JP6915800B2 - Construction method of crushed stone structure and crushed stone structure - Google Patents

Description

The techniques disclosed herein relate to methods of constructing crushed stone structures and crushed stone structures.

For example, in the field of large-scale infrastructure construction such as high-rise houses and highways, a method of forming crushed stone pillars in the ground (for example, Patent Document 1) and concrete in the ground for ground improvement such as ground strengthening and liquefaction countermeasures. Methods for forming underground structures such as piles have been developed. The ground that requires ground improvement has different geology and surface properties (for example, inclined surface, etc.) for each ground, and it is necessary to improve the ground according to the properties of the ground. For example, for ground having an inclined surface, it may be necessary to improve the ground to prevent landslides. In such a case, a flat surface in the middle of the inclined surface or above the inclined surface has a wall shape. Underground structures may be formed in the ground. In this way, since it is necessary to perform ground improvement suitable for the ground for each ground, the size and shape of the underground structure for ground improvement also differ for each ground. For example, Patent Document 2 discloses an underground structure in which a row of concrete piles is constructed along a slope and concrete piles are formed in a wall shape.

Japanese Unexamined Patent Publication No. 2010-248885 Japanese Unexamined Patent Publication No. 7-238554

The underground structure of Patent Document 2 suppresses landslides on inclined surfaces by placing concrete pile rows in a wall shape. However, since the underground structure of Patent Document 2 is formed of concrete, there are problems such as that it takes time and effort to construct, and that it becomes difficult to dispose of the concrete solidified in the ground when it is removed. there were. The present specification discloses a technique for easily forming a structure having a desired shape and size having strength as a structure and water permeability using a crushed stone column in the ground.

The method for constructing a crushed stone structure disclosed in the present specification is to construct a crushed stone structure in the ground. In this method, a first excavation step of forming a first space in the ground and a first method of forming a first crushed stone pillar by throwing crushed stone into the first space formed by the first excavation step and pressing the crushed stone. A crushed stone pillar forming step, a second excavation step of forming a second space in the ground at a position connected to the first crushed stone pillar, and a second space formed by the second excavation step are pressed by throwing crushed stone. By doing so, a second crushed stone pillar forming step of forming a second crushed stone pillar connected to the first crushed stone pillar is provided.

In the above method for constructing a crushed stone structure, a second crushed stone column connected to the first crushed stone column can be formed by forming a second space at a position connected to the first crushed stone column. Therefore, it is possible to construct a crushed stone structure in which a plurality of crushed stone columns are continuous in the ground. Since crushed stone is used instead of concrete, a structure having appropriate water permeability and strength can be easily formed in the ground. In addition, the method of constructing the crushed stone structure corresponds to the production method and the manufacturing method of the crushed stone structure, and can also be said to be the production method and the manufacturing method of the crushed stone structure.

Further, the crushed stone structure disclosed in the present specification is formed in a space formed in the ground. The crushed stone structure includes a plurality of crushed stone columns composed of crushed stones. At least one of the plurality of crushed stone columns is connected to another crushed stone column adjacent to the crushed stone column. At least one crushed stone column and the other crushed stone column among the plurality of crushed stone columns form one structure in succession.

In the above-mentioned crushed stone structure, a plurality of crushed stone columns are continuously formed as one structure. Therefore, a crushed stone structure having a desired shape, size, water permeability, and strength can be easily formed in the ground.

The perspective view which shows an example of the crushed stone structure which concerns on Example. The top view which shows a part of the crushed stone structure which concerns on Example. The figure which shows the schematic structure of the crushed stone pillar forming apparatus. The cross-sectional view which shows the structure of the cylindrical part and the spiral part of an attachment. The flowchart which shows the manufacturing method of the crushed stone structure which concerns on Example. It is a figure which shows the manufacturing method of the crushed stone structure which concerns on Example, and shows the state which formed the 1st space. It is a figure which shows the manufacturing method of the crushed stone structure which concerns on Example, and shows the state which formed the crushed stone pillar in the 1st space. It is a figure which shows the manufacturing method of the crushed stone structure which concerns on Example, and shows the state which formed the 2nd space. The figure which shows another example of the crushed stone structure which concerns on Example. The figure which shows the state which the crushed stone structure, the drainage pipe and the stand pipe are installed on the inclined surface. The figure which shows still another example of the crushed stone structure which concerns on Example.

The main features of the examples described below are listed. It should be noted that the technical elements described below are independent technical elements and exhibit technical usefulness alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. do not have.

(Characteristic 1) In the method of constructing the crushed stone structure disclosed in the present specification, in the second excavation step, a part of the formed first crushed stone pillar and the land adjacent to the first crushed stone pillar are excavated into the ground. A second space may be formed. In the second crushed stone pillar forming step, the second crushed stone pillar is formed so that a part of the diameter of the first crushed stone pillar formed by the first excavation step and the diameter of the second crushed stone pillar overlap when viewed in a plan view. May be good. According to such a configuration, by forming the second crushed stone column so that the diameter of the first crushed stone column and a part of the diameter of the second crushed stone column overlap, a more reliable continuous underground structure can be constructed. Can be done. Therefore, it is possible to construct a crushed stone structure in the ground in which a desired shape, size, permeability, and strength are adaptively adjusted to the geology.

