JP2006312877A - Construction method for preventing leakage of water/drain for construction work of bank - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a construction method which can easily prevent the leakage of water and the wash-out of the construction work of a bank at a low cost, and enables the soil or the like of the original ground to be used in its natural condition. <P>SOLUTION: A particle-sealing body (6) is provided which seals a particle containing the soil at a part which is a penetration line of a bank body by an impervious sheet. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a ground improvement method for preventing liquefaction, a water leakage and runoff prevention method for embankment construction, an earth retaining method for embankment, and a ground improvement method for preventing landslides.

  As described above, the present invention relates to a construction method having four different purposes, namely, a ground improvement method for preventing liquefaction, a water leakage / runoff prevention method for embankment construction, an earth retaining method for embankment, and a ground improvement method for preventing landslides. Here, the conventional techniques of the above methods will be described.

  First, the ground improvement method for preventing liquefaction will be described. Conventionally, in order to prevent liquefaction, (1) a method to increase the strength of the ground, (2) a method to dissipate excess pore water pressure, (3) a method to lower the groundwater level, (4) design of the structure There was a method to restrain the deformation of the structure at the time of earthquake.

  The method (1) for increasing the strength of the ground is a method for increasing the strength of the soil itself. This method includes a compaction method such as sand compaction, and a cement-based mixed stirring method. Sand compaction is a method of compacting the soil of the ground. According to the sand compaction, as shown in FIG. 12 (a), the soil containing a lot of gaps before the improvement, the soil particles are densely arranged after the compaction, and as a result, the frictional resistance between the particles increases, Can be prevented.

  The cement-based mixed stirring method is a method of mixing and solidifying a binder such as cement with the soil of the ground to be improved. According to this cement-based mixing and stirring method, as shown in FIG. 12 (b), cement can enter between the soil particles after the improvement, and the particles can be bonded together, thereby preventing liquefaction.

  The method of dissipating the excess pore water pressure in (2) is a method of suppressing the pore water pressure by discharging the excessive increase in the pore water pressure causing ground liquefaction to the outside of the ground through a drain pipe such as a crushed drain pipe. Say. In order to realize this method, as shown in FIG. 13, a drain pipe is inserted so as to reach a depth below the groundwater level of the ground, and a filter such as crushed stone is discharged so that only water can be discharged into the drain pipe. Fill the material. By providing such a structure, when there is a strong impact such as an earthquake, excess water can be quickly discharged to the outside. As a result, since the pore water pressure is kept low, the contact of soil particles is not lost, and liquefaction can be prevented.

  The method for lowering the groundwater level in (3) focuses on the fact that liquefaction occurs in shallow ground within 15 m from the ground surface and occurs in ground where groundwater penetrates.

  Specifically, as shown in FIG. 14, a pipe is inserted deep underground of the structure, the groundwater is pumped up by a pump, and the groundwater level is kept low. By this method, the ground supporting the structure is prevented from being infiltrated by the groundwater, and the supporting ground of the structure can be prevented from being liquefied even by a strong impact such as an earthquake.

  The method of restraining deformation of a structure at the time of earthquake by designing the structure in (4) is a method in which piles are driven into a deep ground that is not liquefied and the structures are supported by these piles. According to this construction method, even if liquefaction occurs in the shallow ground, the structure can be inclined and prevented.

  Next, a conventional method for preventing leakage from a dike or preventing sediment from flowing out will be described with reference to FIG. Generally, river embankments are formed by raising soil. Since the water of this levee can pass water, the water pressure (water pressure of the seepage line) gradually decreases. However, when the cross-sectional area of the levee body is insufficient, water leakage occurs over a long period of time.

  On the other hand, conventionally, the cross-sectional area of the levee body has been increased so that the water pressure of the seepage line is equal to the pressure of groundwater outside the river inside the dam body. As shown in FIG. 15, the cross-sectional area of the levee body has been increased by providing additional layers (portions indicated as front and back steps in FIG. 15) on the dam body. Due to this increased cross-sectional area of the dam body, river water will not leak out of the levee.

