JP6624730B2 - Slope stabilization structure - Google Patents

Description

  The present invention relates to a slope stabilizing structure for stabilizing a slope by driving a pile into a ground.

  As a technique for stabilizing a slope by driving a pile into the ground, a pile-blocking construction method disclosed in Patent Document 1 is known. In this method, the vertical piles are laid in a row on a small step in the cut slope, and slant piles are laid in a row on the slope immediately above the slope. The pile heads are rigidly connected to each other by a foundation beam to form a pile and stabilize the slope. This method is landslide reinforcement that is used as a pile to prevent horizontal forces. It is used in combination with a general-purpose reinforced soil method on a cut slope where there is sufficient room for the site, and tension, bending, shearing force, etc. It is intended to develop a large proof stress.

FIG. 11 of Patent Document 2 shows a route pile construction method in which piles (small-diameter piles) made of reinforcing steel and solidified material are laid in a mesh shape as reinforcing materials on the ground to suppress deformation of the soil. . Here, the mesh shape means that the pile containing the rebar core material is cast and arranged in an oblique mesh shape having different directions, thereby suppressing the deformation of the soil and the slipping of the soil between the piles, and the reinforcing material such as reinforcing steel and the soil. Are integrated.

JP 2002-275907 A JP 2003-268767 A

  By the way, when the construction is carried out by the pile pile restraining method of Patent Document 1, while the cut slope is formed in a stepwise manner from the upper side to the lower side, the vertical pile is inclined with the small pile in the middle of the first area I. Pile is piled up one by one, these pile heads are rigidly connected by foundation beam, then the lower second area II is cut and another step is provided. Repeating the work of laying out one row and stiffening it with the foundation beam is repeated, which greatly restricts the site and construction. Therefore, the applicable range is narrow and limited.

  In addition, although this pile pile restraint method is a combination of vertical piles and slanted piles, basically, in order to compensate for the lack of bending strength (horizontal bearing capacity) of conventional single row vertical piles, It is just the one with the head rigidly combined. For this reason, a reinforcing effect is expected more than a single row of vertical piles, but the inclined pile N receives the earth pressure on the entire surface in a state substantially perpendicular to the sliding surface 201 on the rear surface of the vertical pile M and reduces the shear force. In order to resist, the earth pressure applied to the vertical pile M is reduced and the supporting force as a vertical pile is secured, but a synergistic reinforcing effect as a set pile composed of the vertical pile A and the inclined pile B can be expected. No (see FIG. 13, 202 is a cut slope in the figure). Accordingly, it is difficult to say that there is a sufficient increase in the reinforcing effect that is compatible with the construction cost and the construction time that are increased by the construction of the inclined pile, and the cost performance is inferior.

  In addition, the root pile method of Patent Document 2 is a reinforced earth method, and a large number of small-diameter reinforcing materials are cast in a mesh so that the soil can be integrated, and the interaction between the soil and the reinforcing material. Accordingly, the reinforcing material can exhibit the reinforcing effect following the deformation of the ground. In other words, the pile is not a deterrent pile that can expect the axial resistance of the pile to the sliding force and the supporting force of the pile.

  The present invention has been proposed in view of the above-described problems, and the ground reaction force between the front surface of the pile and the pile can be effectively utilized by the pile group on the landslide slope, and at the same time, restrictions on the ground and construction work. It is an object of the present invention to provide a reasonable slope stabilizing structure which has few restrictions on the above and is excellent in versatility.

The slope stabilizing structure of the present invention includes a straight pile that is driven to a depth side of the one slip surface in a direction substantially perpendicular to the one slip surface inside the slope of the ground, and an upper side of the straight pile. at spaced locations, said sleeping inclined to approach horizontally from a direction substantially perpendicular to one of the sliding surface, has a Hasukui being pouring deep side of the one sliding surface, the natural ground slope The pile head of the straight pile and the pile head of the slant pile, which are arranged at positions separated from each other , are rigidly connected, and the straight pile closer to the ground slope surface layer than the one slip surface, A non-plasticized region maintaining the internal stress of the ground itself is left between the inclined piles .
According to this, the inclined piles inclined so as to approach the horizontal from the direction substantially perpendicular to the slip surface effectively support the earth pressure on the back side of the pile, and between the inclined pile and the straight pile and the straight pile. The ground reaction force on the front side of the pile is maintained, and the plasticization of the ground between the pile front and the pile is suppressed as much as possible. Therefore, both the inclined pile and the straight pile rigidly connected as a set of piles in two rows in the front-rear direction can express the maximum supporting force and stabilize the slope. That is, the inclined pile is inclined so as to approach horizontal more than the direction substantially perpendicular to the slip surface, that is, by sleeping, the local shear force is resisted only by the bending strength of the pile. , Stress can be dispersed in the length direction, and the ground reaction force due to the earth pressure dispersion can be effectively developed. As a result, an earth pressure is generated between the front of the inclined pile and the straight pile, which bears the external force, and the load sharing of the straight pile is greatly reduced, while the ground reaction force on the front side of the straight pile is also maintained. Then, the straight pile, which is located in the ground where the stabilization is maintained by the inclined piles and is expected to have a direct tensile rigidity by being substantially perpendicular to the slip surface, is located in front of the group pile. The arrangement of the piles prevents deformation of the slant piles. Further, since the straight pile and the oblique pile are rigidly connected to the head, the mutual deformation is prevented. As a result, the slanted pile protects the straight pile while the straight pile protects the slanted pile, and the plasticization of the soil at the back and front of the pile and between the piles is prevented as much as possible. Each of the piles can exhibit an effective bearing force from an early stage of displacement generation, and both piles can ultimately exhibit a maximum bearing force. Further, in the present invention, the straight pile and the inclined pile are those which are driven in a direction substantially perpendicular to the slip surface inside the slope and in a direction inclined closer to horizontal than the same, so that the vertical pile and the inclined pile are There is no need to form a step in the middle of the slope, and there are few restrictions on the land used in the construction and there are no restrictions on the construction, and the versatility is excellent. In addition, the existing stabilization structure using deterrent piles, when a large deterrent force was required, had to deal with a larger pile diameter and a higher tensile strength pile material. Although it was restricted or the economic efficiency was impaired, in the present invention, even with the use of a small-diameter group pile with good mobility, the large deterrent is utilized by maximizing the internal stress held by the ground itself without collapsing. And the slope can be stabilized, and the slope can be reinforced rationally with excellent economic efficiency and construction efficiency.

