Frost heaving-resistant pressure-receiving structure, and construction method for the same

Abstract

To propose a ground improvement body construction device and a construction method for the same that can reduce costs compared to conventional methods and suppress defects caused by frost heaving.SOLUTION: A frost heaving-resistant pressure-receiving structure 1 is provided at a head 14 side of an anchor material 12 fixed to the ground 10 and comprises a first pressure-receiving plate 2 made of a material containing synthetic resin and in contact with a surface of the ground 10 while surrounding the head 14, and a second pressure-receiving plate 3 made of metal and overlapping a surface of the first pressure-receiving plate 2 while surrounding a periphery of the head 14.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a frost heave-resistant pressure-receiving structure and a construction method thereof. [Background technology]

[0002] Conventionally, anchor work such as ground anchor work and rock bolt work has been used as a construction method for reinforcing the ground on cut slopes and the like.

[0003] In ground anchor construction, high-strength anchor materials such as PC steel are inserted into holes drilled in the ground, and their tips are anchored deep into the ground. After inserting a pressure plate into the head of the anchor, a fixing device is attached to the head of the anchor while pulling the head with a hydraulic jack or similar. This allows the tension of the anchor to act on the surface layer of the ground through the pressure plate, tightening and reinforcing the ground.

[0004] In rock bolt construction, a rock bolt, which is an anchor material, is inserted into an insertion hole drilled in the ground, and the entire rock bolt inserted into the insertion hole is fixed into the ground using mortar, cement milk, etc. Then, a pressure plate is inserted into the head of the anchor material, and a fixing device such as a nut is attached to the head of the anchor material. When the ground tries to deform, a tensile force is passively generated in the rock bolt, which can resist the sliding force of the soil mass, thereby providing a reinforcing effect to the ground.

[0005] In cold regions, when the temperature of the ground surface layer drops due to cold air, the moisture in the ground freezes and the ground surface layer expands, causing frost heave. When frost heave occurs, the anchor material is deformed to the plastic region by the expanding ground surface layer, and when the frozen ground surface layer thaws and shrinks, the ground reinforcement effect may be lost.

[0006] As a technique for suppressing such defects due to frost heaving, for example, Patent Document 1 discloses a frost heaving-resistant pressure-receiving structure provided on the head side of an anchor material. This structure includes a disc spring, a pressure plate, a first support plate, and a second support plate, with the first support plate interposed between the disc spring and the pressure plate, and the second support plate abutting against the disc spring from the opposite side of the first support plate. The disc spring absorbs the expansion of the ground that occurs during frost heaving, suppressing deformation of the anchor material and maintaining the reinforcing effect even when the ground thaws. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Patent No. 4122641 Summary of the Invention [Problem to be solved by the invention]

[0008] However, the frost heave-resistant pressure structure of Patent Document 1 requires a first support plate and a second support plate in addition to the disc springs as mentioned above, which increases the cost of materials and also increases the construction costs.

[0009] In view of the above-mentioned problems of the conventional art, the present invention proposes a ground improvement body construction device and a construction method thereof that can suppress problems caused by frost heave while reducing costs compared to conventional methods. [Means for solving the problem]

[0010] The present invention is a frost heave-resistant pressure structure provided on the head side of an anchor material fixed to the ground, comprising: a first pressure plate formed of a material containing synthetic resin and surrounding the head while in contact with the surface of the ground; and a second pressure plate made of metal and overlapping the surface of the first pressure plate while surrounding the head.

[0011] In such a frost heave resistant pressure-receiving structure, the first pressure plate is preferably formed of a thermosetting resin foam reinforced with glass fibers.

[0012] The first pressure plate may be made of extruded polystyrene foam.

[0013] It is preferable that an end portion of the first pressure plate is located outside an end portion of the second pressure plate.

