JP2006299605A - Equipment for countermeasure against liquefaction of ground immediately below underground structure, and equipment and construction method for countermeasure against liquefaction of ground immediately below fill - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide equipment for countermeasures against the liquefaction of not only ground immediately below an underground structure but also ground immediately below fill, which can prevent the settlement and lift of the underground structure and the collapse of the fill due to the liquefaction of the ground by effectively suppressing the flow-around of soil, caused by the liquefaction of the ground, by virtue of an excess-pore-water-pressure dissipating effect and a ground reinforcing effect, and which can sufficiently ensure the stability of the ground for countermeasures against giant earthquakes. <P>SOLUTION: A drain pipe with a drainage part is driven into the ground at each predetermined interval along the following longitudinal direction from a ground surface side 17 near the longitudinal side surface of the ground structure 14, or from a section of a toe 39 of slope in the longitudinal direction of the fill 34. The drain pipe is constituted by pairing a vertically-driven vertical drain pipe 11 and an inclined drain pipe 12 which is driven in the direction of inclination, making a certain angle with the vertical direction. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention is a liquefaction countermeasure facility and construction method for a direct foundation board of underground structure as a countermeasure for preventing floating of underground structure due to liquefaction of ground, and further, as a countermeasure for preventing collapse of embankment due to liquefaction of ground. Liquefaction countermeasure equipment and construction method for direct foundation board of embankment.

  In response to the Hyogoken-Nanbu Earthquake, there is a strong demand for improved earthquake resistance through social capital. Earthquake damage to underground structures such as sewerage facilities is most often caused by liquefaction of the ground, so measures to reduce the damage caused by liquefaction of the ground are required.

  In addition, the embankments were severely damaged by huge earthquakes such as the Hyogoken-Nanbu Earthquake and the Niigata Chuetsu Earthquake. The earthquake survey report reports that there are many embankments in the collapsed areas of the road, and the area around the collapsed area was high in groundwater level and contained a lot of water. The conventional embankment design has not been seismic design from the viewpoint of ease of restoration and cost. However, the embankment is also liquefied due to reasons such as securing emergency supplies and evacuation routes. It is considered important to have sufficient earthquake resistance including countermeasures.

  Here, the most important issue related to road reinforcement is the selection of construction methods and equipment that perform the required functions at a minimum cost. Due to the nature of the road, if one location is collapsed, even if the other location is not collapsed, there will be a major obstacle to the function of the emergency transport road, so at least minimum reinforcement is required for the entire route. That's why. The same applies to railways. Therefore, a construction method and equipment capable of simply and inexpensively implementing seismic reinforcement of embankments with insufficient seismic strength are desired in terms of promoting earthquake disaster prevention measures.

  In general, the liquefaction phenomenon of the ground means a phenomenon in which the pore water pressure of the ground rises at the time of an earthquake and the ground is fluidized by shear deformation of the ground. When ground such as a sand layer that is loosely saturated with groundwater is shaken violently by earthquake motion, the sand particles are disengaged and the sand particles float into a liquid state, and the pore water pressure rises (excess pore water pressure). Sand and water erupt on the ground surface and the ground surface sinks, causing various damage.

  Various methods have been proposed as countermeasures against ground liquefaction, but these principles can be broadly divided into measures to design the structure to be safe even if the ground is liquefied, and ground liquefaction. Classified as measures to prevent outbreaks. A typical example of the former method of designing the structure so that it is safe even after liquefaction is a pile foundation method considering the degree of liquefaction. On the other hand, for the latter, several countermeasures have been proposed based on the principle of liquefaction. Among them, typical examples of existing underground structures and embankments are steel sheet pile wall methods that surround the ground with steel sheet piles and suppress the shear deformation of the ground during earthquakes or liquefaction. Can be mentioned.

  Further, in Patent Document 1, a through hole provided in a footing of a structure so as to pass from the upper surface to the lower surface, and a liquefaction prediction layer of the footing direct base plate is inserted from the through hole to the direct base plate of the footing. There is disclosed a liquefaction countermeasure device for a structure-underlying base plate, comprising a water-permeable drain pipe that forms a drain reaching the upper surface of the footing.

