JP5223079B2 - Strengthening of ground around existing small semi-permanent permanent underground structures - Google Patents

Description

The present invention relates to a method for strengthening the surrounding ground of an existing small-scale semi-permanent permanent underground structure, and in particular, an existing equipment used for suppressing the levitation of a semi-permanent permanent underground structure due to ground liquefaction during an earthquake. The present invention relates to a method for strengthening the surrounding ground of a small-scale semi-permanent permanent underground structure (hereinafter sometimes simply referred to as “underground structure”) .

  In recent large earthquakes, the existing small-scale underground structures have been greatly damaged. In particular, as an example of an existing small-scale underground structure, problems such as traffic obstacles and sewage flow failure have occurred due to the rise of manholes as sewerage facilities. This is because a small underground structure having a small volume specific gravity such as a manhole is levitated due to the buoyancy of the liquefied ground. The liquefaction of the ground is a phenomenon in which when the earthquake occurs, the ground is repeatedly subjected to shear deformation in an almost undrained state, and the ground becomes close to liquid due to an increase in excess pore water pressure.

  Conventionally, a method for strengthening the surrounding ground of an existing small-scale underground structure has been performed by the following method, for example. A predetermined length of liquefaction suppression sheet pile with a drainage function to dissipate excess pore water pressure generated in the ground during an earthquake is specified on both sides of the buried structure built in the ground from both sides of the buried structure. It installs at intervals (for example, refer patent document 1).

  In addition, a vibrator equipped with a vibrating rod is inserted into the ground around an existing small-scale underground structure, and the ground is liquefied by applying vibration to the ground. A ground compacting method is known in which excess pore water generated at the same time is discharged through a drain pipe inserted along the rod (see, for example, Patent Document 2).

JP 05-255941 A (Claims) Japanese Patent Laid-Open No. 04-272314 (Claims)

  However, the method for strengthening the surrounding ground of an existing small-scale underground structure disclosed in Patent Document 1 has the following problems. That is the problem that the excess pore water pressure locally increases in the area surrounded by the liquefaction suppression sheet pile, and it is difficult to reduce the excess pore water pressure after the earthquake. Moreover, since this method greatly cuts the surrounding road of an existing small-scale underground structure, a large-scale construction facility is required. For this reason, in addition to the cost increase, the construction period becomes longer, and it is difficult to perform construction when ground surface piping or ground electric wires or telephone lines are arranged around existing small underground structures. There is also a problem.

  On the other hand, the ground compaction method disclosed in Patent Document 2 has the same problem as the method disclosed in Patent Document 1 described above. Moreover, in such a conventional construction method, the range in which the surrounding ground of the existing small-scale underground structure can be vibrated is limited by the diameter of the vibrating rod, and the entire surrounding ground of the existing small-scale underground structure is limited, The transmission efficiency of vibration energy is not good. For this reason, there is a problem that it becomes difficult to obtain an effect of securely compacting the ground.

  The present invention has been made to solve the above-described problems, and the object of the present invention is not to require a large-scale construction facility, and is excellent in vibration energy transmission efficiency at low cost. The purpose is to provide a method for strengthening the ground around existing small underground structures.

In order to achieve the above object, the present invention is a method for strengthening the surrounding ground (excluding the case of being partitioned by a water shielding wall) of an existing small-scale semi-permanent permanent underground structure, and includes at least a structure main body. A method for strengthening the surrounding ground of existing small-scale underground structures where a vibrator is provided at the top and / or inside of the object, and the underground structure is vibrated as a vibration medium by the vibration of the vibrator (measures against ground liquefaction In order to forcibly remove the moisture in the frame of the water-blocking wall, the foundation ground of existing equipment structures such as oil storage facilities, A drainage well is installed in which a steel pipe, which is an underground structure with a vibrator, is installed. After the resonant vibration is applied by a vibrator, residual water around the steel pipe is introduced into the steel pipe and drained, and then the steel pipe is removed. Excluding cases) .

