Construction method for reinforced soil on slopes with long-term durability

Abstract

This invention provides a method for constructing reinforced soil on slopes that can apply tension to the ground on the slope over a long period of time and can be implemented at a low cost. [Solution] A hole 2 is drilled into the ground C from the slope 1, a reinforcing material 3 is inserted into the hole 2, primary grout material 8 is injected into the hole 2 to form a reinforcing material fixing part D1', after the reinforcing material fixing part D1' is formed, a tension plate 10 is installed directly above the hole 2 in the slope 1, and the head 3a of the reinforcing material 3 is made to protrude from the through hole 10a of the tension plate 10, and the tension nuts 11 are temporarily tightened, and the tension plate 10 is used as a reaction force to tension the reinforcing material 3 with the tensioning means 12, and while the reinforcing material 3 is in a tensioned state, secondary grout material 9 is injected into the hole 2 from the slope 1 to form a reinforcing material tension anchorage part D2', after the reinforcing material tension anchorage part D2' is formed, the tension nuts 11 are fully tightened and the tensioning means 12 is removed.

Description

Technical Field

[0001] The present invention relates to a method for constructing reinforced soil applied to a slope.

Background Art

[0002] In view of the problem that the conventional reinforced soil applied to a slope has a problem in long-term durability, the applicant of the present application arranges a reinforcing material inside a grout material filled in a hole drilled from the slope to the ground, and arranges a load transmission member along the reinforcing material. The tip side of the load transmission member is connected to the surrounding grout material in the section of the tip side of the reinforcing material, and the ground surface side of the load transmission member is connected to the surrounding grout material of the sleeve pipe covering the section of the ground surface side of the reinforcing material, thereby stabilizing the slope and preventing the slope from collapsing, and thus proposing a reinforced soil structure (Patent Document 1) that can achieve long-term durability of the slope.

[0003] In addition, in view of the problem that the conventional ground anchor method has local stress concentration on the anchor body and sequential destruction progresses, and the durability of the anchor decreases year by year, the applicant of the present application drills a hole from the ground surface to the immovable layer deep in the ground, inserts a tendon into the hole after drilling, injects cement for the tendon fixing part around the tip of the tendon in the hole of the immovable layer to form a tendon fixing part, and after forming the tendon fixing part, installs a temporary pressure receiving plate on the ground surface, and with the temporary pressure receiving plate as a reaction force, injects super high-strength cement for the tendon tension fixing part into the hole from the immovable layer except the tip of the tendon to the moving layer in the shallow ground to form a tendon tension fixing part. After forming the tendon tension fixing part, the temporary pressure receiving plate is removed. As a result, substantially uniform stress is generated in the entire fixing section, and the durability is improved. The applicant has previously proposed a ground anchor method (Patent Document 2).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

[0005] However, the reinforced soil structure described in Patent Document 1 had the problem that, in an attempt to improve durability, the use of expensive carbon fiber cables for load transmission members and mirror-finished stainless steel pipes for sleeve pipes resulted in high costs. Furthermore, the ground anchor method described in Patent Document 2 had the problem that, depending on the ground conditions, the tension of the tendons in the ground would decrease after the removal of the temporary pressure plate, requiring the tendons to be tensioned again.

[0006] This invention has been made in view of the above-mentioned problems, and aims to provide a method for constructing reinforced soil for slopes that can apply tension to the ground of a slope over a long period of time and can be constructed at low cost. [Means for solving the problem]

