JP4282654B2 - Guardrail foundation structure - Google Patents

Description

  The present invention relates to a guardrail foundation structure configured using a guardrail foundation block. More specifically, the guardrail foundation block is laid in a connected state along a shoulder whose edges are protected by retaining walls. In this case, on the basis of providing a gap between the upper end surface of the retaining wall and the lower surface of the foundation block, the impact load when the automobile collides with the guard rail is applied to the retaining wall existing on the lower side of the foundation block. The present invention relates to a guardrail foundation structure designed to prevent transmission.

  As shown in FIG. 25, a conventional guardrail foundation structure d in which a guardrail foundation block a for building a guardrail is laid in a connected state along a road shoulder c whose edge is protected by a retaining wall b. The base block a is laid in a state where the lower surface g of the base block a is in contact with the upper end surface f of the retaining wall b, or as shown in FIG. 26, the front end of the base block a For example, the base block a is laid in a connected state in a state where h is shifted from the rear edge (road side edge) j of the upper end surface f of the retaining wall b to the road side by about 30 cm, for example.

  In the case of the guard rail foundation structure d in which the lower surface g of the foundation block a is brought into contact with the upper end face f of the retaining wall b, since the guard rail can be constructed on the upper part of the retaining wall b, the road width is increased accordingly. There was an advantage that could be expanded. However, when an automobile collides with the guard rail k, the guard rail supporting portion m of the foundation block a is bent downwardly with the base end side n as the center, and therefore exists below the foundation block a. The impact load was transmitted to the retaining wall b. When the impact load is transmitted to the retaining wall b, the retaining wall b may be damaged, and when it is severe, problems such as sliding in the foundation portion of the retaining wall b and falling of the retaining wall b may occur. Such a sliding may cause a crack in the road surface q on the rear side of the retaining wall.

  Therefore, in order to prevent the retaining wall b from being damaged even if such an impact load is transmitted, the retaining wall has a rigid structure such that the retaining wall is built thick in consideration of the impact load. Had to be. In addition, the existing retaining wall required large-scale reinforcement work such as reinforcing the retaining wall thickly or filling the back side (back side) of the retaining wall with backfill concrete. Furthermore, there has been a problem in that the construction cost has been significantly increased, such as the need to rebuild the retaining wall.

  As shown in FIG. 26, when laying the foundation block a avoiding the upper side of the upper end surface f of the retaining wall b, there is an advantage that the impact load when the automobile collides with the guard rail k is not transmitted to the retaining wall b. However, the necessary road width could not be secured. In that case, if it is necessary to secure the width of the road, there will be a problem of securing the land, such as rebuilding the retaining wall with the retaining wall extended outward, or scraping the road side cliff. In addition to the problems that led to a significant increase in the construction cost of guardrails, there were cases where it was impossible to construct guardrails where there were land restrictions.

JP 2002-309594 A (page 2-3, FIG. 2)

  The present invention has been developed in view of the above-mentioned conventional problems, and it is possible to effectively utilize the upper space on the upper end surface of the retaining wall to secure the required road width, while the impact when the automobile collides with the guard rail. It is an object to provide a guardrail foundation structure that does not transmit a load to a retaining wall.

In order to solve the above problems, the present invention employs the following means.
That is, the guardrail foundation structure according to the present invention includes a plurality of guardrail foundation blocks for supporting the guardrail so as to cover the upper end surface of the retaining wall along the road shoulder whose edge is protected by the retaining wall. It is a guardrail foundation structure in which pieces are laid in a connected state, and the foundation block has a standing wall portion standing along the road shoulder at a portion near the front end of the bottom plate portion, and the bottom block portion of the standing wall portion The rear side (road side) is a toe plate portion and the front side of the standing wall portion is a heel plate portion, and the lower end portion of the column is fixed in a state where it contacts the upper surface of the heel plate portion and the front surface of the standing wall portion. A guardrail support portion is provided, and the lower surface of the toe plate portion is formed horizontally. And the foundation concrete is formed under the toe plate part , and the upper surface of the foundation concrete is formed to be flush with the upper end surface of the retaining wall or lower than the upper end surface, A floor mortar is formed on the upper surface of the foundation concrete, and the toe plate portion having a horizontal lower surface is placed on the upper surface of the floor mortar, and the upper end surface of the retaining wall and the lower surface of the guard rail supporting portion of the foundation block A gap of 10 to 30 mm is provided between the base concrete and a foundation crushed stone layer that transmits a load to the soil behind the retaining wall is formed below the foundation concrete, and is further buried on the toe plate portion. A return portion and a road surface are formed.

