JP2019019490A - Sandy soil compaction method - Google Patents

Abstract

To provide a sandy soil compaction method capable of further improving compaction efficiency at low cost.SOLUTION: A sandy soil compaction method for compacting sandy soil 1 by vibrating a rod 5 comprises the steps of driving the rod 5 into shallow layer portion 2 of the sandy soil 1 to penetrate it to a predetermined depth, then pulling out the rod 5 by a predetermined length to apply vibration and impact to a tip portion 5a of the rod 5 to drop sediment 1a of the surrounding ground into a hollow portion K formed around it, and then redoing the rod 5 to compact the shallow layer portion 2.SELECTED DRAWING: Figure 1

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 pressing material sand into the ground through a casing pipe is known.

JP 2008-291479 A

  In the conventional sandy ground compaction method, the sandy ground gap is reduced by press-fitting the material sand, but in the shallow layer it often causes swell and lateral displacement. In many cases, countermeasures such as buffer holes were required.

  Then, this invention is made | formed in order to solve the above-mentioned subject, and it aims at providing the sandy ground compaction construction method which can improve compaction efficiency further at low cost.

  The invention of claim 1 is a sandy ground compacting method in which sandy ground is compacted by vibration of a rod, the rod is driven into a shallow depth portion of the sandy ground and penetrated, and then The rod is pulled out by a predetermined length, and vibration / impact is applied to the tip of the rod to drop the surrounding ground into the cavity formed around the rod, and then the rod is driven back to compact the shallow layer portion. It is characterized by that.

  A second aspect of the present invention is the sandy ground compacting method according to the first aspect, characterized in that the rod is driven and pulled obliquely with respect to the shallow layer portion of the sandy ground.

  Invention of Claim 3 is the sandy ground compaction method of Claim 2, Comprising: From one place which carries out the ground treatment of the deep layer part at this process in the previous process which improves the deep layer part of the said sandy ground. After obliquely penetrating and pulling out the shallow layer portion from a different direction, the rod is subjected to subsidence treatment, and then the rod is driven back to compact the shallow layer portion. In the present step, the ground is improved by press-fitting material sand into the deep layer.

  A fourth aspect of the present invention is the sandy ground compaction method according to the first aspect, characterized in that the rod is driven and pulled out vertically with respect to the shallow layer portion of the sandy ground.

  As described above, according to the first aspect of the present invention, the rod is driven into the shallow layer portion of the sandy ground to a predetermined depth and penetrated, and then the rod is pulled out by a predetermined length to the tip of the rod. By applying vibration and impact, the surrounding ground is dropped into the cavity around it, and then the rod is driven back and the shallow layer is compacted to promote settlement of the surrounding ground around the rod. , The compaction efficiency can be improved.

  According to the second aspect of the present invention, the rod is obliquely driven and pulled out from the shallow layer portion of the sandy ground, so that the earth and sand in the surrounding ground at the top of the rod can easily fall into the hollow portion from which the rod has been pulled out. Compared with the case where the pits are installed vertically and driven / pulled out, the efficiency of the settlement process can be further improved.

  According to the invention of claim 3, in the previous step of improving the ground layer of the sandy ground, the rod is inclined to the shallow layer part several times from different directions diagonally from one place where the deep layer is grounded in this step. After intrusion / pulling, the shallow layer is settled, and then the rod is driven back to compact the shallow layer, and then the sand is pressed into the deep layer in this process to improve the ground. By doing this, a wide range of sandy ground is compacted by slanting and pulling the rod multiple times from one location, causing subsidence and lateral pull-in displacement, and then material sand press-fitting performed in this process It is possible to cancel out the bulging and lateral displacement caused by hardening, and the ground improvement in the deep layer can be easily and reliably performed at low cost.

  According to the fourth aspect of the present invention, the rod is vertically driven into and pulled out from the shallow layer portion of the sandy ground, so that the hollow portion formed on the lower side of the tip end portion of the rod is surrounded by the surrounding ground around the rod. Sediment can be dropped reliably.

(A) is sectional drawing which shows the penetration | invasion state of the rod by the sandy ground compaction method in the case of installing the rod of 1st Embodiment of this invention diagonally, (b) is sectional drawing at the time of extraction of the rod, c) is a cross-sectional view when the rod is driven back. It is a top view explaining the relationship between the front process and this process of the sandy ground compaction construction method of the said 1st Embodiment. (A) is sectional drawing which shows the penetration | invasion state of the rod by the sandy ground compaction construction method in the case of installing the rod of 2nd Embodiment of this invention vertically, (b) is sectional drawing at the time of extraction of the rod, c) is a cross-sectional view when the rod is driven back. It is a side view at the time of driving and extracting a rod diagonally in a medium-sized soil tank for experiments. It is a top view at the time of driving and extracting a rod diagonally in a medium-sized soil tank for experiments. It is a side view at the time of driving and extracting a rod vertically in a medium-sized soil tank for experiments. It is a top view at the time of driving and extracting a rod vertically in a medium-sized soil tank for experiments. It is explanatory drawing which shows the relationship between the total number of times of impact and the amount of subsidence of the simulated ground when the rod is driven / pulled obliquely and when the rod is driven / pulled vertically in an experimental medium-sized soil tank.