[0007] To solve the above problems, the method for constructing reinforced soil on slopes according to the present invention is: From the slope, drill holes with a diameter of 30 to 115 mm and a length of 1 to 30 m into the ground. Reinforcement material inside the hole after drilling The system includes a first injection pipe positioned at the tip of the reinforcing material to inject primary grout material for fixing the reinforcing material around the tip of the reinforcing material, and a second injection pipe positioned at the tip of the reinforcing member excluding the tip of the reinforcing material to inject secondary grout material for tensioning and anchoring the reinforcing material into the holes around the reinforcing member excluding the tip of the reinforcing material. Insert and position, inside the hole From the tip of the aforementioned first injection tube A primary grout material for fixing the reinforcing material is injected around the tip of the reinforcing material to form the reinforcing material fixing part. After the reinforcing material fixing portion is formed, a tension plate having a through portion in the thickness direction is installed directly above the hole in the slope, and the head of the reinforcing material is made to protrude from the through portion of the tension plate. Furthermore, the portion of the second injection pipe that protrudes from the inclined surface protrudes from the through portion of the tension plate. Then, the tension nut, which is in contact with the outer surface of the tension plate, is temporarily fastened to the head of the reinforcing member, and in this state, the reinforcing member is tensioned by the tensioning means using the tension plate as a reaction force. With the reinforcing material tensioned to a predetermined tension load by the tensioning means, from the slope through the penetration portion of the tensioning plate From the tip of the second injection tubeA secondary grout material for the tensioning and fixing portion of the reinforcing member is injected into the holes surrounding the reinforcing member, excluding the tip portion of the reinforcing member, to form the tensioning and fixing portion of the reinforcing member. The first feature is that after the tensioning and fixing portion of the reinforcing material is formed, the tensioning nut is tightened and the tensioning means is removed.

[0008] For primary and secondary grouting materials, it is desirable to use high-early-strength cement or ultra-fast-setting cement, which develops strength quickly.

[0009] The method for constructing reinforced soil on a slope according to the present invention is: A second feature is that, before injecting the secondary grout material for the tensioned anchoring portion of the reinforcing member into the hole surrounding the reinforcing member, excluding the tip of the reinforcing member, a preliminary load exceeding the predetermined tension load is applied for a predetermined time using a tensioning means, and then the preliminary load is reduced to the predetermined tension load before injecting the secondary grout material.

[0010] The method for constructing reinforced soil on a slope according to the present invention is: From the slope, boreholes with a diameter of 30 to 115 mm and a length of 1 to 30 m are drilled down to the deep sedimentary layer. Reinforcement material inside the hole after drilling The system includes a first injection pipe positioned at the tip of the reinforcing material to inject primary grout material for fixing the reinforcing material around the tip of the reinforcing material, and a second injection pipe positioned at the tip of the reinforcing member excluding the tip of the reinforcing material to inject secondary grout material for tensioning and anchoring the reinforcing material into the holes around the reinforcing member excluding the tip of the reinforcing material. Insert and position, In the pores of the immobile layer From the tip of the aforementioned first injection tube A primary grout material for fixing the reinforcing material is injected around the tip of the reinforcing material to form the reinforcing material fixing part. After the reinforcing material fixing portion is formed, a tension plate having a through portion in the thickness direction is installed directly above the hole in the slope, and the head of the reinforcing material is made to protrude from the through portion of the tension plate. Furthermore, the portion of the second injection pipe that protrudes from the inclined surface protrudes from the through portion of the tension plate. Then, the tension nut, which is in contact with the outer surface of the tension plate, is temporarily fastened to the head of the reinforcing member, and in this state, the reinforcing member is tensioned by the tensioning means using the tension plate as a reaction force. With the reinforcing material tensioned by the tensioning means, from the slope through the penetration portion of the tensioning plate From the tip of the second injection tube A secondary grout material for the tension-and-anchoring section of the reinforcing material is injected into the borehole around the intermediate portion of the reinforcing material, excluding the tip, extending from the immovable layer deep in the ground to the moving layer shallow in the ground, thereby forming the tension-and-anchoring section of the reinforcing material. A third feature is that after the formation of the reinforcing material tension fixing part, the tension nut is tightened to remove the tension means.

[0011] Here, the immovable layer in the deep ground refers to the ground layer where toppling or landslides do not occur in the deep part of the ground, and the movable layer in the shallow ground refers to the layer where toppling collapse or landslides occur on the ground surface side of the ground.

Advantages of the Invention

[0012] According to the present invention, a substantially uniform tension force acts on the entire fixing section of the reinforcing material arranged in the hole of the ground from the slope, enabling the stabilization of the slope and the prevention of slope collapse. In particular, compared with conventional reinforced soil, a predetermined tension force can be introduced into the ground from the initial stage of construction, and the excellent effect of stably protecting the ground of the slope from the construction stage to the long term after construction can be achieved.

[0013] Also, according to the present invention, the reinforced soil on the slope can be constructed without using expensive materials, achieving a reduction in construction costs and also a reduction in maintenance costs after construction.