In the slope stabilizing structure of the present invention, the slanted pile is a first slanted pile, and approaches a horizontal plane in a direction substantially orthogonal to the one slip plane at a position above and separated from the first slanted pile. sleeping inclined such, has a second Hasukui being pouring deep side of the one sliding surface, the vertical piles which are positioned away along the natural ground slope pile The part, the pile head of the first slant pile and the pile head of the second slant pile are rigidly connected, and the straight pile and the first pile closer to the ground slope surface layer than the one slip surface. Non-plasticized regions that maintain the internal stress of the ground itself are left between the slanted piles and between the first slanted pile and the second slanted pile .
According to this, the ultimate shear strength on the slip surface is further enhanced by using the second inclined pile and rigidly connecting the pile heads of the straight pile, the first inclined pile, and the second inclined pile. be able to.

The slope stabilizing structure of the present invention is characterized in that the rigid body of the straight pile and the inclined pile, or the rigid body of the straight pile, the first inclined pile, and the second inclined pile, It is characterized by being arranged side by side along the lateral direction of the slope.
According to this, a stable slope structure having a high landslide suppression force can be formed in a wide range.

In the slope stabilizing structure of the present invention, the straight pile and the slope pile, or the straight pile, the first slope pile, and the second slope pile each include a steel pipe having a diameter of 100 to 300 mm and a grout material. And a fixing layer formed by the injection of
According to this, by using a pile made of a small-diameter steel pipe having a diameter of 100 to 300 mm, it is possible to further reduce the restrictions on construction, and to attach a substantially perpendicular direction or an inclination angle to the slip surface of the slope. Can be easily performed.

In the slope stabilizing structure of the present invention, an angle formed between the inclined pile and the one slip surface immediately below the inclined pile is set to 65 ° to 75 °, or the first inclined pile and the The angle formed by the one slip surface immediately below the first slant pile is 65 degrees to 75 degrees, and the angle formed by the second slant pile and the one slip surface immediately below the second slant pile is It is characterized in that the angle is set to 65 degrees to 75 degrees.
According to this, by making the axial direction of the slant pile or the first and second slant piles optimally obliquely intersect with the shear plane, the peripheral friction of the slant pile or the first and second slant piles can be reduced from an early stage. By utilizing the force in the tensile direction, it is possible to obtain the ground reaction force on the front side of the slanted pile or the first and second slanted piles, and to quickly and surely exert the shear resistance force while the shear displacement is small. it can. Therefore, generation of large shear displacement and shear stress can be suppressed, and the stability of the slope can be further enhanced.

  The stabilizing structure of the slope of the present invention enables the ground reaction force between the front of the pile and the pile to be used to the utmost with the pile pile on the landslide slope, and the rigidly connected slope pile and the straight pile are both used. In this way, the maximum supporting force can be expressed to each other to stabilize the slope. In addition, there are few restrictions on land use and construction, and it has excellent versatility and has extremely high rationality.