[0014] The present invention also relates to a construction method for a frost heave-resistant pressure-receiving structure provided on the head of an anchor material fixed to the ground, the construction method including the steps of: installing a first pressure plate formed of a material containing synthetic resin on the surface of the ground while surrounding the head; and overlapping a second pressure plate made of metal on the surface of the first pressure plate while surrounding the head. Effect of the Invention

[0015] The frost heave-resistant pressure-receiving structure of the present invention can ensure the necessary strength for ground reinforcement by using the second metal pressure plate. In addition, the first pressure plate, which is made of a material containing synthetic resin, is installed so as to be in contact with the surface of the ground, making it difficult for cold air to penetrate into the inside of the ground, suppressing the freezing of moisture (reducing the freezing depth). In other words, the expansion of the surface layer of the ground due to frost heave is suppressed, so problems due to frost heave can be suppressed. In addition, the number of parts is reduced compared to the structure of Patent Document 1, so costs can also be reduced. [Brief description of the drawings]

[0016] [Figure 1] FIG. 1A is a schematic diagram showing one embodiment of a frost heave-resistant pressure structure according to the present invention when installed on the ground, FIG. 1B is a plan view of the same, and FIG. 1C is a plan view of another embodiment. [Diagram 2] FIG. 1 is a schematic diagram showing a state in which a load test is performed, in which (a) is a side view and (b) is a plan view. [Diagram 3]1A to 1D are schematic diagrams showing the frost heave-resistant pressure-receiving structures used in the load tests, where (a) is the first embodiment, (b) is the second embodiment, (c) is the third embodiment, and (d) is the fourth embodiment. [Figure 4] FIG. 11 is a diagram showing the results of a load test of the first embodiment. [Diagram 5] FIG. 13 is a diagram showing the results of a load test of the second embodiment. [Figure 6] FIG. 13 is a diagram showing the results of a load test of the third embodiment. [Figure 7] FIG. 13 is a diagram showing the results of a load test of the fourth embodiment. [Figure 8] FIG. 1 shows schematic diagrams of the frost heave-resistant pressure structures used in field tests conducted on the ground in cold regions, where (a) is the fifth embodiment, (b) is the sixth embodiment, (c) is the seventh embodiment, and (d) is a comparative example. [Figure 9] FIG. 9 is a diagram showing test results regarding tension applied to the anchor material in the field test of FIG. 8. [Figure 10] FIG. 9 is a diagram showing test results regarding underground temperature in the fifth embodiment in the field test of FIG. 8. [Figure 11] FIG. 9 is a diagram showing test results regarding underground temperature in the sixth embodiment in the field test of FIG. 8. [Figure 12] FIG. 9 is a diagram showing test results regarding underground temperature in the seventh embodiment in the field test of FIG. 8. [Figure 13] FIG. 9 is a diagram showing test results regarding underground temperature of the comparative example in the field test of FIG. 8. [Figure 14] FIG. 10 is a diagram showing test results of tension applied to anchor materials in a field test carried out in a winter period different from the winter period in which the field test of FIG. 9 was carried out. [Figure 15] FIG. 17 shows test results on tension applied to anchor materials for field tests conducted in a winter period different from the winter period in which the field tests shown in FIGS. 9 and 14 were conducted. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] Hereinafter, an embodiment of a frost heave-resistant pressure-receiving structure and an implementation method thereof according to the present invention will be described with reference to the drawings.

[0018] FIG. 1 shows a frost heave-resistant pressure-receiving structure 1, which is one embodiment of the frost heave-resistant pressure-receiving structure according to the present invention, in a state where the structure is installed in ground 10 by anchoring work. In this embodiment, a ground anchor work is used as the anchor work. An insertion hole 11 is formed in the ground 10 by using a rock drill, a boring machine, or the like. An anchor material 12 such as a PC steel member is inserted into the insertion hole 11, and a tip portion 13 of the anchor material 12 is fixed deep in the ground 10 by mortar, cement milk, or the like. Here, the anchor material 12 is fixed in a state where a head portion 14 protrudes from the surface of the ground 10, and the frost heave-resistant pressure-receiving structure 1 is attached to this head portion 14.

