Ground improvement method

Abstract

To provide a ground improvement method that forms a drainage channel from the upper surface side, instead of the slope surface, of a banking soil so as to form simply and strongly a drainage channel under the banked ground even in a narrow place in a mountainous area.SOLUTION: A ground improvement method according to the present invention includes: (1) providing a first excavation hole 1 by rotatively inserting an auger 10 from an upper surface of a banked ground in an underground direction and charging a drainage material 7 into the first excavation hole 1; then, (2) providing a second excavation hole 2 by rotatively inserting the auger 10 from the upper surface of the ground in the underground direction at a position in proximity to the first excavation hole 1 and charging the drainage material 7 into the second excavation hole 2; and (3) excavating a boundary region 3 between the first excavation hole 1 and the second excavation hole 2 by the auger 10 to communicate the first excavation hole 1 and the second excavation hole 2 with each other, and mixing the drainage material 7 in both holes to form a drainage 4.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a ground formed by an embankment, and more particularly to a method for improving the embanked ground by forming a drainage channel in the embankment from the ground surface side using an auger. [Background technology]

[0002] In recent years, earthquakes have been occurring frequently in the Japanese archipelago, and in mountainous areas, roads have been closed due to ground collapses caused by earthquakes. When building roads in mountainous areas, soil from land higher than the road is usually used to fill land lower than the road, and the road is then built.

[0003] In mountainous roads built in ancient times, when embankments were built on low-lying land, they were often built without creating drainage channels for rainwater and groundwater. Even if drainage channels are built within the embankment, they may not function effectively as drainage channels due to a lack of adequate maintenance over the years or the amount of rainfall exceeding that expected at the time of construction. In such roads, the embankment contains a lot of water, and if an earthquake occurs, the ground may collapse and cause the road itself, as well as the embankment surrounding the road, to collapse.

[0004] In order to avoid such situations, in recent years, various techniques have been proposed for reinforcing the ground formed by embankments to solve drainage problems within the embankments, such as burying drainage material using casing pipes from the slope (face) of the embankment (Prior Document 1) or inserting new drainage pipes from the face (Prior Document 2). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2022-130793 [Patent Document 2] Japanese Patent Publication No. 2021-152313 Summary of the Invention [Problem to be solved by the invention]

[0006] In the aforementioned reinforcement work for drainage channels, which involves inserting casing pipes or drainage pipes into embankments, the pipes must be inserted from the slope side. In mountainous roadside embankments, the slope is exposed on the road surface. Therefore, when reinforcement work for these exposed sections is possible, drainage channels can sometimes be installed from the slope sidewall, if work can be done on the road. However, inserting drainage materials or channels from the slope side generally requires ample working space. However, the slope side often limits working space, making it difficult to set up the necessary equipment. Furthermore, when the embankment ground is relatively hard, considerable pressure is required to insert the pipes into the embankment, posing construction challenges, such as the inability to apply sufficient pressure from the slope side.

[0007] In fact, in mountainous areas, when the road itself is built on an embankment, the slope is usually steep, making it impossible to install pipes from the slope, and making it difficult to reinforce the drainage channel under the road.

[0008] In view of the above, the present invention aims to provide a ground improvement method that forms a drainage channel from the top side of the embankment rather than from the slope side, thereby easily and firmly forming a drainage channel under the embankment, even in narrow places in mountainous regions. [Means for solving the problem]

[0009] In order to achieve the above-mentioned object, the method for improving embanked ground according to the present invention is characterized in that (1) a first excavation hole is created by inserting and rotating an auger from the top surface of the embanked ground toward the ground, and drainage material is poured into the first excavation hole; (2) a second excavation hole is created by inserting and rotating an auger from the top surface of the ground toward the ground at a position close to the first excavation hole toward the ground, and drainage material is poured into the second excavation hole; and (3) the boundary area between the first excavation hole and the second excavation hole is excavated with an auger, thereby connecting the first excavation hole and the second excavation hole to form a drainage channel.

[0010] The method for improving filled ground according to the present invention is characterized in that an auger is inserted and rotated from the surface of the boundary area toward the ground to dig up the boundary area and mix both drainage materials.