FIG. 2 is a schematic cross-sectional view illustrating a stabilization structure of a slope according to the first embodiment of the present invention. Sectional explanatory drawing which shows the rigid connection part of the straight pile, the 1st slope pile, and the 2nd slope pile in the slope stabilization structure of 1st Embodiment. (A)-(e) is sectional explanatory drawing which shows the construction process of the pile in the slope stabilization structure of 1st Embodiment. FIG. 9 is a schematic cross-sectional view illustrating a stabilization structure of a slope according to a second embodiment of the present invention. The block diagram of a model experiment apparatus. (A), (b) is explanatory drawing which shows the pile arrangement | positioning of the 1st Example and 1st comparative example in a model experiment apparatus, (c), (d) 2nd Example and 2nd comparative example in a model experimental apparatus. FIG. (1) is a graph showing the relationship between the shear displacement and the shear stress of the first embodiment and the first comparative example based on the model experiment, and (2) is the shear displacement and the shear stress of the second embodiment and the second comparative example based on the model experiment. The graph which shows the relationship. (A) is a model diagram for three-dimensional FEM analysis corresponding to the first embodiment, (b) is a model diagram for three-dimensional FEM analysis corresponding to the first comparative example, and (c) is a model diagram corresponding to the second embodiment. FIG. 4B is a model diagram for three-dimensional FEM analysis, and FIG. 4B is a model diagram for three-dimensional FEM analysis corresponding to the second comparative example. (A) is a plastic region distribution diagram in the longitudinal direction in the model for analysis according to the first embodiment, and (b) is a plastic region distribution diagram in the longitudinal direction in the model for analysis corresponding to the first comparative example. (A) is a 3D model diagram showing a plastic zone distribution immediately above a shear surface (slip surface) in the analysis model corresponding to the first embodiment, and (b) is a shear surface (slip surface) immediately above the analysis model corresponding to the first comparative example. 3D model diagram showing a plastic region distribution of FIG. (A) is a distribution diagram of the plastic region in the longitudinal direction in the model for analysis according to the second embodiment, and (b) is a distribution map of the plastic region in the longitudinal direction in the model for analysis corresponding to the second comparative example. (A) is a 3D model diagram showing a plastic zone distribution immediately above a shear plane (slip surface) in the analysis model corresponding to the second embodiment, and (b) is a shear plane (slip surface) immediately above the analysis model corresponding to the second comparative example. 3D model diagram showing a plastic region distribution of FIG. Reference explanatory drawing of the conventional slope stabilization structure.

[Slope Stabilizing Structure of First Embodiment]
As shown in FIGS. 1 and 2, the slope stabilizing structure according to the first embodiment of the present invention is cast in a direction substantially perpendicular to a slip surface 102 located inside a slope 101 of a ground 100. A straight pile 1, a first slant pile 2, which is slanted at a position above the straight pile 1 at a distance from the slope 101 so as to approach the slip surface 102 more horizontally than in a direction substantially orthogonal to the slope 101, A second slanted pile 3 is installed at a position above the slanted pile 2 at a distance from the slanted surface 101 so as to be closer to the horizontal than a direction substantially perpendicular to the sliding surface 102. The straight pile 1, the first slant pile 2, and the second slant pile 3 are each driven so that a portion on the tip side from the slope 101 reaches the inner side of the slip surface 102.

  The straight pile 1 is driven in a direction substantially perpendicular to the sliding surface 102, and the first inclined pile 2 and the second inclined pile 3 are inclined so as to approach the sliding surface 102 in a direction substantially perpendicular to the sliding surface 102. The pile is composed of three rows of the straight pile 1, the first slanted pile 2, and the second slanted pile 3, and the existing vertical pile which is driven in the vertical direction and the vertical pile It is different from a group pile consisting of slant piles that are cast at a slight angle to the pile.

  The angle α formed between the first inclined pile 2 and the sliding surface 102 immediately below the first inclined pile 2 can be appropriately set by an angle inclined so as to approach horizontal more than a substantially orthogonal direction, It is preferable to set the angle between 65 degrees and 75 degrees. In the illustrated example, the angle α is 70 degrees, and the inclination angle of the first inclined pile 2 with respect to the straight pile 1 is 20 degrees. Similarly, the angle β formed between the second inclined pile 3 and the slip surface 102 immediately below the second inclined pile 3 can be appropriately set by an angle inclined so as to approach horizontal more than a substantially orthogonal direction. However, it is preferable to set the angle between 65 degrees and 75 degrees. In the illustrated example, the angle β is 70 degrees, and the inclination angle of the second inclined pile 3 with respect to the straight pile 1 is 20 degrees. The angles α and β of the inclined piles 2 and 3 are set such that the straight piles 1 and the inclined piles 2 and 3 whose inclinations are inclined are set and changed by using the same construction machine. At a reasonable angle, it does not affect workability.

  Each of the straight pile 1, the first slanted pile 2, and the second slanted pile 3 is made of steel pipes 11, 21, 31 and steel pipes 11, 21, which are formed by injecting grout material and cast into the ground 101 , 31 (see FIG. 3), and pile heads 12, 22, 32 are fixed to the steel pipes 11, 21, 31 by welding, respectively. . As the steel pipes 11, 21, and 31, it is possible to use an appropriate steel pipe capable of obtaining a required pile supporting force. However, if the steel pipe is a small-diameter steel pipe having a diameter of 100 to 300 mm, the restriction on the construction is further reduced. It is preferable because it is possible to easily perform the driving in a direction substantially perpendicular to the slip surface of the slope or at an inclined angle.