JP 2000-154551 A

  However, the steel sheet pile wall construction method assumes that the sheet pile is healthy against the earth pressure acting on the sheet pile during an earthquake, but if it is able to cope with a huge earthquake, the bending stiffness of the sheet pile and the support ground There is a problem that the economic efficiency is impaired due to the large penetration length. In addition, in the case of underground structures under the road surface, the steel sheet pile wall method leaves the steel sheet pile to the ground, so this removal work takes a lot of time and cost, and traffic congestion is caused. There is a problem of causing.

  In addition, the amount of lift of the steel sheet pile wall method is predicted by the sum of the amount of lift due to wraparound in the sheet pile and the amount of lift due to sheet pile deflection, so the separation from the structure and the stiffness of the sheet pile are the decisive factors for the countermeasure effect. In the case of underground structures, there are usually manholes, branch pipes, etc., and there is a problem that the countermeasure effect may not be sufficiently exhibited because there are missing portions of the sheet pile wall in some places.

  In addition, the self-supporting steel sheet pile wall method is an easy and economical construction method. However, because the sheet pile wall is self-supporting, the bending stiffness of the sheet pile and the length of penetration into the support ground for a large earthquake Therefore, economic efficiency may be impaired. In addition, the construction method that uses tie rods to reinforce the steel sheet pile wall can reduce the bending stiffness of the sheet pile and the penetration length into the supporting ground compared to the self-supporting steel sheet pile wall construction method. Since the bottom is penetrated in the horizontal direction, problems remain in workability. Furthermore, in any case, there is a problem that the settlement damage due to the shear deformation of the embankment cannot be suppressed.

  On the other hand, in the invention described in Patent Document 1, the problem of subsidence / lifting of underground structures due to the ground flowing due to liquefaction of the ground, and the problem of collapse of the embankment due to ground liquefaction are completely considered. It has not been.

  The object of the present invention is to prevent the subsidence / floating of underground structures and collapse of embankments caused by ground liquefaction due to ground liquefaction, and the soil generated by liquefaction of ground due to the effect of dissipating excess pore water pressure and ground reinforcing This effectively suppresses the sneaking around and can ensure sufficient stability of the countermeasure ground in the event of a large earthquake, while improving the efficiency of construction and reducing construction costs. It is to provide a liquefaction countermeasure facility and construction method, and a liquefaction countermeasure facility and construction method for a direct foundation board of embankment.

  In order to solve the above-mentioned problem, the liquefaction countermeasure facility for the direct foundation board of the underground structure according to the first aspect of the present invention is along the longitudinal direction from the surface side near the side surface in the longitudinal direction of the underground structure. At a predetermined interval, a drain pipe having a drainage portion is driven into the ground, and the drain pipe is driven in an inclined direction that forms a certain angle with the vertical drain pipe that is driven in the vertical direction. The slanted drain pipe is formed in a pair.

  When a structure such as a lifeline such as a common ditch, sewer pipe, and dedicated wiring pipe is installed in the ground, there is no means for securely fixing the underground structure in the ground, and the structure is isolated. If the ground does not flow, the movement of underground structures cannot occur, but if the soil that exists in the ground moves due to the liquefaction of the ground due to a large earthquake, the movement of the ground The structure will rise and fall.

According to the present invention, since the vertical drain pipe having the drainage portion and the inclined drain pipe form a pair in the ground from the surface side near the side surface in the longitudinal direction of the underground structure, the vertical drain The region sandwiched (enclosed) between the tube and the inclined drain tube is the portion where the liquefaction hardly occurs because water is most easily discharged. In the event of a major earthquake, this area continues to exist as a kind of wall without being liquefied, and works to block the flow of liquefied soil on both sides (surroundings) of this wall.
In other words, the action of the wall based on the action of dissipating excess pore water pressure in the drain pipe and the ground reinforcement effect of the drain pipe itself effectively prevent the liquefied ground from entering the lower side of the underground structure. Therefore, the underground structure can be prevented from rising and sinking, and the stability of the countermeasure ground in the event of a huge earthquake can be secured sufficiently.