  Also, the river head may rise beyond expectations due to abnormal weather such as a typhoon and flow out beyond the top of the dike. In such a case, the soil above the levee may be washed away by flooded water, and some breaching holes may grow rapidly, leading to large levee breaching.

  On the other hand, conventionally, sandbags have been piled up in order to prevent the soil on the top of the bank from being washed away. As a result, it was possible to prevent the soil from flowing over the top of the dike, and to prevent the breakage of a large dike.

  Next, a conventional earth retaining method for embankment will be described. As shown in FIG. 16, the embankment is formed by raising the soil on the slope. At the step portion of this embankment, a slope is formed for stability. The slope of the conventional embankment is a slope with a gentle slope less than a certain slope, except when special earth retaining work such as concrete protective walls or piles for retaining soil is applied. Vegetation was applied on top to prevent runoff of earth and sand. The earth retaining of the embankment is realized by the gentle slope of the slope and the vegetation that prevents the sediment from being washed away.

  Next, a conventional ground improvement method for preventing landslide will be described. Conventional methods for preventing landslides were largely based on soil removal and surface water treatment.

  Excavation is a method of reducing the load on the landslide slope and reducing the sliding force, either cutting off a part of the soil mass on the slope or removing all the sliding soil mass on the landslide slope to stabilize the slope.

In the case of arc slip, the amount of earth removal is divided as shown in FIG. 17 by dividing the soil block on the landslide surface of the slope, and performing the stable calculation shown in the following formula for each divided soil block, and exceeding a certain safety factor To be determined.

  Cutting the head of the landslide slope is effective for the position of earth removal. Appropriate soil removal improves the landslide safety factor and stabilizes the slope.

  Next, another conventional surface water treatment method for preventing landslide will be described.

The surface water treatment method for preventing landslide is a method for quickly discharging surface water that induces or promotes landslide to the outside of the landslide area. FIG. 18 shows an example of surface drainage works for the surface water discharge.
JP 2006-214145 A JP 2006-057325 A

  However, the conventional ground improvement method for preventing liquefaction, water leakage and runoff prevention method for embankment construction, earth retaining method for embankment, and ground improvement method for prevention of landslide are respectively large work, and therefore the construction cost is also high. I had to soar.

  Moreover, in the conventional ground improvement etc., in order to replace the soil of the original ground with high quality soil, cement, etc., it was necessary to consider the disposal and reuse of the soil of the original ground.

  Accordingly, the problem to be solved by the present invention is to provide a construction method that can prevent leakage and runoff of embankment construction by an inexpensive and simple method, and can use the soil of the original ground as it is.

  The water leakage prevention method in embankment construction according to the present invention is characterized by providing a granular material sealing body in which a granular material containing soil is sealed with an impermeable sheet at a portion corresponding to the permeation line of the levee body.

  The runoff prevention construction method in embankment construction according to the present invention is characterized in that a granular material sealing body in which a granular material containing soil is sealed with an impermeable sheet is provided on the upper portion of the bank body.

  The granular material sealing body is formed with a concave portion in the shape of the granular material sealing body during the embankment embankment process, an impermeable sheet is laid on the inner surface of the concave portion, and soil is put into the concave portion, and then the impermeable property The sheet can be sealed.

  The granular material sealing body may be composed of a plurality of small sealed bodies in which the granular material is sealed.

  The water-impermeable sheet can be composed of either a stretchable water-impermeable sheet or a non-extensible water-impermeable sheet.

  According to the water leakage / runoff prevention method in the embankment construction of the present invention, the granular material sealing body is formed at the upper part of the embankment or at the central portion corresponding to the permeation line.

  Since this granular material sealing body is sealed by the water-impermeable sheet, it is possible to prevent water from passing therethrough and outflow of earth and sand inside.

  When the granular material sealing body is provided at the upper part of the levee, even if water runs over the levee and flows out, it is possible to prevent the levee sediment from being washed away and to prevent the levee from being broken.

