JP6943658B2 - Sandy ground compaction method - Google Patents

Description

The present invention relates to a sandy ground compaction method for compacting sandy ground via a rod, a casing pipe, or the like.

As this type of sandy ground compaction method, a method of compacting sandy ground by press-fitting material sand into the ground through a casing pipe is known.

Japanese Unexamined Patent Publication No. 2008-291479

In the conventional sandy ground compaction method, the gaps in the sandy ground are reduced by press-fitting the material sand, but in the shallow layer, swelling and lateral extrusion displacement often occur, resulting in displacement. In many cases, measures such as buffer holes were required.

Therefore, the present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a sandy ground compaction method capable of further improving the compaction efficiency at low cost.

The invention of claim 1 is a sandy ground compaction method for compacting sandy ground by vibration of a rod, in which the deep layer portion is ground-treated in a pre-step for ground improvement of the shallow layer portion of the sandy ground. The rod is driven into the shallow layer portion several times from different directions at an angle from one place to penetrate the rod to a predetermined depth, and then the rod is pulled out by a predetermined length and vibrates at the tip of the rod. -Apply an impact to drop the surrounding ground into the cavity formed around it, then hit the rod back to compact the shallow layer, and then press-fit the material sand into the deep layer in this step. It is characterized by applying and improving the ground.

As described above, according to the invention of claim 1, the rod is driven into the shallow layer of the sandy ground to a predetermined depth and penetrated, and then the rod is pulled out by a predetermined length to reach the tip of the rod. By applying vibration and impact to drop the surrounding ground into the cavity created around it, and then hitting the rod back to compact the shallow layer, the subsidence of the surrounding ground around the rod can be promoted. , The compaction efficiency can be improved. In particular, in the pre-process of improving the deep part of the sandy ground, a wide range of sandy ground is compacted by diagonally driving and pulling out the rod multiple times from one place to cause subsidence and lateral pulling displacement. It is possible to offset the swelling and lateral extrusion displacement that occur in the subsequent press-fitting and compaction of the material sand, and it is possible to easily and reliably improve the ground in the deep layer at low cost. ..

(A) is a cross-sectional view showing the penetration state of the rod by the sandy ground compaction method when the rod of the first embodiment of the present invention is installed diagonally, and (b) is a cross-sectional view when the rod is pulled out. c) is a cross-sectional view of the rod at the time of hitting back. It is a top view explaining the relationship between the pre-process and this process of the sandy ground compaction method of the first embodiment. (A) is a cross-sectional view showing the penetration state of the rod by the sandy ground compaction method when the rod of the second embodiment of the present invention is installed vertically, and (b) is a cross-sectional view when the rod is pulled out. c) is a cross-sectional view of the rod at the time of hitting back. It is a side view at the time of driving and pulling out a rod diagonally in a medium-sized soil tank for an experiment. It is a top view in the case of driving and pulling out a rod diagonally in a medium-sized soil tank for an experiment. It is a side view at the time of vertically driving and pulling out a rod in a medium-sized soil tank for an experiment. It is a top view when the rod is vertically driven and pulled out in a medium-sized soil tank for an experiment. It is explanatory drawing which shows the relationship between the total number of hits and the subsidence amount of the simulated ground when the rod is driven and pulled out diagonally and when the rod is driven and pulled out vertically in a medium-sized soil tank for an experiment.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 (a) is a cross-sectional view showing a state of penetration of the rod by the sandy ground compaction method when the rod of the first embodiment of the present invention is installed diagonally, and FIG. 1 (b) is a cross-sectional view when the rod is pulled out. A cross-sectional view and FIG. 1 (c) is a cross-sectional view of the rod when it is driven back.

In the sandy ground compaction method of the first embodiment, as shown in FIGS. 1 (a) to 1 (c), the shallow layer portion 2 of the sandy ground 1 is subjected to the vibration S of the tip portion 5a of the rod 5 and the vibration S of the tip portion 5a of the rod 5. It is a construction method of compacting by impact G, and uses a rod 5 provided with a vibration / impact applying device 6 that applies vibration S and impact G to the tip portion 5a. Reference numeral 3 in the figure indicates a deep part of the sandy ground 1.

Next, FIGS. 1 (a) to 1 (c) describe a procedure for compacting the shallow layer portion 2 which is a pre-process for improving the deep layer portion 3 of the sandy ground 1 by the vibration / impact of the tip portion 5a of the rod 5. ) Will be described.

First, as shown in FIG. 1A, the rod 5 is driven diagonally into the shallow layer 2 of the sandy ground 1 while rotating the rod 5 to a predetermined depth (about 5 to 6 m in depth). Penetrate.