The present invention has the following excellent effects.
(1) According to the present invention, it is formed between the upper end surface of the retaining wall and the lower surface of the foundation block even when the foundation block is bent and deformed downward by an impact load when the automobile collides with the guard rail. The gap can prevent the bent and deformed portion from contacting the upper portion of the retaining wall. Thereby, the impact load when the automobile collides with the guard rail can be absorbed by the foundation block itself, and a guard rail foundation structure that does not transmit the impact load to the retaining wall can be provided. As a result, it is possible to construct a guardrail that ensures the required road width by effectively utilizing the upper space on the upper end surface of the retaining wall.

  Since it is possible to construct a guardrail at the top of the retaining wall in this way, even when the road width is insufficient for guardrail construction, the retaining wall itself can be changed to a rigid structure, etc. Since large-scale reinforcement work is not required, it is possible not only to easily build a guardrail on the upper part of the existing retaining wall, where the construction of the guardrail has not been considered so far, but without requiring such large-scale reinforcement work. Moreover, since there is no increase in the construction cost accompanying the increase in the secured land, the construction cost can be greatly reduced. Indeed, for example, as compared to a basic block as disclosed in JP-A-2002-309594, the cost of the basic block itself increases as the member thickness of the basic block increases or the length of the toe plate portion increases. Although it occurs, the cost can be greatly reduced as compared with the cost increase required for the large-scale reinforcement work or securing the necessary site.

(2) When the foundation block has a configuration in which the standing wall portion is erected on the front end side of the bottom plate portion, the end surfaces of the standing wall portion are connected to each other by a connecting shaft member having a positioning function and having a required shear resistance. When doing so, since the adjacent foundation blocks can be positioned correctly via the connecting shaft member, the laying construction of the foundation blocks can be performed accurately and efficiently. In addition, since the foundation block group connected in the road extension direction receives the impact load generated when the automobile collides with the guard rail by the shear resistance force of the connecting shaft member, the bending deformation There is an advantage that can be suppressed.

  FIG. 1 illustrates a guard rail foundation structure 1 according to the present invention. For a guard rail having a guard rail support portion 3 for supporting the guard rail 2 shown in FIGS. The foundation block 5 is laid in a connected state along the shoulder 7 (FIGS. 6 and 9) whose edge is protected by the retaining wall 6 and so as to cover the upper end surface 9 of the retaining wall 6. In consideration of the range of the magnitude of the impact load, the retaining wall 6 should not be transmitted to the retaining wall 6 existing on the lower side when the automobile collides with the guard rail 2. A gap 8 of about 10 to 30 mm is provided between the upper end surface 9 of the base plate 5 and the lower surface 10 of the foundation block 5.

  The basic block 5 shown in FIGS. 2 to 3 is laid along the road shoulder 7 in a section where the road 11 is linear, as shown in FIGS. A standing wall portion 13 is erected at a portion near the front end of the bottom plate portion 12 which has a long rectangular plate shape and the lower surface 10 is formed horizontally. The rear side of the standing wall portion 13 of the bottom plate portion 12 (road 11 Side) is a toe plate portion 15 and the front side of the standing wall portion 13 is a heel plate portion 16. The guardrail support portion 3 is provided in a state where the upper surface 17 of the heel plate portion 16 and the front surface 19 of the standing wall portion 13 are in contact with each other at the central portion in the length direction of the heel plate portion 16. The portion 3 is provided with a bottomed circular support hole 22 into which the lower end portion 21 (FIG. 1) of the support column 20 that fixes the guard rail 2 is inserted.

  And the connection metal fittings 26 and 26 are provided in the embedded state so as to be positioned before and after the both end portions 25 and 25 of the upper surface 23 of the toe plate portion 15. The connection fitting 26 has a recess 27 whose upper end is open, and an outer surface 30 a of a connection piece 30 provided with a bolt insertion hole 29 is formed flush with the end surface 31 of the bottom plate portion 12.

  In this embodiment, as shown in FIGS. 2 to 3, a connecting shaft member 33 that connects the adjacent standing wall portions 13, 13 to the end surfaces 32, 32 of the standing wall portion 13 and exhibits a required shear resistance. Tapered connecting recesses 35 and 35 are provided for fitting the portions on both ends of (FIG. 8). As shown in FIG. 8, the connecting shaft member 33 is a synthetic resin in which taper shaft-like fitting connecting pieces 36 and 36 closely fitted into the connecting recess 35 are integrated back to back at the large diameter ends. It is formed as a solid or hollow member made of metal or metal. In the present embodiment, for example, it is formed as a solid member made of polypropylene.