  In addition, according to the present invention, the conventional steel sheet pile method requires a large construction machine, and in many cases, close construction is difficult, but because a drain pipe is used without using a steel sheet pile, construction with a small machine is possible. In addition, not only can construction be performed in close proximity, but also low vibration and noise can be achieved, and there is little influence on the surrounding environment, and construction can be performed even in places close to private houses. In addition, since the local applicability is also high, in addition to contributing to the efficiency of construction and reduction of construction costs, manholes, branch pipes, etc., are places where defects occur in the case of sheet pile walls. However, the effect of dissipating excess pore water pressure can be obtained easily and economically. Furthermore, since the removal work within 2.5 m below the road surface, which is difficult with the conventional construction method, is easy by using the drain pipe, there will be no trouble in other construction plans in the future.

According to a second aspect of the present invention, in the first aspect of the invention for a liquefaction countermeasure facility for a direct foundation board of an underground structure, the vertical drain pipes and the inclined drain pipes are alternately arranged in a staggered pattern. It is characterized by being.
According to the present invention, in addition to the function and effect of the first aspect, the vertical drain pipes and the inclined drain pipes are alternately arranged in a staggered manner, so that the walls that are not liquefied can be efficiently formed. Thus, the liquefied ground is more effectively prevented from going downward in the underground structure.

According to a third aspect of the present invention, in the first or second aspect, the drain pipe according to the third aspect of the present invention is directed to a liquefaction countermeasure facility for a direct foundation board. It is formed in a rhombus shape in a plan view.
According to the present invention, in addition to the operational effects of the first or second aspect, the vicinity of the tip of the driving head of the drain pipe is formed in a rhombus shape in plan view, so that the ground reinforcement effect due to the pulling resistance force is further increased. Become strong.

According to a fourth aspect of the present invention, there is provided an invention for a liquefaction countermeasure facility for a direct foundation board of an underground structure according to any one of the first to third aspects, wherein the drain pipe is reinforced to reinforce the drain pipe. It is characterized by having a material.
According to the present invention, in addition to the operational effects of any one of the first to third aspects, since the drain pipe is reinforced by the reinforcing material, the ground reinforcing effect is reliably exhibited even in a huge earthquake, and liquefaction is achieved. The sneak around the ground is further suppressed.

The invention of the liquefaction countermeasure construction method for the direct foundation board of the embankment according to the fifth aspect of the present invention is the drainage section at predetermined intervals along the longitudinal direction from the surface side near the longitudinal side surface of the underground structure. A drain pipe having a vertical direction, and a vertical drain pipe that is placed in the vertical direction and an inclined drain pipe that is placed in an inclined direction that forms a fixed angle with the vertical direction. It is characterized by comprising.
According to the construction method of the present invention, it is possible to obtain the same function and effect as the first aspect.

  According to the sixth aspect of the present invention, the liquefaction countermeasure equipment for the direct foundation board of the embankment is provided with a drain pipe having a drainage section at predetermined intervals along the longitudinal direction from the glue bottom portion in the longitudinal direction of the embankment. The drain pipe is formed in the ground, and the drain pipe is composed of a vertical drain pipe placed in the vertical direction and an inclined drain pipe placed in an inclined direction that forms a fixed angle with the vertical direction. It is characterized by being.

  According to the present invention, since the vertical drain pipe having the drainage portion and the inclined drain pipe are placed in the ground from the embankment of the embankment, they are sandwiched between the vertical drain pipe and the inclined drain. The (enclosed) region is the portion where the liquefaction hardly occurs because water is most easily discharged. In the event of a major earthquake, this area continues to exist as a kind of wall without being liquefied, and works to block the flow of liquefied soil on both sides (surroundings) of this wall.