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

  FIG. 1 (a) is a cross-sectional view showing a rod penetration state by a sandy ground compaction method when the rod of the first embodiment of the present invention is installed obliquely, and FIG. 1 (b) is when the rod is pulled out. A cross-sectional view and FIG. 1C are cross-sectional views when the rod 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 vibration S and the tip 5a of the rod 5. This is a method of compaction 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 5a. In addition, the code | symbol 3 in a figure shows the deep layer part of the sandy ground 1. FIG.

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

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

  Thereafter, 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 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 and supplied from the periphery to the cavity K formed around the tip portion 5a of the drawn rod 5, and the cavity K is filled.

  Thereafter, as shown in FIG. 1C, the rod 5 is driven back, for example, 40 cm, and the portion corresponding to 20 cm is compacted. This operation is performed continuously, and about 5 to 6 m of the shallow layer portion 2 is compacted. This compacted portion is indicated by the symbol M in FIG.

  In this way, when the rod 5 is obliquely driven and pulled out from the shallow layer portion 2 of the sandy ground 1, the earth and sand 1 a in the surrounding ground above the rod 5 easily falls into the cavity K from which the rod 5 has been pulled out. , The efficiency of the settlement process is improved. That is, by allowing the rod 5 to penetrate diagonally, the drop of the earth and sand 1a in the surrounding ground above the rod 5 is promoted, and compaction efficiency is improved. Furthermore, by compacting the rod 5, the compaction effect is further increased.

  In addition, for example, when constructing a pavement by making a hole in the pavement, such as improving the ground of an airport, by inserting the rod 5 at an angle, it is accompanied by press-fitting of material sand by secondary compaction in the primary compaction in the previous process. The range of vibration and impact that is not present can be expanded to an oblique range by the oblique penetration of the rod 5 instead of directly under the hole of the pavement, and the ground can be improved easily and at low cost.

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

  As shown in FIG. 2, in the previous step (primary compaction) for improving the deep layer 3 of the sandy ground 1, the direction different from the one place where the deep layer 3 is grounded in this step (secondary compaction). The rod 5 is inserted into and pulled out of the shallow layer portion 2 obliquely (for example, in a radial 2-4 direction) 2-4 times, and the subsidence processing of the shallow layer portion 2 and the sediment 1a of the surrounding ground are dropped.

  After the rod 5 is driven back and the shallow layer portion 2 is compacted, in this step, material sand is pressed into the deep layer portion 3 through the casing pipe 7 to improve the ground.

  Thus, in the previous step of improving the ground of the deep layer 3, the rod 5 is inserted into and pulled out of the shallow layer 2 obliquely from a different direction from one place where the casing pipe 7 is inserted into the sandy ground 1. After the subsidence process of the shallow layer part 2 and the earth and sand 1a dropping process of the surrounding ground are performed and the shallow layer part 2 is compacted, in this step, the material sand is pressed into the deep layer part 3 through the casing pipe 7 and the ground. By making improvements, a wide range of sandy ground 1 is compacted by slanting and pulling out the rod 5 from a plurality of directions from one place to cause subsidence and lateral pull-in displacement, and this is performed in the subsequent step. It is possible to cancel out the rise and lateral displacement generated by press-fitting the material sand, and the ground improvement of the deep layer portion 3 can be easily and reliably performed at low cost.

  FIG. 3 (a) is a cross-sectional view showing the state of penetration 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. 3 (b) is when the rod is pulled out. A cross-sectional view and FIG. 3C are cross-sectional views when the rod 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 vibration S and impact G of the tip portion 5a of the rod 5, and the vibration S and impact are applied to the tip portion 5a. A rod 5 provided with a vibration / impact applying device 6 for applying G is used. In addition, the code | symbol 3 in a figure shows the deep layer part of the sandy ground 1. FIG.

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

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

  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 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 and supplied from the periphery to the cavity K formed around the distal end portion 5a of the drawn rod 5 to fill the cavity K.