Brief Description of the Drawings

[0014] [Figure 1] Cross-sectional view of the reinforced soil to which the present invention is applied to the slope, [Figure 2] Shows the construction procedure of the present invention, cross-sectional view after boring the ground, [Figure 3] Cross-sectional view of the state where the reinforcing material and the injection pipe are inserted into the hole, [Figure 4] Cross-sectional view of the state where the primary grout material is filled in the primary injection section in the hole, [Figure 5] Cross-sectional view showing the state where the reinforcing material is tensioned, [Figure 6] Front view of the tension plate, [Figure 7] Cross-sectional view showing the state where the secondary grout material is filled in the secondary injection section in the hole in the state where the reinforcing material is tensioned, [Figure 8] It is a cross-sectional view after removing the tension device. [Modes for carrying out the invention]

[0015] The best mode for carrying out the present invention will be described below with reference to the drawings. Figure 1 shows an example of a reinforced soil structure to which the present invention is applied to a slope, and Figures 2 to 8 show the procedure for constructing reinforced soil using the present invention. The following description will follow the construction procedure.

[0016] First, as shown in Figure 2, holes 2 with a diameter of 30 to 115 mm and a length of 1 to less than 30 m are drilled using a drilling machine from the surface of the slope 1 into the ground C to insert the reinforcing material 3 (see Figure 3).

[0017] Next, as shown in Figure 3, the reinforcing material 3 is inserted into the hole 2. The reinforcing material 3 is a deformed reinforcing bar with a diameter of 16 to 39 mm, having screw-shaped protrusions on the surface to enhance adhesion, and having a rust-preventive surface treatment. The reinforcing material 3 is equipped with an injection pipe 4 for injecting primary grout material into the primary injection section D1 on the tip side of the reinforcing material 3, and the reinforcing material 3 Each injection pipe 5, which injects secondary grout material into the secondary injection section D2 on the ground surface, is fixed by binding wire 6.

[0018] Multiple spacers 7 are attached to the reinforcing member 3 at regular intervals, and the multiple spacers 7 ensure that the reinforcing member 3 is positioned at the center of the cross-section of the hole 2, maintaining a constant distance from the inner circumferential wall of the hole 2.

[0019] In the example shown in Figure 3, a hole 3 is drilled from the slope 1 from the anchoring layer C1 to the moving layer C2. In this case, the primary injection section D1 on the tip side of the reinforcing material 3 is set to fit within the anchoring layer C1. 3 The secondary injection section D2 on the ground surface is set from the anchoring layer C1 to the moving layer C2. However, the scope of the present invention is not limited thereto.

[0020] Furthermore, the anchoring layer C1 mentioned above corresponds to the deep, immovable layer of ground C (a layer where toring collapse or landslides do not occur at depth), while the moving layer C2 corresponds to the shallow, moving layer of ground C (a layer where toring collapse or landslides occur at shallow depths near the surface).

[0021] Next, as shown in Figure 4, primary grout material 8 is injected from the ground surface side of the slope 1 through the injection pipe 4, and from the tip of the injection pipe 4 into the primary injection section D1 in the hole 2. The injected primary grout material 8 fills the gap between the reinforcing material 3 and the hole 2, and the solidification of the primary grout material 8 forms a reinforcing material fixing section D1' in the same section.

[0022] For the primary grout material 8, to speed up the work, it is preferable to use ultra-fast hardening cement or semi-ultra-fast hardening cement that hardens in a short time. Ultra-fast hardening cement should have a hardness of 20-30 N / mm² at 3 hours of curing time. 2 This refers to cement that exhibits a certain uniaxial compressive strength. To ensure the fluidity of the grout material during the 15-30 minute injection time, 0.05-1.5% by mass of a setting retarder is added to the ultrafast-setting cement, and the water-cement ratio (W / C) is set to 13-23%.

[0023] If no collapse occurs in hole 2, high-early-strength cement or ordinary cement may be used. By using the tension plate 10 described later, the tension of the reinforcing material can be maintained until the cement necessary for anchoring the reinforcing material 3 has set. The secondary grout material 9 described later uses the same cement as the primary grout material 8.