  That is, the glue bottom is firmly suppressed by the action of the wall based on the action of dissipating excess pore water pressure of the drain pipe and the ground reinforcement effect of the drain pipe itself, and the collapse of the glue bottom is suppressed. Therefore, the collapse of the embankment due to the liquefaction of the ground is effectively prevented, and the stability of the countermeasure ground during a huge earthquake can be sufficiently secured. Thus, according to the present invention, unlike the case where only conventional embankment or only liquefaction countermeasures are targeted, liquefaction countermeasures for ground and embankment stabilization can be performed simultaneously.

  In addition, according to the present invention, since a drain pipe is used instead of a steel sheet pile, construction with a small machine and proximity construction are possible, and even if there is a severe land restriction near the embankment, on the slope surface In addition to being able to perform construction within the site restrictions, it can be constructed in places where private houses are close, with low vibration and low noise, and little impact on the surrounding environment. it can.

  In addition, it is limited to places where the level of applicability is high, the box culvert orthogonal to the axial direction of the embankment, the vicinity of the pipe pit, the back of the abutment, and the road surface is prone to road subsidence, where the level difference is a problem. Since it can also be applied, it contributes to the efficiency of construction and the reduction of construction costs. Furthermore, the removal work within 2.5 m below the road surface, which is difficult with the conventional construction method, is easy, so there will be no hindrance to future plans.

According to a seventh aspect of the present invention, in the sixth aspect, the vertical drain pipe and the inclined drain pipe are alternately arranged in a staggered pattern. It is a feature.
According to the present invention, in addition to the function and effect of the sixth aspect, the vertical drain pipes and the inclined drain pipes are alternately arranged in a staggered pattern, so that the walls that do not liquefy can be efficiently formed. Thus, the collapse of the embankment is prevented more effectively.

According to an eighth aspect of the present invention, in the sixth or seventh aspect, the drain pipe according to the sixth aspect of the present invention is the drain pipe, wherein the drain pipe is located in a plan view near the tip of the driving head located at the tip. It is formed in a rhombus shape.
According to the present invention, in addition to the operational effects of the sixth or seventh aspect, the vicinity of the tip of the driving head of the drain pipe is formed in a rhombus shape in plan view. Become strong.

According to a ninth aspect of the present invention, in the invention for a liquefaction countermeasure facility for a direct foundation board for embankment according to any one of the sixth to eighth aspects, the drain pipe is provided with a reinforcing material for reinforcing the drain pipe. It is characterized by.
According to the present invention, in addition to the operational effects of any of the sixth to eighth aspects, the drain pipe is reinforced by the reinforcing material, so that the ground reinforcing effect is reliably exhibited even in a huge earthquake, The wraparound is further suppressed and the embankment body is further stabilized.

The invention of the liquefaction countermeasure construction method of the direct foundation board of the embankment according to the tenth aspect of the present invention is a method of providing a drain pipe having a drainage portion at a predetermined interval along the longitudinal direction from a glue bottom portion in the longitudinal direction of the embankment. The drain pipe is constructed in such a manner that a vertical drain pipe placed in the vertical direction and an inclined drain pipe placed in an inclined direction that forms an angle with the vertical direction form a pair. It is characterized by.
According to the construction method of the present invention, the same effect as that of the sixth aspect can be obtained.

  According to the liquefaction countermeasure facility or construction method for a direct foundation board of an underground structure of the present invention, a vertical drain pipe having a drainage portion and an inclined drain pipe are paired from the surface side near the longitudinal side surface of the underground structure. Because it is formed and placed in the ground, the area between the vertical drain pipe and the inclined drain pipe (the enclosed area) is the part where water is most likely to be drained, so it is the most unlikely to cause liquefaction It becomes. In the event of a major earthquake, this area continues to exist as a kind of wall without being liquefied, and works to block the flow of liquefied soil on both sides (surroundings) of this wall. In other words, the action of the wall based on the action of dissipating excess pore water pressure in the drain pipe and the ground reinforcement effect of the drain pipe itself effectively prevent the liquefied ground from entering the lower side of the underground structure. Therefore, the underground structure can be prevented from rising and sinking, and the stability of the countermeasure ground in the event of a huge earthquake can be secured sufficiently.

