcements 2 are installed, and will not reach the flat surface FS at the top of the existing embankment that needs to be protected, and the flat surface FS on which the road has been built will not collapse.

[0027] As shown by 2T in FIG. 7, the valley side end of the horizontal reinforcement 2 protrudes further toward the valley side (right side in FIG. 7) than the vertical reinforcement 1. As shown in Figure 8, if the area 2T (Figures 7 and 8) of the horizontal reinforcement 2 that protrudes toward the valley side (the side that will collapse: the right side in Figures 7 and 8) is longer than the vertical reinforcement 1, when the existing embankment EE collapses, the horizontal reinforcement 2 will be carried away by the collapsed existing embankment EE (arrow B) and will also come out, and at the same time, a large amount of the soil between the vertical reinforcement 1 will be lost. Here, if the region 2T (Figs. 7 and 8) of the horizontal reinforcement 2 that protrudes further toward the valley side (the side that will collapse: the right side in Figs. 7 and 8) than the vertical reinforcement 1 is shorter, the horizontal reinforcement 2 is prevented from being carried away by the collapsed existing embankment EE, and holes between the vertical reinforcement 1 are also prevented. In Figs. 5 to 8, the length of the region 2T of the horizontal reinforcement 2 that protrudes further toward the valley side than the vertical reinforcement 1 is shortened, which is called "edge cutting."

[0028] Here, instead of shortening the length of the region 2T of the horizontal reinforcement 2 that protrudes toward the valley side more than the vertical reinforcement 1, the region 2T of the horizontal reinforcement 2 that protrudes toward the valley side more than the vertical reinforcement 1 may be made easier to break, so that the ``region 2T protruding toward the valley side'' will be broken when the existing embankment EE collapses. By cutting the edges or by making the area 2T protruding toward the valley side easier to break, only the area of ​​the horizontal reinforcement 2 on the valley side of the broken point is carried away by the collapsed embankment EE, and the horizontal reinforcement 2 on the natural ground side of the broken point (the left side in Figures 5 and 7: the opposite side to the collapse) is not carried away. In FIG. 7, the portion of the horizontal reinforcement 2 that is further toward the valley side than the protruding region 2T (the region indicated by the broken line in FIG. 7) is filled with a hardening material.

[0029] 5 to 8, it is assumed that the sliding (collapse) of the existing embankment EE can be prevented only by the vertical reinforcement 1. This is because the horizontal reinforcement 2 is provided not to prevent the collapse of the existing embankment EE but to prevent holes in the areas between the vertical reinforcement 1. Other configurations and effects of the second embodiment are the same as those of the embodiment shown in FIGS.

[0030] A modification of the second embodiment will be described with reference to FIGS. In Figure 9, which shows an overview of this modified example, as with the first modified example of the first embodiment shown in Figure 2, a first vertical reinforcement 1 is installed at the end of the valley side of the flat surface FS of the top (the right side in Figure 9: the side where sliding or collapse occurs), and a second vertical reinforcement 1-1 is installed closer to the valley than the first vertical reinforcement 1. In the modified examples of Figures 9 and 10, the first vertical reinforcement 1 and the second vertical reinforcement 1-1 are installed in the same cross section, but the cross section where the first vertical reinforcement 1 is installed and the cross section where the second vertical reinforcement 1 is installed do not have to be in the same position (in the direction perpendicular to the paper surface of Figure 9) in the strict sense. It is sufficient that the distance between the vertical reinforcement 1 and the vertical reinforcement 1-1 in the direction perpendicular to the paper surface of Figure 9 is set so that the flat surface FS does not collapse, and such a distance can be calculated, for example, using existing strength calculations. In FIG. 9, the sliding surface is indicated by the symbol SS10.