  Moreover, when the said granular material sealing body is provided in the center part of a levee, permeation of water can be prevented and the leakage of a levee can be prevented.

  Next, referring to the attached drawings, embodiments of the ground improvement method for preventing liquefaction according to the present invention, the method for preventing leakage and runoff in embankment construction, the earth retaining method for embankment, and the ground improvement method for preventing landslide are used. Will be described below.

  First, the ground improvement method for preventing liquefaction will be described. FIG. 1 conceptually shows a ground improvement method for preventing liquefaction with respect to a ground structure.

  Part (a) of FIG. 1 shows the ground before improvement. In FIG. 1, reference numeral 1 is the ground surface, 2 is the groundwater level, and 3 is the depth at which liquefaction occurs. Depth 3 at which liquefaction occurs is the deepest depth at which liquefaction occurs and varies depending on the soil quality, but is about 15 m in the case of soils that are liable to liquefy. It is known that the liquefaction phenomenon occurs in the ground having a groundwater level of 2 or less and a depth of 3 or more where liquefaction occurs.

  Here, “below” of “groundwater level 2 or lower” means that it is equal to or deeper than groundwater level 2, and “more than” of “depth 3 or higher” is equal to or shallower than depth 3. Is the meaning. In this specification, “above” and “below” are used as described above.

  In the ground improvement method for preventing liquefaction according to the present embodiment, preferably, all ground where liquefaction occurs is excavated, and an impervious sheet 5 is laid on the inner surface of the excavated hole 4, and soil is put into the hole 4. After the backfilling, the water-impermeable sheet 5 is sealed to form the granular material sealing body 6. The above process is shown in FIGS. 1B and 1C. The granular material sealing body 6 is sealed with an impermeable sheet 5 so that groundwater or the like does not enter after the backfilling.

  As for the excavation, it is preferable to excavate all the soil in the range where liquefaction occurs as in the above embodiment. However, due to the loose design condition of the structure, a hole having a depth not reaching depth 3 where liquefaction occurs is excavated. The granular material sealing body 6 may be formed.

  The water-impermeable sheet 5 is a sheet made of a flexible water-impermeable material having corrosion resistance in addition to a rubber sheet and a polyethylene sheet. Furthermore, when the granular material sealing body 6 is to be deformed to be brought into close contact with the hole 4, an extensible impermeable sheet having extensibility is used. On the other hand, when it is desired to maintain the shape of the granular material sealing body 6 in the ground, a non-extensible impermeable sheet having no extensibility is used.

  As a sealing method of the water-impermeable sheet 5, there are adhesion by an adhesive, thermal welding by heat, pressure bonding by pressure, and the like.

  The reason why the inside of the granular material sealing body 6 is filled with the backfilling soil is that the backfilling soil can be used and is the most rational in construction. In the present invention, the granular material sealing body 6 is formed by the backfilling soil. It is not limited to the above, and any particulate material having appropriate internal friction or adhesive strength may be used.

  After forming the granular material sealing body 6 as described above, normal soil can be backfilled above the granular material sealing body 6 (FIG. 1 (d)), and a ground structure can be constructed thereon. (FIG. 1 (e) part).

  In addition, the magnitude | size and shape of the granular material sealing body 6 are not restricted to the thing of embodiment of FIG. FIG. 2 shows a modified example of the granular material sealing body 6. The granular material sealing body 6 of FIG. 2A shows a case where it is formed in a layer shape. The granular material sealing body 6 in FIG. 2B is formed by forming a large number of sandbag-like small sealing bodies and constraining the whole. These modified examples of the granular material sealing body 6 are convenient when the granular material sealing body 6 is manufactured according to a predetermined standard and used.

  As shown in FIG. 1 (e), liquefaction can be prevented by replacing the soil of the liquefied portion of the ground with the granular material sealing body 6.