  According to the liquefaction countermeasure facility or construction method of the direct foundation board of the embankment of the present invention, a vertical drain pipe having a drainage part and an inclined drain pipe form a pair and are placed in the ground from the paste bottom part of the embankment. Therefore, the region sandwiched (enclosed) between the vertical drain pipe and the inclined drain is the portion where water is most likely to be discharged, and thus the portion where liquefaction hardly occurs. In the event of a major earthquake, this area continues to exist as a kind of wall without being liquefied, and works to block the flow of liquefied soil on both sides (surroundings) of this wall. That is, the glue butt is firmly suppressed by the action of the wall based on the action of dissipating the excess pore water pressure of the drain pipe and the ground reinforcing effect of the drain pipe itself, and the fall of the glue butt is prevented. Therefore, the collapse of the embankment due to the liquefaction of the ground is effectively prevented, and the stability of the countermeasure ground during a huge earthquake can be sufficiently secured.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. First, an embodiment of a liquefaction countermeasure facility for a direct foundation board of an underground structure according to the present invention will be described.
FIG. 1 is a longitudinal sectional view showing an embodiment of a liquefaction countermeasure facility for a direct foundation board of an underground structure according to the present invention. FIG. 2 is a plan view of the same liquefaction countermeasure facility as in FIG. FIG. 3 is a schematic view showing an example of a drain pipe used in the present invention. FIG. 4 is a plan view (a) and a sectional view taken along line AA showing a part of both ends showing another example of the screen tube as a drainage portion in the drain tube used in the present invention. FIGS. 5A and 5B are a plan view (a) and a cross-sectional view taken along the line B-B showing a part of both ends in a cross section showing still another example of a screen tube as a drainage portion in a drain tube used in the present invention. FIG. 6 is a plan view (a) showing a cross section of a part of both ends showing still another example of a screen tube as a drainage portion in the drain tube used in the present invention, and a cross-sectional view taken along the line CC. It is.

As shown in FIG. 1, the liquefaction countermeasure facility 10 for the direct foundation board of the underground structure has a groove on the ground surface side 17 in the vicinity of the side surface in the longitudinal direction of the underground structure 14 disposed in the water permeable layer 15 in the ground. 9, and the vertical drain pipe 11 and the inclined drain pipe 12 inclined to the lower outside of the underground structure 14 are alternately staggered from the bottom of the groove 9 at predetermined intervals as shown in FIG. It has been cast. The vertical drain pipe 11 and the inclined drain pipe 12 are arranged so as to intersect with each other in the water permeable layer 15, but the drains 11 and 12 do not necessarily intersect if the uppermost portion is not largely separated and is at substantially the same position. However, it is preferable that both drains 11 and 12 are arranged in an intersecting structure as shown in FIG.
Here, the vertical drain pipe 11 and the inclined drain pipe 12 are placed in pairs when the ground liquefaction occurs as compared with the case where the same number of drain pipes are driven only in the vertical direction. This is because it is more effective in mechanically suppressing the flow of the ground.

  The vertical drain pipe 11 does not have to be truly vertical, and is almost vertical. In the present embodiment, the inclination of the inclined drain 12 is 5 to 60 degrees, preferably 30 to 45 degrees with respect to the vertical direction, and the adjacent interval between the drain pipes 11 and 12 is 500 to 1500 mm. The vertical drain pipe 11 and the inclined drain pipe 12 are provided such that their tips (lower ends) penetrate the water permeable layer 15 and reach the water impermeable layer 16. After the drain pipes 11 and 12 are placed in the ground, the crushed stone 13 is laid in the groove 9 to form the drainage channel 6.

  As shown in FIG. 3A, the vertical drain pipe 11 and the inclined drain pipe 12 are provided with a driving head 21 at the tip, and a screen pipe as a drainage section having a spiral slot 22 c behind the driving head 21. 22 is provided, and an opening end 23 of a non-porous steel pipe is provided behind the screen pipe 22. In the present embodiment, the vicinity of the tip of the driving head 21 is a rhombus-shaped portion 21a in plan view, and the ground reinforcement effect due to the pulling resistance force based on this shape is further increased. In addition, the shape which raises drawing resistance force is not limited to the said rhombus, Other shapes, such as a collar shape, may be sufficient. As shown in FIG. 3 (b), the screen tube 22 as a drainage portion has a circular cross-section core material 22b arranged in a circular shape and a triangular cross-section wire 22a with the top portion inside. It is configured to be integrated by winding in a spiral. The wire 22a is spirally wound and a slot 22c is formed between adjacent wires. The inner diameter of the screen tube 22 is 50 to 150 mm.