  According to this, it is not necessary to use a large-scale construction facility, and the surrounding ground of an existing small-scale underground structure can be strengthened at a low cost. By providing the exciter on the top and / or inside of the underground structure, the existing small-scale underground structure is vibrated as a vibration medium by horizontal vibration in the lateral direction of the exciter. For this reason, since the vibration rod does not penetrate into the surrounding ground of the existing small-scale underground structure as compared with the prior art, it is not necessary to cut the ground greatly. Therefore, a large-scale construction facility is not required, and construction can be performed even when ground surface piping, ground electric wires, telephone lines, or the like are arranged around an existing small-scale underground structure. As a result, the cost can be reduced and the construction period can be shortened.

  In addition to the previous invention, another invention of the present invention is a method for strengthening the surrounding ground of an existing small-scale underground structure in which the underground structure is a manhole having an opening to the ground.

  According to this, when ground liquefaction occurs due to an earthquake, as a concrete example of an existing small-scale underground structure, problems such as traffic obstacles and sewer dysfunction occur due to the rise of manholes as sewerage facilities. It becomes possible to eliminate.

  In addition to the previous invention, another invention of the present invention is an existing small-scale underground structure in which the underground structure is further provided with a guide path for circulating excess pore water accompanying liquefaction outside the underground structure. It is a method for strengthening the ground surrounding the structure.

  Since the entire underground structure vibrates using the vibration medium, when the underground structure is vibrated in this way, excess water is generated in the ground surrounding the underground structure due to the vibration. It is discharged through the path part. Therefore, liquefaction around the underground structure is prevented, vibration energy of the underground structure is effectively transmitted, and the ground around the underground structure is surely strengthened.

  Further, in another invention, in addition to the previous invention, the underground structure further includes excess pore water outside the underground structure in a through hole that penetrates the peripheral wall on the lower end side of the underground structure. A water-absorbing device for distribution is provided, the guide path is provided inside the underground structure, the first opening leading to the outside of the underground structure on the lower end side, and the underground structure on the upper end side. A method for strengthening the surrounding ground of an existing small-scale underground structure having a second opening leading to the inside and connecting the first opening and the water absorbing device.

  By providing the water absorption device, when excess pore water is generated due to liquefaction of the ground surrounding the underground structure due to vibration of the underground structure itself by the vibrator, excess pore water around the underground structure is It is quickly sucked into the underground structure through the induction pipe by the water absorption device. For this reason, excess pore water does not accumulate around the underground structure, and the vibration energy transmission efficiency from the underground structure to the surrounding ground is enhanced. As a result, the ground around the underground structure can be strengthened efficiently.

  In addition to the previous invention, another invention of the present invention is a method for strengthening the surrounding ground of an existing small-scale underground structure in which the second opening is positioned above the groundwater surface.

  According to this, excess pore water generated around the underground structure is more quickly discharged into the underground structure. For this reason, excess pore water does not accumulate around the underground structure, and the vibration energy transmission efficiency from the underground structure to the surrounding ground is enhanced. As a result, the ground around the underground structure can be strengthened more reliably.

  In addition to the previous invention, another invention of the present invention is a method for strengthening the surrounding ground of an existing small-scale underground structure in which the water absorption device includes a filtering member that filters excess pore water flowing through the guide path portion.

  According to this, by providing the filtration member in the water absorbing device, it is possible to efficiently remove suspended matters such as earth and sand or mud contained in the excess pore water. For this reason, earth or sand or mud does not flow into the sewer pipe, and blockage in the pipe can be prevented.

  The structure applied to the method for strengthening the surrounding ground of an existing small-scale underground structure according to the present invention is particularly limited as long as the structure is small-scale and all or part of the structure is buried in the ground. In addition to manholes, there are small tunnels or underground tanks, for example.

