JP6263979B2 - Natural mountain reinforcement and natural mountain reinforcement structure - Google Patents

Description

  The present invention relates to a natural ground reinforcing material and a natural ground reinforcing structure, and more specifically, to a technique for effectively resisting an axial force generated on a ground excavation surface and stabilizing a tunnel natural ground.

  In tunnel excavation in unconsolidated earth and sand ground and extrudable ground with large earth cover, mirror bolts are installed as countermeasures against mirror surface extrusion and face destabilization. This mirror bolt is composed of steel pipes and GFRP pipes that are driven from the tunnel face to the front ground, and fillers such as mortar injected into the inside and outside. The steel pipe that has become resistant to the tension accompanying mirror extrusion etc. prevents collapse and the like.

  The following techniques have been proposed for such a mirror reinforcing structure. That is, a general part made of a steel pipe and a threaded joint part provided at both ends of the general part for the purpose of keeping the natural ground in a stable state without breaking from the threaded joint part by a tensile force. A steel pipe for ground reinforcement, in which the above-described threaded joint portion is configured so that its tensile strength is approximately equal to the tensile strength of the general part (Patent Document 1) has been proposed. Yes.

Japanese Unexamined Patent Publication No. 2011-7000

  However, particularly in a highly expansive ground and a tunnel with a large covering thickness, the pushing force of the mirror surface is very large, so an excessive axial force that exceeds the tensile strength of the mirror bolt acts. Each mirror bolt that has received an excessive axial force exceeding its tensile strength will break one after another at a predetermined location such as a joint. Such breakage of the mirror bolt leads to loss of the reinforcing function on the mirror surface, and causes problems such as increased extrusion on the mirror surface and occurrence of collapse.

  Then, this invention aims at provision of the technique which resists the axial force produced at the time of tunnel construction effectively, and aims at the stabilization of a tunnel ground.

A natural ground reinforcing material that solves the above-mentioned problems is a steel pipe placed in a tunnel natural ground, a rod-like GFRP material inserted into the steel pipe, and an inner wall of the steel pipe between the steel pipe inner wall and the GFRP material. Ri Do and a filler is filled in, the steel pipe projecting portion extending in a circumferential direction along the inner wall is provided, the convex portion has a discontinuous in the circumferential direction, the convex portion, the axis of the steel pipe A plurality of rows are provided in the direction, and the position of each discontinuous portion between a pair of adjacent convex portions is only partially matched in the steel pipe axial direction .

  According to this, the GFRP material integrated with the steel pipe through the filler effectively resists the axial force caused by the strong extrusion generated on the mirror surface in the expandable natural ground, and the whole natural ground reinforcing material The tensile strength of the tensile shaft is improved. Therefore, even in a tunnel having a large soil covering thickness, it is possible to avoid a situation in which an increase in the extrusion of the mirror surface or a collapse occurs due to the steel pipe fracture. Therefore, it is possible to effectively resist the axial force generated on the excavation surface of the natural ground, and to reliably stabilize the tunnel natural ground.

Further, a convex portion extending in the circumferential direction is provided along the inner wall of the steel pipe, and the convex portion is discontinuous in the circumferential direction. Since it can pass through the discontinuous part of the part, it can flow efficiently in the direction of the pipe axis without being particularly obstructed, and the overall construction efficiency can be kept good. The material reliably adheres to the steel pipe via the filler, and the tensile axial force acting on the steel pipe from the tunnel ground can be effectively transmitted to the GFRP material. Therefore, the GFRP material integrated with the steel pipe through the filler can be more effectively resisted against the axial force caused by the strong extrusion generated on the mirror surface in the expandable ground.

Furthermore, the above-mentioned ground reinforcing material is provided with a plurality of rows of the convex portions in the axial direction of the steel pipe, and the positions of the discontinuous portions between the adjacent sets of the convex portions are steel pipe shafts. Due to the fact that only part of them match in the direction, the projections provided on the inner wall of the steel pipe provide more reliable adhesion between the GFRP material and the steel pipe via the filler, and the tensile force acting on the steel pipe from the tunnel ground Axial force can be transmitted to the GFRP material more effectively, and at least a part of the discontinuous portion is overlapped between the convex portions, so as not to hinder the flow of waste mud in the steel pipe, The overall construction efficiency can be kept good.

Also, the natural ground reinforcing construction of the present invention is characterized by formed by construction the natural ground reinforcing material to the tunnel natural ground.

  According to this, the GFRP material integrated with the steel pipe through the filler effectively resists the axial force caused by the strong extrusion generated on the mirror surface in the expandable natural ground, and the whole natural ground reinforcing material The structure in which the tensile shaft yield strength is improved is formed. Therefore, even in a tunnel having a large soil covering thickness, it is possible to avoid a situation in which an increase in the extrusion of the mirror surface or a collapse occurs due to the steel pipe fracture. Therefore, it is possible to effectively resist the axial force generated on the excavation surface of the natural ground, and to reliably stabilize the tunnel natural ground.