[0011] The method for improving filled ground according to the present invention is characterized in that the auger is reinserted into the first or second excavation hole, and the boundary area is excavated by rotating the auger while applying pressure toward the boundary area, thereby mixing both drainage materials.

[0012] The method for improving embanked ground according to the present invention is characterized in that rust-proofed steel sheet piles having flow passage holes are buried in the embankment where the drainage channel is formed.

[0013] The method for improving embanked ground according to the present invention is characterized by burying a retaining wall consisting of a series of H-shaped steel piles with rust-proofed treatment and flow path holes in the embankment where the drainage channel is formed.

[0014] The method for improving embanked ground according to the present invention is characterized in that the retaining wall made of the continuous piles uses a plurality of H-shaped steel piles, each having a pair of flange portions and a web portion connecting the pair of flange portions, and is arranged alternately so that one H-shaped steel pile is approximately in contact with another H-shaped steel pile, and the length of the flange portion of one H-shaped steel pile is shorter than the web portion of the other H-shaped steel pile and the length of the web portion is longer than the flange portion of the other H-shaped steel pile, and the flange portion of one H-shaped steel pile is arranged within the area surrounded by the flange portions and web portions of the other H-shaped steel pile so as to be approximately parallel to the web portion of the other H-shaped steel pile.

[0015] The method for improving filled ground according to the present invention is characterized in that the steps (1) and (2) are carried out simultaneously using a plurality of augers.

[0016] The method for improving filled ground according to the present invention is characterized in that sand, gravel, gravel, drainage material or a mixture of these materials is used as the drainage material.

[0017] The method for improving filled ground according to the present invention is characterized in that an auger is inserted and rotated using a device having an excavation capability using an auger.

[0018] The method for improving embanked ground according to the present invention is characterized by using as the device a construction machine having a boom whose tip position can be moved in three dimensions, and a rotary drive mechanism having a vertical rotary shaft suspended from the tip of the boom. [Effects of the Invention]

[0019] In the method of the present invention, a drainage channel is formed by using an auger to drill a hole from the top surface of the embankment toward the ground and then digging out the boundary area, which makes it possible to work from the top of the embankment (above the road, if there is one) rather than from the slope of the embankment, ensuring sufficient working space and making it possible to form a new drainage channel in the embankment even in narrow places such as mountainous regions. Furthermore, even if the ground is somewhat solid, because work can be done from the top of the embankment (above the road, if there is one), a large weight can be applied from above, and the method of the present invention makes it easy to form a drainage channel in the embankment below a road, even at sites with a steep slope. [Brief explanation of the drawings]

[0020] [Figure 1] 1 is a cross-sectional view illustrating an embodiment of the method for improving filled ground according to the present invention. [Figure 2] 1 is a cross-sectional view illustrating an embodiment of the method for improving filled ground according to the present invention. [Figure 3] 1 is a top view illustrating an embodiment of a method for improving filled ground according to the present invention; [Figure 4] FIG. 10 is a plan view of an auger excavating movement illustrating another embodiment of the method for improving filled ground according to the present invention. [Figure 5] 1 is a cross-sectional explanatory diagram of a side view and a plan view illustrating another embodiment of the method for improving filled ground according to the present invention. [Figure 6] FIG. 1 is a perspective explanatory diagram showing a retaining wall made of a series of H-shaped steel piles used in the method for improving embanked ground according to the present invention. [Figure 7] An explanatory perspective view showing an example of a steel sheet pile and an H-shaped steel pile used in the method for improving the filled ground according to the present invention. [Figure 8] FIG. 1 is a side view of an example of a device (hole digging and pole erection vehicle) used in the method for improving the filled ground according to the present invention. [Figure 9] 1 is a side view and a plan view illustrating an example of an auger used in a method for improving filled ground according to the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0021] As shown in Figures 1 to 3, the method for improving filled ground according to the present invention involves, for example, (1) creating a first excavation hole 1 by rotating an auger 10 from the top surface of the filled ground toward the ground, and pouring an appropriate amount of drainage material 7 into the first excavation hole 1; then, (2) creating a second excavation hole 2 by inserting and rotating an auger 10 from the top surface of the ground toward the ground at a position close to the first excavation hole 1 toward the ground, and pouring an appropriate amount of drainage material 7 into the second excavation hole 2; and (3) using the auger 10 to excavate the boundary area 3 between the first excavation hole 1 and the second excavation hole 2, connecting the first excavation hole 1 and the second excavation hole 2, and mixing the drainage materials 7 from both holes to form a drainage channel 4.