[0019] The frost heave-resistant pressure-receiving structure 1 of this embodiment includes a first pressure-receiving plate 2, a second pressure-receiving plate 3, and a fixing device 4.

[0020] The first pressure plate 2 is formed of a material containing synthetic resin, and is attached so as to be in contact with the surface of the ground 10 while surrounding the head 14. The material containing synthetic resin used for the first pressure plate 2 is selected from materials that will not be crushed (only undergo restorable deformation even when tension is applied) even when the fixing device 4 is attached to the head 14 as shown in the figure (in this embodiment, the state in which the tension of the anchor material 12 in the ground anchor work is applied to the first pressure plate 2 via the second pressure plate 3).

[0021] In this way, the first pressure plate 2 is made of a material containing synthetic resin with low thermal conductivity, so heat transfer is suppressed. Therefore, even if the outside air temperature drops, cold air is not easily transferred to the ground 10 that the first pressure plate 2 is in contact with, so a drop in the temperature of the ground 10 can be suppressed.

[0022] An example of the first pressure plate 2 is a composite material in which a hard resin foam material is reinforced with inorganic fibers. The hard resin foam material is, for example, a hard thermosetting resin such as urethane resin or epoxy resin. The inorganic fibers are glass fibers, carbon fibers, etc. From the viewpoints of strength and cost, a thermosetting resin foam reinforced with glass fibers, in particular FFU (Fiber reinforced Foamed Urethane) using a hard urethane resin, is preferable.

[0023] Another example of the first pressure plate 2 is extruded polystyrene foam (XPS). The extruded polystyrene foam has an allowable compressive stress of 100 to 200 kN / m, taking into consideration the effect of crushing when fixed to the anchor material 12. 2 , compressive strength is 200kN / m 2 The above materials are suitable. In addition, as a material containing synthetic resin, there is bead-type polystyrene foam (EPS). Since EPS has low allowable compressive stress and compressive strength (generally, the allowable compressive stress of EPS is 20 to 90 kN / m 2 The compressive strength is about 40kN / m 2 or more (at most 180kN / m 2 The above) are suitable for adjusting the unevenness of the surface of the ground 10, but there is a risk that the frost heave resistance effect will not be obtained if the material is crushed while fixed to the anchor material 12. For this reason, it is preferable to select a material that has an allowable compressive stress and compressive strength that exceed EPS.

[0024] The shape of the first pressure plate 2 can be selected from various shapes, and may be the same as or different from the shape of the second pressure plate 3 in plan view. However, in consideration of frost heave resistance, it is preferable that the end of the first pressure plate 2 is located outside the end of the second pressure plate 3. That is, it is preferable that the first pressure plate 2 is larger in plan view than the second pressure plate 3. Since the area covering the ground 10 becomes larger as the first pressure plate 2 becomes larger, it becomes more difficult for cold air to be transmitted to the ground 10. In addition, since the first pressure plate 2, which has a lower hardness than the second pressure plate 3, comes into contact with the ground 10, it becomes easier to follow the ground 10, which has a lower hardness, and therefore the reinforcing effect can be maintained. As an example of the shape of the first pressure plate 2, a square shape in plan view can be cited. In this case, a hole into which the head 14 is inserted is provided in the center of the first pressure plate 2. Furthermore, the first pressure plate 2 is not limited to being composed of one piece, and as shown in Fig. 3(d), a plurality of first pressure plate portions 2a may be arranged vertically and horizontally to surround the head portion 14 to form a single first pressure plate 2. The thickness of the first pressure plate 2 can be appropriately selected depending on the crushing properties, heat transferability, cost, etc., when fixed to the anchor material 12, and is preferably 10 to 80 mm, more preferably 20 to 70 mm, and even more preferably 30 to 60 mm, for example.

[0025] The second pressure plate 3 is made of metal, and is attached so as to be overlapped on the surface of the first pressure plate 2 while surrounding the head 14. Examples of metals used for the second pressure plate 3 include steel and aluminum, but it is preferable to use a steel second pressure plate 3 in order to obtain sufficient strength to withstand the high tension of the anchor material 12.

