JP2018123575A - Countermeasure method for soil liquefaction, and pile block used in the method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable a pile to have water permeability and compression strength and to make it possible to recycle waste in a countermeasure method for soil liquefaction using a pile in which a plurality of pile blocks are layered.SOLUTION: The countermeasure method for soil liquefaction comprises forming a drilled hole in a ground, and constructing one pile 10 by layering within the drilled hole a plurality of pile blocks 1 having water permeability which includes a solid, substantially columnar main body that is a solidified object of compounded materials including at least cement, aggregate which is crushed roofing materials, additive and water. The pile 10 is embedded in a non-liquefied layer 21 located below a liquefied layer 22 in the ground. The pile 10, which is constructed by the plurality of pile blocks 1, is used as a foundation pile for a building structure or a civil engineering structure. The weight compounding ratio of crushed roofing materials is 3.5 to 4.5 for 1 of the cement, or the weight compounding ratio of crushed roofing materials is 3.5 to 4.5 and the weight compounding ratio of water is 0.5 to 0.6 for 1 of the cement.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a liquefaction countermeasure method for a ground that may be liquefied and a permeable pile block used therefor.

  If liquefaction occurs when an earthquake occurs, it will cause major damage to houses and residential land. As countermeasures for liquefaction in residential areas, the groundwater level lowering method, the grid-like underground wall method, the density increasing method, the pore water pressure dissipation method, etc. have been proposed.

  However, the groundwater level lowering method requires permanent running costs such as power consumption and drain pipe maintenance. A certain range of regional agreement is necessary for the latticed underground wall method. The density increasing method has large ground deformation during construction. The pore water pressure dissipation method is a construction using a large machine. Therefore, these methods have their respective problems when applied to detached houses.

  Patent Document 1 discloses a pile unit for ground improvement / liquefaction countermeasures having both ground improvement and liquefaction countermeasure functions. This pile unit is made of water-permeable concrete with a hollow cylindrical shape, and a long pile structure can be formed by stacking a plurality of layers vertically with an annular cushioning material interposed therebetween. When liquefaction occurs, the surrounding groundwater enters the hollow interior and is discharged to the ground through the hollow.

Japanese Patent Laying-Open No. 2015-52253

  However, since the pile unit of patent document 1 is a hollow cylinder shape, if a cylindrical wall is made thin, the drainage effect will become high, but compressive strength will become small and the intensity | strength as a pile will fall.

  An object of the present invention is to enable recycling of waste materials while a pile has water permeability and compressive strength in a liquefaction countermeasure method using a pile in which a plurality of pile blocks are stacked. Furthermore, the objective of this invention is providing the pile block used for such a liquefaction countermeasure construction method.

In order to solve the above-described problems, the present invention has the following configuration. The numbers in parentheses are reference numerals in the drawings to be described later, and are attached for reference.
-The aspect of this invention is a liquefaction countermeasure construction method, Comprising: The solidified material of the compounding material which contains a step which forms a drilling hole (40) in the ground, and cement, aggregates which are crushed tiles, an admixture, and water at least Constructing a single pile (10) by stacking a plurality of water-permeable pile blocks (1) having a solid substantially cylindrical body in the drilling hole (40). It is characterized by that.
-In the said aspect, it is suitable to root the said pile (10) in the non-liquefaction layer (21) located below the liquefaction layer (22) in the ground.
-In the said aspect, it is suitable that the pile (10) constructed | assembled by the said some pile block (1) is used as a foundation pile of a building structure or a civil engineering structure.
-In the said aspect, it is suitable for the said mixing | blending material that a crushing roof tile is the weight mixing ratio of 3.5-4.5 with respect to the cement 1. FIG.
-In the said aspect, it is suitable for the said mixing | blending material that the crushing tile is 3.5-4.5 with respect to the cement 1, and the weight mixing ratio of water is 0.5-0.6.
-Another aspect of the present invention is a pile block (1) used in the liquefaction countermeasure construction method, for constructing one pile (10) by stacking a plurality of pieces in the vertical direction, A columnar main body is provided, and the main body is a solidified material of a blended material containing at least cement, aggregates that are crushed tiles, an admixture, and water.
-In the said aspect, in the said compounding material, it is suitable that the crushing roof tiles are the weight mixing ratios of 3.5-4.5 with respect to the cement 1. FIG.
-In the said aspect, in the said compounding material, it is suitable with respect to the cement 1 that the crushing roof tiles are 3.5-4.5 and water is 0.5-0.6 weight mixing ratio.

  In the liquefaction countermeasure method according to the present invention, one pile is constructed by stacking water-permeable pile blocks. Since the pile block has a cement-based solidified body using a crushed tile as an aggregate, a foundation pile excellent in water permeability and compressive strength can be constructed. Since pile blocks that have been manufactured in advance are brought into the site for construction, the on-site facilities can be simplified and stable quality can be ensured by factory production. Moreover, since a pile block is lightweight, there are few burdens of conveyance and construction.

  When liquefaction occurs, piles constructed with highly permeable pile blocks absorb excess surplus water and discharge it to the ground, thereby suppressing the increase in excess pore water pressure and dissipating pore water pressure. To reduce liquefaction damage.

  The tile before crushing is made of clay fired at a high temperature and has waterproof properties. However, the crushed tile obtained by crushing the tile has good water permeability because the porous gap exposed by the high temperature firing is exposed on the crushing surface. Moreover, since it is porous, it is lightweight. The present invention makes it possible to effectively use waste tiles.

FIG. 1 is a perspective view showing an example of an embodiment of a pile block according to the present invention. 2 is a cross-sectional view taken along the line II of FIG. FIG. 3 is a cross-sectional view schematically showing an example of a state in which the pile block shown in FIGS. 1 and 2 is constructed on the target ground. 4A, 4B, and 4C are schematic views illustrating an example of another embodiment of a pile block. FIGS. 5A to 5F are diagrams schematically showing an example of a construction method for constructing the pile block shown in FIGS. 1 and 2 on the target ground.