  In liquefaction, groundwater enters between the soil particles, and in normal conditions, sedimentation is maintained by the frictional force between the soil particles. The contact between each other is lost, the soil particles are evenly dispersed in the water, and when the soil particles are rearranged, the water is separated and the volume of the ground is reduced. Due to such a generation mechanism, liquefaction occurs in the ground below the groundwater level and above the depth at which liquefaction occurs.

  According to this embodiment, the backfill soil is contained in the granular material sealing body 6 with an appropriate water content, and no further groundwater enters after the backfill. That is, it is possible to eliminate the condition that the granular material sealing body 6 has a lump of soil dried (meaning having an appropriate water content) in the ground and liquefaction occurs below the groundwater level. it can. Thereby, liquefaction is prevented.

  FIG. 3 shows a second embodiment of the present invention. In FIG. 3, the same parts as those in FIG.

  In the ground improvement method for preventing liquefaction according to the second embodiment of the present invention, measures against leakage are taken for the granular material sealing body 6 used in the ground improvement method of the first embodiment of FIG. .

  In the ground improvement method for preventing liquefaction according to the second embodiment, the inside and outside of the granular material sealing body 6 are communicated, and the drain pipe 8 having the crushed stone 7 is provided inside. The drain pipe 8 has a lower end communicating with the bottom of the granular material sealing body 6, an upper end protruding a predetermined height from the ground surface 1, and has a check valve 9 for preventing a backflow.

  The inside of the drain pipe 8 is not limited to the crushed stone 7, and any known filter material can be used in addition to a fibrous filter made of resin or the like.

  According to the ground improvement method for preventing liquefaction according to the second embodiment, liquefaction can be prevented even if the sealed state of the granular material sealing body 6 is flooded in the future due to an unexpected cause.

  It is conceivable that the granular material sealing body 6 enters a saturated state due to water entering the inside due to breakage of the water-impermeable sheet 5 and peeling of the sealed joint portion. However, according to the ground improvement method for preventing liquefaction of the second embodiment, since the drain pipe 8 is inserted, when the pore water pressure rises only by a strong impact such as an earthquake, an excessive pore water pressure is generated. It can be discharged quickly to the outside. Thus, since the increase in pore water pressure is quickly suppressed, the friction of the soil particles is not lost and liquefaction can be prevented. Note that only the water in the muddy water is discharged by the filter material of the drain pipe 8.

  In FIG. 3, the pore water pressure at which water is discharged substantially corresponds to the head up to the upper end of the drain pipe 8, but the pore water pressure at which water is discharged can be adjusted by adjusting the head. it can.

  Next, the ground improvement construction method for preventing liquefaction when an underground structure is constructed will be described. FIG. 4 conceptually shows a ground improvement method for preventing liquefaction when an underground structure according to the third embodiment of the present invention is constructed. In FIG. 4, the same parts as those in FIG.

  Part (a) of FIG. 4 shows the ground before improvement. When constructing an underground structure, as shown in FIG. 4B, excavation is performed to a depth of 3 or less where liquefaction occurs. A mountain retaining material 10 such as a sheet pile is installed on the peripheral surface of the hole.

  As described with reference to FIG. 1, the portion corresponding to the lower portion of the underground structure at the bottom of the hole is laid with a water-impermeable sheet 5 and backfilled to a depth below the bottom surface of the underground structure. Is sealed to form the granular material sealing body 6 (see FIG. 4B).

  Next, as shown in FIG. 4C, the underground structure 11 is constructed on the granular material sealing body 6.

  After the underground structure 11 is constructed, as shown in FIG. 4D, the impermeable sheet 5 is spread around the underground structure 11 and in the space between the mountain retaining materials 10 and buried. Return. After the backfilling is completed, the impervious sheet 5 is sealed at the top to form the granular material sealing body 6.

  Finally, when the mountain retaining material 10 is removed, as shown in FIG. 4 (e), the granular material sealing body 6 is installed around and below the underground structure 11.

  In the underground structure having the structure shown in FIG. 4 (e), as described in the first embodiment, since the surrounding ground prevents water from entering by the granular material sealing body 6, the underground water level rises. Even if it does, it has moderate water content and does not become a saturated state of water. Thereby, even if it receives impacts, such as an earthquake, the contact of soil is not lost and it does not liquefy. As a result, the underground structure 11 can be stably held.