[0024] Next, after the formation of the reinforcing member fixing portion D1', as shown in Figures 5 and 6, a tension plate 10 is placed directly above the hole 2 in the inclined surface 1. The tension plate 10 is a rectangular flat plate with sides of length 30 to 50 cm, and has a central through-hole 10a for the reinforcing member and a through-hole 10b for the injection pipe that penetrates in the thickness direction of the plate. The tension plate 10 is then temporarily fixed to the head 3a of the reinforcing member 3 with tension nuts 11.

[0025] The head 3a of the reinforcing member 3 protrudes from the central penetration 10a of the tension plate 10, and the injection pipe 5 of the secondary grout material 9 protrudes from the injection pipe penetration 10b of the tension plate 10 towards the ground surface of the slope 1.

[0026] Next, the jack device 12 is placed on the tension plate 10, and the tension member 14 is connected to the head 3a of the reinforcing member 3 via the connecting nut 13. Then, the jack device 12 applies a predetermined tension force (tensile load) P (e.g., 10-150 KN) to the reinforcing member 3 via the tension member 14.

[0027] If the ground C is such that the tension plate 10 settles under a predetermined tension force (tensile load) P, a pre-load (the predetermined tension force P plus a certain load (e.g., (0.05~0.25) × P)) P' is applied for a predetermined time (e.g., 2~60 minutes), and once the settlement of the tension plate 10 has stopped, the tension force P is returned to the predetermined tension force. This prevents the settlement of the tension plate 10 and maintains the predetermined tension force P during the injection and solidification of the secondary grout material 9.

[0028] Next, with a predetermined tension force (tensile load) P applied to the reinforcing material 3, as shown in Figure 7, secondary grout material 9 is injected from the tip of the injection pipe 5 through the injection pipe 5 into the secondary injection section D2 in the hole 2 from the ground surface side of the slope 1. The injected secondary grout material 9 fills the gap between the reinforcing material 3 and the hole 2, and the solidification of the secondary grout material 9 forms a reinforcing material tension section D2' in the same section.

[0029] In addition, depending on the ground conditions, settlement of the tension plate 10 may progress during the injection of the secondary grout material 9. In such cases, a constant load (e.g., (0.05~0.15) × P) is applied to the tension force P during the injection of the secondary grout material 9 to prevent further settlement of the tension blade 10. Once the secondary grout material 9 has solidified, the tension force P is returned to the predetermined level, and then maintained thereafter.

[0030] Next, the tension nut 11, which is temporarily fastened to the head 3a of the reinforcing member 3, is tightened (tightening the tension nut 11 integrates the reinforcing member 3 and the tension plate 10), and the connecting nut 13 is loosened to remove the tension member 14 and the jack device 12 from the reinforcing member 3 and the tension plate 10 (see Figure 8).

[0031] After the tension member 14 and jacking device 12 are removed, the tension force P applied to the reinforcing member 3 is maintained by the reaction force of the tension plate 10 on the slope 1, thereby applying a long-term tension force to the slope 1, and also introducing constant prestress between the moving layer C2 and the anchoring layer C1 of the ground C shown in Figure 3.

[0032] According to the reinforced soil constructed using this embodiment, prestress is constantly introduced into the ground, thereby suppressing the progression of deformation of the slope 1 and preventing rock expansion due to weathering of the slope 1. Furthermore, in the above reinforced soil structure, prestress can be introduced between the tension plate 10 and the anchoring layer of the ground, thereby improving slope stabilization compared to conventional methods.

[0033] The reinforced soil according to this embodiment does not use mirror-finished stainless steel pipes or carbon fiber cables as materials, so it can be constructed at a low cost, and it can also reduce the maintenance costs of the slope after construction.

[0034] In the above embodiment, the tension plate 10 is placed on the slope 1, but a wire mesh for slope greening and a wire mesh for slope mortar spraying may be attached to the tension plate 10. [Industrial applicability]

[0035] This invention can be used as a method for constructing reinforced soil on slopes.