[0031] In the modified examples shown in Figures 9 and 10, in Figure 10, which is a view taken along arrow A11 in Figure 9, the relative positions of vertical reinforcement 1-1 to vertical reinforcement 1 (left-right positions in Figure 10) can be roughly the same as shown by the solid lines, or they can be arranged alternately (so-called "staggered") as shown by the dashed lines. In the staggered arrangement, the second vertical reinforcement shown by the dashed lines is designated by the symbol 1-1A. In Figure 10, when vertical reinforcement 1 and vertical reinforcement 1-1A are arranged alternately (staggered), the horizontal (left-right direction in Figure 10) spacing L11 between vertical reinforcement 1 and vertical reinforcement 1-1A often becomes narrow, and if the spacing L11 between vertical reinforcement 1 and 1-1 is short, there is little risk of the soil in the area of ​​spacing L11 becoming hollowed out, and horizontal reinforcement 2 is not necessary. On the other hand, as shown in Figure 10, when the relative positions (in the left-right direction of Figure 10) of the vertical reinforcement 1 and the vertical reinforcement 1-1 are roughly the same, the horizontal distance L11-1 between the vertical reinforcement 1 and the vertical reinforcement 1-1 is often large, and if the distance L11-1 between the vertical reinforcements 1 and 1-1 is long, there is a risk of holes occurring in the area of ​​the distance L11-1. For this reason, a horizontal reinforcement 2 (not shown in Figure 10) is often installed between the vertical reinforcements 1 and 1-1. In the modified example of Figs. 9 and 10, two longitudinal reinforcements 1, 1-1 are installed, so the strength to prevent the natural ground EE from sliding (collapse) is greater than in the second embodiment of Figs. Other configurations and effects of the modified examples of FIGS. 9 and 10 are similar to those of the embodiment of FIGS.

[0032] Next, a third embodiment of the present invention will be described with reference to FIGS. In Figure 11, in addition to the vertical reinforcement 1, as in the second embodiment of Figures 5 to 10, multiple (e.g., 5 to 10) horizontal reinforcement members 2 are provided vertically in the area between adjacent vertical reinforcement members 1 in the direction perpendicular to the paper surface of Figure 11. Unlike the second embodiment shown in Figures 5 to 10, in the third embodiment shown in Figure 11, some of the multiple horizontal reinforcements 2 reach the natural ground OG. In other words, in the third embodiment shown in Figure 11, horizontal reinforcements 2 that have not reached the natural ground OG and horizontal reinforcements 2-1 that have reached the natural ground OG are mixed together. The horizontal reinforcements that have not reached the natural ground OG are represented by the symbol "2", and the horizontal reinforcements that have reached the natural ground OG are represented by the symbol "2-1". The horizontal reinforcement members 2, 2-1 are made of rebars or the like, and are not ground anchors. The boreholes into which the horizontal reinforcement members 2, 2-1 made of rebars or the like are inserted are filled with a hardener or the like, and the horizontal reinforcement members 2-1 (which have reached the natural ground OG) are fixed to the natural ground OG. The vertical spacing (pitch) of the horizontal reinforcement members 2, 2-1 is, for example, 1.5 m or less, and preferably 0.5 to 1.5 m. Unlike ground anchors, there is no need to apply tension to the horizontal reinforcement 2-1 that reaches the natural ground OG, and there is no need for a structure such as a ground anchor head. Unlike the second embodiment of Figures 5 to 10, in the third embodiment of Figure 11, collapse (slide) of the existing embankment EE is prevented not only by the vertical reinforcement 1 but also by the horizontal reinforcement 2-1 that reaches the ground OG. The sliding surface in the third embodiment of FIG. 11 is indicated by SS12.

[0033] In the third embodiment shown in Figure 11, it is preferable to provide a structure that increases adhesion and has a bearing effect to prevent deformation of the vertical members 1 toward the valley side (the side that will collapse: the right side in Figure 11) in the horizontal reinforcement 2-1 that has reached the natural ground OG. This structure is called the portion P indicated by the dashed line in Figure 11. Examples of structures that increase adhesion and have a bearing effect to prevent deformation of the vertical members 1 toward the valley side include packers 4 (see Figure 12; not shown in Figure 11), enlarged sections, and structures that allow grout material to permeate the surrounding ground. The following explanation assumes that packers are provided. As shown in Figure 12, if a packer 4 is installed in a section where the horizontal reinforcement 2-1 protrudes further toward the valley than the vertical reinforcement 1, when a force that tries to move in the direction of arrow X (toward the valley) acts on the vertical reinforcement 1 due to the collapse (slide) of the embankment EE, a force in the direction of arrow Y (toward the valley) acts on the packer 4. The force in the direction of arrow Y acting on the packer 4 can be supported by the horizontal reinforcement 2-1 that has reached the natural ground, and therefore the force that tries to move the vertical reinforcement 1 can also be supported by the horizontal reinforcement 2-1 (horizontal reinforcement that has reached the natural ground). As a result, the force that causes the slide (collapse) is supported not only by the vertical reinforcement 1 but also by the horizontal reinforcement 2-1 that reaches the ground OG, further suppressing the slide of the embankment EE. Other configurations and effects of the third embodiment shown in FIGS. 11 and 12 are similar to those of the embodiment shown in FIGS.