  According to the present invention, it is possible to effectively resist the axial force generated on the excavation surface of the natural ground, and to reliably stabilize the tunnel natural ground.

It is a perspective view which shows the structural example of the natural ground reinforcement in this embodiment. It is a figure which shows the construction form of the natural ground reinforcement material in this embodiment. It is a sectional side view which shows the structural example of the natural ground reinforcement material in this embodiment. It is a figure which shows the example 1 of a cross section in the natural ground reinforcement material of this embodiment. It is a figure which shows the example 2 of a cross section in the natural ground reinforcement material of this embodiment. It is a figure which shows the cross-sectional example 1 of another natural ground reinforcement. It is a figure which shows the example 2 of a cross section of another natural ground reinforcement. It is a figure which shows the material specification of the natural ground reinforcement material in this embodiment. It is a figure which shows the specimen type of the natural ground reinforcement in this embodiment. It is a figure which shows the tension test result in this embodiment. It is a figure which shows the graph of the tension test result in this embodiment. It is a figure which shows the load distribution at the time of the joint fracture | rupture in this embodiment.

  Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a perspective view showing a structural example of the natural ground reinforcing material 10 in the present embodiment, and FIG. 2 is a diagram showing a construction form of the natural ground reinforcing material in the present embodiment. The natural ground reinforcing material 10 according to the present embodiment reliably resists the axial force associated with the above-described extrusion in a construction situation where strong extrusion occurs on the mirror surface 200, such as when the construction target in tunnel construction is an expandable natural ground. However, it is intended to stabilize the natural ground.

  As illustrated in FIG. 1, the natural ground reinforcing material 10 includes a steel pipe 2 placed in the tunnel natural ground 1, a GFRP (Glass fiber reinforced plastics) material 3 inserted into the steel pipe 2, and a steel pipe 2. And a filler 7 such as mortar filled between the steel pipe inner wall 6 and the GFRP material 3 in the inner space 5.

  Among these, the steel pipe 2 is a long steel pipe of about 12 to 13 m, for example, and is set on the drifter 52 of the boom 51 in the hydraulic jumbo 50 arranged in the tunnel pit 45 as shown in FIG. It is placed in the tunnel ground 1 in the direction of excavation. In this case, the steel pipe 2 performs a drilling operation on the tunnel ground 1 by driving the excavation bit 20 provided at the tip portion with the drifter 52, and gradually digs from the mirror surface 200 and is driven into the tunnel ground 1. The Rukoto. A grout material 30 is injected between the cast steel pipe 2 and the surrounding tunnel ground 1 from the inner space 5 of the steel pipe 2 through a predetermined hole, and the tunnel ground 1 and the steel pipe 2 are integrated. Is done.

  Moreover, the above-mentioned GFRP material 3 constituting the natural ground reinforcing material 10 is a rod-like member having a width and a thickness that can be inserted into the inner space 5 of the steel pipe 2. As an example, as shown in FIG. A member formed into a shape can be employed. In the case of the natural ground reinforcing material 10 of the present embodiment, three such flat plate-like GFRP materials 3 are combined via a spacer 4 and inserted into the inner space 5 of the steel pipe 2 as an integral GFRP material 3. .

  The GFRP material 3 is a glass fiber reinforced plastic material, and is a composite material in which glass fiber is mixed into a base material plastic and mainly the tensile strength is increased. The GFRP material 3 is selected in advance so as to have a strength capable of resisting the tensile strength required for the natural ground reinforcing material 10, that is, the axial force accompanying the extrusion acting on the mirror surface 200 from the tunnel natural ground 1. Shall be performed.

  The spacer 4 described above is configured to be fitted to the side surface of each GFRP material 3 at least at both ends of the GFRP material 3 to fix the positional relationship of each GFRP material 3. The spacer 4 has an insertion hole 11 through which the injection tube 8 of the filler 7 is inserted at the center of the cross section. The injection pipe 8 serves as a conduit that guides the filler 7 such as mortar supplied from an appropriate pumping device to the inner space 5 of the steel pipe 2 after the GFRP material 3 is inserted into the inner space 5 of the steel pipe 2. The injection tube 8 in this embodiment includes a plurality of auxiliary injection tubes 9 having different lengths. As illustrated in FIG. 3, the length of each auxiliary injection pipe 9 is set at a constant interval from the mirror surface 200 toward the tip of the steel pipe 2 so that the filler 7 is injected without deviation in the inner space 5 of the steel pipe 2. It corresponds to each length reaching each predetermined position.

