Precast concrete plate and slope reinforcement method using the same

Abstract

To improve workability and economical efficiency when precast concrete plates are connected, and improve earthquake resistance after connection.SOLUTION: A precast concrete plate includes a PC steel bar 24 which is unbonded in a vertical direction of a body part 12 of a precast concrete plate 10, a work hole 16 which is opened on a front face side of the body part 12, and a connecting metal fitting which is mounted in the work hole 16, wherein a male screw part of the PC steel bar 24 projecting above the precast concrete plate at a lower stage is fit into a connection hole of the connecting metal fitting of the precast concrete plate at an upper stage, and a nut 28 is screwed into the male screw part 24a projecting to the work hole 16, and is fastened by a regulation torque and is bound to the connecting metal fitting, and prestress is introduced thereto. Finally, the work hole 16 is filled with mortar 36, and a fixation part is air-tightly protected.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to slope reinforcement for preventing erosion, weathering, and collapse of slopes. [Background technology]

[0002] As a precast concrete plate for reinforcing slopes and a method of reinforcing slopes using the plate, the technology disclosed in Patent Document 1 is publicly known. The outline of the technology is related to a reverse winding method in which precast concrete plates are constructed one layer at a time starting from the top, and the upper and lower precast concrete plates are connected by inserting PC steel bars into insertion holes formed in each precast concrete plate and fastening the upper and lower PC steel bars using a coupler. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 5229913 Summary of the Invention [Problem to be solved by the invention]

[0004] By adopting this reverse winding method, it is possible to reduce the amount of excavated soil and shorten the construction period compared to the forward winding method, in which the soil is piled up from the bottom up. In addition, by tightening the PC steel bars, it is possible to tightly connect the precast concrete panels, which has the effect of improving earthquake resistance.

[0005] However, there are concerns about the problem of ensuring watertightness, as the PC steel bar insertion holes in the precast concrete slabs can be a route for rainwater to enter. If rainwater enters the insertion holes, it is possible that the rainwater that should be drained from the drainage holes, which are provided as a drainage mechanism, will flow out from unexpected places, resulting in rain stains on the surface of the precast concrete slabs and damaging the aesthetic appearance of the structure. One method would be to inject grout into the insertion holes to block the intrusion route, but this was difficult to do adequately given the limited construction period and cost constraints.

[0006] In the conventional technology, the work holes for fastening the PC steel bars were provided on the back side of the precast concrete plate, which meant that there were problems with the ease of fastening the bars and the subsequent filling of the holes. There was also a need for further measures to prevent earthquake resistance from being lost when the PC steel bars corrode due to water seepage caused by improper filling. [Means for solving the problem]

[0007] The present invention proposes the following aspects as means for solving the above problems.

[0008] A first aspect of the present invention is a precast concrete plate that is installed on the front of a slope while being connected in a planar manner in the vertical direction, and comprises a roughly rectangular main body, a PC steel rod that is unbonded in the vertical direction to the main body, a work hole that opens on the front side of the main body, and a connector attached to the work hole, and the main body is connected at upper and lower positions by tightening the PC steel rod and the connector.

[0009] In a second aspect of the present invention, the connector is formed of four metal plates surrounding the work hole in the vertical and horizontal directions, and two of the metal plates surrounding the work hole in the vertical direction are each provided with a connecting hole for fitting with the male threaded portions provided at the upper and lower ends of the PC steel bar.

[0010] A third aspect of the present invention is a precast concrete panel as described in the second aspect, wherein a connecting hole provided in the lower of the two metal plates surrounding the panel in the vertical direction opens to the front side of the main body portion.

[0011] A fourth aspect of the present invention is a precast concrete plate that is installed on the front of a slope while being connected in a planar manner in the vertical direction, and comprises a substantially rectangular main body portion, a female threaded portion provided on at least one of the upper and lower surfaces of the main body portion, a work hole that opens onto the front side of the main body portion at a position opposite to the female threaded portion in the vertical direction, and a connecting device attached to the work hole, and the main body portion is connected at upper and lower positions by tightening the female threaded portion and the connecting device.