(Characteristic 2) In the method for constructing a crushed stone structure disclosed in the present specification, the first excavation step, the first crushed stone column forming step, the second excavation step, and the second crushed stone column forming step use a crushed stone column forming apparatus. It may be done. The crushed stone column forming device may include an attachment including a cylindrical portion and a spiral portion that is rotatably arranged in the cylindrical portion and is connected to a drive device to excavate the ground. In the first excavation step and the second excavation step, the spiral portion and the cylindrical portion may be integrally rotated by a driving device to excavate the ground while inserting the attachment into the ground. In the first crushed stone pillar forming step and the second crushed stone pillar forming step, the crushed stone may be thrown into the cylindrical portion, and the crushed stone pillar may be formed by the crushed stone thrown into the cylindrical portion while raising the attachment from the ground. According to such a configuration, by forming the crushed stone structure using the crushed stone column forming device provided with the above attachment, the second space is formed so as to connect the first crushed stone column and the second crushed stone column. By throwing crushed stone into the second space and pressing it, the first crushed stone pillar and the second crushed stone pillar can be connected. Therefore, a continuous crushed stone structure can be suitably constructed, and a crushed stone structure having a desired shape can be constructed.

(Characteristic 3) In the crushed stone structure disclosed in the present specification, the diameter of at least one crushed stone column among the plurality of crushed stone columns may partially overlap with the diameter of the other crushed stone columns when viewed in a plan view. good. According to such a configuration, the crushed stone structure can be more reliably made into a continuous underground structure. Therefore, the shape of the crushed stone structure can be made into a desired shape.

(Feature 4) In the crushed stone structure disclosed in the present specification, a plurality of crushed stone columns may be arranged in a straight line, or each of the plurality of crushed stone columns may be connected to another adjacent crushed stone column. good. According to such a configuration, the crushed stone structure becomes a wall shape by arranging the plurality of crushed stone columns in a straight line. Therefore, for example, it can be suitably used for ground improvement for suppressing landslides on the ground such as an inclined surface.

(Feature 5) The crushed stone structure disclosed in the present specification may further include a drainage pipe having one end connected to the crushed stone structure in the ground and the other end located on the ground surface. According to such a configuration, for example, by installing the other end of the drainage pipe at a position lower than one end connected to the crushed stone structure or at a position at the same height, the drainage pipe passes between the crushed stones constituting the crushed stone structure. Water permeation can be suitably drained through the drain pipe. Therefore, the water in the ground can be drained suitably, the water level in the ground can be lowered, and the ground collapse due to the liquefaction phenomenon of the ground and the softening of the ground can be prevented.

Hereinafter, the crushed stone structure 50 according to the embodiment will be described. The crushed stone structure 50 is formed by press-fitting crushed stone into a space formed in the ground. The crushed stone structure 50 includes a plurality of crushed stone columns 52. Each of the plurality of crushed stone columns 52a to 52h has a cylindrical shape extending in the z direction. Therefore, when the crushed stone pillar 52 is viewed along the z direction (that is, when the crushed stone pillar 52 is viewed from above), it has a circular shape. In the present specification, the diameter of the circular shape when viewed along the z direction is referred to as the diameter of the crushed stone column 52. As is clear from the explanation described later, the z direction in which the crushed stone pillar 52 extends is the direction of excavating the ground in order to form a space in the ground. Therefore, when the space is formed by excavating perpendicularly to the ground, the crushed stone pillar 52 extends in a direction orthogonal to the ground. When excavating at an angle with respect to the ground to form a space, the crushed stone pillar 52 will extend at an inclination with respect to the ground. As shown in FIG. 1, the crushed stone structure 50 includes eight crushed stone columns 52a to 52h. The eight crushed stone columns 52a to 52h are arranged in a straight line and extend in a row in the x direction. That is, the crushed stone structure 50 has a wall shape. The dimensions of the eight crushed stone columns 52a to 52h in the y direction (that is, the radial dimensions of the crushed stone columns 52a to 52h) are the same. Further, the dimensions of the eight crushed stone columns 52a to 52h in the z direction (that is, the dimensions of the crushed stone columns 52a to 52h in the depth direction) are the same. In the following specification, when it is necessary to distinguish the crushed stone pillar 52, it is described by using the alphabet along the characters such as the crushed stone pillar 52a to 52h, and when it is not necessary to distinguish it, it is simply described as the crushed stone pillar 52. May be done.