  If the dimension of the main part of the foundation block 5 which has this structure is illustrated, the thickness of each part will be about 100 mm comparatively thick compared with this kind of foundation block of the past, in order to aim at the intensity | strength improvement of a foundation block. The front and rear length of the bottom plate portion 12 is set to about 1500 mm, and the left and right length thereof is set to about 2000 mm. The front-to-back length of the toe plate portion 15 is set to about 1000 mm, the front-to-back length of the heel plate portion 16 is set to about 200 mm, and the height of the standing wall portion 13 is set to about 400 mm. In addition, the position of the connecting recess 35 is set to about 100 mm below the upper end of the standing wall 13. Further, the bar arrangement of the foundation block 5 is configured by arranging relatively thick reinforcing bars relatively finely as compared with the conventional foundation block.

  Also, the basic block 5 shown in FIGS. 4 to 5 is laid along the shoulder 7 in a section where the road 11 curves, as shown in FIGS. 9 to 10, for example. Both ends in the vertical direction are cut obliquely (inclination angle is, for example, 3 degrees), both end surfaces 39, 39 of the standing wall portion 13, both end surfaces 40, 40 of the toe plate portion 15, and both end surfaces 41, 41 of the heel plate portion 16 are It is formed as an inclined side in plan view. Other configurations are the same as those in the basic block 5.

  In the present embodiment, as shown in FIG. 11, the retaining wall 6 includes an L-shaped retaining wall block 45 in which a horizontal base portion 43 is continuously provided at the lower end of a vertically long retaining wall portion 42, and the horizontal base portion 43. Are constructed in a projecting state inwardly (on the road side), and their joint surfaces 44, 44 are brought into contact with each other and sequentially connected. A cap concrete 46 is formed on the upper end of the retaining wall portion 42 in accordance with a conventional method. The upper end surface (the upper end surface of the retaining wall) 47 of the cap concrete 46, that is, the upper end surface 9 of the retaining wall 6 is formed. Is formed in a horizontal plane. The front-rear width of the upper portion of the retaining wall 6 is set to 300 mm in this embodiment.

  When the guardrail foundation structure 1 is configured using the foundation block 5 having the above-described configuration, as shown in FIGS. 1 and 11, the guardrail construction location set along the road shoulder 7 is set at the upper end of the retaining wall 6. Excavation is carried out on the rear surface side, the crushed stone is filled in the excavated portion to form a basic crushed stone layer 49, and a basic concrete 50 for placing the toe plate portion 15 is formed on the upper portion of the basic crushed stone layer 49. In this embodiment, the thickness of the foundation concrete 50 is set to about 100 mm, for example, and the upper surface 48 is formed flush with the upper end surface 9 of the retaining wall 6. The foundation crushed stone layer 49 is provided so that the foundation concrete 50 can transmit a load to the soil behind the retaining wall, and the rear surface 51 of the upper part of the retaining wall, the foundation crushed stone layer 49 and the foundation concrete. Between the front surfaces 52 and 53 of 50, the shock absorbing material 55 which exhibits the buffering effect which does not influence a retaining wall by unexpected load is arrange | positioned. As the buffer material 55, a synthetic resin foam such as a polystyrene foam having a thickness of 30 to 100 mm (for example, 50 mm) can be used.

  Thereafter, a floor mortar 56 having a thickness of, for example, 20 mm is formed on the upper surface 48 of the foundation concrete 50, and the toe plate portion 15 of the foundation block 5 is placed on the floor mortar 56. At that time, as shown in FIG. 1, the front end 54 of the bottom slab portion 12 is matched with the front edge 58 of the upper end surface 9 of the retaining wall 6. Then, as shown in FIG. 12, the tapered connecting fitting piece 36 of the connecting shaft member 33 is closely fitted into the tapered connecting recess 35 provided on the end surface 32 of the standing wall portion 13. As a result, the other fitting connection piece 36 protrudes from the end face 32. In this way, when laying another foundation block 5b in continuation with the laid foundation block 5a, as shown in FIG. 13, the connecting recess provided in the end face 32b facing the end face 32a of the foundation block 5a. By fitting the fitting connecting piece 36 protruding at the end face 32a into the base plate 35, the base block 5b is correctly positioned so that the upper surfaces 59, 59 of the standing wall portions of the adjacent base blocks 5a, 5b are flush with each other. Positioned.