  The pile head 12 of the straight pile 1 and its vicinity, the pile head 22 of the first inclined pile 2 and its vicinity, and the pile head 32 of the second inclined pile 3 and its vicinity are integrally formed on the slope 101. The pile heads 12, 22, 32 of the straight pile 1, the inclined piles 2, 3 are rigidly connected via the reinforced concrete 4 in this embodiment. The reinforced concrete 4 includes a concrete portion 41 and a reinforcing bar 42 arranged in the concrete portion 41.

  The straight pile 1, the first slanted pile 2, and the second slanted pile 3 of the present embodiment are all driven into the ground 100 by the same construction method. FIG. 3 is a cross-sectional explanatory view showing a construction step of driving a pile 6 constituting the straight pile 1, the first inclined pile 2, or the second inclined pile 3.

  When driving the pile 6, first, a hole 103 is formed from the slope 101 toward the ground 100. In the example of FIG. 3A, a drilling rod 51 provided with a bit 53 and a down-the-hole hammer 52 at the tip is inserted into a steel pipe 61, and the drilling rod 51 having the steel pipe 61 as a casing is rotated by a construction machine. Thus, a hole 103 is formed. When the drilling hole 103 reaches a required depth, the drilling rod 51 is pulled out and only the steel pipe 61 remains in the drilling hole 103 (see FIG. 3B). In addition, although the illustrated example is drilling of the down-the-hole hammer method, the drilling can be similarly performed using the steel pipe 61 as a casing by a rotary percussion method or the like, and depending on the soil quality of the ground 100 and the form of the steel pipe 61, It is also possible to drill a hole only by rotation without hitting.

  Thereafter, as shown in FIG. 3 (c), the injection pipe 54 provided with the packer 55 at the tip end is inserted into the steel pipe 61, and inserted until the packer 55 reaches the vicinity of the inside of the hole. Then, the grout material is pressure-fed to the injection pipe 54 and discharged from the tip of the packer 55, and the grout is injected into the surrounding ground 100 from the discharge holes 611 formed at predetermined intervals in the longitudinal direction on the peripheral surface of the steel pipe 61. Inject the material. A fixing layer 63 is formed on the surrounding ground 100 where the grout material has penetrated. The grout material is repeatedly injected while pulling up the packer 55 and the injection pipe 54 to form the fixing layer 63 around the steel pipe 61 (see FIGS. 3D and 3E).

  Then, the injection pipe 54 and the packer 55 are pulled out from the steel pipe 61, and the pile head is fixed to the end of the steel pipe 61 discharged from the slope 101 by welding or the like, and the straight pile 1, the first diagonal pile 2 or the second diagonal pile is fixed. A stake 6 constituting the stake 3 is formed.

  In the first embodiment, rigid bodies formed by rigidly connecting the straight pile 1, the first slant pile 2, and the second slant pile 3 are juxtaposed along the lateral direction of the slope 101 of the ground 100. The pile head 12, the pile head 22 of the first slanted pile 2, and the pile head 32 of the second slanted pile 3 are arranged on a slope 101. It is rigidly connected by a reinforced concrete 4 integrally provided thereon (not shown). By arranging the rigid bodies of the straight pile 1, the first slant pile 2, and the second slant pile 3 side by side, a stable slope structure having a high landslide suppressing force can be formed in a wide range.

  According to the slope stabilizing structure of the first embodiment, the first slanted pile 2 and the second slanted pile 3 that are inclined so as to be closer to the horizontal than the direction substantially orthogonal to the slip surface are the back of the straight pile 1. By effectively supporting the earth pressure on the side, between the second slant pile 3 and the first slant pile 2, between the first slant pile 2 and the straight pile 1, and in front of the straight pile 1 The ground reaction force on the side is maintained, and the plasticization of the ground between the front surface of the straight pile 1 and the pile can be suppressed as much as possible. Therefore, the straight pile 1, the first slanted pile 2, and the third slanted pile 3, which are rigidly connected as a group pile, can express the maximum supporting force to each other and stabilize the slope.

  In other words, the first slanted pile 2 and the second slanted pile 3 are inclined so as to be closer to the horizontal than the direction substantially perpendicular to the slip surface, so that the local shear force can be resisted only by the bending strength of the pile. And the stress is dispersed in the longitudinal direction, and the ground reaction force due to the earth pressure distribution can be effectively developed. As a result, earth pressure is generated between the front surface of the second slanted pile 3 and the first slanted pile 2 and between the first slanted pile 2 and the straight pile 1. While the load sharing is greatly reduced, the ground reaction force on the front side of the straight pile 1 is also maintained. Then, the straight pile 1, which is located in the ground where the stabilization is maintained by the inclined piles 2 and 3 and is expected to have a direct tensile rigidity by being substantially orthogonal to the slip surface, is located in front of the group pile. The arrangement of the straight piles 1 prevents the slanted piles 2 and 3 from being deformed. Further, since the straight pile 1 and the oblique piles 2 and 3 are rigidly connected to the head, deformation of each other is prevented. As a result, the slanted piles 2 and 3 protect the straight piles 1 while the straight piles 1 protect the slanted piles 2 and 3, and the plasticization of the soil between the pile back and the pile front and the pile is prevented as much as possible. At the same time, each of the slant piles 2, 3 and the straight pile 1 can develop an effective bearing force from an early stage of displacement occurrence, and ultimately, each pile can exhibit a maximum bearing force. .