The adjacent crushed stone columns 52 are connected to each other, and the crushed stone structure 50 forms one structure. As shown in FIG. 2, when the crushed stone structure 50 is viewed from above in a plan view (that is, when viewed along the z direction), a part of the crushed stone pillar 52a and a part of the crushed stone pillar 52b overlap, and the crushed stone pillar 52b And a part of the crushed stone pillar 52c overlap. Specifically, the diameter R1 of the crushed stone pillar 52a and the diameter R2 of the crushed stone pillar 52b overlap by the length L1. The length L1 can be, for example, a length of 0% or more and 50% or less of the diameter R1 of the crushed stone pillar 52a and the diameter R2 of the crushed stone pillar 52b. Preferably, by setting the length L1 to 0% or more of the diameters R1 and R2, the crushed stone columns 52a and 52b can be connected to form a continuous structure. Further, by setting the length L1 to 50% or less of the diameters R1 and R2, it is possible to suppress an increase in the number of crushed stone columns 52 constituting the crushed stone structure 50. More preferably, the length L1 may be 5% or more and 25% or less of the diameters R1 and R2. Similarly, the diameter R2 of the crushed stone pillar 52b and the diameter R3 of the crushed stone pillar 52c overlap by the length L2, and the length L2 is 0% or more of the diameter R2 of the crushed stone pillar 52b and the diameter R3 of the crushed stone pillar 52c, and , The length is 50% or less. In this way, all the eight crushed stone columns 52 constituting the crushed stone structure 50 overlap with the adjacent crushed stone columns 52 when viewed in a plan view.

Although the diameters of the crushed stone columns 52 of this embodiment are the same, the diameter is not limited to such a configuration. The plurality of crushed stone columns 52 constituting the crushed stone structure 50 may be connected to each other, and the diameters of the crushed stone columns may be different. When the diameter of each crushed stone column is different, it is preferable that the crushed stone column having the smaller diameter among the adjacent crushed stone columns overlaps with the adjacent crushed stone column within the above range. Further, in this embodiment, the dimensions of each crushed stone pillar 52 in the depth direction are the same for all the crushed stone pillars 52, but the dimensions of each crushed stone pillar 52 in the depth direction are different for each crushed stone pillar 52. It may be a dimension. As a result, even if there are restrictions on the formation of crushed stone columns due to hard rock, etc., the distance from the ground surface to the upper surface of the crushed stone columns can be kept constant by changing the dimensions of each crushed stone column in the depth direction. It is possible to flexibly respond to the construction of the crushed stone structure kept at.

Each crushed stone pillar 52 constituting the crushed stone structure 50 is formed by using the crushed stone pillar forming device 100. Here, the crushed stone column forming device 100 will be described. As shown in FIG. 3, the crushed stone pillar forming device 100 includes a ground improvement machine 40 as a construction machine and an attachment 10 attached to the ground improvement machine 40. As shown in FIG. 3, the ground improvement machine 40 includes a ground improvement machine main body structure 1, a cabin 7 as a driver's seat, a crawler 6 which is an endless track capable of moving on rough terrain with low ground pressure, and a construction time. The outrigger 5 that suppresses the swing of the ground improvement machine 40 is provided.

The ground improvement machine 40 further includes a drive device 11 that supplies a rotational driving force to the attachment 10 via a motor output shaft 27, a leader 4 having an elevating guide rail 9, and a leader as a configuration for operating the attachment 10. It includes a leader mounting base 2 for supporting the leader 4, a hydraulic cylinder 3 for controlling the inclination of the leader 4, and an extension pedestal 8 integrally formed with the leader 4 at the lower end of the leader 4. ..

The attachment 10 has a cylindrical portion 12 provided with fins 13, a spiral portion 14, a surrounding frame 30 for restraining the steady rest of the cylindrical portion 12, a hanger stay 18 having a bifurcated fork shape, and a cam protrusion 17. The top cover case 16, the crushed stone loading device 32, the mounting plate 37 that supports the surrounding frame 30, the support arm 39 that supports the crushed stone loading device 32, and the construction management device 41 that manages the construction state by the attachment 10. I have.

A crushed stone input hole 15 is formed in the cylindrical portion 12, and the crushed stone input hole 15 is closed by an opening / closing lid 20. The crushed stone throwing device 32 includes a hopper portion 33 and a chute portion 34 arranged below the hopper portion 33. The crushed stone input hole 15 is closed by the opening / closing lid 20 when the attachment 10 excavates the ground. As a result, it is possible to prevent earth and sand from entering through the crushed stone input hole 15. Further, when the crushed stone is put into the cylindrical portion 12, the opening / closing lid 20 is opened. As a result, the crushed stone thrown into the crushed stone throwing device 32 can be thrown into the cylindrical portion 12 through the crushed stone throwing hole 15. The commonly used crushed stone is not a fixed shape because it is crushed rock, and has a diameter of about 2 to 50 mm, but is not limited to this. The crushed stone may contain one having a diameter smaller than 2 mm, or may contain one having a diameter larger than 50 mm. By changing the shape of the attachment, it is possible to handle objects with a diameter larger than 50 mm.

FIG. 4 is a cross-sectional view showing the configuration of the cylindrical portion 12 and the spiral portion 14. The spiral portion 14 is integrally formed with the rotary input shaft 26 and the core rod 22. The rotary input shaft 26 is connected to the motor output shaft 27 of the drive device 11. The rotary input shaft 26 rotates according to the rotational driving force of the motor output shaft 27, and transmits the rotational driving force to the spiral portion 14 via the integrally coupled core rod 22. An excavation blade is provided at the tip of the spiral portion 14. The excavation blade is formed in a spiral shape in which the diameter increases toward the tip of the spiral portion 14. Approximately the entire excavation blade is arranged in the cylindrical portion 12, and only a part of the tip of the excavation blade protrudes from the tip of the cylindrical portion 12.