  In this state, as shown in FIG. 1, the guard rail support portion 3 that forms the front portion of the base block 5 covers the upper end surface 9 of the retaining wall 6. And since the lower surface 10 of the bottom plate part 12 is formed in the horizontal surface as mentioned above, the upper end surface 9 of the retaining wall 6 and the front side part of the foundation block 5 (the guard rail support part whose front-rear width is about 300 mm). A gap 8 having a vertical width of about 20 mm is formed between the lower surface 10a and the lower surface 10a.

  Then, by performing backfilling on the toe plate portion 15, a road surface 61 continuous with the upper surface 59 of the standing wall portion 13 is formed as shown in FIGS. In this way, each base block 5 brings the end surfaces 32, 32 of the adjacent standing wall portions 13, 13 into contact with each other along the shoulder 7 and as shown in FIG. It is laid and connected by.

  And as shown in FIG. 14, the base plate parts 12 and 12 which are in contact with the end faces 31 and 31 of the adjacent base blocks 5 and 5 are connected to the connecting piece parts 30 and 30 provided in the connecting metal fitting 26, respectively. 30 is in a contact state in which the bolt insertion holes 29 and 29 communicate with each other. Therefore, the bolts 62 are inserted into both the bolt insertion holes 29 and 29 and the nut 63 is tightened using a torque wrench, whereby the bottom plate portions 12 and 12 are connected. The bolts are connected to each other. As the bolt 62, for example, a high tension bolt capable of introducing 5 tons of prestress is used, and the bottom plate portions 12 and 12 are connected to each other by introducing prestress through a washer 65. The tightening by the bolt 62 may be performed by screwing nuts 67 and 69 to both ends of one screw shaft 66 having no bolt head as shown in FIG.

  After the base blocks 5 and 5 are connected to each other in this way, the toe plate portion 15 is backfilled to the height of the upper surface 59 of the standing wall portion 13 as shown in FIG. The fall of the foundation block 5 is prevented by the loading load by the backfilling unit 70. Then, asphalt is laid on the upper portion of the backfill portion 70 to form the road surface 61. By this backfilling, the toe plate portion 15 is buried, and the vertical width is about 20 mm between the lower surface 10 a of the front guardrail support portion 3 of the foundation block 5 and the upper end surface 9 of the retaining wall 6. As shown in FIGS. 6 to 7 and FIGS. 9 to 10, the guardrail foundation structure 1 in which the gap 8 is formed is configured in a continuous state along the road shoulder 7.

  As shown in FIGS. 1, 6, and 9, the lower end portion 21 of the support column 20 is inserted in the embedded state in the support hole 22, and the support column 20 is set up in an upright state. The guard rail 2 is fixed to the bolt.

  When the guardrail foundation structure 1 having such a structure is used, depending on the magnitude of the impact load generated when the automobile collides with the guardrail 2, the joint portion between the toe plate portion 15 and the standing wall portion 13 that is a weak portion in strength ( With the base end portion 71 (FIG. 1) of the guard rail support portion 3 as a fulcrum, a downward rotating action is generated in the guard rail support portion 3 that is on the front side of the joint portion 71. For example, as shown in FIG. 16, even if the guard rail support portion 3 is bent and deformed downward as shown in FIG. 16, the vertical width of the gap 8 depends on the thickness and arrangement of the foundation block 5. In consideration of various factors such as the straight state, the front-rear width of the upper end surface 9 of the retaining wall 6, and the front-rear length of the toe plate portion 15, the length is set to about 10 to 30 mm as described above. The guardrail support portion 3 can be prevented from coming into contact with the upper end surface 9 of the retaining wall 6 without fear of breaking the guardrail support portion 3. Therefore, the impact load can be absorbed by the foundation block 5 itself, and the impact load is not transmitted to the retaining wall 6 existing on the lower side of the foundation block 5, so that the influence of the impact load on the retaining wall 6 can be avoided. Become.

  In particular, in this embodiment, as shown in FIGS. 6 and 9, the connecting shaft member 33 having the required shear resistance force is formed between the end surfaces 32 and 32 of the standing wall portions 13 and 13 of the adjacent foundation blocks 5 and 5. Therefore, the impact load generated when the automobile collides with the guard rail 2 is received by the shear resistance force of the connecting shaft member 33 integrally with the group of foundation blocks arranged in parallel in the road extending direction. Thus, bending deformation of the foundation block can be suppressed. In particular, in the present embodiment, as described above, the bolt connection between the bottom plate portions 12 and 12 is performed by introducing prestress, so that the integration of the foundation block group becomes stronger and the bending Deformation can be suppressed more effectively.