  In addition, since the straight pile 1 and the inclined piles 2 and 3 are driven in a direction substantially perpendicular to the slip surface inside the slope and in a direction inclined so as to be more horizontal than the slip plane inside the slope, it is like a vertical pile. There is no need to form a step in the middle of the slope, and there are few restrictions on the land and construction during construction, and it is excellent in versatility. In addition, the existing stabilization structure using deterrent piles, when a large deterrent force was required, had to deal with a larger pile diameter and a higher tensile strength pile material. Although it was restricted or the economic efficiency was impaired, in the first embodiment, even if a small-diameter group pile with good mobility is used, the internal stress held by the ground itself is maximized without collapsing and the large pile is used. The deterrent can be obtained, the slope can be stabilized, and the slope can be reinforced rationally with excellent economic efficiency and construction efficiency.

  Further, the second slanted pile 3 is used in addition to the first slanted pile 2, and the pile heads 12, 22, 32 of the straight pile 1, the first slanted pile 2, and the second slanted pile 3 are rigidly connected. By doing so, the ultimate shear strength on the slip surface can be further increased.

  Also, by setting the angle α of the first slanted pile 2 and the angle β of the second slanted pile 3 to 65 degrees to 75 degrees, the axial direction of the first slanted pile 2 and the second slanted pile 3 can be changed. By making an oblique cross-section optimally with the shear plane, the force in the tensile direction is exerted from the early stage by utilizing the peripheral friction of the first slant pile 2 and the second slant pile 3, and the first slant pile 2, the second slant pile 2 The ground reaction force on the front side of the inclined pile 3 can be obtained, and the shear resistance can be quickly and reliably applied while the shear displacement is small. Therefore, generation of large shear displacement and shear stress can be suppressed, and the stability of the slope can be further enhanced.

[Slope Stabilization Structure of Second Embodiment]
As shown in FIG. 4, the slope stabilizing structure of the second embodiment according to the present invention is the slope stabilizing structure without the second slope pile 3 in the first embodiment, and the slope 101 of the ground 100. And a straight pile 1a which is driven in a direction substantially perpendicular to the slip surface 102 inside, and at a position above the straight pile 1a and separated from the slope 101 in a direction substantially perpendicular to the slip surface 102. The sloping pile 2a is installed so as to be inclined so as to approach, and the straight stake 1a and the sloping pile 2a are installed so that a portion on the tip side from the slope 101 reaches the inner side of the slip surface 102, respectively. Things. The straight pile 1a and the slanted pile 2a have the same configuration as the straight pile 1 and the first slanted pile 2 of the first embodiment, and are driven in the same manner as the straight pile 1 and the first slanted pile 2.

  The pile head of the straight pile 1a and the vicinity thereof, and the pile head of the slant pile 2a and the vicinity thereof are embedded in the reinforced concrete 4 provided integrally on the slope 101. The pile head of the pile 1a and the pile head of the inclined pile 2a are rigidly connected via reinforced concrete 4. As in the first embodiment, the reinforced concrete 4 includes a concrete portion 41 and a reinforcing bar 42 disposed in the concrete portion 41. In the second embodiment, a set pile is constituted by the straight pile 1a and the inclined pile 2a.

  The straight pile 1a and the slanted pile 2a have the same configuration as the straight pile 1 and the first slanted pile 2 of the first embodiment, respectively, and as shown in FIG. It is driven in the same way as the slant pile 1. The angle α formed between the inclined pile 2a and the slip surface 102 immediately below is set in the same manner as the angle α formed between the first inclined pile 2 and the slip surface 102 immediately below.

  In the second embodiment, rigid bodies formed by rigidly connecting the straight pile 1a and the inclined pile 2a are arranged side by side along the lateral direction of the slope 101 of the ground 100, and the plurality of rigid bodies are arranged side by side. The pile head of the rigid pile 1a and the pile head of the inclined pile 2a are rigidly connected by reinforced concrete 4 integrally provided on the slope 101 (not shown). By arranging the rigid bodies of the straight pile 1a and the inclined pile 2a side by side, a stable slope structure having a high landslide suppressing force can be formed in a wide range.

  According to the slope stabilizing structure of the second embodiment, the inclined pile 2a inclined so as to approach horizontal more than the direction substantially perpendicular to the slip surface effectively supports the earth pressure on the back side of the straight pile 1a. Thereby, the ground reaction force between the inclined pile 2a and the straight pile 1a and on the front side of the straight pile 1a is maintained, and the plasticization of the ground between the front face of the straight pile 1a and the pile can be suppressed as much as possible. Therefore, the straight pile 1a and the inclined pile 2a rigidly connected as a group pile can express the maximum supporting force to each other and stabilize the slope.