After that, as shown in FIG. 1B, the rod 5 is pulled out by a predetermined length (for example, about 60 cm), and vibration / impact is applied to the surrounding ground from the tip portion 5a of the rod 5 for a predetermined time (for example, about 1 to 3 minutes). In addition, the earth and sand 1a of the surrounding ground is dropped from the periphery into the cavity K formed around the tip portion 5a of the pulled out rod 5 and supplied to fill the cavity K.

After that, as shown in FIG. 1 (c), the rod 5 is driven back by, for example, 40 cm to compact the rod 5 equivalent to 20 cm. This work is continuously performed to compact about 5 to 6 m of the shallow layer portion 2. This compacted portion is indicated by reference numeral M in FIG. 1 (c).

By driving and pulling out the rod 5 diagonally with respect to the shallow layer portion 2 of the sandy ground 1 in this way, the earth and sand 1a of the peripheral ground above the rod 5 can easily fall into the hollow portion K from which the rod 5 is pulled out. , The efficiency of settlement treatment is improved. That is, by penetrating the rod 5 diagonally, the depression of the earth and sand 1a in the peripheral ground above the rod 5 is promoted, and the compaction efficiency is improved. Further, by hitting back the rod 5, the compaction effect becomes larger.

In addition, for example, when constructing by making a hole in the pavement, such as in the ground improvement of an airport, by penetrating the rod 5 diagonally, the material sand is press-fitted by the secondary compaction in the primary compaction in the previous process. The range of action of no vibration / impact can be expanded to a diagonal range by the diagonal penetration of the rod 5 instead of directly under the pavement hole, and the ground can be improved easily and at low cost.

FIG. 2 is a plan view illustrating the relationship between the pre-process and the main process of the sandy ground compaction method of the first embodiment.

As shown in FIG. 2, in the pre-process (primary compaction) for improving the ground of the deep layer 3 of the sandy ground 1, the direction different from that of one place where the deep layer 3 is ground-treated in the main process (secondary compaction). The rod 5 is obliquely penetrated and pulled out into the shallow layer portion 2 from (for example, in 2 to 4 radial directions) 2 to 4 times to perform a subsidence treatment of the shallow layer portion 2 and a drop treatment of earth and sand 1a in the surrounding ground.

Then, after the rod 5 is driven back and the shallow layer portion 2 is compacted, the material sand is press-fitted into the deep layer portion 3 through the casing pipe 7 to improve the ground.

In this way, in the pre-step of ground improvement of the deep layer portion 3, the rod 5 is inserted and pulled out diagonally from a different direction into the shallow layer portion 2 from one place where the casing pipe 7 is penetrated into the sandy ground 1. After the shallow layer 2 is subsided and the surrounding ground sand 1a is dropped and the shallow layer 2 is compacted, the material sand is press-fitted into the deep layer 3 through the casing pipe 7 in this step. By making improvements, the sandy ground 1 in a wide range will be compacted by diagonally driving and pulling out the rod 5 from multiple directions from one place to cause subsidence and lateral pull-in displacement, which will be performed in the subsequent main step. It is possible to offset the swelling and lateral extrusion displacement generated by the press-fitting and compaction of the material sand, and it is possible to easily and surely improve the ground of the deep layer 3 at low cost.

FIG. 3A is a cross-sectional view showing the penetration state of the rod by the sandy ground compaction method when the rod of the second embodiment of the present invention is installed vertically, and FIG. 3B is a cross-sectional view when the rod is pulled out. A cross-sectional view and FIG. 3 (c) is a cross-sectional view of the rod when it is driven back.

The sandy ground compaction method of the second embodiment is also a method of compacting the shallow layer portion 2 of the sandy ground 1 by the vibration S and the impact G of the tip portion 5a of the rod 5, and the vibration S and the impact are applied to the tip portion 5a. A rod 5 provided with a vibration / impact applying device 6 for applying G is used. Reference numeral 3 in the figure indicates a deep part of the sandy ground 1.

Next, the procedure of compacting the shallow layer portion 2 which is the pre-process of improving the deep layer portion 3 of the sandy ground 1 by the vibration / impact of the tip portion 5a of the rod 5 is described in FIGS. 3 (a) to 3 (c). ) Will be described.

First, as shown in FIG. 3A, the rod 5 is driven vertically into the shallow layer 2 of the sandy ground 1 while rotating the rod 5 to a predetermined depth (about 5 to 6 m in depth). Penetrate.

After that, as shown in FIG. 3B, the rod 5 is pulled out by a predetermined length (for example, about 60 cm), and vibration / impact is applied to the surrounding ground from the tip portion 5a of the rod 5 for a predetermined time (for example, about 1 to 3 minutes). In addition, earth and sand (peripheral ground) is dropped from the periphery into the cavity K formed around the tip portion 5a of the pulled out rod 5, and the cavity K is filled.