[0034] Next, a fourth embodiment of the present invention will be described with reference to FIGS. In Figure 13, a hole prevention wall 5 is constructed at the top end of the vertical reinforcement 1 installed at the end of the valley side of the flat surface FS (the right side in Figure 13: the side where a slide or collapse will occur). The hole prevention wall 5 extends in a direction perpendicular to the plane of the paper in Figure 13. In Figure 13, if only vertical reinforcement 1 is installed, there is a risk of the soil between adjacent vertical reinforcement 1 in the direction perpendicular to the plane of the paper in Figure 13 becoming hollow. The hollow prevention wall 5 in Figure 13 is constructed across the spaces between the adjacent vertical reinforcement 1, so even if the hollow described above (hollow in the area between the vertical reinforcement 1) occurs, as shown in Figure 14, at least the paved surface of the road or the crushed stone section of the railway built on the flat surface FS of the top of the embankment to be protected will be protected.

[0035] In Fig. 14, the hole prevention walls 5 extend in a direction perpendicular to the plane of the paper in Fig. 14, or multiple walls are provided intermittently in a direction perpendicular to the plane of the paper in Fig. 14. Even if the above-mentioned hole occurs, the hole prevention walls 5 restrain the movement of the road pavement surface or the crushed stone section RR of the railway in the direction of arrow C (collapse direction), thereby preventing sliding (collapse). Here, the thickness (depth) dimension L15 of the hole-opening prevention wall 5 is set to a thickness that can protect only the pavement of the road or the crushed stone portion of the railway. In FIG. 13, the sliding surface in the fourth embodiment is designated by the symbol SS14.

[0036] In Figure 15, which shows a modified example of the fourth embodiment, similar to Figures 3 and 4, in addition to the vertical reinforcement 1 provided at the valley side edge (right end in Figure 15) of the flat surface FS of the top of the existing embankment EE, a second vertical reinforcement 1-2 is provided at the center of the flat surface FS (center in the left-right direction in Figure 15: near the center line if it is a road). As mentioned above with reference to Figure 3, by installing vertical reinforcement 1 (vertical reinforcement with a hole prevention wall 5 constructed above) at the end of the valley side of the road on the flat surface FS (right side in Figure 15), as well as vertical reinforcement 1-2 around the center line of the road, it is possible to prevent collapse of at least the area on the natural ground OG side (left side in Figure 15) of vertical reinforcement 1-2, and if the top of the existing embankment EE is a road, it will enable so-called "one-way traffic," and if the top of the existing embankment is a double-track railway, it will enable railway operation as a single track. In Figure 15, the slide surface of the existing embankment EE is indicated by the symbol SS16. Other configurations and effects of the fourth embodiment shown in FIGS. 13 to 15 are the same as those of the embodiment shown in FIGS.

[0037] Next, a fifth embodiment of the present invention will be described with reference to FIGS. In Figure 16, in addition to the vertical reinforcement 1 installed at the end of the valley side of the flat surface FS (the right side in Figure 16: the side where sliding or collapse occurs), there are also provided ground anchors 3 and beam-like members 27 (beams) extending in a direction perpendicular to the plane of the paper in Figure 16. The ground anchor 3 has tendons 3A that extend in a direction inclined relative to the horizontal (or in the horizontal direction), and an anchor head 3B (see Figures 17 and 18: not shown in Figure 16) is provided at the upper end of the vertical reinforcement 1. The beam-like member 27, which extends in a direction perpendicular to the plane of the paper in Figure 16, is glued to the valley side of the vertical reinforcement 1 and installed on the crest side of the ground anchor 3. The beam-like member 27 has the function of transmitting the force of the ground anchor 3 to the vertical reinforcement 3 and suppressing deformation of the vertical reinforcement 1 towards the valley side. In other words, when installing ground anchors 3 between vertical reinforcement 1, it is necessary to transmit the force of the ground anchor 3 to the vertical reinforcement 1 and suppress deformation of the vertical reinforcement 1 towards the valley side. It is also possible to connect the ground anchor 3 directly to the head of the vertical reinforcement 1. In FIG. 16, a plurality of vertical reinforcements 1 and ground anchors 3 are installed in a direction perpendicular to the plane of the paper in FIG. Since the restraint length portion 3C of the ground anchor 3 reaches the natural ground OG, both the longitudinal reinforcement 1 and the ground anchor 3 can resist the sliding of the existing embankment EE.

