JP6359148B2 - Sand sand countermeasure structure - Google Patents

Description

  The present invention relates to a structure for countermeasures against sand blowing to cope with a phenomenon of sand blowing.

  When liquefaction occurs in a saturated sand ground or the like, soil particles such as sand may be ejected together with pore water in the ground. This phenomenon (hereinafter referred to as the “sandstorm phenomenon”) may continue for several tens of minutes to several hours after the earthquake. May interfere.

  As a technique for preventing the liquefaction phenomenon and the sand blowing phenomenon, for example, those disclosed in Patent Documents 1 and 2 are known.

  The technique of patent document 1 suppresses generation | occurrence | production of the liquefaction phenomenon in the circumference | surroundings of an embedded structure by providing a sheet pile with a drainage function on both sides of an embedded structure, and discharging pore water through the sheet pile. On the other hand, the technique of Patent Document 2 provides a permeable layer above the groundwater surface and below the landfill, and a pressure relief pipe extending from the permeable layer to the ground surface, and discharging pore water through the pressure relief pipe. This suppresses the occurrence of the phenomenon.

Japanese Patent No. 2725516 Japanese Patent No. 2871524

  According to the techniques of Patent Documents 1 and 2, although it is said that the liquefaction phenomenon and the sandstorm phenomenon can be suppressed, in the area where the magnitude of the earthquake is larger than expected, etc. However, there is concern about the occurrence of the sand blowing phenomenon. As described above, when the sand blowing phenomenon occurs, there is a risk that rapid evacuation and recovery may be hindered.

  From such a point of view, an object of the present invention is to provide a sandblast countermeasure structure capable of controlling a zone that allows and prevents a sandblast phenomenon on the ground surface.

The present invention for solving the above problems, the ground surface of the ground, and sand boils introducing zone that allows the occurrence of sand boil phenomenon, the land of the jetted sand introducing zone which prevents the occurrence of sand boiling phenomenon is utilized as a passage immediately after the earthquake A sand sand prevention structure that is divided into a sand sand prevention zone with a higher elevation than the surface, comprising sand sand guiding means from the inside of the liquefied layer that is not subjected to liquefaction suppression to the sand sand guiding zone. It is characterized by.
In the present specification, the liquefaction suppression means means for suppressing liquefaction of the ground, such as a ground compaction method, a crushed stone drain method, and a sand blowing prevention mat method.
Further, the sand buff prevention area includes one or both of an altitude division area and an inflow prevention wall standing along a boundary with the buff sand guidance area, and the sand buff induction area includes a liquefied layer. The present invention is characterized in that there is provided a sand sand guiding means made of a columnar body made of crushed stone from the inside to the ground surface, a resin pipe, or a steel for construction. Further, the high section area is formed by placing an embankment made of a ground material or a concrete plate having a predetermined thickness on the ground surface, and the sand sand guiding means includes the sand sand guiding area and the sand sand preventing area. It is formed near the boundary.

  According to the present invention, when the pore water pressure of the liquefied layer is increased due to the earthquake motion, the earth and sand in the liquefied layer is ejected into the sand sand guiding area through the sand sand guiding means (= the sand sand path). Become. That is, according to the present invention, the erupted positions of the liquefied earth and sand are concentrated in the sand blowing guidance area, so that it is possible to suppress the occurrence of the sand blowing phenomenon in the sand blocking area. In addition, this invention controls the generation | occurrence | production position of a sandblast while allowing generation | occurrence | production of a liquefaction phenomenon, and does not suppress generation | occurrence | production of a liquefaction phenomenon actively.

  Moreover, the said sand buff prevention area | region may have a high altitude division area | region where an altitude is higher than the ground surface in the said sand buff guidance area | region. If a high-altitude zone is provided, even if the earth and sand that erupted into the sand-sand guidance zone flows into the sand-sand block zone, it will remain around the high-zone zone. It can be used as an evacuation passage and a material transportation route. In addition, although the high place division area can be formed by embankment, for example, it may be formed by concrete or the like.

  Alternatively, the sand buff prevention area may have an inflow prevention wall standing along a boundary with the sand buff induction area. If an inflow prevention wall is provided, the earth and sand ejected to the sand blowing guidance area will be blocked by the inflow prevention wall, so it becomes possible to prevent the sand prevention area from being covered with earth and sand. Immediately after the earthquake occurs, it will be possible to use the sand-sand blockage area as an evacuation passage and a material loading / unloading route.