  The natural ground reinforcing material 10 thus constructed from the mirror surface 200 to the tunnel natural ground 1 forms a natural ground reinforcing structure 100 that resists the tensile axial force accompanying extrusion. In the example of FIG. 2, the ground reinforcing material 10 as a mirror bolt to be placed in the tunnel excavation direction is shown, but in addition to this, a leg reinforcing pile such as a leg pile or a side pile, or a lock The natural ground reinforcing material 10 of this embodiment may be applied to the bolt.

  Then, the characteristic structure of the inner wall 6 of the inner space 5 in the steel pipe 2 mentioned above is demonstrated. FIG. 3 is a side sectional view showing a structural example of the natural ground reinforcing material 10 in the present embodiment, FIG. 4 is a diagram showing a cross sectional example 1 in the natural ground reinforcing material 10 in the present embodiment, and FIG. It is a figure which shows the example 2 of a cross section in the natural ground reinforcement. The ground reinforcement structure 100 to be constructed from the mirror surface 200 to the tunnel ground 1 is sufficiently separated from the mirror surface 200 in the tunnel excavation direction in order to secure a fulcrum against the above-described axial force, and the pushing action in the tunnel ground 1 is predetermined. It is necessary to place and fix the tip portion 110 at an appropriate position estimated to be below the level.

  Therefore, when the steel pipe 2 is placed, the plurality of steel pipes 2 are continuously connected by the joint structure 17 until the tip of the steel pipe 2 reaches the position of the tip portion 110 described above. The joint structure 17 in each steel pipe 2 is a threaded joint provided at the end of the steel pipe.

  Moreover, the inner wall 6 of the steel pipe 2 in the present embodiment is provided with a convex portion 15 extending in the circumferential direction at a position separated from the end of the steel pipe by a predetermined distance. As shown in FIGS. 4 and 5, the convex portion 15 is arranged on the circumference of the inner wall 6 in a circumferential shape with the discontinuous portion 16 interposed therebetween. 4 and 5, in order to clearly show the structure of the convex portion 15, the inner wall 6 when the inner space 5 of the steel pipe 2 is observed from the viewpoint toward the end portion 18 on the mirror surface 200 side from the joint structure 17. Is shown with a sense of perspective.

  When the steel pipe 2 is driven to the tunnel ground 1, the mud must be efficiently discharged in the inner space 5 of the steel pipe 2 in order to discharge the excavated soil generated by the excavating bit 20 at the tip of the steel pipe. Since the efficiency of the waste mud increases and decreases depending on the smoothness of the inner wall 6 of the steel pipe 2, a smooth inner wall 6 surface is suitable for the steel pipe placing process, but on the other hand, between the steel pipe 2 and the GFRP material 3 In order to ensure integration, it is also necessary that the filler 7 filled between the two adheres securely to the inner wall 6. Therefore, the convex portion 15 described above is arranged on the inner wall 6 of the steel pipe 2 in the present embodiment with the discontinuous portion 16 interposed therebetween, and the waste mud in the inner space 5 can flow in the axial direction of the steel pipe 2 through the discontinuous portion 16. It has a simple structure. Therefore, in the inner space 5 of the steel pipe 2, the sludge can flow efficiently without being particularly obstructed, and the overall construction efficiency can be kept good. On the other hand, the projection 15 of the inner wall 6 ensures that the GFRP material 3 adheres to the steel pipe 2 via the filler 7 and effectively transmits the tensile axial force acting on the steel pipe 2 from the tunnel ground 1 to the GFRP material 3. It becomes possible to do. Since the GFRP material 3 exhibits a sufficient tensile strength, the GFRP material 3 reliably resists the axial force transmitted from the steel pipe 2, and the tensile strength necessary for the natural ground reinforcing material 10 is ensured.

  Moreover, the case where the convex part 15 mentioned above is only one row like FIG. 4 and the case where multiple rows | lines are provided in the axial direction of the steel pipe 2 like FIG. 5 are employable. Among these, when the convex parts 15 are provided in a plurality of rows, the positions of the discontinuous parts 16 are arranged so as to at least partially coincide with each other between the rows of the convex parts 15. With such an arrangement, the GFRP material 3 is more reliably attached to the steel pipe 2 via the filler 7 by the plurality of rows of projections 15 than in the case of only one row of projections 15. become. On the other hand, even in a structure in which a plurality of rows of convex portions 15 are arranged, the discontinuous portions 16 are partially communicated, and the waste mud can flow efficiently without being particularly disturbed. Therefore, the overall construction efficiency can be kept good.

  In addition, in this embodiment, although the convex part 15 showed the example located in the inner wall 6 within the predetermined distance from the joint structure 17, ie, the edge part of the steel pipe 2, the specification which provides the convex part 15 in the steel pipe 2 from the time of manufacture In this case, the convex portion 15 may be arranged regardless of the distance from the end portion of the steel pipe.