The core rod 22 is rotatably connected to the cylindrical portion 12 by the bearing tube 23 and the radiation stay 24, and shares the rotating shaft with the cylindrical portion 12. On the other hand, the cylindrical portion 12 has spiral fins 13 around it. The fin 13 has a spiral shape in the same direction as the spiral of the spiral portion 14 (that is, the excavation blade). That is, when excavating, the cylindrical portion 12 and the spiral portion 14 rotate in the same direction. As a result, the excavated earth and sand generated by the excavation of the spiral portion 14 is transported to the ground surface by the fins 13.

The attachment 10 further includes a one-way clutch mechanism (not shown) between the rotation input shaft 26 and the core rod 22 inside the top cover case 16. The one-way clutch mechanism is in an operating state in which the spiral portion 14 and the cylindrical portion 12 automatically rotate as a unit when driven in the rotational direction during excavation. As a result, the earth and sand excavated by the spiral portion 14 as described above can be discharged to the ground by the fins 13 of the cylindrical portion 12. On the other hand, in the rotational drive in the direction opposite to the rotational direction during excavation, the spiral portion 14 can apply pressure to the crushed stone and the cylindrical portion 12 can automatically stop the rotation. Hereinafter, the direction in which the cylindrical portion 12 and the spiral portion 14 rotate in the same direction, that is, the rotation direction during excavation is referred to as a "forward rotation direction", and the direction in which the cylindrical portion 12 and the spiral portion 14 rotate in the direction opposite to the rotation direction during excavation, that is, the spiral portion. The direction of rotation in which pressure is applied to the crushed stone at 14 is sometimes referred to as the "reversal direction".

It is preferable that the crushed stone column forming device 100 further includes a ruler 71 for positioning the attachment 10 and a positioning pile 72. The positioning stake 72 is attached to the ruler 71, and the ruler 71 is attached to the surrounding frame 30. With the positioning pile 72, the excavation position by the attachment 10 (that is, the formation position of the crushed stone pillar 52) can be easily and surely positioned. In this embodiment, one positioning pile 72 is provided, but the configuration is not limited to this. For example, two or more positioning piles 72 may be provided. By providing two or more positioning piles 72 and fixing them along the circumference of the crushed stone pillar 52 constructed earlier, the positioning accuracy can be improved and the displacement of the attachment 10 due to vibration during excavation can be prevented. ..

A method for manufacturing the crushed stone structure 50 will be described with reference to FIGS. 5 to 8. The crushed stone structure 50 is constructed by forming one crushed stone pillar 52 constituting the crushed stone structure 50. In this embodiment, the crushed stone columns 52a are first formed, and then the crushed stone columns 52b to 52h are formed in order.

As shown in FIG. 5, first, the first excavation step is executed (S12). In the first excavation step, the underground is excavated using the crushed stone pillar forming device 100 to form the first space 60 for forming the crushed stone pillar 52a. The first excavation process is performed by the following procedure. First, the attachment 10 is aligned. The alignment of the attachment 10 is performed by adjusting the position and direction of the ground improvement machine 40 by driving the crawler 6. After adjusting the position and direction of the ground improvement machine 40, the ground improvement machine 40 may be fixed by the outrigger 5. As a result, it is possible to suppress swinging and misalignment of the ground improvement machine 40 during construction. After fixing the ground improvement machine 40, the attachment 10 is lowered while driving the drive device 11. The drive device 11 drives the cylindrical portion 12 and the spiral portion 14 so as to rotate in the forward rotation direction. Therefore, the attachment 10 inserts the attachment 10 into the ground while rotating in the forward rotation direction to excavate the ground. The earth and sand discharged by excavation in the ground is carried to the outer circumference of the cylindrical portion 12 and discharged to the ground surface by the fins 13. As shown in FIG. 6, when the attachment 10 reaches a predetermined depth, the driving of the forward rotation of the driving device 11 is stopped, and the excavation is completed. Then, the first space 60 is formed in the ground. As is clear from the above description, the first space 60 has a cylindrical shape extending in the excavation direction (z direction).

Next, the crushed stone pillar forming step of forming the crushed stone pillar 52a in the first space 60 formed in the first excavation step of step S12 is executed (S14). The crushed stone column forming step is performed by the following procedure. First, with the opening / closing lid 20 open, crushed stone is charged into the crushed stone loading device 32. The crushed stone thrown into the crushed stone throwing device 32 is thrown into the cylindrical portion 12 through the crushed stone throwing hole 15. Next, the drive device 11 is driven so that the spiral portion 14 rotates in the reverse direction. Then, the attachment 10 rises while rotating in the reverse direction, and discharges the crushed stone thrown into the cylindrical portion 12 while pressing it from the spiral portion 14. Therefore, the attachment 10 is pushed out from the first space 60, and the crushed stone pillar 52a is formed in the first space 60. As shown in FIG. 7, when the attachment 10 is pushed out to the ground surface, the drive of the reverse rotation of the drive device 11 is stopped. Then, the crushed stone pillar 52a is formed in the first space 60. As is clear from the above description, the crushed stone column 52a has a cylindrical shape extending in the excavation direction (z direction).