A drainage layer may be provided in the sand sand guidance area. If a drainage layer is provided, the ejected earth and sand (liquefied earth and sand) will permeate into the drainage layer, so that the ejected earth and sand can be prevented from flowing out into the sand ejection prevention area, and eventually the sand ejection prevention area. Can be prevented from being covered with earth and sand.
Moreover, you may provide the sand-sand guidance layer which guides sand sand to a sand-sand guidance area in the said sand sand prevention area. In this way, even when the sand (liquefied earth and sand) rises toward the sand blocking zone, the sand is guided to the sand blowing guidance zone, so it is difficult for the sand to appear on the surface of the sand blocking zone. Become.
In addition, a drainage layer may be provided in the sand ejection guidance area, and a sand sand guidance layer may be provided next to the water drainage layer, or at least one of the water drainage layer and the sand sand guidance layer may be disposed.

  The sand sand guiding means may be a resin pipe, a columnar body made of crushed stone, or a steel material for construction (for example, steel pipe, H-shaped steel, I-shaped steel, angle steel, grooved steel, steel sheet pile, sheet, cable, etc.). . If the sand blowing guidance means is constructed from materials that can be easily procured, it will be possible to reduce costs.

  According to the present invention, it becomes possible to control the area where the sand blowing phenomenon is allowed and the area where the sand blowing phenomenon is prevented on the ground surface, so that even if the sand blowing phenomenon occurs, an evacuation route, a material carrying-in / out route, etc. can be secured. As a result, it becomes possible to contribute to quick evacuation and restoration immediately after the earthquake.

It is a figure which shows the sand-sand countermeasure structure which concerns on embodiment of this invention, Comprising: (a) is a top view, (b) is BB sectional drawing of (a). It is sectional drawing which shows the modification of the sand sand countermeasure structure which concerns on embodiment of this invention. It is sectional drawing which shows the other modification of the sand-sand countermeasure structure which concerns on embodiment of this invention.

  As shown in FIG. 1 (a), the ground sand countermeasure structure A according to the embodiment of the present invention divides the ground surface where there is a concern about the occurrence of sand sand during an earthquake into a sand sand guiding area 1 and a sand sand blocking area 2. As shown in FIG. 1B, the liquefaction layer is not liquefied from the inside of the liquefied layer (the formation in which liquefaction is a concern during an earthquake) L that has not been subjected to liquefaction suppression. A plurality of sand-sand guidance means 3, 3,..., Passing through the layer G and reaching the ground surface of the sand-sand guidance area 1, the drainage layer 4 provided in the sand-sand guidance area 1, and the sand-sand guidance provided in the sand-sand prevention area 2 Layer 5. Note that the non-liquefied layer G is a soil layer in which liquefaction hardly occurs (for example, a viscous soil layer, a soil layer positioned above the groundwater surface, etc.), and is positioned above the liquefied layer L. .

  The sand blowing guidance area 1 is an area that allows the occurrence of the sand blowing phenomenon. The sand sand guidance area 1 is set in a site where the sand sand countermeasure structure A is formed so as not to greatly affect evacuation and disaster recovery even if covered with sand sand.

  The sand blowing prevention zone 2 is a zone where the occurrence of the sand blowing phenomenon should be prevented. The sand clogging prevention zone 2 is set in a passage where the sand sand countermeasure structure A is formed and is not covered with sand sand. “A passage that is difficult to cover with sand” is a passage that is used immediately after the earthquake. For example, an evacuation passage from a building on the site to a road outside the site, transportation of materials for disaster recovery, etc. In addition to roads, parking lots for emergency vehicles and expensive vehicles are also included.

  The sand-sand block area 2 of the present embodiment is set in an area including a passage, and includes a high-altitude partition area 2a and an inflow blocking wall 2b. In addition, you may abbreviate | omit one or both of the high part division area | region 2a and the inflow prevention wall 2b.