[0026] The shape of the second pressure plate 3 can be selected from various shapes. Examples of the shape of the second pressure plate 3 include a roughly rectangular shape called a square type as shown in FIG. 1(b) and a roughly cross shape called a cross type as shown in FIG. 1(c). The size of the second pressure plate 3 can also be appropriately selected. For example, the square type has a diagonal length of about 1600 to 2900 mm and a thickness of about 100 to 200 mm, while the cross type has a length from one end to the other end of about 1600 to 2900 mm and a thickness of about 100 to 230 mm. A hole into which the head 14 is inserted is also provided in the center of the second pressure plate 3.

[0027] The fixing tool 4 is attached to the head 14 and has the function of pressing the first pressure plate 2 and the second pressure plate 3 against the ground 10. The fixing tool 4 is appropriately selected according to the shape of the head 14, and for example, a wedge-shaped or nut-shaped fixing tool is used.

[0028] When constructing such a frost heave-resistant pressure-receiving structure 1 on the ground 10 shown in FIG. 1, the following method can be adopted.

[0029] First, an insertion hole 11 is made in the ground 10 using a rock drill or a boring machine. Next, the anchor material 12 is inserted into the insertion hole 11. The anchor material 12 is left in a state where its head 14 protrudes from the surface of the ground 10. Thereafter, mortar, cement milk, or the like is poured into the insertion hole 11, and the tip 13 is fixed deep in the ground 10.

[0030] Next, the head 14 is inserted into a hole provided in the center of the first pressure plate 2, and the first pressure plate 2 is placed on the surface of the ground 10. When a single first pressure plate 2 is made up of multiple first pressure plate portions 2a as shown in FIG. 3(d), these are placed on the surface of the ground 10 so as to surround the head 14.

[0031] Thereafter, the head 14 is inserted into the hole provided in the center of the second pressure plate 3, and the second pressure plate 3 is placed so as to overlap the surface of the first pressure plate 2.

[0032] Thereafter, the head 14 is pulled by a hydraulic jack or the like, and the fixing device 4 is attached to the head 14. This causes the second pressure plate 3 and the first pressure plate 2 to be pressed against the ground 10, tightening and reinforcing the ground 10.

[0033] As described above, the first pressure plate 2 is made of a material containing synthetic resin, so that heat transfer is suppressed. That is, even if the outside temperature is low in winter, cold air is not easily transferred to the ground 10 that the first pressure plate 2 is in contact with, so that a drop in the temperature of the ground 10 is suppressed. Therefore, moisture in the ground 10 is less likely to freeze, and damage from frost heave can be effectively prevented.

[0034] Next, the effects obtained by the frost heave resistant pressure-receiving structure according to the present invention will be described in detail based on the results of actual tests.

[0035] First, in order to confirm the deformation amount and behavior of each member when tension is applied from the anchor material to the frost heave resistant pressure bearing structure, a loading test was performed by the method shown in Fig. 2(a). In the loading test, polyethylene foam 22 simulating the ground is laid on a concrete reaction table 20 (on which a rod 21 likened to an anchor material is installed), and the first pressure plate 2 and the second pressure plate 3 are laid on top of it in order. Then, loading is performed by pulling the rod 21 with a hydraulic jack (not shown). The load in the loading test is measured by a load cell 23 inserted into the rod 21. The deformation amount of the first pressure plate 2 and the second pressure plate 3 is measured by a displacement meter installed at the measurement points P1 to P9 shown in Fig. 2(b).