[0038] The relative positions on a plane (relative positions in the direction perpendicular to the plane of Figure 16) between the vertical reinforcement 1 and the ground anchors 3 (tendons 3A, anchor heads 3B) are as shown in Figure 17, with the vertical reinforcement 1 and ground anchors 3 installed alternately (in the direction perpendicular to the plane of Figure 16). In Figure 17, the straight line EL indicates the valley side edge line of the flat surface FS at the top of the existing embankment EE, and the arrow A18 indicates the valley side direction. The beam-like member 27 extends left and right in Figure 17 (in the direction perpendicular to the plane of Figure 16). Here, the vertical reinforcement 1 and ground anchor 3 can be placed in the same position in the direction perpendicular to the plane of the paper in Figure 16. If the diameter of the through hole of the ground anchor 3 is larger than that of the vertical reinforcement 1 and it is difficult to install the ground anchor 3 by penetrating the vertical reinforcement 1, it is possible to provide a concrete block 1C integrated with the vertical reinforcement 1, place the tendon 3A of the ground anchor 3 so that it penetrates the concrete block 1C, and apply tension to the tendon 3A at the anchor head 3B provided in the concrete block 1C, as shown in Figure 18. Although not shown in Figure 18, a jack (not shown) can be installed at the anchor head 3B of the concrete block 1C, and tension can be applied to the tendon 3A of the ground anchor 3 by using the jack. In FIG. 16, the sliding surface is designated by the symbol SS17. Other configurations and effects of the fifth embodiment shown in FIGS. 16 to 18 are the same as those of the embodiments shown in FIGS.

[0039] Next, a sixth embodiment of the present invention will be described with reference to FIG. The sixth embodiment in FIG. 19 is a technique that combines the second embodiment in FIGS. 5 to 10 and the fifth embodiment in FIGS. In Figure 19, vertical reinforcement 1 is provided at the end of the valley side of the flat surface FS (the right side in Figure 19: the side where sliding or collapse occurs), and multiple (e.g., 2 to 4) vertical reinforcement 1 are installed in the direction perpendicular to the plane of Figure 19. Horizontal reinforcement 2 is installed in the area between adjacent vertical reinforcement 1 in the direction perpendicular to the plane of Figure 19. Multiple (e.g., 5 to 10) horizontal reinforcement 2 are installed along the length (vertical direction) of the vertical reinforcement 1. The bottom end of the horizontal reinforcement 2 (the left end in Figure 19: the end on the natural ground side) does not reach the natural ground OG, and the valley side end of the horizontal reinforcement 2 protrudes further into the valley than the vertical reinforcement 1. In addition to the vertical reinforcement 1 and horizontal reinforcement 2, there are provided ground anchors 3 and beam-like members 27 (beams) extending in a direction perpendicular to the plane of the paper in Figure 19. The ground anchors 3 have the same configuration as the ground anchors 3 in the fifth embodiment (Figure 16), and have tendons 3A and anchor heads 3B, with the restraint length portion 3C reaching the natural ground OG. Like the vertical reinforcement 1, multiple ground anchors 3 are installed in a direction perpendicular to the plane of the paper in Figure 19. The beam-like member 27, which extends in a direction perpendicular to the plane of the paper in Figure 19, is glued to the valley side of the vertical reinforcement 1 and is installed on the crest side of the ground anchor 3. The beam-like member 27 has the function of transmitting the force of the ground anchor 3 to the vertical reinforcement 3 and suppressing deformation of the vertical reinforcement 1 towards the valley side. It is also possible to connect the ground anchor 3 directly to the head of the vertical reinforcement 1. In the sixth embodiment of Fig. 19, the sliding of the existing embankment EE can be resisted by both the vertical reinforcement 1 and the ground anchors 3. Furthermore, the horizontal reinforcement 1 can prevent soil from being lost between adjacent vertical reinforcement 1 in the direction perpendicular to the paper surface of Fig. 19. The sliding surface in FIG. 19 is designated by the symbol SS20. Other configurations and effects of the sixth embodiment in FIG. 19 are the same as those of the embodiments in FIGS.