  The high altitude division area 2a is an area whose altitude is higher than the ground surface of the sand blowing guidance area 1. The upper surface of the high altitude area 2a is normally used as a passage and serves as an evacuation passage when a disaster occurs. The elevation difference between the ground surface of the sand blowing guidance area 1 and the high altitude area 2a may be set as appropriate in consideration of the amount of sand that is assumed. Since there is a possibility of causing trouble when crossing the road and construction costs may increase, it is desirable to set the range of 5 to 100 cm. The high-altitude partition area 2a of the present embodiment is formed by embankment made of a suitable ground material (for example, earth and sand, crushed stone, rock sludge, concrete glass, etc.). In addition, there is no restriction | limiting in the formation method of the high altitude division area 2a, for example, a concrete plate of predetermined thickness may be mounted on the ground surface, and the high altitude division area 2a may be formed, or the sand sand guidance area 1 is dug down. Thus, the high-altitude partition region 2a may be formed.

  The inflow blocking wall 2b prevents the sand that has spouted into the sand blowing guidance area 1 from flowing into the sand blowing prevention area 2, and is erected along the boundary with the sand blowing guiding area 1. The inflow prevention wall 2b of the present embodiment is made of concrete, is formed along the edge of the sand injection prevention area 2, and is embedded in the surface layer portion of the ground. There is no limitation on the type of the inflow prevention wall 2b. For example, a concrete L-type retaining wall or a reverse T-type retaining wall placed on the ground surface may be used as the inflow prevention wall 2b, or a plurality of columnar members (steel sheet piles). , Shaped steel, steel pipes, wooden piles, etc.) may be continuously provided without gaps as the inflow blocking wall 2b. Although the height of the upper end of the inflow prevention wall 2b may be set as appropriate in consideration of the assumed amount of sand, etc., in this embodiment, it exceeds the altitude of the upper surface of the high-altitude partition region 2a. In addition, it is good also considering the height of the upper end of the inflow prevention wall 2b as below the altitude of the upper surface of the high place division area | region 2a.

  The sand sand guiding means 3, 3,... Form a “water channel” that guides the mud generated in the liquefied layer L to the sand sand guiding area 1, and is arranged in a row only around the sand sand preventing area 2. ing. In this embodiment, two rows of the sand sand guiding means 3 are arranged on both sides of the sand sand blocking area 2 and the upper end of the sand sand guiding means 3 is positioned outside the region sandwiched between the inflow blocking walls 2b and 2b. However, this is not intended to limit the number and arrangement of the sand sand guiding means 3.

  Each sand sand guiding means 3 is a columnar body (so-called gravel drain) formed by putting crushed stone into a vertical hole. The lower end portion of the sand sand guiding means 3 reaches the inside of the liquefied layer L, and the upper end portion of the sand sand guiding means 3 reaches a region adjacent to the sand sand blocking area 2 in the sand sand guiding area 1. The structure of the sand blowing guidance means 3 is not particularly limited as long as it can penetrate the non-liquefied layer G and form a water channel (passing sand path) in the ground. For example, a perforated pipe made of resin (So-called drain pipes) and columnar bodies made of construction steel (steel pipe, H-shaped steel, I-shaped steel, angle steel, grooved steel, steel sheet pile, sheet-like material (sheet), wire-like material (cable), etc.) The sand sand guiding means 3 may be used.

  The drainage layer 4 functions as a sand-sand-absorbing layer that absorbs sand-sand that appears on the ground surface of the sand-sand guiding area 1, and is provided on the upper surface of the non-liquefied layer G. The water permeability coefficient of the drainage layer 4 is larger than the water permeability coefficient of the non-liquefied layer G. The drainage layer 4 is preferably formed of crushed stone or concrete glass so that the ejected earth and sand (liquefied earth and sand) can permeate quickly. In order to form the drainage layer 4, crushed stone or the like may be sprinkled on the upper surface of the original ground (non-liquefied layer G in the present embodiment), or the crushed stone or the like may be sprinkled after the raw ground is dug down. The layer thickness of the drainage layer 4 may be set as appropriate in consideration of the amount of sand sand expected, but if it is made larger than necessary, the construction cost may increase, so it should be in the range of 5 to 200 cm. desirable.