[0036] In the loading test, the frost heaving resistant pressure bearing structures of the first to fourth embodiments shown in Fig. 3(a) to (d) were used. The second pressure bearing plates 3 of the first to fourth embodiments are all square steel plates with a side length of 1623 mm and a thickness of 106 mm. The first pressure bearing plates 2 of the first to fourth embodiments are all FFU, and the first embodiment of Fig. 3(a) is a square with a side length of 1630 mm and a thickness of 30 mm, the second embodiment of Fig. 3(b) is a square with a side length of 1630 mm and a thickness of 60 mm, the third embodiment of Fig. 3(c) is a square with a side length of 2400 mm and a thickness of 60 mm, and the fourth embodiment of Fig. 3(d) is a square with a side length of 800 mm and a thickness of 60 mm, which are combined vertically and horizontally.

[0037] 4 to 7, the horizontal axis indicates the time when the measurement was performed, and the vertical axis indicates the load value obtained by load cell 23 and the amount of displacement obtained by each displacement gauge during the measurement.

[0038] In the loading test using the first embodiment, as shown by the load values ​​in Fig. 4, the rod 21 was pulled stepwise to about 1.5 times the allowable load of the second pressure plate 3, and then the pulling force on the rod 21 was released, and the rod 21 was further pulled in one go to the allowable load of the second pressure plate 3, and then the pulling force on the rod 21 was released, and the displacement amounts at the measurement points P1 to P5 were measured in the same manner as the load values ​​during pulling, as is clear from Fig. 4.

[0039] In the load test using the second embodiment, as shown by the load values ​​in Fig. 5, the rod 21 was pulled stepwise up to the allowable load of the second pressure plate 3, then the pulling force on the rod 21 was loosened, the rod 21 was pulled again in one go up to about the allowable load of the second pressure plate 3, and further pulled stepwise up to about 1.5 times the allowable load, then the pulling force on the rod 21 was loosened, and the rod 21 was pulled again in one go up to about the allowable load of the second pressure plate 3, and then the pulling force on the rod 21 was loosened, and the displacement amounts at the measurement points P1 to P5 were measured in the same manner as the load values ​​during pulling. As is clear from Fig. 5, the displacement amounts at the measurement points P1 to P5 changed in the same manner as the load values ​​during pulling.

[0040] In the loading test using the third embodiment, as shown by the load values ​​in Fig. 6, the rod 21 was pulled in stages to the allowable load of the second pressure plate 3, then the pulling force on the rod 21 was loosened, the rod 21 was pulled again in one go to about the allowable load of the second pressure plate 3, and further pulled in stages to about 1.5 times the allowable load, then the pulling force on the rod 21 was loosened, and the rod 21 was pulled again in one go to about the allowable load of the second pressure plate 3, and then the pulling force on the rod 21 was loosened, and the displacement amounts at the measurement points P1 to P9 were measured in the same manner as the load values ​​during pulling. As is clear from Fig. 6, the displacement amounts at the measurement points P1 to P9 changed in the same manner as the load values ​​during pulling.

[0041] In the load test using the fourth embodiment, as shown by the load values ​​in Fig. 7, the rod 21 was pulled in stages to the allowable load of the second pressure plate 3, then the pulling force on the rod 21 was loosened, the rod 21 was pulled again in one go to about the allowable load of the second pressure plate 3, and further pulled in stages to about 1.5 times the allowable load, and then the pulling force on the rod 21 was loosened, and the rod 21 was pulled again in one go to about the allowable load of the second pressure plate 3, and then the pulling force on the rod 21 was loosened, and the displacement amounts at the measurement points P1 to P9 were measured in the same manner as the load values ​​during pulling. As is clear from Fig. 7, the displacement amounts at the measurement points P1 to P9 changed in the same manner as the load values ​​during pulling.

[0042] As described above, in the above-mentioned loading test, even when the maximum anticipated force is repeatedly applied, the first pressure plate 2 and the second pressure plate 3 are displaced in the same manner as the applied force, and therefore no defects such as crushing or damage of the first pressure plate 2 and the second pressure plate 3 are observed, and it is recognized that the intended performance is exhibited. Therefore, when the frost heave-resistant pressure structure according to the present invention is applied to the ground, it is expected that the ground can be stably reinforced. In addition, since the first pressure plate 2 is effective even when multiple plates are combined, it is understood that when the size of the first pressure plate 2 is large, multiple small plates may be combined.