[0040] Next, a seventh embodiment of the present invention will be described with reference to FIG. The seventh embodiment in FIG. 20 relates to a technique that combines the third embodiment in FIGS. 11 and 12 with the fifth embodiment in FIGS. In the seventh embodiment of FIG. 20, similarly to the sixth embodiment of FIG. 19, the vertical reinforcement 1, the horizontal reinforcement 2 、 The ground anchor 3 (tendon 3A, anchor head 3B) and a beam-like member 27 (beam) extending in a direction perpendicular to the plane of the paper in FIG. 20 are provided. Here, in the seventh embodiment, some of the horizontal reinforcements 2 (reference numeral 2-1) have their ends on the natural ground OB side reaching the natural ground OG (anchored to the natural ground OG). In other words, in the seventh embodiment shown in Fig. 20, horizontal reinforcements 2 that have not reached the natural ground OG and horizontal reinforcements 2-1 that have reached the natural ground OG are mixed together. In Fig. 20, the horizontal reinforcements that have not reached the natural ground OG are indicated by reference numeral 2, and the horizontal reinforcements that have reached the natural ground OG are indicated by reference numeral 2-1. The horizontal reinforcements 2 that have not reached the natural ground OG and the horizontal reinforcements 2-1 that have reached the natural ground OG are arranged alternately in the vertical direction in Fig. 20. Therefore, the seventh embodiment of Fig. 20 can resist collapse and sliding of the existing embankment EE not only by the vertical reinforcement 1 and ground anchors 3, but also by the horizontal reinforcement 2-1 that reaches the natural ground OG. The horizontal reinforcement 2 that does not reach the natural ground OG is effective in preventing soil from becoming hollowed out between the vertical reinforcement 1. In Figure 20, a beam-like member 27 extending perpendicular to the paper surface is glued to the valley side of the vertical reinforcement 1 and installed on the crest side of the ground anchor 3, and has the function of transmitting the force of the ground anchor 3 to the vertical reinforcement 3 and suppressing deformation of the vertical reinforcement 1 towards the valley side. The ground anchor 3 can also be connected directly to the head of the vertical reinforcement 1. In FIG. 20, the sliding surface is indicated by the symbol SS21. Other configurations and effects of the seventh embodiment in FIG. 20 are the same as those of the embodiments in FIGS.

[0041] Next, an eighth embodiment of the present invention will be described with reference to FIGS. In FIG. 21, two vertical reinforcements 1 and 1-3 constitute a structure such as a so-called pile assembly (a structure formed by combining a plurality of piles whose pile axes are oriented in different directions). In Figure 21, vertically extending vertical reinforcement 1 is installed at the end of the valley side of the flat surface FS (the right side in Figure 21: the side where sliding or collapse occurs). Then, vertical reinforcement 1-3 is installed, extending at an angle to the vertical direction. The vertical reinforcement 1 and the inclined vertical reinforcement 1-3 form a set to form a pile. Here, multiple sets of vertical reinforcement 1 and inclined vertical reinforcement 1-3 in Figure 21 are installed in the natural ground OG and existing embankment EE, which extend perpendicular to the plane of the paper in Figure 21. As in the above-described embodiment, the vicinity of the lower end of the vertical reinforcement 1 also reaches the natural ground OG. The vicinity of the lower end of the inclined vertical reinforcement 1-3 also reaches the natural ground OG, and is located closer to the natural ground OG (to the left in Figure 21) than the vertical reinforcement 1. The upper end of the vertical reinforcement 1 and the upper end of the inclined vertical reinforcement 1-3 are connected in a known manner. In addition, it is preferable that the pair of vertical reinforcement 1 and vertical reinforcement 1-3 shown in Figure 21 and the adjacent pair of vertical reinforcement 1 perpendicular to the paper surface and the inclined vertical reinforcement 1-3 are connected to each other. In the embodiment of FIG. 21, the pile is composed of the longitudinal reinforcement 1 and the inclined longitudinal reinforcement 1-3, and therefore exhibits good strength and can cope with sliding and collapse. In FIG. 21, the sliding surface is designated by the symbol SS22.