  In the above-described third embodiment of the present invention, the case where the bottom surface of the underground structure 11 is shallower than the depth 3 at which liquefaction occurs is described. However, the depth of the bottom surface of the underground structure 11 from depth 3 at which liquefaction occurs. When deep, the granular material sealing body 6 below the underground structure 11 can be omitted. This is because the bottom surface of the underground structure 11 is supported by the deep ground that is not liquefied.

  In this embodiment as well, the granular material sealing body 6 is made into a plurality of small sealed bodies, the granular material sealing body 6 is filled with granular materials in place of soil, and the impermeable sheet 5 is made to be extensible impermeable water. The use of an expandable sheet or a non-extensible impermeable sheet, the provision of a drain pipe, etc. can be made exactly the same as in the first and second embodiments.

  Next, the leakage and runoff prevention method in the embankment construction according to the present invention will be described.

  FIG. 5 conceptually shows a water leakage prevention method in embankment construction that is the fourth embodiment of the present invention. In FIG. 5, the same parts as those in FIG.

  The water leakage prevention method of this embodiment is to provide a granular material sealing body at a portion corresponding to the seepage line of the bank body. For this reason, in the water leakage prevention method of this embodiment, as shown in FIG. 5 (a), the recess 12 is formed in the shape of the granular material sealing body 6 during the embankment embedding process, and the inner surface of the recess 12 is not formed. After the water-permeable sheet 5 is laid and soil is put in the recess 6, the water-impermeable sheet 5 is sealed to form the granular material sealing body 6.

  After the granular material sealing body 6 is formed, the bank body 13 is built up to a predetermined height, and the sheet pile 14 provided to prevent water from entering is removed. Thereby, as shown in FIG.5 (b) part, the granular material sealing body 6 will be provided in the part which hits the permeation line of the water of the center part of a bank.

  Since the particulate matter sealing body 6 in the dam body 13 does not allow water to pass through, the water that has permeated from the river or the like is blocked by the particulate matter sealing body 6. FIG. 5B illustrates the osmotic pressure of the water osmosis line. Although the osmotic pressure of water naturally decreases by passing through the dam body 13, the water pressure at the lower end of the granular material sealing body 6 is behind the granular material sealing body 6. After passing through the granular material sealing body 6, it drops again and becomes the same water pressure as the groundwater outside the dike, and no further outflow occurs. Leakage of the levee can be prevented by this decrease and balance of water pressure.

  In the fourth embodiment, the concave portion 12 is formed in the shape of the granular material sealing body 6 during the embankment process, and the water-impermeable sheet 5 is laid on the backfill. There is. In this modified example, the embankment is first performed up to the height indicated by the dotted line X in FIG. 5B, and the remaining soil is accumulated after the granular material sealing body 6 is formed. In this case, the granular material sealing body 6 may be formed on a dike, or may be formed in a predetermined shape at a prefab site near a factory or a site and disposed on the dike. The modification in this embankment process can be adopted in common with other embodiments of the present invention.

  Next, an explanation will be given of a method for preventing runoff of earth and sand in embankment construction that is a fifth embodiment of the present invention.

  FIG. 6 conceptually shows a method for preventing runoff of earth and sand in embankment construction according to the fifth embodiment of the present invention. In FIG. 6, the same parts as those in FIG.

  The method for preventing the loss of earth and sand in the embankment work according to the fifth embodiment differs from the water leakage preventing method according to the fourth embodiment described above only in the installation position of the granular material sealing body 6.

  That is, the water leakage prevention method according to the fourth embodiment provides the granular material sealing body 6 on the permeation line, that is, at the center of the levee body 13, whereas the erosion prevention method such as earth and sand of embankment construction according to the fifth embodiment Installed on top of body 13.