  The sand sand guiding layer 5 is provided below the embankment portion of the high altitude partition region 2a and communicates with the drainage layer 4 or the ground surface. The blast sand guiding layer 5 is provided on the upper surface of the non-liquefied layer G, and the blast sand (liquefied earth and sand) rising through the non-liquefied layer G toward the blast sand blocking area 2 is Through to the drainage layer 4. The sand buff induction layer 5 is formed of a ground material such as earth and sand, crushed stone, rock slurries, and concrete galley, and the hydraulic conductivity of the sand buff induction layer 5 is set so that the sand boil moves quickly to the drainage layer 4. In order to form the sand buff induction layer 5, crushed stone or the like may be sprinkled on the upper surface of the original ground (non-liquefied layer G in the present embodiment), or the raw ground may be dug down to crushed crushed stone or the like. The layer thickness of the sand sand guiding layer 5 may be set as appropriate in consideration of the expected amount of sand sand, etc., but if it is made larger than necessary, the construction cost may increase. Is desirable. The sand sand guiding layer 5 is preferably provided when the sand sand blocking area 2 is wide (for example, 5 m or more). In the case where the sand ejection can be controlled only by the sand sand guiding means 3 such as when the width of the sand sand blocking area 2 is narrow, the sand sand guiding layer 5 may be omitted.

  According to the sand sand countermeasure structure A according to the present embodiment, when the pore water pressure of the liquefied layer L is increased due to the earthquake motion, the sand sand guiding means 3, 3, in which the earth and sand in the liquefied layer L is a path of sand sand ... through the ground surface in the sand sand guiding area 1 (in this embodiment, the upper surface of the drainage layer 4). In other words, according to the sand sand countermeasure structure A, the sand sand outlet (spout position) is controlled, and the ground position of the liquefied earth and sand is concentrated in the sand sand guiding area 1. Occurrence can be suppressed. Further, since the sand sand guiding means 3 is formed only in the vicinity of the boundary between the sand sand guiding area 1 and the sand sand blocking area 2, the cost is lower than when the liquefaction suppression process is applied to the entire liquefied layer L.

  Moreover, in the sand sand countermeasure structure A, since the inflow prevention wall 2b is provided in the edge part of the sand discharge prevention area 2, the earth and sand which spouted to the sand injection guidance area 1 will be blocked by the inflow prevention wall 2b. That is, according to the sand sand prevention structure A, it becomes possible to prevent the sand sand blocking area 2 from being covered with earth and sand. It becomes possible to use as such.

  In addition, in the sand sand countermeasure structure A, the sand sand guiding layer 5 is provided. Therefore, even when the sand sand rises toward the sand sand blocking area 2, the sand sand is guided to the drainage layer 4 and therefore the sand sand blocking action. It is difficult for sandblast to appear on the surface of area 2. Furthermore, in the sand sand countermeasure structure A, the high sand zone 2a is provided in the sand sand blocking zone 2, so that even if the earth and sand discharged into the sand sand guiding zone 1 flows into the sand sand blocking zone 2, Stay around.

  Moreover, in the sand sand countermeasure structure A, since the drainage layer 4 is provided in the surface layer part (the range of the predetermined depth from the ground surface of the sand sand guidance area 1) of the sand sand guidance area 1, it ejected to the ground surface of the sand sand guidance area 1 The earth and sand can permeate into the drainage layer 4, and therefore, the discharged earth and sand can be prevented from flowing out into the sand discharge prevention area 2, and thus the sand discharge prevention area 2 can be prevented from being covered with earth and sand. It becomes possible.

  In addition, in the sand sand countermeasure structure A, the high-altitude partition region 2a, the inflow blocking wall 2b, the sand sand guiding means 3 and the drainage layer 4 are constructed of materials that can be easily procured, so that the cost can be reduced. .

In addition, you may change the structure of the sand-sand countermeasure structure A suitably.
In the present embodiment, for example, the case where both the high altitude division region 2a and the inflow prevention wall 2b are constructed in the sand blowing prevention zone 2 is illustrated, but both or one of the high altitude division region 2a and the inflow prevention wall 2b is omitted. May be.