  According to the present invention, it is possible to provide a method for strengthening the surrounding ground of an existing small-scale underground structure that does not require a large-scale construction facility, is low in cost, and is excellent in vibration energy transmission efficiency.

  Hereinafter, preferred embodiments of a method for strengthening the surrounding ground of an existing small-scale underground structure according to the present invention will be described in detail with reference to the drawings. However, the present invention is not limited to the embodiments described below.

(First embodiment)
FIG. 1 is a cross-sectional view showing a manhole 100 applied to a method for strengthening the surrounding ground of an existing small-scale underground structure according to the first embodiment of the present invention.

  As shown in FIG. 1, a manhole 100 is embedded in the ground, is formed of cylindrical concrete, and has a manhole body 5 having an opening to the ground on the upper end side, and a peripheral wall on the lower end side of the manhole body 5 And a drain pipe 60 for connecting the inside and outside of the manhole body 5 to the inside and outside of the manhole body 5. A metal manhole cover 20 is detachably provided at the opening formed at the upper end of the manhole body 5, and the periphery of the opening is paved.

  Next, a method for strengthening the surrounding ground of the existing small-scale underground structure according to the first embodiment of the present invention will be described.

  FIG. 2 is a diagram in which the exciter 10 is attached to the manhole 100 shown in FIG.

  As shown in FIG. 2, the exciter 10 was attached to the top of the manhole 100 via the mounting portion 30. The vibrator 10 applies a horizontal force to the manhole 100 to vibrate the manhole 100 in the ground. As the vibrator 10, a known one can be suitably selected and used according to the size of the manhole 100 and the ground condition. For example, the exciter 10 which includes an eccentric rotator and a hydraulic motor or an electric motor which is a driving source thereof is included. A lateral vibration is generated according to the eccentric rotational motion of the eccentric rotating body, and this vibration is applied to the manhole 100, thereby vibrating the manhole 100 as a vibration medium. Then, vibration energy is transmitted to the surrounding ground through the manhole 100, a shearing force acts on the surrounding ground, and an excessive pore water pressure is easily generated. For this reason, strengthening of the surrounding ground of the manhole 100 is performed reliably.

  The mounting method of the vibrator 10 is not particularly limited, and a known method may be adopted. In particular, a method that can be detachably mounted between the vibrator 10 and the manhole 100 is preferable.

  FIG. 3 is a view in which the vibrator 10 is attached to the manhole 100 shown in FIG. 1 having another form.

  As shown in FIG. 3, unlike the above-described embodiment, the exciter 10 may be attached to the bottom of the manhole 100 via the mounting portion 30. Moreover, you may provide the vibrator 30 in both the top part and the bottom part of the manhole 100 as needed. As described above, since the vibrator 10 is provided at the top and / or inside of the manhole 100, it is not necessary to penetrate the vibrating rod into the surrounding ground of the manhole 100 as compared with the prior art. For this reason, it is not necessary to excavate the ground greatly. Therefore, a large-scale construction facility is not required, and the construction can be performed even when ground surface piping, ground electric wires or telephone lines are arranged around the manhole 100. As a result, the cost can be reduced and the construction period can be shortened, and it is possible to prevent problems such as traffic troubles and sewage flow function troubles due to the rise of the manhole 100 when an earthquake occurs.

(Second embodiment)
Next, the manhole 200 applied to the surrounding ground reinforcement method of the existing small-scale underground structure according to the second embodiment of the present invention will be described.

  The manhole 200 according to the second embodiment has a common part with the manhole 100 according to the first embodiment described above. In the following description of the second and subsequent embodiments, common parts are denoted by the same reference numerals as those in the first embodiment, and redundant descriptions are omitted.

  FIG. 4 is a cross-sectional view showing a manhole 200 applied to the method for strengthening the surrounding ground of an existing small-scale underground structure according to the second embodiment of the present invention. FIG. 5 is a cross-sectional view of the manhole 200 shown in FIG.