  Therefore, according to the present invention, the guard rail 2 can be provided via the support column 20 so as to be positioned above the upper end surface 9 of the retaining wall 6, so that a general retaining wall that is not rigidly constructed can be provided. However, it is possible to avoid the danger of causing damage or sliding of the retaining wall and to construct the guard rail by effectively utilizing the upper space of the upper end surface 9 of the retaining wall.

  FIG. 17 shows a state in which a low-resilience water-stopping elastic body 72 is interposed in the gap 8 in the guard rail basic structure 1 configured as described above. As such a low-resilience water-stopping elastic body 72, a closed cell sponge-like water-stopping elastic body having an expansion ratio of about 3 to 5 times can be used. If rainwater enters the rear side (rear side) of the retaining wall 6 through the gap 8, there is a risk of adversely affecting the retaining wall due to water pressure. It is preferable to fill the waterstop elastic body 72. Since the waterstop elastic body 72 has low resilience, the impact load is not transmitted to the retaining wall 6 even when the waterstop elastic body 72 is compressed.

  As shown in FIG. 17, the water-stopping elastic body 72 is disposed so as to fill the entire gap 8, and the front end side 60a of the gap 8, the intermediate portion 60b, the rear end side 60c, It may be interposed only between the front end side 60a and the rear end side 60c. The waterstop elastic body 72 can be placed in an intervening state by, for example, laying the foundation block 5 in a state of being bonded to the upper end surface 9 of the retaining wall 6 in advance.

  The present invention is by no means limited to those shown in the above-described embodiments, and it goes without saying that various design changes can be made within the scope of the claims. One example is as follows.

(1) FIG. 18 shows another aspect of the guardrail foundation structure 1 according to the present invention, and the upper surface 48 is lower than the upper end surface 9 of the retaining wall 6 by about 10 mm on the rear surface side of the retaining wall 6. A foundation mortar 56 having a thickness of, for example, 20 mm is formed on the upper surface 48 of the foundation concrete 50, and the toe plate portion 15 of the foundation block 5 is placed on the foundation concrete 50. The front edge 58 of the end face 9 and the front end 54 of the bottom plate portion 12 are matched. A gap 8 of about 10 mm is formed between the lower surface 10a of the guardrail support portion 3 and the upper end surface 9 of the retaining wall.

(2) FIGS. 19 to 20 show another embodiment of the guardrail foundation structure 1 according to the present invention. FIG. 19 shows that the guardrail support portion 3 is the retaining wall in order to secure a larger road width. 6 shows a case where the foundation block 5 is laid so as to protrude forward from the front edge 58 of the upper end surface 9 of FIG. A gap 8 of about 20 mm, for example, is formed between the lower surface 10 of the foundation block 5 and the upper end surface 9 of the retaining wall 6. In order to be able to constitute such a guardrail foundation structure 1, the foundation block 5 can be installed and then backfilled stably even when the guardrail support portion 3 is in a protruding state, and backfilling can be performed. It is required that the foundation block 5 can be prevented from overturning by the upper load of the portion 70. In the present embodiment, for example, the amount of protrusion from the front edge 58 is set to about 350 mm, and the longitudinal length of the bottom plate portion 12 is set to 2000 mm.
In FIG. 20, on the contrary, the base block 5 is laid so that the front end 54 of the bottom slab portion 12 is retracted inward from the front edge 58 of the upper end surface 9 of the retaining wall 6. Shows the case. A gap 8 of about 20 mm, for example, is formed between the lower surface 10 of the foundation block 5 and the upper end surface 9 of the retaining wall 6.

(3) FIG. 21 shows another embodiment of the basic block 5 used in the present invention, and the lower surface 10 a of the guardrail support portion 3 is lifted via a step 72. The amount of lifting is set to, for example, 10 to 30 mm, for example, about 20 mm. FIG. 22 shows a guardrail foundation structure 1 configured using such a foundation block 5. When such a foundation block 5 is used, there is an advantage that it is easy to absorb construction errors when laying the foundation block 5.

(4) FIG. 23 shows another embodiment of the basic block 5 used in the present invention, and support holes 22 and 22 are provided on both sides of the guardrail support portion 3 to support the support column 20. Yes.