  That is, by inclining the inclined pile 2a so as to be closer to the horizontal than the direction substantially perpendicular to the slip surface, it is possible to avoid a state in which local shearing force is resisted only by the bending strength of the pile, and in the longitudinal direction. The stress can be dispersed, and the ground reaction force due to the earth pressure dispersion can be effectively developed. As a result, an earth pressure is generated between the slanted pile 2a and the straight pile 1a, which bears the external force, and the load sharing of the straight pile 1a is greatly reduced, while the ground reaction force on the front side of the straight pile 1a is also maintained. . Then, the straight pile 1a, which is located in the ground where the stabilization is maintained by the inclined pile 2a and is expected to have a direct tensile rigidity by being substantially orthogonal to the slip surface, is located in front of the group pile, The arrangement of the straight piles 1a prevents the slant piles 2a from being deformed. Further, since the straight pile 1a and the inclined pile 2a are rigidly connected to the head, deformation of each other is prevented. As a result, the slanted pile 2a protects the straight pile 1a while the straight pile 1a protects the slanted pile 2a, and the plasticization of the soil between the pile back surface and the pile front surface and between the piles is prevented as much as possible. Each of the stake 2a and the straight stake 1a can exhibit an effective supporting force from an early stage of the occurrence of displacement, and each of the stakes can ultimately exhibit a maximum supporting force.

  In addition, since the straight pile 1a and the inclined pile 2a are driven in a direction substantially orthogonal to the slip surface inside the slope and in a direction inclined closer to horizontal than the same, the slope like a vertical pile is used. There is no need to form a step on the way, and there are few restrictions on land and construction during construction, and it is excellent in versatility. In addition, the existing stabilization structure using deterrent piles, when a large deterrent force was required, had to deal with a larger pile diameter and a higher tensile strength pile material. Although it was restricted or the economic efficiency was impaired, in the second embodiment, even if a pile with a small diameter having good mobility was used, the internal stress held by the ground itself was maximized without collapsing and the large pile was used. The deterrent can be obtained, the slope can be stabilized, and the slope can be reinforced rationally with excellent economic efficiency and construction efficiency. In addition, the corresponding effects are obtained from the configuration corresponding to the first embodiment.

[Comparison between Example and Comparative Example]
In the slope stabilization structure according to the present invention, a first example of a model example corresponding to the structure of the first embodiment in which three rows of a straight pile 1 + a first slope pile 2 + a second slope pile 3 forms one set. And the second example of the model example corresponding to the structure of the second embodiment in which two rows of the straight pile 1a and the slanted pile 2a form one set, confirms the effectiveness of the model example compared to the same number of straight piles. For this purpose, model experiments of the first embodiment, the second embodiment, and the comparative example were performed. In this model experiment, the behavior at each position can be measured as a numerical value by providing a sensor in the pile or ground model.

  FIG. 5 is a configuration diagram of the model experiment apparatus. The model experiment apparatus 500 has a pair of shear boxes 501 in an upper box section 502 and a lower box section 503, and fills the shear box 501 with silica sand 7 so as to have a relative density of 80% to create a simulated ground. In this simulated ground, an aluminum square bar 10 mm x 10 mm x 260 mm (hollow, 1 mm thick) having a similarity ratio of 1/10 was assumed as a model pile 504, assuming a φ114.3 mm steel pipe pile, as an example and a comparative example. It was arranged so that it might become. In FIG. 5, reference numeral 505 denotes a shear plane corresponding to the slip surface 102.

  FIG. 6 shows the pile arrangement in the model experiment. 6A and 6B show pile arrangements of the first embodiment and a first comparative example which is a comparative example thereof. In the first embodiment, a straight pile 1 + a first oblique pile 2 + a second oblique pile are shown. The model pile 504 is arranged in the upper box part 502 and the lower box part 503 so as to correspond to the three piles 3, and the heads of the three model piles 504 are similarly rigidized with an aluminum rod φ3 mm considering the similarity ratio. Tied. In the first comparative example, three model piles 504 substantially orthogonal to the shear surface 505 are arranged in the upper box portion 502 and the lower box portion 503 so as to correspond to the case where the straight piles 1 are driven in three rows. The heads of the three model piles 504 were similarly rigidly connected with an aluminum rod φ3 mm in consideration of the similarity ratio.

  FIGS. 6 (c) and 6 (d) show pile arrangements of the second embodiment and a second comparative example which is a comparative example thereof. In the second embodiment, the pile arrangement corresponds to two of the straight pile 1a and the inclined pile 2a. The model pile 504 is placed in the upper box part 502 and the lower box part 503 while holding the tip thereof, and the heads located at the rear ends of the two model piles 504 are similarly made of aluminum rods in consideration of the similarity ratio. It was rigidly connected at φ3mm. In the second comparative example, two model piles 504 that are substantially perpendicular to the shear surface 505 are placed in the upper box portion 502 and the lower box portion 503 in the tip portions so as to correspond to the case where the straight piles 1a are driven in two rows. And the heads located at the rear ends of the two model piles 504 were similarly rigidly connected with an aluminum rod φ3 mm in consideration of the similarity ratio.