[0012] A fifth aspect of the present invention is a precast concrete plate according to the fourth aspect, wherein the connector is formed of a metal plate surrounding at least one of the upper and lower faces and both left and right faces of the work hole, and a connecting hole is provided in the metal plate on the face surrounding the upper or lower face for fitting a bolt screwed into the female threaded portion.

[0013] A sixth aspect of the present invention is a slope reinforcement method in which the precast concrete plates according to the second or third aspect are installed in front of a slope from the upper tier to the lower tier, and includes the steps of excavating below the upper tier precast concrete plate, transporting the lower tier precast concrete plate into the excavated area, fitting the male threaded portion provided at the upper end of the PC steel bar of the lower tier precast concrete plate into a connecting hole of a connector provided at the bottom of the upper tier precast concrete plate and fastening the male threaded portion to the connector using a nut, injecting back grout between the lower tier precast concrete plate and the slope, and fixing the precast concrete plate to the slope using reinforcing bars.

[0014] A seventh aspect of the present invention is a slope reinforcement method in which the precast concrete plates according to the fifth aspect are installed in front of a slope from the upper tier to the lower tier, and includes the steps of excavating below the upper tier precast concrete plate, transporting the lower tier precast concrete plate into the excavated area, aligning the female threaded portion provided at the top of the lower tier precast concrete plate with the connecting hole of a connector provided at the bottom of the upper tier precast concrete plate and tightening the bolt fitted into the connecting hole and the female threaded portion, injecting back grout between the lower tier precast concrete plate and the slope, and fixing the lower tier precast concrete plate to the slope using reinforcing bars.

[0015] An eighth aspect of the present invention is a slope reinforcement method in which a precast concrete plate according to the second or third aspect is installed in front of a natural ground slope from the lower tier to the upper tier, and includes the steps of installing the lower tier precast concrete plate, transporting the upper tier precast concrete plate, engaging the male threaded portion provided at the upper end of the PC steel bar of the lower tier precast concrete plate with a connecting hole of a connector provided at the bottom of the upper tier precast concrete plate and fastening the male threaded portion to the connector using a nut, backfilling the space between the upper tier precast concrete plate and the natural ground slope, and fixing the upper tier precast concrete plate to the natural ground slope using reinforcing bars.

[0016] A ninth aspect of the present invention is a slope reinforcement method in which the precast concrete plates according to the fifth aspect are installed in front of a natural ground slope from the lower tier to the upper tier, and includes the steps of installing the lower tier precast concrete plate, transporting the upper tier precast concrete plate, aligning the female threaded portion provided at the top of the lower tier precast concrete plate with the connecting hole of the connector provided at the bottom of the upper tier precast concrete plate and tightening the bolt fitted into the connecting hole and the female threaded portion, backfilling the space between the upper tier precast concrete plate and the natural ground slope, and fixing the upper tier precast concrete plate to the natural ground slope using reinforcing bars. Effect of the Invention

[0017] The effects obtained by the present invention are as follows. First, when connecting precast concrete panels, the work of inserting PC steel bars into the insertion holes as in the conventional technology can be omitted, and the connection work can be performed through the work holes provided on the front side, so that improvement in workability and safety is expected. Second, since the precast concrete panels do not have insertion holes that serve as a route for rainwater and the like to enter, watertightness is ensured and the original drainage function is not hindered. This makes it possible to avoid problems such as rain stains on the precast concrete panels, which would cause the panels to lose their aesthetic appearance. Third, by providing the work holes on the front side, which are provided on the back side in the conventional technology, it is possible to easily and accurately fill the gaps after the connection work, so that improvement in workability and watertightness are expected. Fourth, by applying a combination of PC steel bars and connectors to connect precast concrete panels, anchor plates and couplers as in the conventional technology are not required, so that improvement in economy is expected. In the first to third aspects, the unbonded PC steel bars can be prestressed while embedded in the precast concrete plate, eliminating the need for filling the insertion holes after inserting the PC steel bars as in the conventional technology, which is expected to improve workability and economy. Furthermore, the connection between the PC steel bars and the connectors can be protected watertight with mortar or the like, which prevents the prestress of the PC steel bars from decreasing due to corrosion, etc., and is expected to ensure earthquake resistance as a permanently prestressed structure. [Brief description of the drawings]