  As shown in FIGS. 4 and 5, the manhole 200 is embedded in the ground, is formed of concrete in a cylindrical shape, and has a manhole body 5 having an opening to the ground on the upper end side, and a lower end of the manhole body 5. A drainage pipe 60 is provided that is connected to a through hole that penetrates the peripheral wall on the inner side and the outer side, and that allows sewage to flow inside and outside the manhole body 5. A metal manhole cover 20 is detachably provided at the opening formed at the upper end of the manhole body 5, and the periphery of the opening is paved.

  Further, the manhole 200 includes a guide path portion 40 that is provided on the inner peripheral surface side of the peripheral wall of the manhole body 5 and introduces excess pore water accompanying liquefaction of the ground during an earthquake into the manhole body 5, and a water absorption device 50. With. The water absorption device 50 has an outer peripheral surface of the drain pipe 60 connected to a side surface of the water absorption device 50 through a seal, and the guide path portion 40 is attached to the top surface. The guide path portion 40 is composed of a guide tube, and is provided on the ground side with a first opening 41 that is on the lower end side of the manhole body 5 and connected to the top surface of the water absorbing device 50 so as to communicate with the outside of the manhole body 5. And a second opening 42 communicating with the manhole body 5. As the guide pipe, various pipes such as a steel pipe, a porous pipe or a drain pipe made of an artificial material can be used. The second opening 42 is provided above the groundwater surface. For this reason, groundwater is not introduced into the manhole body 5 at normal times, and excess pore water generated around the manhole 200 during vibration is quickly discharged into the manhole 200 through the water absorption device 50. As a result, excess pore water does not accumulate around the manhole 200, the vibration energy transmission efficiency from the manhole 200 to the surrounding ground can be increased, and the surrounding ground of the manhole 200 can be reliably strengthened.

  In addition, the water absorption device 50 includes a filtering member that filters excess pore water flowing through the guide path portion 40. By configuring in this way, suspended substances such as earth and sand or mud contained in excess pore water can be efficiently removed, so that earth and sand or mud and the like do not flow into the sewer pipe, and blockage in the pipe can be prevented.

  As a filtering member attached to the water absorption device 50, for example, a porous unglazed product obtained by mixing and baking wood powder or rice husk and a plant stem in viscous soil such as sediment waste from rivers and lakes, relatively rough gravel Or filtration materials, such as crushed stone, porous ceramics, or an artificial lightweight aggregate, are mentioned. Of these filtration materials, it is particularly preferable to use an artificial lightweight aggregate from the viewpoint of low strength. For this reason, when vibration is generated, if the manhole body 5 and the drain pipe 60 are shaken, the filter member is broken and damaged, so that the filter member absorbs the shake and the manhole body 5 and the drain pipe 60. Breakage and damage can be prevented. However, the above-mentioned filtration material is only an example, and other filtration materials may be adopted. In addition, one kind of filtration material as described above or a mixture of two or more kinds of filtration materials may be used.

  Next, a method for strengthening the surrounding ground of the existing small-scale underground structure according to the first embodiment of the present invention will be described.

  FIG. 6 is a view in which the vibrator 10 is attached to the manhole 200 shown in FIG.

  As shown in FIG. 6, in the second embodiment, as in the first embodiment, the vibrator 10 is attached to the top of the manhole 200 via the mounting portion 30. The vibrator 10 applies a horizontal force to the manhole 200 and vibrates using the manhole 200 as a vibration medium. Then, vibration energy is transmitted to the surrounding ground through the manhole 200, a shearing force acts on the surrounding ground, and an excessive pore water pressure is easily generated. Further, the generated excess pore water pressure is absorbed by the water absorption device 50 and discharged into the manhole 200 through the guide path portion 40. For this reason, liquefaction around the manhole 200 can be prevented, and the surrounding ground around the manhole 100 is more reliably strengthened.