[0043] Next, a field test performed by installing a frost heave-resistant pressure-receiving structure on the ground in a cold region will be described. In the field test, the frost heave-resistant pressure-receiving structures of the fifth to seventh embodiments shown in Figs. 8(a) to (c) were used. For comparison, a frost heave-resistant pressure-receiving structure of a comparative example shown in Fig. 8(d) was also used. Here, the fifth embodiment uses a steel square type with a side of 2358 mm and a thickness of 131 mm as the second pressure-receiving plate 3, and an XPS with a side of 2400 mm and a thickness of 50 mm as the first pressure-receiving plate 2. Moreover, the sixth embodiment uses a steel square type with a side of 1623 mm and a thickness of 106 mm as the second pressure-receiving plate 3, and an FFU with a side of 2400 mm and a thickness of 60 mm as the first pressure-receiving plate 2. In the seventh embodiment, a square steel type with a side of 2358 mm and a thickness of 131 mm is used as the second pressure plate 3, and an FFU with a side of 2400 mm and a thickness of 60 mm is used as the first pressure plate 2. In the comparative example, the first pressure plate 2 is not used, and a square steel type with a side of 2358 mm and a thickness of 131 mm is used as the second pressure plate 3. The frost heave-resistant pressure structures of the fifth to seventh embodiments and the comparative example were installed on the ground in a cold region as shown in FIG. 1 (in the comparative example, the first pressure plate 2 is not used, and the second pressure plate 3 is installed on the surface of the ground), and the tension of the anchor material and the underground temperature directly below the first pressure plate 2 were measured during the winter period. In the sixth embodiment, the tension of the anchor material could not be measured midway due to a malfunction of the measuring device, so FIG. 9 shows the results before the malfunction occurred.

[0044] FIG. 9 shows the change in tension of the anchor material measured in the field test. The horizontal axis in FIG. 9 is the measurement date, and the vertical axis is the tension of the anchor material (load value by a load cell attached to the head of the anchor material), and measurements were taken from the beginning to the end of the winter period. As is clear from FIG. 9, the tension of the anchor material is large in the comparative example, and it is found to be affected by frost heave. On the other hand, in the fifth to seventh examples, the tension of the anchor material is smaller than that of the comparative example even under the same environment, and it is found that the effect of frost heave is suppressed. In particular, in the fifth example in which XPS is used for the first pressure plate 2, the tension of the anchor material is smaller than that of the sixth and seventh examples in which FFU is used for the first pressure plate 2, and it is found that the effect of frost heave is further suppressed.

[0045] Figures 10 to 13 show the change in underground temperature directly beneath the first pressure plate 2 measured in a field test (the change in underground temperature directly beneath the second pressure plate 3 in the comparative example), with Figure 10 showing the results for the fifth embodiment, Figure 11 for the sixth embodiment, Figure 12 for the seventh embodiment, and Figure 13 for the comparative example. The horizontal axis in Figures 10 to 13 indicates the measurement date, and the vertical axis indicates the underground temperature, with measurements being taken from the beginning to the end of the winter season. The underground temperatures shown in the figures are the temperatures at the ground surface where the first pressure plate 2 is in contact (GL.0), at a depth of 20 cm from the ground surface (GL.-20 cm), and at a depth of 50 cm from the ground surface (GL.-50 cm).

[0046] As shown in FIG. 13, the underground temperature in the comparative example dropped significantly. In particular, from the middle of the measurement period, the temperature almost always dropped below 0°C even at a depth of 50 cm from the ground surface, and it can be seen that the effects of frost heaving became significant. On the other hand, as is clear from a comparison of FIG. 10 to FIG. 13 with FIG. 10, the underground temperature in the fifth to seventh examples was higher than that in the comparative example. That is, it can be seen that the effects of frost heaving are suppressed in the fifth to seventh examples compared to the comparative example. Furthermore, when comparing the fifth example in which XPS was used for the first pressure plate 2 with the sixth and seventh examples in which FFU was used for the first pressure plate 2, it can be seen that the temperature in the fifth example was higher at the initial stage of the measurement period and the temperature drop was more gradual, and therefore the effects of frost heaving were suppressed more in the XPS than in the FFU.