[0018] [Figure 1] A diagram showing the structure of the first precast concrete slab [Diagram 2] Diagram showing the structure of the connector [Diagram 3] A diagram showing the connection structure of the first precast concrete plate [Figure 4] A diagram showing how the first precast concrete slab is installed [Diagram 5] Diagram showing the structure of the second precast concrete slab [Figure 6] Diagram showing the structure of the connector [Figure 7] A diagram showing the connection structure of the second precast concrete plate [Figure 8] Diagram showing how the second precast concrete slab is installed [Figure 9] Diagram showing how to install precast concrete panels using the normal rolling method [Figure 10] A diagram showing the structure of the prior art DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] [First precast concrete panel structure] First, the structure of the first precast concrete plate will be described with reference to Figures 1 to 3. Figure 1 shows a front view and a side view of the first precast concrete plate. The precast concrete plate 10 mainly comprises a concrete body 12 that has a horizontally long rectangular shape when viewed from the front, and the standard overall size is 1000 mm long, 2000 mm wide, and 160 mm or 225 mm deep.

[0020] The main body 12 has a fixing hole 14 at approximately the center thereof, penetrating from the front side to the rear side. Two working holes 16, opening on the front side and the bottom side, are provided near both ends. The working hole 16 is a space having an approximately cubic shape, and a connecting fitting 18 is attached to the working hole 16. The connecting fitting 18 is made of a metal plate having four sides that are shaped like a square in a plan view and surround the space in the vertical and horizontal directions. As shown in FIG. 2, the connecting fitting 18 has connecting holes 20 and 22 on the top and bottom surfaces thereof, penetrating the metal plate. Of these, the connecting hole 22 on the bottom surface opens toward the front side of the main body 12.

[0021] Two unbonded PC steel rods 24 are embedded near both ends of the main body 12, each extending in the vertical direction. The upper end of the PC steel rod 24 protrudes outward from the top of the main body 12, and the protruding portion is male-threaded (male-threaded portion 24a). The lower end passes through the connecting hole 20 of the connecting fitting 18 and protrudes inside the work hole 16. The protruding portion is male-threaded, and is fastened to the connecting fitting 18 using a nut 26.

[0022] As shown in Fig. 3, the upper precast concrete slab 10a and the lower precast concrete slab 10b are connected by fastening the male threaded portion 24a of the PC steel bar to the connecting metal fitting 18 with a nut 28. Because the connecting hole 22 of the connecting metal fitting 18 opens on the front side of the precast concrete slab 10a, the lower precast concrete slab 10b, which is aligned directly below the upper precast concrete slab 10a, is pushed toward the rear side while the male threaded portion 24a is fitted into the connecting hole 22. The nut 28 is then tightened with a specified torque (260 N m) to fasten the male threaded portion 24a to the connecting metal fitting 18 and introduce prestress.

[0023] [First precast concrete panel construction method] Next, a method for constructing the precast concrete panels 10 will be described with reference to Fig. 4. Fig. 4 shows an example in which three precast concrete panels 10 are constructed using the reverse rolling method.

[0024] After the upper precast concrete plate 10 is installed, the area below the slope 30 is excavated by an amount equivalent to the height of one stage, and after shaping, the lower precast concrete plate 10 is temporarily placed. Next, the upper and lower precast concrete plates 10 are connected, and mortar 36 is filled into the work holes 16 to protect the fixing parts watertight. Finally, back grout 32 is injected between the precast concrete plate 10 and the slope 30, and the precast concrete plate 10 is fixed using reinforcing bars 34. By repeating this series of operations multiple times, the precast concrete plates 10 are constructed one stage at a time from top to bottom.