After that, as shown in FIG. 3C, the rod 5 is driven back by, for example, 40 cm to compact the rod 5 equivalent to 20 cm. This work is continuously performed to compact about 5 to 6 m of the shallow layer portion 2. This compacted portion is indicated by reference numeral M in FIG. 3 (c).

In this way, by vertically driving and pulling out the rod 5 with respect to the shallow layer portion 2 of the sandy ground 1, the earth and sand 1a of the surrounding ground around the rod 5 becomes the rod 5 as in the first embodiment. It is easy to fall into the hollow portion K from which the rod has been pulled out, and the efficiency of the settlement treatment is improved. Further, by hitting back the rod 5, the compaction effect is increased.

According to the first embodiment, the rod is inserted and pulled out from the radial 2 to 4 directions diagonally from one place where the deep layer is ground-treated in this step. The rod may be inserted into or pulled out from the shallow layer diagonally from above the direction.

FIG. 4 is a side view when the rod is diagonally driven and pulled out in the experimental medium-sized soil tank, and FIG. 5 is a plan view when the rod is diagonally driven and pulled out in the experimental medium-sized soil tank. Is a side view when the rod is vertically driven and pulled out in the experimental medium-sized soil tank, and FIG. 7 is a plan view when the rod is vertically driven and pulled out in the experimental medium-sized soil tank.

As shown in FIGS. 4 to 7, an experimental bottomed cylinder used when the rod 5 is diagonally driven / pulled out and compacted, and when the rod 5 is vertically driven / pulled out and compacted. The medium-sized clay tank 10 has the same size with an inner diameter of φ400 mm and a height of 400 mm. In this medium-sized soil tank 10, four vinyl chloride pipes (VP25, φ32 mm) as rods 5 were installed, and the surroundings were dried, for example, a blended sand of Ube silica sand No. 6 and No. 7 (No. 6:: A simulated ground (sandy ground) 11 was prepared by filling (5 layers × layer thickness 70 mm = height 350 mm) so as to have a predetermined density (set Dr = 50%) at No. 7 = 7: 3).

In the test of the simulated ground 11, a pipe made of vinyl chloride as a rod 5 is pulled out by 5 cm, and the pipe is hit with a mallet to give an impact. After that, the short pipe is pulled out and hit five times in the same procedure, and finally the short pipe is completely pulled out from the simulated ground 11. This is repeated four times. After the completion of four lines, the amount of subsidence of the sand surface 11a of the simulated ground 11 was measured to confirm the degree of compaction. The measurement result is shown in FIG.

That is, in FIG. 8, the amount of subsidence of the sand surface 11a in the case of diagonal penetration of 6, 60, and 300 times is indicated by a black square, and in the case of vertical penetration, the total number of hits of the sand surface 11a is 300. The amount of subsidence of is indicated by a white (white) triangle.

As shown in FIG. 8, in the test using the medium-sized clay tank 10, the subsidence amount of the sand surface 11a at a total number of hits of 6 times was -4.5 mm, and at 60 times, it was -6.9 mm, 300. The number of hits is -16.8 mm, and the amount of subsidence of the sand surface 11a is -10.7 mm when the total number of hits is 300 in the case of vertical penetration. It was found that when the subsidence of the sand surface 11a is to be generated, the diagonal intrusive rock is more efficient than the vertical intrusive rock in about 1/2 the number of hits. That is, rather than vertically penetrating the rod 5 that generates vibration and impact, it is possible to induce subsidence of the ground directly above the rod by penetrating it diagonally and pulling it out, and the efficiency of pulling in and subsidence is good, and the rod 5 It is possible to reduce the construction time by about half and to compact the simulated ground 11 more efficiently by pulling out the ground by penetrating it diagonally than by pulling it out by penetrating it vertically.

1 Sandy ground 2 Shallow layer 3 Deep layer 5 Rod 5a Tip 11 Simulated ground (sandy ground)
S Vibration G Impact K Cavity

Claims (1)

It is a sandy ground compaction method that compacts the sandy ground by the vibration of the rod.
In the pre-step of ground improvement of the shallow layer portion of the sandy ground, the rod is placed in the shallow layer portion to a predetermined depth in the shallow layer portion a plurality of times from different directions at an angle from one place where the deep layer portion is ground-treated. Drive in and penetrate, then pull out the rod to a predetermined length, apply vibration and impact to the tip of the rod, drop the surrounding ground into the cavity formed around it, and then drive the rod back. A sandy ground compaction method characterized in that after compacting the shallow layer portion , material sand is press-fitted into the deep layer portion to improve the ground in this step.

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