  Thereafter, as shown in FIG. 3C, the rod 5 is driven back, for example, 40 cm, and the portion corresponding to 20 cm is compacted. This operation is performed continuously, and about 5 to 6 m of the shallow layer portion 2 is compacted. This compacted portion is indicated by the symbol M in FIG.

  In this manner, by driving the rod 5 vertically to the shallow layer portion 2 of the sandy ground 1 and pulling it out, the earth and sand 1a of the surrounding ground around the rod 5 is removed from the rod 5 as in the first embodiment. It is easy to fall into the cavity K from which the material is pulled out, and the efficiency of the settlement process is improved. Furthermore, by compacting the rod 5, the compaction effect is increased.

  In addition, according to the said 1st Embodiment, although the rod was penetrated and extracted to the shallow layer part from the radial 2-4 directions diagonally from one place which ground-processes a deep layer part at this process, radial 5 The rod may be inserted into and pulled out from the shallow layer obliquely from above the direction.

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

  As shown in FIG. 4 to FIG. 7, an experimental bottomed cylinder used when the rod 5 is obliquely driven / pulled and compacted, and when the rod 5 is vertically driven / pulled and compacted. The medium-sized soil tank 10 has the same size with an inner diameter of 400 mm and a height of 400 mm. For example, Ube silica sand No. 6 and No. 7 blend sand (No. 6: No. 6: Ube Silica Sand) was installed in this medium-sized earth basin 10 with four pipes made of vinyl chloride (VP25, φ32 mm) as the rod 5. No. 7 = 7: 3) was filled (5 layers × layer thickness 70 mm = height 350 mm) so as to obtain a predetermined density (setting Dr = 50%), and a simulated ground (sandy ground) 11 was produced.

  In the test of the simulated ground 11, a pipe made of vinyl chloride as the rod 5 is pulled out by 5 cm at a time, and the pipe is hit with a wooden rod to apply an impact. Thereafter, pulling and striking are performed five times in the same procedure, and finally the short pipe is completely pulled out from the simulated ground 11. Repeat this four times. After the completion of the four, the amount of settlement of the sand surface 11a of the simulated ground 11 was measured to confirm the degree of compaction. The measurement results are shown in FIG.

  That is, in FIG. 8, the amount of subsidence of the sand surface 11a when the slant penetration is 6 times, 60 times, and 300 times is indicated by a black rectangle, and the sand surface 11a is 300 times when the impact is vertical. The amount of subsidence is indicated by a white (outlined) triangle.

  As shown in FIG. 8, in the test using the medium-sized earth tub 10, the sinking amount of the sand surface 11 a at the total number of hits of 6 in the case of oblique penetration is −4.5 mm, −6.9 mm at 300 times, 300 In the case of vertical penetration, the amount of subsidence of the sand surface 11a at the total number of hits of 300 is -10.7 mm, and when the number of hits is changed between oblique penetration and vertical penetration, It was found that in order to cause the sand surface 11a to sink to a certain degree, the oblique intrusion requires about half the number of impacts compared to the vertical intrusion and is efficient. That is, when the rod 5 that generates vibration and impact is penetrated vertically, it is possible to induce the subsidence of the ground directly above the rod, and the pulling-in and subsidence efficiency is improved. It is possible to reduce the construction time to about a half by pulling out and pulling in diagonally, and to compact the simulated ground 11 more efficiently than pulling out and pulling vertically.

1 Sandy Ground 2 Shallow Layer 3 Deep Layer 5 Rod 5a Tip 11 Simulated Ground (Sandy Ground)
S Vibration G Shock K Cavity

Claims (4)

It is a sandy ground compaction method that compacts sandy ground by vibration of the rod,
A hollow formed in the periphery of the sandy ground by driving the rod to a predetermined depth and penetrating it, and then pulling out the rod to a predetermined length and applying vibration and impact to the tip of the rod. The sandy ground compaction method is characterized in that the surrounding ground is dropped into the part and then the rod is driven back to compact the shallow layer part. The sandy ground compaction method according to claim 1,
A sandy ground compaction method, characterized in that the rod is driven obliquely and pulled out with respect to a shallow layer portion of the sandy ground. The sandy ground compaction method according to claim 2,
In the previous step of ground improvement of the deep layer portion of the sandy ground, the rod is penetrated and pulled out from the shallow layer portion multiple times from different directions diagonally from one place where the deep layer portion is grounded in this step. After the subsidence treatment of the shallow layer portion is performed, and then the rod is driven back and the shallow layer portion is compacted, the material sand is pressed into the deep layer portion in this step to improve the ground. A sandy ground compaction method that is characterized. The sandy ground compaction method according to claim 1,
A sandy ground compaction method, characterized in that the rod is driven and pulled vertically with respect to a shallow part of the sandy ground.

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