[0025] The precast concrete plates 10 can also be constructed by a forward rolling method, which is constructed from the bottom to the top. The forward rolling method will be described with reference to FIG. 9. FIG. 9 shows an example in which three precast concrete plates 10 are constructed using the forward rolling method. After the bottom precast concrete plate 10 is installed using the reverse rolling method, the precast concrete plate 10 in the middle is connected, a back bank 82 is formed on the back side, and the work hole 16 is filled with mortar 36 to protect the fixing part watertight. Finally, the precast concrete plate 10 is fixed to the natural ground slope 80 via the back bank 82 using the reinforcing steel bar 34. By repeating this series of operations multiple times, the precast concrete plates 10 are constructed one by one from bottom to top.

[0026] [Second precast concrete panel structure] Next, the structure of the second precast concrete slab will be described with reference to Figures 5 to 7. Figure 5 shows a front view and a side view of the second precast concrete slab. The precast concrete slab 40 mainly comprises a concrete main body 42 that has a horizontally long rectangular shape when viewed from the front, and the standard overall size is 1000 mm long, 2000 mm wide, and 160 mm or 225 mm deep.

[0027] The main body 42 has a fixing hole 44 formed in the approximate center thereof, penetrating from the front side to the rear side. Two working holes 46 opening to the front side and the bottom side are formed near both ends. The working hole 46 is a space having an approximately cubic shape, and a connecting fitting 48 is attached to the working hole 46. The connecting fitting 48 is formed of a metal plate having three sides that are U-shaped in plan view and surround the space in the downward and left-right directions. As shown in FIG. 6, a connecting hole 50 is formed on the bottom surface of the connecting fitting 48, penetrating the metal plate. Two insert nuts 52 (female threaded portions) are embedded in the top surface of the main body 42, near both ends.

[0028] The upper precast concrete plate 40a and the lower precast concrete plate 40b are connected by fastening the insert nut 52 and the connecting metal fitting 48 with a bolt 54, as shown in Fig. 7. The lower precast concrete plate 40b is temporarily placed directly below the upper precast concrete plate 40a, the insert nut 52 is aligned with the connecting hole 50 of the connecting metal fitting 48, and the bolt 54 inserted from the work hole 46 side is screwed into the insert nut 52 through the connecting hole 50. Finally, the insert nut 52 and the connecting metal fitting 48 are fastened by tightening with the specified torque (260 N m).

[0029] [Second precast concrete panel construction method] Next, a method for constructing the precast concrete panels 40 will be described with reference to Fig. 8. Fig. 8 shows an example in which three precast concrete panels 40 are constructed using the reverse winding method.

[0030] After the upper precast concrete plate 40 is installed, the area below the slope 60 is excavated by an amount equivalent to the height of one stage, and after shaping, the lower precast concrete plate 40 is temporarily placed. Next, the upper precast concrete plate 40 and the lower precast concrete plate 40 are connected, and mortar 66 is filled into the work hole 46 to protect the fixing part watertight. Finally, back grout 62 is injected between the precast concrete plate 40 and the slope 60, and the precast concrete plate 40 is fixed using reinforcing bars 64. By repeating this series of operations multiple times, the precast concrete plates 40 are constructed one stage at a time from top to bottom.

[0031] The precast concrete plates 40 can also be constructed by a forward rolling method, which is constructed from the bottom to the top. In the forward rolling method, after the lower precast concrete plate 40 is installed, a precast concrete plate 40 is temporarily placed on top of it, and the upper and lower precast concrete plates 40 are connected. Backfilling is performed between the upper precast concrete plate 40 and the natural ground slope, and mortar 66 is filled into the work holes 46 to protect the fixing parts watertight. Finally, the precast concrete plate 10 is fixed to the natural ground slope 80 via the backfilling 82 using reinforcing bars 64. By repeating this series of operations multiple times, the precast concrete plate 10 is constructed one layer at a time from bottom to top. [Explanation of symbols]

[0032] 10 Precast concrete slab 12 Main body 14 Fixation hole 16 Working Hole 18 Connectors 20 connection hole 22 Connection hole 24 PC steel bar 24a Male thread 26 Nut 28 Nut 30 Slope 32 Rear Grout 34 Reinforcing steel bars 36 Mortar 40 Precast concrete slab 42 Main body 46 Working Hole 48 Connectors 50 connection hole 52 Insert nut 54 Volts 62 Rear Grout 64 Reinforcing steel bars 66 Mortar 80 Natural ground slope 82 Rear embankment

Claims

1. A precast concrete plate that is connected in a planar manner in the vertical direction and installed in front of the slope. A PC steel rod unbonded in the vertical direction to the main body portion, a work hole opening on the front side of the main body portion, and a connector attached to the work hole, The PC steel rod and the connector are fastened to connect the main body at the upper and lower positions. Precast concrete slab.