[0036] 1. Slope 2 holes 3. Reinforcement material 4,5 Injection tube 5 holes 6 Binding wire 7 Spacers 8. Primary grout material 9. Secondary grout material 10 Tension Plate 11 Tension nuts 12 Jacking device 13 Connecting nuts 14. Tension members C ground C1 Fixation layer C2 Moving Layer D1 First Injection Interval D1' Reinforcing Material Fixing Part D2 Secondary Injection Interval D2' Reinforcing Tension Section P tension P' Pre-load

Claims

1. From the slope, drill holes with a diameter of 30 to 115 mm and a length of 1 to 30 m into the ground. A reinforcing material is placed inside the drilled hole, a first injection pipe is positioned with its tip in the section of the reinforcing material to inject primary grout material for fixing the reinforcing material around the tip of the reinforcing material, and a second injection pipe is positioned with its tip in the section of the reinforcing member excluding the tip of the reinforcing material to inject secondary grout material for tensioning and fixing the reinforcing material into the hole around the reinforcing member excluding the tip of the reinforcing material. In the hole, primary grout material for the reinforcing material fixing part is injected from the tip of the first injection pipe around the tip of the reinforcing material to form the reinforcing material fixing part. After the reinforcing member fixing portion is formed, a tensioning plate having a through portion in the thickness direction is installed directly above the hole in the slope, the head of the reinforcing member is made to protrude from the through portion of the tensioning plate, and the portion of the second injection pipe protruding from the slope is made to protrude from the through portion of the tensioning plate, and a tensioning nut that is in contact with the outer surface of the tensioning plate is temporarily fastened to the head of the reinforcing member, and in this state, the reinforcing member is tensioned by the tensioning means using the tensioning plate as a reaction force, With the reinforcing member tensioned to a predetermined tension load by the tensioning means, secondary grout material for the reinforcing member tension anchoring section is injected from the slope through the penetration portion of the tensioning plate and into the hole around the reinforcing member, excluding the tip portion of the reinforcing member, from the tip of the second injection pipe to form the reinforcing member tension anchoring section. After the reinforcement tension fixing section is formed, the tension nut is tightened and the tensioning means is removed. A method for constructing reinforced soil for slopes, characterized by the following features.

2. Before injecting secondary grout material for the tensioned anchoring portion of the reinforcing member into the hole surrounding the reinforcing member, excluding the tip of the reinforcing member, a preliminary load exceeding the predetermined tension load is applied by a tensioning means for a predetermined time, and then the preliminary load is reduced to the predetermined tension load before injecting the secondary grout material. The method for constructing reinforced soil for a slope according to feature 1.

3. From the slope, drill holes with a diameter of 30 to 115 mm and a length of 1 to 30 m down to the deep sedimentary layer. A reinforcing material is placed inside the drilled hole, a first injection pipe is positioned with its tip in the section of the reinforcing material to inject primary grout material for fixing the reinforcing material around the tip of the reinforcing material, and a second injection pipe is positioned with its tip in the section of the reinforcing member excluding the tip of the reinforcing material to inject secondary grout material for tensioning and fixing the reinforcing material into the hole around the reinforcing member excluding the tip of the reinforcing material. In the hole of the immovable layer, primary grout material for the reinforcing material fixing part is injected from the tip of the first injection pipe around the tip of the reinforcing material to form the reinforcing material fixing part. After the reinforcing member fixing portion is formed, a tensioning plate having a through portion in the thickness direction is installed directly above the hole in the slope, the head of the reinforcing member is made to protrude from the through portion of the tensioning plate, and the portion of the second injection pipe protruding from the slope is made to protrude from the through portion of the tensioning plate, and a tensioning nut that is in contact with the outer surface of the tensioning plate is temporarily fastened to the head of the reinforcing member, and in this state, the reinforcing member is tensioned by the tensioning means using the tensioning plate as a reaction force, With the reinforcing material tensioned by the tensioning means, secondary grout material for the tensioned anchoring portion of the reinforcing material is injected into the hole from the slope, through the penetration portion of the tensioning plate, and from the tip of the second injection pipe around the intermediate portion of the reinforcing material excluding the tip, extending from the immovable layer deep in the ground to the movable layer shallow in the ground, thereby forming the tensioned anchoring portion of the reinforcing material. After the reinforcement tension fixing section is formed, the tension nut is tightened and the tensioning means is removed. A method for constructing reinforced soil for slopes, characterized by the following features.

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