  In this construction method, as shown in FIG. 6 (a), in the embankment process of embankment construction, a recess 12 is provided in the upper part of the bank body, and an impervious sheet 5 is laid on the inner surface of the recess 12 to refill the soil. After refilling the soil, the impermeable sheet 5 is sealed. Thereby, the granular material sealing body 6 is formed in the upper part of the bank 13 as shown in FIG.6 (b) part. Since this granular material sealing body 6 encloses the soil and prevents the ingress of water, even if the water exceeds the upper end of the embankment, the sediment will be washed away by the water flow and the embankment will break. Can be prevented.

  In the fourth and fifth embodiments, the granular material sealing body 6 is a plurality of small sealed bodies, the granular material sealing body 6 is filled with a granular material instead of soil, and the water-impermeable sheet 5 is filled. The use of a stretchable water-impermeable sheet or a non-stretchable water-impermeable sheet can be performed in exactly the same manner as in the first to third embodiments.

  In the fourth and fifth embodiments, the granular material sealing body 6 can be formed into a shape suitable for the structure of a dike, and further, a granular material sealing body for preventing water leakage and a granular material sealing for preventing sediment loss. It can also be combined with the body. FIG. 7 shows an example in which the granular material sealing body for preventing water leakage is combined with the granular material sealing body for preventing sediment loss.

  Next, the earth retaining method for embankment according to the present invention will be described. The earth retaining method for embankment according to the present invention is to dispose a granular material sealing body in the vicinity of a stepped portion of the embankment. FIG. 8 conceptually shows the embankment earth retaining method according to the sixth embodiment of the present invention. In FIG. 5, the same parts as those in FIG.

  As shown in FIG. 5, the embankment according to this embodiment is obtained by embedding an embankment 16 on an original ground 15. In this embodiment, the granular material sealing body 6 is provided at the largest step portion of the embankment 16.

  Thus, by providing the granular material sealing body 6 at the step portion of the embankment 16, even when the groundwater level 17 rises, the inside of the granular material sealing body 6 can prevent water from entering. Thereby, collapse, erosion, etc. due to runoff of earth and sand at the stepped portion of the embankment can be prevented.

  In addition, in the example of FIG. 8, since the granular material sealing body 6 is made into the trapezoidal cross section, after forming the granular material sealing body 6 initially, it constructs so that embankment may be piled up inside.

  Moreover, also in this embodiment, the granular material sealing body 6 is made into a plurality of small sealing bodies, the granular material sealing body 6 is filled with a granular material in place of soil, and the impermeable sheet 5 is extensible and impermeable. The use of an expandable sheet or a non-extensible impermeable sheet, the provision of a drain pipe, etc. can be made exactly the same as in the first to third embodiments.

  Next, the ground improvement method for preventing landslide according to the present invention will be described. A ground improvement method for preventing landslide according to a seventh embodiment of the present invention is conceptually shown in FIG.

  The ground improvement method for preventing landslide according to the seventh embodiment is to replace soil in a depth range in which stability is maintained by eliminating pore water pressure in stability calculation of a landslide slope with a sealed granular material. .

  In FIG. 9, it is assumed that there is a groundwater level 19 along the slope 18. It is assumed that the landslide surface of this slope is an arc landslide surface 20.

上式から分かるように、分子の垂直荷重は地下水等の間隙水圧によって減少するので、地下水が浸透する部分では、安定性が低下する。また、安定性の計算のほかにも、地表水は地滑りの誘因となることも知られている。 As described above, the slope stability calculation is performed by dividing the lump on the landslide surface into pieces as shown in FIG. 9 and calculating the normal stress and internal friction angle of each piece according to the following equation. Calculate the ratio and calculate the safety factor of stability by the ratio of the sum of its numerator and denominator.

As can be seen from the above equation, the vertical load of the molecule is reduced by the pore water pressure such as groundwater, so the stability is lowered in the portion where the groundwater penetrates. In addition to calculating stability, surface water is also known to trigger landslides.

  On the other hand, the ground improvement method for preventing landslide according to the present embodiment replaces the ground into which groundwater penetrates with the granular material sealing body 6.