[0022] The specific method for improving the embanked ground is as follows:

[0023] First, markers 12 are placed on the ground (on the top surface of the embankment) at the site where the embankment has been filled, indicating the location where the drainage channel will be formed within the embankment. The markers 12 are placed on the ground at the location where the drainage channel will be formed, and serve as guides for using an auger to form excavation holes and for proceeding with the erosion of the boundary area according to the markings. For example, the markers can be placed by drawing a white line on the ground, scraping away the soil on the ground, or, if the aboveground portion is an asphalt road, scraping away the asphalt where the excavation hole will be formed. However, the method is not limited to these, and any method can be used as long as the location where the drainage channel will be formed can be seen from the ground.

[0024] Next, as shown in Figures 1 and 2, the auger 10 is aligned with the mark 12, and the rotary drive mechanism 54 of the device 5 as shown in Figure 8 is driven to rotate the auger 10 while digging to a predetermined depth.After reaching the predetermined depth, the auger 10 is pulled up to the ground and withdrawn, thereby forming a first excavation hole 1 from the top surface of the embankment toward the ground.

[0025] After the first excavation hole 1 is formed, an appropriately selected amount of drainage material 7 suitable for draining underground moisture, such as sand, gravel, gravel, drainage material, or a mixture of the above materials, is poured into the first excavation hole 1. The amount of drainage material to be poured is adjusted appropriately depending on the shape of the excavation hole, the size of the drainage channel to be formed, etc.

[0026] Again, using the device 5 or the like, the auger 10 is further excavated along the marker 12 at a position close to the first excavation hole 1 that has already been formed, from the surface of the ground (the top surface of the embankment) toward the ground to a predetermined depth, and after reaching the predetermined depth, the auger 10 is pulled up to the ground and withdrawn, thereby forming a second excavation hole 2 from the top surface of the embankment toward the ground.

[0027] After the second excavation hole 2 is formed, an appropriately selected amount of the aforementioned drainage material 7, which may be sand, gravel, gravel, drainage material, or a mixture of the above materials, is poured into the second excavation hole 2. Again, the amount of drainage material poured is adjusted appropriately depending on the shape of the excavation hole, the size of the drainage channel to be formed, etc.

[0028] The first and second excavated holes 1 and 2 are excavated until they reach the position in the embankment where the drainage channel 4 will be installed. If the depth of the drainage channel 4 is to be constant within the embankment, the depth of the excavated holes can be made uniform, but if the drainage channel is to have a slope within the embankment, the depth of the excavated holes can be changed. The size of the excavated holes can be changed appropriately depending on the width of the drainage channel to be formed, and can be adjusted by the shape of the auger, etc.

[0029] After the first excavation hole 1 and the second excavation hole 2 are formed, as shown in Figures 1 to 3, the boundary region 3 between the first excavation hole 1 and the second excavation hole 2 is excavated with an auger 10 to connect the first excavation hole 1 and the second excavation hole 2 and form a drainage channel 4. The boundary region 3 refers to the region from the ground surface to underground that exists between the outline of the first excavation hole 1 and the outline of the second excavation hole 2.