Next, the second excavation step is executed (S16). In the second excavation step, the crushed stone pillar forming device 100 is used to excavate a part of the crushed stone pillar 52a in the ground or the ground at a position substantially in contact with the crushed stone pillar 52a to form the crushed stone pillar 52b. Second space 62 is formed. As described above, the crushed stone column forming apparatus 100 slightly expands the formed space toward the outer periphery in the crushed stone column forming step (for example, step S14). Therefore, by forming the second space 62 at a position substantially in contact with the crushed stone pillar 52a, it is possible to form a space for forming the crushed stone pillar 52 connected to the crushed stone pillar 52a. The second excavation process is performed by the following procedure. First, the position of the attachment 10 is moved to align the attachment 10. As shown in FIG. 2, the crushed stone pillar 52b is obtained by subtracting R2-L1 (that is, the dimension L1 of the length in which the crushed stone pillars 52a and 52b overlap from the radial dimension R2 of the crushed stone pillar 52b) from the position of the crushed stone pillar 52a. It is formed at a position moved in the + x direction by (the dimension). Therefore, the attachment 10 is moved by R2-L1 in the x direction. Since the procedure for aligning the attachment 10 is the same as that in step S12, detailed description thereof will be omitted. After aligning the attachment 10, the attachment 10 is lowered while driving the drive device 11 so that the spiral portion 14 rotates in the forward rotation direction. Then, the attachment 10 excavates a part of the underground and the crushed stone pillar 52a while rotating in the normal rotation direction. As described above, the crushed stone pillar 52a merely presses and integrates the crushed stone thrown into the cylindrical portion 12. Therefore, only a part of the crushed stone pillar 52a can be excavated by the attachment 10 without destroying the crushed stone pillar 52a. Since the excavation procedure is the same as in step S12, detailed description thereof will be omitted. As shown in FIG. 8, when the attachment 10 reaches a predetermined depth, a second space 62 is formed in the ground.

Next, the crushed stone pillar forming step of forming the crushed stone pillar 52b in the second space 62 formed in the second excavation step of step S16 is executed (S18). Since the procedure of the crushed stone pillar forming step in step S18 is the same as that of the crushed stone pillar forming step in step S14, detailed description thereof will be omitted. The second space 62 is formed by excavating a part of the crushed stone pillar 52a in the ground. Therefore, by forming the crushed stone pillar 52b in the second space 62, a structure in which the crushed stone pillar 52a and the crushed stone pillar 52b are connected is formed in the ground.

Next, it is determined whether or not all the crushed stone columns 52 constituting the crushed stone structure 50 have been formed (S20). That is, it is determined whether or not all the crushed stone columns 52a to 52h are formed. If there is a crushed stone column 52 that has not been formed among the crushed stone columns 52a to 52h (NO in step S20), the process returns to step S16, and steps S16 and S18 are repeated. That is, a part of the formed crushed stone pillar 52 and the underground adjacent to the crushed stone pillar 52 are excavated. Then, the crushed stone pillar 52 is formed in the space formed by the excavation. For example, if only the crushed stone pillar 52a and the crushed stone pillar 52b are formed, a part of the crushed stone pillar 52b in the + x direction and the ground adjacent to the crushed stone pillar 52b in the + x direction are excavated. Then, a crushed stone pillar 52c is formed in the space formed by excavation. In this way, steps S16 and S18 are repeated until all the crushed stone columns 52a to 52h constituting the crushed stone structure 50 are formed. Then, when all the crushed stone columns 52a to 52h are formed (YES in step S20), the construction of the crushed stone structure 50 is completed. In addition, when forming crushed stone pillars 52a to 52h, it is not limited to the above, and after forming crushed stone pillars by skipping one by one like 52a, 52c, 52e, crushed stone pillars such as 52b and 52d are formed in the gap. You may. By constructing the crushed stone structure 50 in this order, the load applied to the attachment 10 can be made evenly close to the left and right, and excavability with a stable set angle can be obtained.

In this embodiment, a part of the crushed stone pillar 52 and the underground adjacent to the crushed stone pillar 52 are excavated, and the crushed stone pillar 52 is formed in the space formed by the excavation. Therefore, the adjacent crushed stone columns 52 can be connected. By forming the plurality of crushed stone columns 52 in this way, it is possible to construct a crushed stone structure 50 in which the plurality of crushed stone columns 52 are continuous in the ground.

In this embodiment, in the second excavation step, the crushed stone columns 52b to 52h are formed so that the crushed stone columns 52a to 52h are arranged in a straight line, but the configuration is not limited to this. The crushed stone column 52 formed later may be formed so as to be connected to the crushed stone column 52 formed earlier, and the crushed stone column 52 formed later may be in any direction with respect to the crushed stone column 52 formed earlier. They may be adjacent to each other. For example, as shown in FIG. 9, in the crushed stone structure 150, the crushed stone pillars 52i are connected to five crushed stone pillars 52j to 52n. As described above, the crushed stone structure 150 may be configured such that one crushed stone pillar 52 is connected to a plurality of three or more crushed stone pillars 52. Further, the crushed stone structure 150 includes a portion 53 in which three crushed stone columns 52i to 52k overlap. As described above, the crushed stone structure 150 may include an overlapping portion 53 in which a plurality of three or more crushed stone columns 52 overlap. By constructing in this way, the strength of the crushed stone structure 150 can be further increased. In this way, by combining the plurality of crushed stone columns 52, a crushed stone structure having a desired shape can be constructed in the ground.