Then, with the upper surface of the shearing box 501 constrained at a confining pressure of 25 kN / m ² , an experiment was performed on the lower box portion 503 by applying a shearing force from the side at a speed of 1 mm / min. Sensors such as an earth pressure gauge and a strain gauge were attached to each model pile 504 at a predetermined pitch in the depth direction, and the earth pressure, strain, and the like applied to each model pile 504 were obtained.

  FIG. 7 shows the relationship between the shear displacement and the shear stress obtained by this model experiment. The solid line of the locus of the black point in FIG. 7A is the result of the first example, the dotted line of the locus of the white point is the result of the first comparative example, and the solid line of the locus of the black point in FIG. As a result of the second embodiment, the dotted line of the locus of the white point is the result of the second comparative example, and the signals obtained by the shear stress measurement sensor and the displacement sensor respectively installed in the model experiment apparatus 500 are converted by a computer. , In a graph. In addition, the shear stress referred to here is not the shear stress of the model pile 504, but the shear stress of the simulated ground reproduced in the experimental box, and the shear displacement referred to herein is the shear displacement of the simulated ground. .

  According to the results of this model experiment, in the first example, although the initial stiffness is almost the same as the shear experiment result of the first comparative example corresponding to the three rows of head stiffening of the straight pile 1, the first example eventually ends up. It turns out that it expresses a large shear stress, that is, it has a high reinforcing effect.

  On the other hand, in the second embodiment and the second comparative example corresponding to the two rows of head stiffening of the straight pile 1a, the initial rigidity of the second embodiment is higher than that of the second comparative example, but the subsequent shear stress is higher. -There is not much difference in the shear displacement curve, and ultimately the shear stress is lower than in the second comparative example. However, although the result is a shear stress-shear displacement curve, according to the data of the earth pressure gauge detected at the same time, the distribution of the earth pressure generated in the model pile 504 differs greatly between the second embodiment and the second comparative example. Was found to occur.

  The natural ground can always move, and there are “broken ground” and “unbroken ground” even if the ground has the same displacement for a certain load. Unbroken ground keeps itself as an elastic body even if deformed, so that it does not collapse. If the ground is broken and plasticized, it collapses beyond the support capacity of the pile. Such a difference in ground properties is considered to have a correlation with a difference in earth pressure distribution.

  Therefore, paying attention to the difference in earth pressure generated in the shear test between the first and second examples and the first and second comparative examples, the ground corresponding to the front / rear surfaces of the pile and the ground between the piles was determined by a model corresponding to the model experiment. Properties were evaluated by three-dimensional FEM analysis. The three-dimensional FEM analysis is to analyze the stress and deformation of the ground on a three-dimensional axis by viewing the ground as an elasto-plastic body under static conditions, and to analyze the stress and deformation of the ground. This is advantageous for grasping continuous behavior and three-dimensional behavior.

  In the three-dimensional FEM analysis, analysis conditions were determined and parameters were set so as to be most consistent with each data obtained by a model experiment, and FEM analysis was performed using the conditions and parameters. Then, by processing the data so that it could be visually recognized, the ground condition between the piles and before and after the pile was confirmed.

  FIGS. 8A and 8B show three-dimensional FEM analysis model diagrams corresponding to the first embodiment and the first comparative example, and FIGS. 8C and 8D show the second embodiment and the second comparative example. It is a corresponding three-dimensional FEM analysis model diagram, in which 601 is a model straight pile, 602 is a model oblique pile, and 603 is a shear plane. In each model, three sets of the set pile of the first example, the set pile of the first comparative example, the set pile of the second example, and the set pile of the second comparative example are juxtaposed in the horizontal direction. Is generally rigidly connected.

  FIGS. 9 to 12 show three-dimensional FEM analysis using models corresponding to FIGS. 8A, 8B, 8C, and 8D. The analysis result immediately above the surface (slip surface) is taken out, binarized with a predetermined threshold value, and the portion painted black is represented as plasticized ground, and the portion not painted is represented as non-plasticized ground. 9 (a) and 10 (a) are the model for analysis of the first embodiment, FIGS. 9 (b) and 10 (b) are the model for analysis of the first comparative example, FIGS. 11 (a) and 12 (A) shows the model for analysis of the second embodiment, and FIGS. 11 (b) and 12 (b) show the model for analysis of the second comparative example.

  According to the distribution of the plastic zone in the longitudinal direction in FIGS. 9 and 11, in the models corresponding to the first and second embodiments, the non-plasticized zone is located between the piles above the slip surface (closer to the slope surface layer). It can be seen that even in the eventual displacement state, the ground that maintains the ground reaction force without breaking remains. On the other hand, in the models corresponding to the first comparative example and the second comparative example, it can be seen that the ground between the piles is almost entirely plasticized. The ground once plasticized cannot exhibit ground reaction force as an elastic body between the piles.