[0030] In the method of the present invention, it is important to excavate the boundary region 3. That is, when a first excavation hole 1 is formed and a second excavation hole 2 is formed in a position adjacent to it, if the distance between the first excavation hole 1 and the second excavation hole 2 is too close, the auger will interfere with the first excavation hole 1 already excavated during excavation, making it impossible to form the second excavation hole 2 in the desired position. Therefore, a certain distance must be maintained between the first excavation hole 1 and the second excavation hole 2. On the other hand, if the distance between the first excavation hole 1 and the second excavation hole 2 is too large, the boundary region 3 between them will form a wall, making it impossible to form a drainage channel 4 in the depth direction of the embankment. In this regard, a similar technique is used, in which an auger is used to excavate the ground in advance to bury sheet piles, steel sheet piles, piles, etc. In this case, even if there is a small wall in the boundary region 3, pressure is applied to the boundary region when burying the sheet piles, etc., and the wall will naturally be excavated. Therefore, a small distance between the first excavation hole 1 and the second excavation hole 2 does not cause any problems, and there is no need to separately treat the boundary region 3. On the other hand, in one embodiment of the present invention, the drainage channel 4 can be simply provided under the embankment without burying sheet piles or the like, and in such a case, if there is no step of digging up the boundary area 3, a wall will remain in the boundary area 3, making it impossible to construct the drainage channel 4. Therefore, the present invention is characterized in that it deliberately includes a step of digging up the boundary area 3 with an auger 10.

[0031] As a method for using the auger 10 to collapse the boundary region 3 between the first excavation hole 1 and the second excavation hole 2, for example, the auger 10 can be inserted and rotated from the surface (top surface of the embankment) of the boundary region 3 toward the ground, thereby collapsing the boundary region 3. Specifically, as shown in Figure 2, using a device 5 such as that shown in Figure 8, the tip of the auger 10 is set on the ground surface of the boundary region 3, and pressure is applied toward the ground while rotating the auger 10 using a rotation drive mechanism 54, thereby collapsing the wall of the boundary region 3 from above. The amount of pressure to be applied is adjusted as appropriate depending on the thickness, hardness, etc. of the wall of the boundary region.

[0032] Alternatively, instead of inserting the auger 10 into the surface of the boundary region 3, the auger 10 can be inserted again into the first excavated hole 1 or the second excavated hole 2, and the boundary region 3 can be excavated by rotating the auger 10 while applying pressure diagonally downward toward the boundary region 3 (toward the excavated hole into which the auger is not inserted). In this case, the auger 10 is driven using a device 5 such as that shown in Figure 8.

[0033] When the auger 10 that has excavated the boundary area 3 is pulled out, the auger 10 is slowly rotated in the reverse direction, leaving the mixed drainage material adhering to the auger 10 in the excavated hole.

[0034] Thereafter, the excavated hole formed by the auger 10 is backfilled with soil and sand up to the top of the excavated hole, thereby completing the drainage channel 4.

[0035] So far, we have explained how to form two excavation holes, the first excavation hole 1 and the second excavation hole 2, and then form a drainage channel 4 by eroding the boundary area 3 with an auger 10. However, it is of course also possible to form a long drainage channel by forming multiple excavation holes and then eroding the boundary area.

[0036] For example, a further excavation hole (not shown) is formed near the aforementioned second excavation hole 2, and then other excavation holes are formed in the same manner in succession at locations where drainage channel 4 is to be formed, following marker 12, and drainage material is poured into the excavation holes. Then, by using auger 10 to excavate the boundary areas between second excavation hole 2 and the excavation holes formed in the adjacent locations, and further between the excavation holes formed in the adjacent locations, it is possible to finally form a drainage channel 4 of the desired length.

[0037] Although the above example describes a method using one auger, multiple augers can also be used, as shown in FIG. 4 . For example, the auger 10 is buried to a predetermined depth using the apparatus 5, the auger 10 is removed from the apparatus 5, and another auger 11 is connected to the apparatus 5 and buried to a predetermined depth in a location adjacent to the previously buried auger 10. The auger 11 is then removed from the apparatus 5, the previously buried auger 10 is reconnected to the apparatus 5, and the rotary drive mechanism 54 of the apparatus 5 is rotated to raise the auger 10 to the surface, and then withdrawn, a drilled hole is formed, and an appropriate amount of drainage material 7 is poured into the drilled hole. The withdrawn auger 10 is then reburied in a location adjacent to the auger 11. After the auger 10 is reburied, the auger 11 is withdrawn, a drilled hole is formed, and an appropriate amount of drainage material 7 is poured into the drilled hole. The auger 11 is then reburied to a predetermined depth in a location adjacent to the previously buried auger 10. This process is repeated to form multiple excavation holes, and then the boundary areas between the excavation holes are excavated with the auger 10 to form the drainage channel 4. The same process can also be carried out when three or more augers are used.