2. The connector is composed of four metal plates surrounding the work hole in the vertical and horizontal directions, and two metal plates surrounding the work hole in the vertical direction are provided with connection holes for fitting male threads provided at the upper and lower ends of the PC steel rod, 2. The precast concrete panel of claim 1.

3. A connecting hole provided in the lower metal plate of the two metal plates surrounding the main body in the up-down direction is open to the front side of the main body.

3. A precast concrete panel according to claim 2.

4. A precast concrete plate that is connected in a planar manner in the vertical direction and installed in front of the slope. A generally rectangular main body, a female screw portion provided on at least one of the upper and lower surfaces of the main body, a work hole opening to the front side of the main body at a position opposite to the female screw portion in the vertical direction, and a connector attached to the work hole, The main body is connected at the upper and lower positions by fastening the female thread portion and the connector. Precast concrete slab.

5. The connector is made of a metal plate surrounding at least one of the upper and lower faces and both the left and right faces of the work hole, and a connecting hole is provided in the metal plate on the face surrounding the upper or lower face to fit a bolt screwed into the female threaded portion.

5. A precast concrete panel according to claim 4.

6. A slope reinforcement method in which the precast concrete plate according to claim 2 or 3 is installed on the front surface of a slope from the upper stage to the lower stage, excavating beneath the upper precast concrete slab; A process of carrying the lower precast concrete plate into the excavated area; a step of fitting a male threaded portion provided at an upper end of the PC steel bar of the lower precast concrete plate into a connecting hole of a connecting metal fitting provided at the lower part of the upper precast concrete plate, and fastening the male threaded portion and the connecting tool using a nut; injecting back grout between the lower precast concrete slab and the slope; A process of fixing the lower precast concrete plate to the slope using reinforcing bars; Slope reinforcement method including.

7. A slope reinforcement method in which the precast concrete plate according to claim 5 is installed on the front surface of a slope from the upper stage to the lower stage, excavating beneath the upper precast concrete slab; A process of carrying the lower precast concrete plate into the excavated area; A step of aligning a female threaded portion provided on an upper portion of the lower precast concrete slab with a connecting hole of a connector provided on a lower portion of the upper precast concrete slab, and fastening a bolt fitted into the connecting hole to the female threaded portion; injecting back grout between the lower precast concrete slab and the slope; A process of fixing the lower precast concrete plate to the slope using reinforcing bars; Slope reinforcement method including.

8. A slope reinforcement method in which the precast concrete plate according to claim 2 or 3 is installed on the front surface of a natural ground slope from the lower stage to the upper stage, Installing the lower precast concrete slab; The process of bringing in the upper precast concrete slabs; A step of fitting a male threaded portion provided at an upper end of the PC steel bar of the lower precast concrete plate into a connecting hole of a connector provided at a lower part of the upper precast concrete plate, and fastening the male threaded portion and the connector using a nut; A step of filling the backfill between the upper precast concrete plate and the natural ground slope; a step of fixing the upper precast concrete plate to the natural ground slope using reinforcing bars; Slope reinforcement method including.

9. A slope reinforcement method in which the precast concrete plate according to claim 5 is installed on the front surface of a natural ground slope from the lower stage to the upper stage, Installing the lower precast concrete slab; The process of bringing in the upper precast concrete slabs; A step of aligning a female threaded portion provided on an upper portion of the lower precast concrete slab with a connecting hole of a connector provided on a lower portion of the upper precast concrete slab, and fastening a bolt fitted into the connecting hole to the female threaded portion; A step of filling the backfill between the upper precast concrete plate and the natural ground slope; a step of fixing the upper precast concrete plate to the natural ground slope using reinforcing bars; Slope reinforcement method including.

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