  As described above, the granular material sealing body 6 can prevent entry of groundwater or the like. Therefore, the pore water pressure U is 0 in the calculation of the stability of the strip corresponding to the granular material sealing body 6 by installing the granular material sealing body 6. Thereby, stability of a slope improves and the prevention of landslide can be designed. Moreover, since the surface water which becomes the cause of a landslide and an incentive is excluded by the granular material sealing body 6, the ground which is hard to landslide can be obtained.

  Next, a ground improvement method for preventing landslide according to another method of the present invention will be described.

  FIG. 10 conceptually shows a ground improvement method for preventing landslide that is an eighth embodiment of the present invention. In FIG. 10, the same parts as those of FIG.

  In the eighth embodiment, instead of eliminating the influence of pore water pressure due to groundwater in the slope stability calculation described above, landslide is prevented by reducing the shear stress of the sliding surface.

  That is, as shown in FIG. 10, the landslide surface 20 is excavated stepwise to form the granular material sealing body 6 thereon. Thus, by forming the granular material sealing body 6 having a stepped bottom surface, a portion corresponding to the granular material sealing body 6 on the landslide slope 20 is calculated in the above-described stability calculation formula. The shear stress T at the sliding surface in each strip becomes small.

  Thereby, stability of a slope improves and the prevention of landslide can be designed. Moreover, the surface water used as the cause and cause of a landslide is excluded by the granular material sealing body 6, and it can prevent generation | occurrence | production of a landslide similarly to 7th Embodiment.

  In addition, also in the said 7th, 8th embodiment, the granular material sealing body 6 is made into a some small sealing body, the granular material instead of soil is filled inside the granular material sealing body 6, and the water-impermeable sheet 5 The use of a stretchable water-impermeable sheet or a non-stretchable water-impermeable sheet, the provision of a drain pipe, etc. can be performed in exactly the same manner as in the first to third embodiments.

  Finally, in order to prevent both earth retaining and landslide when embankment work is performed on an inclined slope, an example of combining the above earth retaining method and ground improvement method for preventing landslide will be described. .

  FIG. 11 shows a cross section of the ground when the above-mentioned embankment work is performed. In this figure, the same parts as those in FIG.

  As shown in FIG. 11, in order to prevent the earth retaining and the landslide in this way, the granular material sealing body 6 a for the earth retaining is first formed on the step portion of the embankment 16. Next, preferably, the slope of the original ground 15 is excavated a little to form a stepped shape, and a granular material sealing body 6b for preventing landslide is formed thereon. After the granular material sealing body 6b is formed, the embankment is piled on it and the surface is formed on a platform. Thereby, even if the groundwater level 17 rises in the future mentioned above, it is possible to prevent the slope collapse and landslide due to the groundwater.

  As is clear from the above explanation, according to the ground improvement method for preventing liquefaction of the present invention, conventional cement or the like is mixed with the ground, or the backfill soil is impervious to the sand compaction. The construction is easy and inexpensive, such as sealing with, and there is no problem with the disposal of backfill soil. Moreover, since the granular material sealing body formed in this way can prevent the ingress of groundwater, the inside thereof is not saturated with the groundwater. Thereby, even if it receives a strong impact such as an earthquake, it is possible to prevent a liquefaction phenomenon caused by diffusion of soil particles into moisture.

  According to the water leakage / runoff prevention method in the embankment construction of the present invention, a part of the embankment embankment is sealed with an impervious sheet so that a sealed granular material is formed in the upper part of the embankment or in the central portion that hits the seepage line. . Since this granular material sealing body is sealed by the water-impermeable sheet, it is possible to prevent water from passing therethrough and outflow of earth and sand inside. According to the construction method of the present invention, it is possible to prevent leakage of levee and sediment loss much more easily than the conventional method of providing front and rear steps and the method of stacking sandbags to prevent sediment loss.