[0038] In the method using two augers described above, when auger 11 is buried, the top end of auger 10 is above ground, so by using this as a landmark and burying it to the same depth as auger 10, the depth direction of the excavated hole can be aligned, making it easy to form a drainage channel at a constant depth. In addition, the circumferential surface of auger 10 remaining underground continues to press against the surface of the hole to prevent it from collapsing, forming a retaining wall, making the wall of the excavated hole less likely to collapse, and collapsing is less likely than with the method of digging with one auger, then immediately withdrawing it and digging the next hole.

[0039] As described above, this invention uses a method in which an auger is used to drill multiple excavation holes from above ground toward the ground, and then the boundary areas between the drilled holes are excavated, making it possible to easily form drainage channels from the top surface of the embankment (above the road, if there is one) rather than from the slope of the embankment. As a result, for example, as shown in Figure 5, this invention makes it easy to form a network of drainage channels 4 (drainage ditches 64 at the ends) within embankment 62 in road 63 built on embankment 62 facing natural ground 61.

[0040] In the present invention, as shown in Figure 5, in a road 63 built on an embankment 62 facing a natural ground 61, in order to further reinforce the embankment 62 or to reinforce the road 63 itself, steel sheet piles 8 and retaining walls 9 can be further formed not only at the position where the drainage channel 4 is formed or on the drainage channel 4 but also at any position within the embankment 62.

[0041] Specifically, the equipment 5 is used to place the steel sheet piles 8 and H-shaped steel piles 91, 92 at desired positions, and after erecting them, they are buried by methods such as pressing in or driving. However, when an earth retaining wall 9 consisting of the steel sheet piles 8 and the continuous piles of H-shaped steel piles is installed in the embankment 62, it is necessary to devise a way to prevent the steel sheet piles 8 and the earth retaining wall 9 consisting of the continuous piles of H-shaped steel piles from obstructing drainage within the embankment 62.

[0042] In order to avoid obstructing drainage within the embankment 62, it is conceivable to avoid installing steel sheet piles 8 or earth retaining walls 9 above the drainage channel 4 within the embankment 62 as much as possible. However, as shown in FIG. 5, there are cases where it is necessary to install them above the drainage channel 4. In such cases, it is particularly preferable to use steel sheet piles 8 or earth retaining walls 9 with a structure different from that of conventional steel sheet piles 8 or earth retaining walls 9. Specifically, steel sheet piles 8 or earth retaining walls 9 made of continuous H-shaped steel piles with flow passage holes 85, 95 at the intersection with the drainage channel 4 are desirable in terms of improving drainage within the embankment. It goes without saying that the steel sheet piles 8 or earth retaining walls 9 with the flow passage holes 85, 95 may be installed not only above the drainage channel 4 but also in places within the embankment 62 where there is no drainage channel 4.

[0043] The steel sheet piles 8 and the earth retaining wall 9 made of a series of H-shaped steel piles used in the present invention are permanently installed, not temporary. For example, steel sheet piles 8 are originally used for on-site flood control work. When the water level at the site is high, the steel sheet piles 8 are driven, and once the flood control work is completed, the temporary steel sheet piles 8 are removed. However, the steel sheet piles 8 buried in the present invention are permanently installed in the embankment 62 and are intended to semi-permanently protect the embankment 62 and road 63. Therefore, the steel sheet piles 8 themselves must be treated with rust prevention. Therefore, the steel sheet piles 8 delivered to the site and before driving are treated with rust prevention before being driven. The H-shaped steel piles used in the earth retaining wall 9 made of a series of piles are also treated with rust prevention before being driven. Regarding the rust prevention method, any existing rust prevention technology may be used as appropriate.