Further, in the present embodiment, the crushed stone pillar 52 constituting the crushed stone structure 50 is formed so as to reach the vicinity of the ground surface, but is not limited to such a configuration. For example, the crushed stone structure may be buried in the ground without reaching near the surface of the earth. In such a crushed stone structure, when the crushed stone pillar is formed by the crushed stone pillar forming device 100, the crushed stone pillar is formed halfway in the excavated space, and the attachment 10 is taken out from the ground without forming the crushed stone pillar from the middle. Can be built by. In the excavated space, for the portion where the crushed stone pillar is not formed, for example, the earth and sand discharged at the time of excavation may be reintroduced.

Further, in the crushed stone column forming apparatus 100 used in this embodiment, the fin 13 is provided in the cylindrical portion 12, but the configuration is not limited to this. For example, an attachment 10 having a cylindrical portion 12 provided with fins 13 (hereinafter, also referred to as a soil removal type attachment 10) and a cylindrical portion having no fins, which is configured to hardly discharge earth and sand due to excavation to the ground surface. A crushed stone structure may be constructed using both of the attachments (hereinafter, also referred to as non-soil-exhausting type attachments).

In this case, first, a part of the crushed stone pillars 52 selected from the plurality of crushed stone pillars 52 constituting the crushed stone structure 50 (specifically, independently in the ground) using a non-soil-exhausting type attachment. The existing crushed stone column 52 (the crushed stone column 52 that is not adjacent to the other crushed stone column 52 that has already been formed) is formed. After that, the remaining crushed stone pillar 52 is formed by using the soil removal type attachment 10. For example, in the crushed stone structure 50 of FIG. 1, first, crushed stone columns 52a, 52c, 52e, 52g are formed by using a non-soil-exhausting type attachment. After that, the remaining crushed stone columns 52b, 52d, 52f, 52h are formed by using the soil removal type attachment 10. When a non-soil-exhaust type attachment is used, unnecessary earth and sand are compressed and compacted around the space formed by excavation. By using the non-soil-removing type attachment and the soil-removing type attachment 10 in combination in the above order, the continuous crushed stone structure 50 can be suitably constructed even if the non-soil-removing type attachment is used. In this way, the amount of earth and sand discharged can be reduced by using the non-soil discharge type attachment. When the diameters of the crushed stone columns 52 described above are largely overlapped, it is desirable to use the soil removal type attachment 10 as described above. Further, it is also preferable that the crushed stone pillars 52 are in contact with both sides when excavating with the soil removal type attachment 10, so that the excavation load becomes uniform. Here, it is possible to form all the crushed stone columns 52 by using a non-soil-exhausting type attachment, but there may be a case where it is difficult because the excavation resistance becomes large due to the compression of the ground. The diameter of each crushed stone pillar 52 is usually about 25 to 45 cm when the non-soil-removing type attachment is used, and about 30 to 50 cm when the soil-removing type attachment 10 is used. It is not limited to the above configuration. The length of the crushed stone pillar 52 in the depth direction is determined by the height direction (z direction) of the non-soil removal type attachment or the soil removal type attachment 10 and the excavation depth, and is about 4 to 6 m. , Not limited to such a configuration. For example, by changing the size and driving capacity of the crushed stone pillar forming device, a crushed stone pillar larger than the above dimensions can be formed.

Further, since the crushed stone structure 50 constructed by using the construction method of this embodiment is formed of crushed stone, a gap is formed between the crushed stone and the crushed stone in the crushed stone structure 50. Therefore, the crushed stone structure 50 constructed by using the construction method of this embodiment can store water such as groundwater flowing underground. An example in which the crushed stone structure 250 constructed by using the construction method of this example is used to prevent ground collapse of an inclined surface or the like will be described below.

As shown in FIG. 10, a crushed stone structure 250 and a drainage pipe 54 are arranged in the ground in order to prevent the ground collapse of the inclined surface. The crushed stone structure 250 is constructed at a position higher than the inclined surface where ground collapse such as landslide may occur (in FIG. 10, the + y direction of the inclined surface). The crushed stone structure 250 is a wall-shaped structure in which crushed stone columns 52 are continuously formed in the x direction, and the number of crushed stone columns 52 constituting the crushed stone structure 250 is the length of the inclined surface for preventing ground collapse. It can be changed according to. Therefore, the number of crushed stone columns 52 constituting the crushed stone structure 250 is different from the number of crushed stone columns 52 (that is, eight) constituting the above-mentioned crushed stone structure 50 (see FIG. 1), and in many cases. The number is greater than the number of crushed stone columns 52 constituting the crushed stone structure 50. The crushed stone structure 250 and the above-mentioned crushed stone structure 50 are different only in that the number of crushed stone columns 52 constituting the crushed stone structure 250 is different, and the other configurations of the crushed stone structure 250 are the same as those of the crushed stone structure 50. Therefore, the details of the configuration of the crushed stone structure 250 and the detailed description of the method of constructing the crushed stone structure 250 will be omitted. By constructing the crushed stone structure 250 having water permeability along the inclined surface, water contained in the soil on the upstream side (+ y direction) of the inclined surface can be appropriately discharged. Therefore, the crushed stone structure having an appropriate water permeability has a significantly improved effect of preventing ground collapse and a conservation effect as compared with the conventional construction method.