  As described above, the manholes 100 and 200 applied to the method for strengthening the surrounding ground of the existing small-scale underground structure according to the embodiment of the present invention have been described. However, the surrounding ground of the existing small-scale underground structure according to the present invention is strengthened. The manholes 100 and 200 applied to the method are not limited to the above-described embodiments, and can be implemented in various modifications.

  For example, a hole for introducing excess pore water accompanying liquefaction is provided in the main body of the underground structure, and the shape, configuration, size, position or number of the holes are appropriately changed as necessary. Is possible.

  In addition, a guide path portion for circulating excess pore water accompanying liquefaction can be provided outside the underground structure.

  INDUSTRIAL APPLICABILITY The present invention can be used in industries that strengthen the surrounding ground of existing small-scale underground structures.

It is sectional drawing which shows the manhole applied to the reinforcement method of the surrounding ground of the existing small-scale underground structure which concerns on the 1st Embodiment of this invention. It is the figure which attached the vibrator to the manhole shown in FIG. It is the figure which attached the vibrator to the manhole shown in FIG. 1 which has another form. It is sectional drawing which shows the manhole applied to the reinforcement | strengthening method of the surrounding ground of the existing small-scale underground structure which concerns on the 2nd Embodiment of this invention. It is the sectional view on the AA line of the manhole shown in FIG. It is the figure which attached the vibrator to the manhole shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 5 ... Manhole body 10 ... Exciter 20 ... Manhole cover 30 ... Mounting part 40 ... Guidance path part 41 ... First opening part 42 ... Second opening part 50 ... Water absorption device 60 ... Drain pipe 100,200 ... Manhole

Claims (6)

A method of strengthening the surrounding ground (excluding the case of being partitioned by a water-impervious wall) of an existing small-scale semi-permanent permanent underground structure,
A vibrator is provided at the top and / or inside of the semi-permanent permanent underground structure including at least the structure body, and the semi-permanent permanent underground structure is vibrated as a vibration medium by vibration of the vibrator. Strengthening the surrounding ground of the existing small-scale semi-permanent permanent underground structure, which is a feature (for the purpose of ground liquefaction countermeasures, the foundation ground of existing equipment structures such as oil storage facilities is within the framework of a water barrier In order to forcibly exclude moisture, a water collecting well in which a steel pipe, which is an underground structure provided with a vibration generator, is provided on the foundation ground within a frame limited to the water shielding wall, and the vibration excitation is performed. Except for removing the steel pipe after applying resonance vibration in the machine to introduce and drain the residual water around the steel pipe into the steel pipe) .   The method for strengthening the surrounding ground of an existing small-scale underground structure according to claim 1, wherein the underground structure is a manhole having an opening to the ground.   3. The existing small-scale underground structure according to claim 1, wherein the underground structure further includes a guide path portion for circulating excess pore water accompanying liquefaction outside the underground structure. 4. A method for strengthening the ground around the structure. The underground structure is further provided with a water absorption device for circulating the excess pore water outside the underground structure in a through hole that penetrates the peripheral wall on the lower end side of the underground structure inside and outside,
The guide path portion is provided inside the underground structure, and has a first opening that leads to the outside of the underground structure on a lower end side and a second opening that leads to the inside of the underground structure on an upper end side. Have
The said 1st opening part and the said water absorption apparatus are connected, The reinforcement | strengthening method of the surrounding ground of the existing small-scale underground structure of Claim 3 characterized by the above-mentioned.   The method for reinforcing the surrounding ground of an existing small-scale underground structure according to claim 4, wherein the second opening is positioned above the groundwater surface.   The said water absorption apparatus is equipped with the filtration member which filters the said excess pore water which distribute | circulates to the said guidance | reduction path | route part, The reinforcement | strengthening method of the surrounding ground of the existing small-scale underground structure of Claim 4 characterized by the above-mentioned.

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