[0047] In order to confirm that the effect of the frost heave resistant pressure bearing structure of the present invention can be reliably obtained, the inventors have carried out a number of field tests in which the frost heave resistant pressure bearing structure is installed on the ground in cold regions. Here, FIG. 14 is a diagram showing the test results on the tension applied to the anchor material in a field test carried out in a winter period different from the winter period in which the field test of FIG. 9 was carried out. Also, FIG. 15 is a diagram showing the test results on the tension applied to the anchor material in a field test carried out in a winter period different from the winter period in which the field tests of FIG. 9 and FIG. 14 were carried out. In the field tests shown in FIG. 14 and FIG. 15, confirmation was carried out using the fifth to seventh examples shown in FIG. 8(a) to (c). In the eighth example, as in FIG. 8(b), a square type steel plate with a side length of 1623 mm and a thickness of 106 mm is used as the second pressure bearing plate 3, but an XPS plate with a side length of 2400 mm and a thickness of 50 mm is used as the first pressure bearing plate 2. The frost heave-resistant pressure-receiving structures of the fifth to eighth embodiments were applied to the ground in a cold region as shown in Fig. 1, and the tension of the anchor material was measured during the winter. As in Fig. 9, the horizontal axis in Figs. 14 and 15 also represents the measurement date and the vertical axis represents the tension of the anchor material, and measurements were taken from the beginning to the end of the winter period.

[0048] As shown in Figures 14 and 15, in the fifth and eighth examples in which XPS was used for the first pressure plate 2, the tension of the anchor material was smaller than in the sixth and seventh examples in which FFU was used for the first pressure plate 2, and it can be seen that XPS is better able to suppress the effects of frost heave than FFU.

[0049] Although one embodiment of the present invention has been described above, the present invention is not limited to the specific embodiment, and various modifications and changes are possible within the scope of the spirit of the present invention described in the claims unless otherwise specifically limited in the above description. Furthermore, the effects of the above embodiment are merely examples of the effects resulting from the present invention, and do not mean that the effects of the present invention are limited to the above effects.

[0050] For example, although not described, the frost heave-resistant pressure-receiving structure and construction method thereof according to the present invention can also be applied to rock bolt construction. [Explanation of symbols]

[0051] 1: Frost-heaving resistant pressure structure 2: First pressure receiving plate 3:Second pressure receiving plate 4: Fixture 10: Ground 11: Insertion hole 12: Anchor material 13:Tip 14:Head 20: Concrete reaction table 21: Rod 22: Polyethylene foam 23: Load cell

Claims

1. A frost heave resistant pressure-receiving structure provided on the head side of an anchor material fixed to the ground, A first pressure plate formed of a material including a synthetic resin and surrounding the head portion and in contact with the surface of the ground; A frost heave-resistant pressure structure comprising: a second pressure plate made of metal and surrounding the head and overlapping the surface of the first pressure plate.

2. The frost heave resistant pressure bearing structure according to claim 1 , wherein the first pressure bearing plate is formed of a thermosetting resin foam reinforced with glass fibers.

3. 2. The frost heave resistant pressure bearing structure according to claim 1, wherein the first pressure bearing plate is made of extruded polystyrene foam.

4. The frost heave resistant pressure structure according to any one of claims 1 to 3, wherein an end portion of the first pressure plate is located outside an end portion of the second pressure plate.

5. A construction method for a frost heave resistant pressure bearing structure provided at the head of an anchor material fixed in the ground, comprising the steps of: A step of installing a first pressure plate formed of a material containing a synthetic resin on the surface of the ground in a state where the first pressure plate surrounds the head portion; and a step of overlapping a second metal pressure plate on the surface of the first pressure plate while surrounding the head.

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