Further, the drainage pipe 54 is connected to the crushed stone structure 250. One end of the drainage pipe 54 is connected to the crushed stone structure 250, and the other end of the drainage pipe 54 is arranged on the ground surface. In FIG. 10, the drainage pipe 54 extends with a gradient capable of draining in a direction opposite to the y direction in principle. By connecting the crushed stone structure 250 to the drain pipe 54, the water in the crushed stone structure 250 can be discharged to the ground surface. The position of the drainage pipe 54 is preferably 0 cm or more and less than 50 cm at the bottom of the crushed stone structure 250, and it is desirable that a plurality of drainage pipes 54 are provided at regular intervals in the x direction of the crushed stone structure 250. In addition to the bottom, it is also effective to provide a drainage pipe (not shown) on the ground surface side of the drainage pipe 54 as a countermeasure against heavy rain such as guerrilla rainstorm. By providing the drainage pipe, the water level in the soil on the upper side (+ y direction) of the crushed stone structure 250 can be lowered, and the strength of the soil can be increased. Further, the stand pipe 56 may be installed on the crushed stone structure 250. One end of the stand pipe 56 is arranged in the crushed stone pillar 52 from the upper surface of the crushed stone pillar 52 constituting the crushed stone structure 250, and the other end is arranged on the ground surface above the crushed stone structure 250. The number of stand pipes 56 installed in the crushed stone structure 250 is not particularly limited. For example, the stand pipes 56 are installed every few with respect to a plurality of crushed stone columns 52 constituting the crushed stone structure 250. You may. The stand pipe 56 and the crushed stone structure 250 can hold down the groundwater at atmospheric pressure and lower the water level in the soil. Therefore, by keeping the groundwater level below a certain level as described above, it is possible to suppress ground collapse such as landslides. The crushed stone structure 250 of this embodiment is located at a position higher than the inclined surface, but is not limited to such a configuration. For example, the crushed stone structure 250 may be located in the middle of the inclined surface. Further, although the stand pipe 56 is installed in this embodiment, the stand pipe 56 may not be installed.

In the crushed stone structures 50, 150, 250 of this embodiment, the plurality of crushed stone columns 52 constituting the crushed stone structures 50, 150, 250 are all arranged in the same direction (parallel to the z direction). It is not limited to such a configuration. The plurality of crushed stone columns constituting the crushed stone structure may be arranged in different directions. For example, as shown in FIG. 11, the crushed stone structure 350 includes crushed stone columns 152a to 152d parallel to the z direction. Crushed stone columns 153a to 153d, which are arranged at an angle in the z direction (inclined in the −y direction in FIG. 11), may be connected. The crushed stone structure 350 is a structure in which the crushed stone columns 152a to 152d and the crushed stone columns 153a to 153d are completely separated from each other near the ground surface and overlap each other in the ground. Such a configuration is constructed by forming the crushed stone columns 152a to 152d in the vertical direction and forming the crushed stone columns 153a to 153d at a slight inclination. With such a structure, a space is created between the crushed stone columns 152a to 152d and the crushed stone columns 153a to 153d. Therefore, for example, while constructing a ground drainage channel, the circumference of the drainage channel is surrounded by the crushed stone columns 152a to 152d. And can be protected by crushed stone pillars 153a to 153d. In the crushed stone structure 350, the crushed stone columns 152a to 152d are arranged parallel to the z direction, and the crushed stone columns 153a to 153d are arranged obliquely in the z direction. The columns may be connected to each other. For example, the crushed stone columns 152a to 152d may be formed at an angle of the z direction, and the crushed stone columns 153a to 153d may be formed at an angle of the z direction. Further, when a plurality of crushed stone columns are arranged in different directions, the overlapping portion of the two connected crushed stone columns may exceed 50% in the xy cross section of the portion where the crushed stone columns are connected.

Further, in the stratum infiltrated with groundwater, it is also effective to make the crushed stone grains of the crushed stone constituting the crushed stone structure as follows. For example, a relatively small crushed stone with a diameter of about 3 cm is put into the lower part of the crushed stone structure (that is, the part far from the ground surface), and the diameter is about 5 cm in the upper part of the crushed stone structure (that is, the part near the ground surface). It is possible to put in relatively large crushed stones. Further, since the crushed stone structure of this embodiment is continuous, the crushed stone structure can also be used as a groundwater channel. In this case, the crushed stone structures are constructed in a straight line and continuously like the above-mentioned crushed stone structures 50 and 250. At this time, crushed stone having a larger particle size than the upper part is put into the lower part of the crushed stone structure. Then, in the lower part of the crushed stone structure, a groundwater channel can be constructed through the space between the crushed stones. Therefore, the groundwater channel can be constructed at a desired underground depth by adjusting the particle size of the crushed stone of the crushed stone structure constructed in the ground in the dimension in the depth direction. It is also possible to mix crushed stones having a relatively large particle size with crushed stones having a small particle size such as gravel. Further, crushed stones having different particle sizes may be added to each crushed stone column. As described above, in the crushed stone structure of the present embodiment, the particle size of the crushed stone constituting the crushed stone structure can be changed for each part in one crushed stone structure. Therefore, the particle size of the crushed stone may be adjusted according to the topography and ground on which the crushed stone structure is constructed, or the statistical value of the drainage condition of the soil during precipitation. In this way, the permeability and strength can be optimized according to the characteristics of the soil.