  According to the distribution of the plastic zone in the cross section immediately above the shear plane (slip surface) in FIGS. 10 and 12, in the models corresponding to the first and second embodiments, the front and rear surfaces of the pile and the distance between the piles are different. However, it can be seen that the unplasticized region remains and a ground reaction force can be expected, whereas the models corresponding to the first comparative example and the second comparative example plasticize most of the ground. That is, it can be said that the present invention does not merely have a merit in terms of a load, but can effectively utilize the earth pressure around the pile material to stably stabilize the slope.

(Modifications of the embodiment, etc.)
The invention disclosed in the present specification, in addition to each invention, each embodiment, and each example, those in which these partial configurations are changed to other configurations disclosed in the present specification and specified within an applicable range, Alternatively, these include configurations specified by adding other configurations disclosed in the present specification to the configurations, or superordinate concepts specified by deleting and specifying these partial configurations to the extent that a partial operation and effect can be obtained. And the following modifications are also included.

  For example, a member that rigidly connects the pile head 12 of the straight pile 1, the pile head 22 of the first slant pile 2, and the pile head 32 of the second slant pile 3, or the pile head of the straight pile 1a and the slant pile The member for rigidly connecting the pile head 2a is not limited to the reinforced concrete 4 and may be any member that can be rigidly connected unless it is rotatable, such as a hinge. The pile head 22 of the first slanted pile 2 and the pile head 32 of the second slanted pile 3 or the pile head of the straight pile 1a and the pile head of the slanted pile 2a are rigidly connected by steel. The configuration may be adopted.

  INDUSTRIAL APPLICATION This invention can be utilized at the time of stabilizing the slope of the ground.

1, 1a ... straight pile 11 ... steel pipe 12 ... pile head 2 ... first slant pile 21 ... steel pipe 22 ... pile head 2a ... slant pile 3 ... second slant pile 31 ... steel pipe 32 ... pile head 4 ... Reinforced concrete 41 ... Concrete part 42 ... Reinforcing rod 51 ... Drilling rod 52 ... Down the hole hammer 53 ... Bit 54 ... Injection pipe 55 ... Packer 6 ... Pile 61 ... Steel pipe 611 ... Discharge hole 63 ... Anchoring layer 100 ... Ground mountain 101 ... Slope 102 ... Slip surface 103: drilling α: angle between the first slanted pile and the slip surface immediately below β: angle between the second slant pile and the slip surface immediately below M: vertical pile N: slant pile 201: slip surface 202: Cut slope 500: Model test equipment 501: Shear box 502: Upper box 503: Lower box 504: Model pile 505: Shear section 601: Model straight pile 602: Model slope pile 603: Shear section

Claims (5)

In a direction substantially orthogonal to one slip surface inside the slope of the ground, a straight pile that is driven to the far side of the one slip surface,
Wherein at spaced locations of the upper vertical piles, the sleeping inclined to approach horizontally from a direction substantially perpendicular to one of the sliding surfaces, have a Hasukui being pouring deep side of the one sliding surface And
The pile head of the straight pile and the pile head of the slant pile, which are arranged at positions separated along the ground slope, are rigidly connected ,
A slope characterized in that a non-plasticized region that maintains the internal stress of the ground itself is left between the straight pile and the slope pile closer to the ground slope surface layer than the one slip surface. Stabilizing structure. The slanted pile is a first slanted pile,
At the upper, spaced apart position of the first slant pile, slantingly slantingly approaches the one slip surface so as to approach horizontally from a direction substantially perpendicular to the one slip surface, and being driven into the inner side of the one slip surface. Having a second slant pile,
A pile head of the straight pile, a pile head of the first diagonal pile, and a pile head of the second diagonal pile, which are arranged at positions separated along the ground slope, are rigidly connected ;
The interior of the ground itself between the straight pile and the first slant pile, and between the first slant pile and the second slant pile, on the side closer to the ground slope surface layer than the one slip surface. The slope stabilizing structure according to claim 1, wherein a non-plasticized region maintaining stress is left .   The rigid body of the straight pile and the slant pile, or the rigid body of the straight pile, the first slant pile, and the second slant pile are juxtaposed along the lateral direction of the slope of the ground. The slope stabilizing structure according to claim 1 or 2, wherein:   Each of the straight pile and the slanted pile, or the straight pile, the first slanted pile, and the second slanted pile are formed of a steel pipe having a diameter of 100 to 300 mm and a fixing layer formed by grout material injection. The slope stabilizing structure according to any one of claims 1 to 3, wherein the slope stabilizing structure is configured. An angle formed between the inclined pile and the one slip surface immediately below the inclined pile is set to 65 degrees to 75 degrees,
Or wherein said angle 65 to 75 degrees formed between the first sliding surface immediately below the first Hasukui first Hasukui, the right under the said and second Hasukui second Hasukui The slope stabilizing structure according to any one of claims 1 to 4, wherein the angle formed by the one slip surface is set to 65 degrees to 75 degrees.

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