[0044] For example, as shown in FIG. 6 , the earth retaining wall 9 made of a series of H-shaped steel piles may be formed by using multiple H-shaped steel piles, each having a pair of flanges and a web connecting the pair of flanges. The H-shaped steel piles 92 are alternately arranged so that each H-shaped steel pile 92 is approximately adjacent to the other H-shaped steel piles 91. The flange length of each H-shaped steel pile 92 is shorter than that of the web of the other H-shaped steel piles 91, while the web length is longer than that of the flange of each H-shaped steel pile 91. The flange of each H-shaped steel pile 92 is arranged within the area surrounded by the flange and web of each other H-shaped steel pile 91, approximately parallel to the web of each other H-shaped steel pile 91. In this case, it is preferable to pierce a portion of the web of each H-shaped steel pile 92 using an oxyacetylene cutting machine or the like to form a channel hole 95 at the intersection with the drainage channel 4, as this facilitates drainage. The shape, size, and location of the channel hole 95 in each H-shaped steel pile are appropriately selected depending on the site conditions.

[0045] The steel sheet pile 8 may be a commercially available existing one, and then, as shown in Fig. 7(a), a part of the pile may be penetrated using an oxyacetylene cutting machine or the like to form a flow path hole 85 at the part where the pile intersects with the drainage channel 4. The shape, size, and position of the flow path hole 85 in the steel sheet pile may be appropriately selected depending on the site conditions.

[0046] As described above, the present invention uses an auger to drill multiple excavation holes from the ground toward the ground, and then digs out the boundary areas between the drilled holes, making it possible to easily form a drainage channel from the top surface of the embankment (above the road, if there is one) rather than from the slope of the embankment.

[0047] 8 shows the configuration of an example of the device according to the present invention used for excavating with an auger, burying steel sheet piles or H-shaped steel piles, etc. Device 5 can be any machine capable of excavating with an auger, and may, for example, have a power unit 52 with a boom 51 whose tip position can be moved in three dimensions, and a rotary drive mechanism 54 with a vertical rotary shaft suspended from the tip of boom 51, and rotary shaft 55 of rotary drive mechanism 54 to which the auger, steel sheet pile, pile, etc. is connected.

[0048] Specifically, for example, it may be a four-wheeled, self-propelled truck with a power unit 52 and a rotary drive mechanism 54 mounted on the bed, and outriggers attached to the four corners of the bed to stably support the bed on the ground. While the example shown in Figure 8 uses a hole-digging pole-setting vehicle, other vehicles, such as mini-excavators, shovels, other concrete-driving machines with leader posts, vehicle-mounted construction machines, and mobile crane construction machines, may also be used, or these vehicles may be modified to excavate using an auger. Unlike concrete-driving machines, which can only work in fixed areas with leader posts, a pole-setting vehicle with a boom can be placed on the road and the boom can be moved to form drainage channels from ground level to ground level, even on sloped ground on both sides of the road.

[0049] The power unit 52 may be a power unit part of a hole digging and erecting vehicle, a mini excavator, a shovel, a concrete pouring machine with a leader, a vehicle-type construction machine, a mobile crane construction machine, etc., which may be used as is or may be modified from these.

[0050] The rotary drive mechanism 54 is equipped with a vertical rotary shaft 55 suspended from the tip of the boom 51, and serves to rotate the auger attached below the rotary shaft, and existing technology can be used for this. The boom 51 is configured to be able to move the lifted object in three dimensions by extending, contracting, swinging, rotating, etc. The boom 51 performs the positioning function of the auger, steel sheet piles, piles, etc. via the power unit 52.

[0051] The shape, diameter, length, material, etc. of the auger used in the present invention are appropriately selected using the ordinary knowledge of a person skilled in the art depending on the conditions at the site, the location where the drainage channel is to be installed, the size of the drainage channel, the width and hardness of the boundary area, etc.