  As shown in FIGS. 4A and 4B, the screen tube 22 may have a shape in which the core 22b is not circular but has a top, and the wire 22a has a circular cross section. Moreover, as shown to Fig.5 (a) (b), the perforated pipe | tube 22f by which the strainer process was carried out inside the core material 22b may be arrange | positioned as a reinforcing material, and it shows to Fig.6 (a) (b). Thus, the cross-shaped steel 22h may be arrange | positioned as a reinforcing material inside the core material 22b. A female screw 22d and a male screw 22e are cut at both ends of the screen tube 22, and are joined to the effective tube or cross-shaped steel by welding. The open end 23 of the non-porous steel pipe is easily separable because it is joined to the screen pipe 22 with a screw. Therefore, the removal work within 2.5 m below the road surface, which is difficult with the conventional method, is easy. , So that future plans are not hindered.

  As shown in FIG. 3A, the drain pipe 20 has a driving head 21 disposed in the impermeable layer 16, and a screen pipe 22 as a drainage section disposed in the layer of the permeable layer 15 and the crushed stone 13 as the drainage channel 6. Then, the open end 23 is disposed in the backfill portion 27.

  Next, the operation of the above embodiment will be described. According to the present embodiment, the vertical drain pipe 11 having the drainage portion (22) and the inclined drain pipe 12 form a pair from the ground surface 17 near the side surface in the longitudinal direction of the underground structure 14 into the ground. Since it is driven, the region 8 sandwiched (enclosed) between the vertical drain pipe 11 and the inclined drain pipe 12 is the portion where water is most easily discharged, and thus is the portion where liquefaction hardly occurs. In the event of a large earthquake, this region 8 continues to exist as a kind of wall 7 without being liquefied, and functions to block the flow of liquefied soil on both sides (surroundings) of the wall 7.

  That is, the liquefied ground moves to the lower side of the underground structure 14 by the action of the wall 7 based on the action of dissipating excess pore water pressure of the drain pipes 11 and 12 and the ground reinforcing effect of the drain pipes 11 and 12 themselves. It is possible to effectively prevent the sneaking around, thereby preventing the underground structure 14 from rising and sinking, and sufficiently securing the stability of the countermeasure ground in the event of a huge earthquake.

  More specifically, the water existing around the screen tube 22 in each of the drain tubes 11 and 12 passes through the spiral groove 22c of the screen tube 22 in contact with the water permeable layer 15 serving as a liquefied layer. Infiltrate inside. The water that has entered the drain pipe 20 passes through the drain pipe 20, overflows from the spiral groove 22 c of the screen pipe 22 that contacts the layer of the crushed stone 13 as the drainage path 6, and is discharged from the drainage path 6. Is done. Therefore, the region 8 sandwiched between the screen tubes 22 is the portion where the water is most easily discharged, so that the region 8 is the least liable to liquefy. During the earthquake, the liquefied soil in the direction indicated by the arrow 18 is prevented from flowing.

  That is, in the present embodiment, it is said that the strong wall 7 is formed by both the drain pipes 11 and 12 themselves and the ground which is sandwiched between the vertical drain pipe 11 and the inclined drain pipe 12 and hardly liquefied. It will be. Accordingly, the wall 7 prevents the liquefied ground from flowing, and effectively prevents the underground structure 14 from sinking or floating due to the liquefaction of the ground.

  In addition, the liquefaction countermeasure equipment for the direct foundation panel of the underground structure of the present invention can be applied to lifelines etc. such as common grooves, sewer pipes, dedicated wiring pipes, etc. It is also effective for sewage facilities, water facilities, sewage treatment plants, and water treatment plants.