(5) In the present invention, the connecting shaft member 33 may be omitted.

(6) The guardrail foundation structure 1 according to the present invention is constructed using the above-described L-shaped retaining wall block, as well as a block stacking wall 6 shown in FIG. 24, a reinforcing earth retaining wall, and a lightweight embankment retaining wall. It can be applied to various retaining walls.

It is sectional drawing explaining the guardrail basic structure which concerns on this invention. It is the perspective view which looked at the basic block laid in the area where a road shows a straight line form from the back side. It is the perspective view seen from the front side. It is the perspective view which looked at the basic block laid in the section where a road curves. It is the perspective view seen from the front side. It is a partial cross section perspective view which shows the construction state of the guardrail constructed | assembled in the area where a road exhibits a linear form. FIG. It is a perspective view which shows a connection shaft member with the connection recessed part of the standing wall part in which the fitting connection piece is press-fit. It is a partial cross section perspective view which shows the construction state of the guardrail in the area where a road curves. FIG. It is a perspective view explaining a retaining wall. It is sectional drawing which shows the state which press-fit one fitting connection piece of this connection shaft member in the standing wall part of one foundation block at the time of connection of connection shaft members. It is sectional drawing which shows the state which connected the standing wall part through the connection shaft member. It is a top view which shows the state which fastened the slab part of the adjacent basic block with the volt | bolt. It is a top view which shows the other aspect of the binding. It is sectional drawing which shows the state which the guardrail support part bent below in the base end part by the impact load which arises when a motor vehicle collides with a guardrail. It is sectional drawing which shows the state which interposed the low-resilience water-stopping elastic body in the clearance gap between the upper end surface of a retaining wall, and the lower surface of a foundation block. It is sectional drawing which shows the other aspect of a guardrail foundation structure. It is sectional drawing which shows the other aspect of a guardrail foundation structure. It is sectional drawing which shows the other aspect of a guardrail foundation structure. It is a perspective view which shows the other aspect of a foundation block. It is sectional drawing which shows the guardrail foundation structure comprised using the foundation block in which the lower surface of a guardrail support part has floated through the level | step difference. It is a perspective view which shows the basic block which provided the support hole which supports a support | pillar on both sides of the guardrail support part. It is sectional drawing which shows the guardrail foundation structure applied to the block stacking wall. It is sectional drawing which shows an example of the conventional guardrail foundation structure. It is sectional drawing which shows the other example of the conventional guardrail basic structure.

DESCRIPTION OF SYMBOLS 1 Guardrail foundation structure 2 Guardrail 3 Guardrail support part 5 Foundation block 6 Retaining wall 7 Road shoulder 8 Gap 9 Upper end surface of retaining wall 10 Lower surface of foundation block 10a Lower surface of guardrail supporting part 11 Road 12 Bottom plate part 13 Standing wall part 15 Toe plate part 16 Heel plate portion 20 Column 22 Support hole 26 Connection fitting 29 Bolt insertion hole 30 Connection piece portion 33 Connection shaft member 35 Connection recess 36 Insertion connection piece 49 Foundation stone layer 50 Foundation concrete 55 Buffer material 62 Bolt 63 Nut 72 Water stop elastic body

Claims (1)

A guard rail in which a plurality of guard rail base blocks for supporting the guard rail are laid in a connected state so as to cover the upper end surface of the retaining wall along the shoulder of which the edge is protected by the retaining wall A basic structure,
The foundation block is provided with a standing wall portion standing along the road shoulder at a portion near the front end of the bottom plate portion, and the rear side (road side) of the bottom plate portion is a toe plate portion and the standing wall. A front side of the heel plate portion is a heel plate portion, a guard rail support portion is provided to fix a lower end portion of the support column in contact with the upper surface of the heel plate portion and the front surface of the standing wall portion, and the lower surface of the toe plate portion is Formed horizontally,
Foundation concrete is formed under the toe plate part , and the upper surface of the foundation concrete is formed so as to be flush with or lower than the upper end surface of the retaining wall,
A floor mortar is formed on the upper surface of the foundation concrete, and the toe plate portion having a horizontal lower surface is placed on the upper surface of the floor mortar, and the upper end surface of the retaining wall and the lower surface of the guard rail supporting portion of the foundation block A gap of 10-30 mm is provided between
A foundation crushed stone layer is formed at the bottom of the foundation concrete to transmit a load to the soil behind the retaining wall,
A guardrail foundation structure, wherein a backfill portion and a road surface are formed on the toe plate portion.

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