[0052] For example, as shown in Figure 9, the auger 10 (11) may be made of a steel pipe or the like, with a pointed tip (bottom end) or a steel pipe provided with a scraping mechanism 17 made of an iron rod with spiral blades or the like attached to the outer surface for scraping up soil generated during excavation, and the outer diameter of the steel pipe may be selected as appropriate. In addition, an engaging screw or pin 18 or the like is provided at the upper end of the auger, which engages with the rotating shaft 55 of the rotary drive mechanism.

[0053] When selecting an auger's shape, consideration should be given to ensuring ease of excavation, minimizing the generation of waste soil, and maintaining a hole as large as possible when the auger is removed. For example, a shape that facilitates excavation is desirable, such as a pointed tip (bottom end) or a scraping mechanism 17 on the outer periphery. Furthermore, the larger the scraping mechanism 17, the easier the excavation proceeds and the larger the hole that can be formed, but more waste soil is produced. On the other hand, a smaller scraping mechanism 17 reduces waste soil but slows the excavation speed and reduces the size of the hole that is formed. Regarding the size of the steel pipe, a thicker pipe allows for the creation of a larger hole, but the thicker the steel pipe, the more power is required to rotate and excavate. Taking these various factors into account, the shape of the auger should be selected appropriately depending on the situation. [Example]

[0054] The following describes a case where the present invention is implemented using one auger with a hole digging and pole erection vehicle 5. However, two or more augers may be used, and a vehicle other than a hole digging and pole erection vehicle may also be used.

[0055] A positioning marker 12 is placed on the ground at the location where the drainage channel 4 is to be formed in advance, and a hole-digging and pole-setting vehicle 5 is prepared near the marker 12. The hole-digging and pole-setting vehicle 5 is fitted with a rotary drive mechanism 54 having a vertical rotary shaft 55 hanging down from the tip of a boom 51.

[0056] To start work, the auger 10 is engaged with the rotary drive mechanism 54 and the boom 51 is operated to move the lower end of the auger 10 directly above the excavation position according to the marker 12, and the rotary drive mechanism 54 is activated to rotate the auger 10, which begins excavation to a predetermined depth (for example, 3 meters). Once excavation to the predetermined position is completed, the rotary drive mechanism 54 is rotated to pull the auger 10 out to the ground, and the first excavation hole 1 is formed.

[0057] After the first excavation hole 1 is formed, an appropriate amount of gravel 7 is poured as a drainage material into the first excavation hole 1 up to about halfway from the bottom, and the gravel is spread over the inside.

[0058] Again, using the hole digging and erection vehicle 5, the auger 10 is moved further along the marker 12 to a position directly above the already formed first excavated hole 1, and the rotary drive mechanism 54 is activated to rotate the auger 10, which begins excavating to a predetermined depth (for example, 3 meters). Once excavation to the predetermined position is completed, the rotary drive mechanism 54 is rotated to pull the auger 10 back down to the ground, and the second excavated hole 2 is formed.

[0059] After the second excavation hole 2 is formed, an appropriate amount of gravel 7 is poured as a drainage material into the second excavation hole 2 up to about halfway from the bottom, and the gravel is spread over the hole.

[0060] Furthermore, using a hole digging and erection vehicle 5, an auger 10 is moved to a position immediately above the second excavated hole 1 that has already been formed, and another excavated hole is formed by further digging with the auger 10. Thereafter, excavated holes are formed in the same manner, following the markers, at locations where drainage channels 4 are to be installed. After these excavated holes are formed, an appropriate amount of gravel 7 is poured into the excavated holes about halfway from the bottom, and the gravel is spread over the entire area.

[0061] After forming the first excavation hole 1, the second excavation hole 2, and several adjacent excavation holes, a hole digging and erection vehicle 5 is used to sequentially move the auger 10 to directly above the boundary area 3 between the adjacent excavation holes that have already been formed, and the rotary drive mechanism 54 is activated to rotate the auger 10, starting excavation and applying pressure underground, thereby digging down the wall of the boundary area 3 from above, mixing the gravel 7, which is the drainage material for both, and forming a drainage channel 4 at the desired location.