  Next, an embodiment of a liquefaction countermeasure facility for a direct foundation board of embankment according to the present invention will be described. Constituent parts similar to those of the above-described embodiment of the liquefaction countermeasure facility for the direct foundation board of the underground structure are given the same reference numerals and description thereof is omitted. FIG. 7: is a longitudinal cross-sectional view which shows one Embodiment of the liquefaction countermeasure equipment of the direct foundation | substrate board of the embankment of this invention. FIG. 8 is a plan view of the same liquefaction countermeasure facility as in FIG. FIG. 9 is a front view showing another embodiment of the liquefaction countermeasure facility for the direct foundation board of embankment according to the present invention.

  As shown in FIG. 7, the liquefaction countermeasure equipment 30 for the direct foundation board of the embankment is arranged inside the vertical drain pipe 11 and the embankment 34 at predetermined intervals along the longitudinal direction from the paste bottom 39 portion in the longitudinal direction of the embankment 34. Inclined drain pipes 12 inclined in a staggered manner are alternately placed in a staggered pattern (FIG. 8). The region 8 sandwiched (enclosed) by the vertical drain pipe 11 and the inclined drain pipe 12 is the portion where water is most easily discharged, and thus is the portion where liquefaction hardly occurs. In the event of a large earthquake, this region 8 continues to exist as a kind of wall 7 without being liquefied, and functions to block the flow of liquefied soil on both sides (surroundings) of the wall 7. After placing both drain pipes 11 and 12 in the ground, the crushed stone 13 as the drainage channel 6 is laid and backfilled to the ground surface by excavating soil or the like (backfill portion, not shown).

  Next, the operation will be described. Since the vertical drain pipe 11 having the drainage portion (22) and the inclined drain pipe 12 are placed in pairs in the ground from the vicinity of the paste bottom 39 of the embankment 34, the vertical drain pipe 11 and the inclined drain 12 The region 8 sandwiched between (enclosed) is the portion where water is most likely to be discharged, and thus is the portion where liquefaction hardly occurs. In the event of a large earthquake, this region 8 continues to exist as a kind of wall 7 without being liquefied, and functions to block the flow of liquefied soil on both sides (surroundings) of the wall 7. That is, the glue buttocks 39 are firmly suppressed by the action of the wall 7 based on the action of dissipating excess pore water pressure of the drain pipes 11 and 12 and the ground reinforcement effect of the drain pipes 11 and 12 themselves. Collapse is prevented. Accordingly, the collapse of the embankment 34 due to the liquefaction of the ground is effectively prevented, and the stability of the countermeasure ground during a huge earthquake can be sufficiently secured.

  In addition, the liquefaction countermeasure facility for the direct foundation board of the embankment of the present invention has a high local applicability, and as shown in FIG. 9, a box culvert 38 perpendicular to the longitudinal (axis) direction of the embankment 34, a pipe culvert, etc. The present invention can also be applied in a limited manner to locations where road surface subsidence is likely to occur, such as in the vicinity, the back of an abutment, and a cut-off boundary.

  The present invention is not limited to the above-described embodiment, and various modifications are possible within the scope of the invention described in the claims, and these are also included in the scope of the present invention. Needless to say.

It is a longitudinal cross-sectional view which shows one Embodiment of the liquefaction countermeasure equipment of the direct foundation board of the underground structure of this invention. It is a top view of the same liquefaction countermeasure equipment as FIG. It is a figure which shows an example of the drain pipe used for this invention, (a) is a side view after placing the drain pipe, (b) is the principal part of a part notch of the screen pipe as a drainage part of a drain pipe An enlarged perspective view is shown. It is a figure which shows another example of the screen pipe as a drainage part in the drain pipe used for this invention, (a) is the top view which showed a part of both ends in cross section, (b) is the cross section of an AA cross section. The figure is shown. It is a figure which shows another example of the screen pipe | tube as a drainage part in the drain pipe used for this invention, (a) is the top view which showed a part of both ends in cross section, (b) is a BB cross section. A cross-sectional view is shown. It is a figure which shows another example of the screen pipe | tube as a drainage part in the drain pipe used for this invention, (a) is the top view which showed a part of both ends in cross section, (b) is CC cross section. FIG. It is a longitudinal cross-sectional view which shows one Embodiment of the liquefaction countermeasure equipment of the direct foundation board | substrate of the embankment of this invention. It is a top view of the same liquefaction countermeasure equipment as FIG. It is a top view which shows other one Embodiment of the liquefaction countermeasure equipment of the direct foundation | substrate board of the embankment of this invention.