  Then, the tension test performed in order to grasp | ascertain the strength improvement effect by the above-mentioned GFRP material 3 about the natural ground reinforcement material 10 in this embodiment is demonstrated. Here, a steel pipe having a length of 1 m is adopted as a specimen, and each steel pipe is connected by welding and a screw joint, and GFRP material (width 40 mm × thickness 7 mm × length 2.0 m: 3 pieces) is formed in the inner space. After insertion, mortar (W / C = 61.1%) as a filler was filled, and a tensile test was performed 24 hours later. In the tensile test, only the steel pipes at both ends of the specimen were fixed to a hydraulic jack, and a tensile load was applied.

  Moreover, about the convex part provided in a steel pipe inner wall, the structure of welding projection full circumference 1 row (refer FIG. 6), welding projection half circumference (3 divisions) x 1 row, and 2 rows (above-mentioned FIG. 4, 5) is object. At the same time, a configuration (see FIG. 7) in which a recess was provided on the inner wall of the steel pipe by grinding was also examined. In addition, each material specification of the steel pipe, GFRP material, and filler as a specimen is shown in FIG. 8, and a list of types of specimens is shown in FIG. 9 (in the figure, the GFRP material is described as “flat bar”). .

  FIG. 10 is a diagram showing a tensile test result in the present embodiment, and FIG. 11 is a diagram showing a graph (load displacement curve) of the tensile test result in the present embodiment. The tensile test results for the above-described specimens indicate that all specimens were broken due to the fracture of the GFRP material or the mortar pull-out after the joint fracture. The displacement in FIGS. 10 and 11 is the tensile displacement of the entire specimen (L = 2 m), and the graph in FIG. 11 also shows the load displacement estimated when only the GFRP material is used.

  Moreover, it calculated about the load distribution of the steel pipe and GFRP material at the time of a joint fracture | rupture, and obtained the calculation result shown in FIG. When calculating the load distribution, the burden load of the steel pipe was calculated by calculating the burden load backward from the strain of the GFRP material and removing it from the total load.

  According to the result of the above tensile test, the adhesion strength between the filled mortar and the steel pipe is estimated to be about 150 kN / m from the test result of the specimen (1). The joint breaking strength was about 500 kN to 540 kN for the welded joint and about 460 kN to 520 kN for the threaded joint. Moreover, according to the burden load of a steel pipe, it turns out that the fracture | rupture of the welded joint single-piece | unit occurred at about 365 kN-400 kN, and the fracture | rupture of the threaded joint single-piece | unit occurred about 300 kN. The burden load of the GFRP material was 100 to 170 kN for the welded joint and 190 to 230 kN for the threaded joint.

  In addition, the reinforcing effect of the GFRP material is based on the unevenness of the inner wall of the steel pipe. (Concavity by machining) <(1 row of weld projection half circumference) <(1 row of weld projection full circumference) <(2 rows of weld projection full circumference) It was found that the reinforcing effect increased in the order of), and the effectiveness of the effect of the convex portion in this embodiment could be confirmed. Moreover, the strength of 500 kN or more was obtained for both the welded joint and the threaded joint by the GFRP material, and it was confirmed that the GFRP material exhibited the yield strength after the joint breakage and exhibited the elastoplastic strength.

  According to the present embodiment, it is possible to effectively resist the axial force generated on the excavation surface of the natural ground and to stabilize the tunnel natural ground.

  As mentioned above, although embodiment of this invention was described concretely based on the embodiment, it is not limited to this and can be variously changed in the range which does not deviate from the summary.

DESCRIPTION OF SYMBOLS 1 Tunnel ground 2 Steel pipe 3 GFRP material 4 Spacer 5 Steel pipe inner space 6 Steel pipe inner wall 7 Filler 8 Injection pipe 9 Auxiliary injection pipe 10 Ground mountain reinforcement 11 Insertion hole 15 Convex part 16 Discontinuous part 17 Joint structure 18 Steel pipe end part 20 Drilling Bit 30 Grout Material 45 Tunnel Tunnel 50 Hydraulic Jumbo 51 Boom 52 Drifter 100 Ground Mountain Reinforcement Structure 110 Tip Part 200 Mirror Surface

Claims (2)

A steel pipe which is Da設the tunnel natural ground, Ri Do from the GFRP material of the rod-shaped to be inserted into the steel pipe, the filling material is filled between the steel pipe inner wall GFRP material in the inner space of the steel pipe,
A convex portion extending in the circumferential direction is provided along the inner wall of the steel pipe, and the convex portion is discontinuous in the circumferential direction,
The convex portions are provided in a plurality of rows in the axial direction of the steel pipe, and the positions of the discontinuous portions are only partially matched in the axial direction of the steel pipe between a pair of adjacent convex portions. A natural reinforcing material characterized by that. A natural ground reinforcement structure, wherein the natural ground reinforcement according to claim 1 is applied to a tunnel natural ground.