[0062] Furthermore, when driving steel sheet piles 8 onto the drainage channel in the embankment 62, a hook attached to a hole-digging vehicle 5 positioned on the road 63 is used to lift up the steel sheet pile 8 with the flow path hole 85 shown in Figure 7(b), and the boom 51 is operated to move it to the location where the drainage channel 4 has been formed using an auger. Further pressure is applied underground, and the steel sheet pile 8 is pressed in or driven so that the flow path hole 85 of the steel sheet pile 8 is positioned above the drainage channel, thereby burying the steel sheet pile 8 above the drainage channel 4 in the embankment 62. Similarly, when burying an earth retaining wall 9 consisting of a series of H-shaped steel piles, the H-shaped steel piles are pressed in or driven and buried above the drainage channel 4 in the embankment 62. [Industrial Applicability]

[0063] The present invention is not limited to the above-described embodiment, and includes various modified designs within the scope of the gist of the invention. [Explanation of symbols]

[0064] 1. First drill hole 2. Second drill hole 3 Boundary area 4 Drainage channel 5 Equipment 7 Drainage materials 8 Steel sheet piles 9 Mountain retaining wall 10 Auger 11 Auger 12 Landmark 17 Raking mechanism 18 Screws or pins 51 Boom 52 Power plant 54 Rotation drive mechanism 55 Rotation axis 61 Natural ground 62 Embankment 63 Road 64 Drain 85 flow hole 91 Other H-shaped steel piles 92 One H-shaped steel pile 95 flow hole

Claims

1. (1) Inserting and rotating an auger from the top surface of the filled ground toward the ground to form a first excavation hole, and pouring drainage material into the first excavation hole; (2) Inserting and rotating an auger from the top surface of the ground toward the ground at a position close to the first excavation hole to form a second excavation hole, and pouring drainage material into the second excavation hole; (3) A boundary area between the first excavated hole and the second excavated hole is excavated with an auger to form a drainage channel connecting the first excavated hole and the second excavated hole. A method for improving embanked ground, characterized by

2. 2. The method for improving ground according to claim 1, wherein the boundary area is excavated by inserting and rotating an auger from the surface of the boundary area toward the ground, and mixing the two drainage materials.

3. 2. The method for improving ground according to claim 1, wherein the auger is reinserted into the first or second excavated hole, and the boundary area is excavated by rotating the auger while applying pressure toward the boundary area, thereby mixing both drainage materials.

4. 4. The method for improving ground according to claim 1, further comprising burying rust-proofed steel sheet piles having flow passage holes in the embankment where the drainage channel is formed.

5. The method for improving ground according to any one of claims 1 to 3, characterized in that a retaining wall made of a series of H-shaped steel piles having flow passage holes and treated with rust prevention is buried in the embankment in which the drainage channel is to be provided.

6. The method for improving ground according to claim 5, wherein the retaining wall made of the continuous piles is formed by using a plurality of H-shaped steel piles each having a pair of flange portions and a web portion connecting the pair of flange portions, and the H-shaped steel piles are alternately arranged in a position where one H-shaped steel pile is approximately in contact with another H-shaped steel pile, the length of the flange portion of one H-shaped steel pile is shorter than the web portion of the other H-shaped steel pile, the length of the web portion of one H-shaped steel pile is longer than the flange portion of the other H-shaped steel pile, and the flange portion of one H-shaped steel pile is arranged in an area surrounded by the flange portions and web portions of the other H-shaped steel pile so as to be approximately parallel to the web portion of the other H-shaped steel pile.

7. 2. The method for improving ground according to claim 1, wherein steps (1) and (2) are carried out simultaneously using a plurality of augers.

8. 2. The method for improving ground according to claim 1, wherein the drainage material is sand, gravel, gravel, drainage material, or a mixture of the above materials.

9. 2. The method for improving ground according to claim 1, wherein an auger is inserted and rotated using a device having an excavation capability using an auger.

10. The method for improving ground according to claim 9, wherein the device used is a construction machine having a boom whose tip position can be moved in three dimensions, and a rotary drive mechanism having a vertical rotary shaft suspended from the tip of the boom.

Images