  Moreover, in this embodiment, although the case where the sand-sand guidance means 3 was extended in the perpendicular direction was illustrated, as shown in FIG. 2, the sand-sand guidance means 3 is arrange | positioned diagonally, and the lower part of the sand-sand guidance means 3 is made into sand sand. It may be located below the blocking area 2. If the sand sand guiding means 3 is formed from the sand sand guiding area 1 toward the liquefied layer L below the sand sand preventing area 2, even if liquefaction occurs below the sand sand preventing area 2, the liquefied earth and sand are removed. It is possible to guide to the sand blowing guidance area 1 more reliably, and therefore it is possible to more reliably suppress the occurrence of sand blowing in the injection blocking area 2.

  Moreover, in this embodiment, although the case where the drainage layer 4 and the sand blowing guidance layer 5 were formed in the whole site was illustrated, you may change suitably. For example, although illustration is omitted, the drainage layer 4 may be formed only in the sand blowing guidance area 1 and the sand blowing guidance layer 5 may be omitted. In addition, a drainage layer having a drainage function may be provided in a part of the sand sand guidance area 1.

As shown in FIG. 3, the drainage layer 4 may be omitted. That is, in the sand sand countermeasure structure A of FIG. 3, the non-liquefied layer G exists in the surface layer part (range of the predetermined depth from the ground surface) of the sand sand guiding area 1, and the sand sand guiding means 3, 3,. From the inside of the liquefied layer L, it penetrates the non-liquefied layer G and reaches the ground surface (the upper surface of the non-liquefied layer G) of the sand sand guiding area 1. In the sand sand countermeasure structure A in FIG. 3, a part of the non-liquefied layer G is replaced with the sand sand guiding layer 5. The sand sand guiding layer 5 is formed directly under the embankment (the high-altitude zone 2 a), and both sides of the sand sand guiding layer 5 enter the sand sand guiding area 1. Although there is no restriction | limiting in the protrusion amount of the sand-sand guidance layer 5, For example, it is good to make about 1-2 m of the both sides of the sand-sand guidance layer 5 enter the sand-sand guidance area 1. FIG. In addition, although illustration is abbreviate | omitted, you may form a sand sand guidance layer in embankment. In addition, when the embankment is omitted and the upper surface of the non-liquefied layer G is paved, the sand sand guiding layer 5 may be formed below the pavement.
According to such a sand sand countermeasure structure A, when the pore water pressure of the liquefied layer L increases, the sand in the liquefied layer L passes through the sand sand guiding means 3, 3,. It will be ejected to the ground surface in area 1. Further, even when the sand blows through the non-liquefied layer G and rises toward the sand blowing prevention zone 2, the sand blowing is guided to the sand blowing guidance area 1 by the sand blowing induction layer 5, so that the sand blowing is filled in the sand blowing prevention zone 2. There is no breakage of the (high altitude area 2a).

  In addition, in this embodiment, although the case where the ground surface of the sand flow guidance area 1 was leveled horizontally was illustrated, it is inclined to the ground surface of the sand sand guidance area 1 so that the sand flows in the direction away from the sand flow prevention area 2. A step, a trench or the like may be provided.

DESCRIPTION OF SYMBOLS 1 Blow sand guidance area 2 Blow sand prevention area 2a Altitude division area 2b Inflow prevention wall 3 Blow sand guidance means 4 Drainage layer 5 Blow sand induction layer L Liquefaction layer G Non-liquefaction layer

Claims (2)

A sand-sand guidance area that allows the occurrence of a sand-sand phenomenon on the ground surface, and a sand-sand prevention area that is higher in elevation than the ground surface of the sand-sand-guiding area that is used as a passage immediately after the occurrence of an earthquake by preventing the occurrence of a sand phenomenon. It is a structure for countermeasures against sand blowing that is divided into
The sand boiling blocking zone is provided with one or both of high plant divided area, and the sand boiling introducing zone erected along the boundary between the to Ru inflow blocking wall,
A sand sand countermeasure structure characterized in that the sand sand guiding area is provided with columnar bodies made of crushed stone from the inside of the liquefied layer to the ground surface, resin sand pipes or sand sand guiding means made of steel for construction. The high section area is formed by placing an embankment made of a ground material, or a concrete plate of a predetermined thickness on the ground surface,
The sand sand guiding means is formed near the boundary between the sand sand guiding area and the sand sand preventing area,
2. The sand sand countermeasure structure according to claim 1, wherein an upper end surface of the inflow blocking wall is higher than a ground surface of the sand sand guiding area.

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