  According to the earth retaining method for embankment of the present invention, a granular material sealing body is formed at a step portion on a part of the embankment. By this granular material sealing body for earth retaining, collapse of the step portion of the embankment can be prevented, and the slope of the step portion can be protected.

  According to the ground improvement method for preventing landslide of the present invention, the formation in the vicinity of the landslide surface is replaced with a granular material sealing body, and the penetration of water is prevented by this granular material sealing body, and the stability of the slope is improved. . In addition, the shape of the granular material sealing body can reduce the shear stress of the landslide surface and obtain a more stable ground. This method is simpler than the conventional surface drainage for surface water discharge because it can easily form a granular sealed body in the embedding process, especially when embankment on slopes. It is possible to carry out construction for preventing landslides at low cost.

The figure which the ground improvement construction method for liquefaction prevention by 1st Embodiment of this invention showed notionally. The figure which showed the modification of the ground improvement construction method for liquefaction prevention by 1st Embodiment of this invention. The figure which the ground improvement construction method for liquefaction prevention by 2nd Embodiment of this invention showed notionally. The figure which showed notionally the ground improvement construction method for liquefaction prevention in the case of constructing the underground structure by 3rd Embodiment of this invention. The figure which showed notionally the water leakage prevention construction method in the embankment construction by 4th Embodiment of this invention. The figure which showed notionally the fall-off prevention method, such as earth and sand, in the embankment construction by 5th Embodiment of this invention. The figure which showed the example which combined the leak prevention construction method and the runoff prevention construction methods, such as earth and sand, in the embankment construction by this invention. The figure which showed notionally the earth retaining method of the embankment by 6th Embodiment of this invention. The figure which showed notionally the ground improvement construction method for the prevention of landslide by 7th Embodiment of this invention. The figure which showed notionally the ground improvement construction method for the prevention of landslide by 8th Embodiment of this invention. The figure which showed the example which combined the earth retaining method of the embankment of this invention, and the ground improvement construction method for landslide prevention. The figure which showed notionally the construction method which aims at the intensity | strength increase of the ground for the conventional liquefaction prevention. The figure which showed notionally the method of dissipating the excess pore water pressure for the conventional liquefaction prevention. The figure which showed notionally the method of reducing the groundwater level for the conventional liquefaction prevention. The figure which showed notionally the method of the leakage prevention of the embankment or the prevention of earth and sand loss. The figure which showed the conventional earth retaining method of embankment notionally. Explanatory drawing explaining stability calculation of a landslide slope. The figure which showed notionally the method of the surface water treatment for the conventional landslide prevention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Ground surface 2 Groundwater level 3 Depth in which liquefaction occurs 4 Hole 5 Impervious sheet 6 Granule sealing body 7 Crushed stone 8 Drain pipe 9 Check valve 10 Mountain retaining material 11 Underground structure 12 Recess 13 Levee body 14 Sheet pile 15 Original ground 16 Filling 17 Groundwater level 18 Slope 19 Groundwater level 20 Arc landslide surface

Claims (5)

  A water leakage prevention method for embankment construction, characterized by providing a granular material sealing body in which a granular material containing soil is sealed with an impervious sheet at a portion corresponding to the seepage line of the levee body.   A method for preventing runoff in embankment construction, characterized by providing a granular material sealing body in which granular material containing soil is sealed with an impermeable sheet at the top of the levee body.   The granular material sealing body is formed with a concave portion in the shape of the granular material sealing body during the embankment embankment process, an impermeable sheet is laid on the inner surface of the concave portion, and soil is put into the concave portion, and then the impermeable property The method for preventing leakage and water loss in embankment construction according to claim 1 or 2, wherein the sheet is hermetically sealed.   The water leakage / runoff prevention method in embankment construction according to claim 1, wherein the granular material sealing body includes a plurality of small sealing bodies in which the granular material is sealed.   The said water-impermeable sheet consists of either a stretchable water-impermeable sheet or a non-stretchable water-impervious sheet, The water leak / flow-off prevention construction method in the embankment construction according to any one of claims 1 to 4 .

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