[0042] In a modified example of the eighth embodiment shown in Figure 22, similar to those shown in Figures 3, 4 and 15, longitudinal reinforcement is provided around the centerline of the road constructed on top of the existing embankment EE in addition to the valley-side edge of the top of the existing embankment. In Figure 22, two longitudinal reinforcements 1 and 1-3 configured like piles are installed at the valley-side (right-hand side in Figure 22) end of a road constructed on a flat surface FS, similar to the eighth embodiment in Figure 21. In addition, a longitudinal reinforcement 1-2 is installed near the center of the flat surface FC (the centerline of the constructed road). Here, multiple longitudinal reinforcements 1, 1-3, and 1-2 in Figure 22 are installed in the natural ground OB and existing embankment EE, which extend perpendicular to the plane of the paper in Figure 22. For example, as mentioned above with reference to Figure 3, by installing the vertical reinforcement 1-2 near the center of the flat surface FC (the center line of the constructed road), even in the event of severe collapse or sliding, it is highly likely that collapse will be prevented at least in the area on the natural ground side of the vertical reinforcement 1-2 (the left side in Figure 22). Therefore, if the top flat surface FS of the existing embankment EE is a road, so-called "one-way traffic" will be possible, and if the top flat surface FS of the existing embankment EE is a railway, it will allow railway operation as a single track. In FIG. 22, the sliding surface is designated by the symbol SS23. Other configurations and effects of the eighth embodiment shown in FIGS. 21 and 22 are similar to those of the embodiments shown in FIGS.

[0043] It should be noted that the illustrated embodiments are merely examples and are not intended to limit the technical scope of the present invention. For example, the illustrated embodiments may be combined in ways not shown. Furthermore, the illustrated embodiment describes a case where a road or railway is built on top of an existing embankment, but the illustrated embodiment can also be applied when other structures (e.g., houses, etc.) are built on top of an existing embankment. [Explanation of symbols]

[0044] 1, 1-1, 1-2, 1-3... Longitudinal reinforcement 2, 2-1...Horizontal reinforcement 3. Ground anchor 3A Tendon 3B···Anchor head EE···Existing embankment FS...Flat surface OG···Natural foundation (base) SS···Slide surface

Claims

1. A method for reinforcing an existing embankment, in which a flat surface is constructed on top of an existing embankment built on a sloping foundation, and a structure is constructed on the flat surface, a step of installing a longitudinal reinforcement member, which is a structural member extending vertically and having a lower end reaching the ground of the existing embankment, at the valley side end of the flat surface; A method for reinforcing an existing embankment, characterized in that the location where the longitudinal reinforcement is to be installed is an area located on the valley side so as to reduce the collapse area at the top of the existing embankment, and is an area that can be constructed from a structure constructed on the flat surface.

2. A method for reinforcing an existing embankment as claimed in claim 1, wherein horizontal reinforcement members extending horizontally or in a direction inclined from the horizontal direction are installed in the areas between the vertical reinforcement members, and the ends of the horizontal reinforcement members on the ground side do not reach the ground.

3. A method for reinforcing an existing embankment as claimed in claim 1, wherein horizontal reinforcement members extending horizontally or in a direction inclined from the horizontal direction are installed in the areas between the vertical reinforcement members, and only a portion of the horizontal reinforcement members is reached by the ground.

4. 2. A method for reinforcing an existing embankment according to claim 1, comprising installing a ground anchor having a tendon extending horizontally or in a direction inclined relative to the horizontal and the vertical reinforcement, the anchor head being provided at a height position above the upper end of the vertical reinforcement.

5. 4. A method for reinforcing an existing embankment according to claim 1, wherein longitudinal reinforcement is provided in the central part of said flat surface in addition to the valley side end of said flat surface.

6. 2. A method for reinforcing an existing embankment according to claim 1, wherein a wall for preventing a hole from being formed at the upper end of said vertical reinforcement members.

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