Explanation of symbols

6 Drainage channel, 7 Wall, 8 Area not easily liquefied, 10 Liquefaction countermeasures for underground structures, 11 Vertical drain pipe, 12 Inclined drain pipe, 13 Crushed stone, 14 Underground structure,
15 water-permeable layer, 16 water-impermeable layer, 17 ground surface side, 21 driving head, 21a bowl-shaped portion 22 screen tube, 22a wire rod, 22b core material, 22c slot, 22d female thread,
22e male thread, 22f perforated tube, 22h cross-shaped steel, 23 open end, 27 backfilling part,
30 Liquefaction countermeasures for embankment, 34 embankment, 38 Box culvert

Claims (10)

  A drain pipe having a drainage portion is driven into the ground at predetermined intervals along the longitudinal direction from the surface side near the side surface in the longitudinal direction of the underground structure, and the drain pipe extends in the vertical direction. The liquid of the direct foundation board of an underground structure characterized in that the vertical drain pipe placed and the inclined drain pipe placed in an inclination direction that makes a certain angle with the vertical direction are paired. Countermeasures.   In Claim 1, the said vertical drain pipe and the said inclined drain pipe are alternately arranged in the zigzag pattern, The liquefaction countermeasure equipment of the direct foundation board | substrate of an underground structure characterized by the above-mentioned.   3. The liquefaction countermeasure device for a direct foundation board of an underground structure according to claim 1 or 2, wherein the drain tube is formed in a rhombus shape in plan view near the tip of the driving head located at the tip thereof. .   The liquefaction countermeasure equipment for a direct foundation board of an underground structure according to any one of claims 1 to 3, wherein the drain pipe is provided with a reinforcing material for reinforcing the drain pipe.   A drain pipe having a drainage portion is driven into the ground at predetermined intervals along the longitudinal direction from the surface side near the side surface in the longitudinal direction of the underground structure, and the drain pipe is driven in the vertical direction. A method for preventing liquefaction of a direct foundation board for underground structures, wherein the vertical drain pipe and the inclined drain pipe placed in an inclined direction that forms a certain angle with the vertical direction form a pair.   A drain pipe having a drainage portion is driven into the ground at a predetermined interval along the longitudinal direction from the glue bottom portion in the longitudinal direction of the embankment, and the drain pipe is vertically driven in the vertical direction. A liquefaction countermeasure facility for a direct foundation board of underground structure, characterized in that a drain pipe and an inclined drain pipe placed in an inclined direction that forms a certain angle with the vertical direction are paired.   In Claim 6, the said vertical drain pipe and the said inclined drain pipe are arranged in the staggered pattern alternately, The liquefaction countermeasure equipment of the direct foundation | ground board | plate of an underground structure characterized by the above-mentioned.   8. The liquefaction countermeasure device for a direct foundation board of an underground structure according to claim 6 or 7, wherein the drain pipe is formed in a rhombus shape in plan view near the tip of the driving head located at the tip thereof. .   9. The liquefaction countermeasure equipment for a direct foundation board of an underground structure according to any one of claims 6 to 8, wherein the drain pipe is provided with a reinforcing material for reinforcing the drain pipe.   A drain pipe having a drainage portion is driven into the ground at predetermined intervals along the longitudinal direction from a glued portion in the longitudinal direction of the embankment, and the drain pipe is a vertical drain pipe driven in the vertical direction. A liquefaction prevention method for a direct foundation board of underground structure, characterized in that it is configured so that a slanted drain pipe placed in a slanting direction that forms a certain angle with the vertical direction is paired.

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