Since the crushed stone structure produced by using the production method of this example is constructed of crushed stone, it can have a certain water storage property and high water permeability. Even when a structure is formed in the ground using permeable concrete, water is stored in the structure (hereinafter, also referred to as a permeable concrete structure). However, while the water-permeable concrete structure has higher water permeability than the normal concrete structure, the gap generated in the structure is smaller and the water permeability is lower than that of the crushed stone structure of the present embodiment. Since the crushed stone structure of this embodiment is formed of crushed stone, it has a certain amount of water storage and can be made highly permeable, so that the water level of groundwater can be lowered. Further, the crushed stone structure 50 of the present embodiment can be manufactured by using the above-mentioned manufacturing method without taking time and effort for construction. It is difficult to reconstruct the above-mentioned water-permeable concrete structure at the same location even if the water permeability is reduced due to the intrusion of earth and sand into the gaps in the structure. The crushed stone structure 50 of this embodiment can be reconstructed at the same location by using the above manufacturing method. Therefore, even if the water storage and water permeability are lowered, the re-construction can be easily performed at the same place, and the water storage and water permeability can be ensured in a good state for a long period of time.

Although specific examples of the techniques disclosed in the present specification have been described in detail above, these are merely examples and do not limit the scope of claims. The techniques described in the claims include various modifications and modifications of the specific examples illustrated above. In addition, the technical elements described in the present specification or the drawings exhibit technical usefulness alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing.

10: Attachment 11: Drive device 12: Cylindrical part 13: Fin 14: Spiral part 15: Crushed stone input hole 20: Opening and closing lid 32: Crushed stone input device 40: Ground improvement machine 50, 150, 250: Crushed stone structure 52: Crushed stone pillar 54: Drainage pipe 60: First space 62: Second space 100: Crushed stone pile forming device

Claims (6)

It is a method of constructing a crushed stone structure in the ground of land with a ground surface with a height difference.
The first excavation process for forming the first space in the ground and
A first crushed stone pillar forming step of forming a first crushed stone pillar by throwing crushed stone into the first space formed by the first excavation step and pressing the crushed stone.
A second excavation step of forming a second space in the ground at a position connected to the first crushed stone pillar,
A second crushed stone pillar forming step of forming a second crushed stone pillar connected to the first crushed stone pillar by throwing crushed stone into the second space formed by the second excavation step and pressing the crushed stone.
It is provided with a drainage pipe installation step in which one end is connected to the crushed stone structure in the ground and the other end is a drainage pipe located on the ground surface.
A method for constructing a crushed stone structure in which the height of the other end of the drainage pipe is the same as the height of the one end or lower than the height of the one end. In the second excavation step, a part of the formed first crushed stone pillar and the land adjacent to the first crushed stone pillar are excavated to form a second space in the ground.
In the second crushed stone pillar forming step, the second crushed stone pillar is formed so that a part of the diameter of the first crushed stone pillar formed by the first excavation step and the diameter of the second crushed stone pillar overlap when viewed in a plan view. The method for constructing a crushed stone structure according to claim 1, wherein the crushed stone structure is formed. The first excavation step, the first crushed stone pillar forming step, the second excavation step, and the second crushed stone pillar forming step are performed by using a crushed stone pillar forming apparatus.
The crushed stone column forming device includes an attachment including a cylindrical portion and a spiral portion rotatably arranged in the cylindrical portion and connected to a drive device to excavate underground.
In the first excavation step and the second excavation step, the spiral portion and the cylindrical portion are integrally rotated by the drive device, and the attachment is inserted into the ground while excavating the ground.
In the first crushed stone pillar forming step and the second crushed stone pillar forming step, crushed stone is thrown into the cylindrical portion, and the crushed stone pillar is formed by the crushed stone thrown into the cylindrical portion while raising the attachment from the ground. , The method for constructing a crushed stone structure according to claim 1 or 2. It is a crushed stone structure formed in the space formed in the ground of the land having a ground surface with a height difference.
Multiple crushed stone columns composed of crushed stone and
One end is connected to the plurality of crushed stone columns in the ground, and the other end is provided with at least one drainage pipe located on the ground surface.
At least one of the plurality of crushed stone columns is connected to another crushed stone column adjacent to the crushed stone column.
At least one of the plurality of crushed stone columns and the other crushed stone columns form one structure in succession.
The drainage pipe is a crushed stone structure in which the height of the other end is the same as the height of the one end or lower than the height of the one end. The crushed stone structure according to claim 4, wherein the diameter of at least one crushed stone column among the plurality of crushed stone columns partially overlaps with the diameter of the other crushed stone columns when viewed in a plan view. The crushed stone structure according to claim 4 or 5, wherein the plurality of crushed stone columns are arranged in a straight line, and each of the plurality of crushed stone columns is connected to another adjacent crushed stone column.

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