  Hereinafter, embodiments of a water-permeable pile block according to the present invention and a liquefaction countermeasure method using the same will be described in detail with reference to the drawings.

  FIG. 1 is a perspective view showing an example of an embodiment of a water-permeable pile block according to the present invention. 2 is a cross-sectional view taken along the line II of FIG.

  The pile block 1 is a member for construction or civil engineering in which a plurality of piles can be built up and down to construct one long pile such as a foundation pile in a house or the like. With reference to FIG.1 and FIG.2, the shape of the pile block 1 is demonstrated first. The pile block 1 has a solid substantially cylindrical main body, and is depressed in the axial direction from the cylindrical portion 2, the fitting convex portion 3 protruding in the axial direction from the upper surface of the cylindrical portion 2, and the lower surface of the cylindrical portion 2. It consists of a fitting recess 4.

  The fitting convex portion 3 and the fitting concave portion 4 have an outer shape that fits each other when the two pile blocks 1 are stacked one above the other. In the illustrated example, the outer shape of the fitting convex portion 3 and the fitting concave portion 4 is substantially a truncated cone shape, and is the shape that can be most easily fitted, but is not limited to this shape. When the fitting convex part 3 and the fitting concave part 4 are fitted, the upper surface of the pile block 1 positioned on the lower side and the lower surface of the pile block 1 positioned on the upper side come into contact with each other. Thereby, the supporting force in the vertical direction is effectively transmitted in the plurality of stacked blocks 1.

  The length L of the cylindrical portion 2 shown in FIG. 2 is, for example, about 1 m to 2 m. The diameter D is, for example, about 400 mm to 600 mm. The length L, the diameter D, and the shapes and sizes of the fitting convex portion 3 and the fitting concave portion 4 are appropriately set as necessary.

  Further, a recess 3 a that opens at the center of the upper surface of the fitting protrusion 3 is formed. In the illustrated example, the recess 3a is a cylindrical space. A pair of suspension rings 5 are attached to the bottom of the recess 3a. These suspension rings 5 are used when the pile block 1 is suspended by a crane or the like. The topmost part of each suspension ring 5 is in the recess 3 a and does not protrude from the fitting protrusion 3. The leg portion of each suspension ring 5 is embedded in the cylindrical portion 2. In order to prevent the suspension ring 5 from easily falling off, it is preferable to bend the tip of the leg as shown in the figure.

Next, the material of the pile block 1 will be described. The pile block 1 is a cement-based solidified material having water permeability. The compounded material before solidification includes at least cement, crushed tiles as aggregates, and formulated water (a mixture of water and an admixture) as components. In addition to these, short fibers may be blended. Table 1 shows formulation examples per 1 m ^{3 of the} material.

As an aggregate of the pile block 1, crushed tiles are used. For example, non-standard products of Sanshu tiles (produced in Nishi Mikawa region, Aichi Prefecture) are crushed. Preferably, those having a particle size in the range of 2 mm to 5 mm (equivalent to sieve No. 7) are selected and used. The characteristics of such crushed roof tiles are, for example, surface dry density: 2.24 g / cm ³ and water absorption: 7.86%. The roof tile used in the present invention is produced by firing clay at a high temperature of 1100 to 1150 ° C., for example.

  The crushing tiles obtained by crushing such tiles have crushing surfaces formed on their surfaces, and porous gaps are exposed on these crushing surfaces. Therefore, the crushed tile has good water absorption, and a pile block having high water permeability can be obtained by using it as an aggregate of cement-based solidified material. Moreover, since the crushed tile is porous, there is also an advantage that it is lighter than crushed stone which is a general aggregate. In addition to non-standard products in the tile production process, waste tiles generated by changing roofs can also be used as a material for shredded tiles.

The admixture is, for example, a high-molecular synthetic resin (trade name “DENKA SUPER S” manufactured by DENKA CORPORATION) having a specific gravity of 1.04 g / cm ³ . The short fiber is, for example, a vinylon fiber having a diameter of 100 μm and a length of 12 mm.

  The water cement ratio W / C is preferably about 60% at the maximum. Since the water absorption rate of the aggregated crushed tile is high, the amount of water absorbed by the crushed tile is taken into consideration, and the W / C is set higher than that of concrete using general aggregate.

  The weight ratio of the cement and crushed tile is preferably 3.5 to 4.5 with respect to the cement 1. Further, the weight ratio of cement, crushed tile, and water is preferably 3.5 to 4.5 for crushed tile and 0.5 to 0.6 for water with respect to cement 1.

Table 2 shows design standard values of the pile block 1.

  The necessary reference values shown in Table 2 can be achieved by adjusting the mixing ratio of the materials. Tables 3 and 4 show the results of measuring the hydraulic conductivity and the compressive strength of the pile blocks manufactured with the formulations shown in Table 1, respectively. The dimensions of the pile block used for measurement are the length L: 1 m and the diameter D: 450 mm shown in FIG. Three samples were manufactured and measured.

  FIG. 3 is a cross-sectional view schematically showing an example of a state in which the pile block 1 shown in FIGS. 1 and 2 is constructed on the target ground. In the illustrated example, a long pile 10 is constructed in the ground by stacking seven pile blocks 1 up and down. The pile 10 is preferably a foundation pile for a house, but may be constructed as a foundation pile for a building or civil engineering structure other than a house, or as a pile for other purposes. When the pile block 1 has a length of 1 m to 2 m, the maximum length of the pile 10 is preferably about 10 m. Moreover, when setting it as the foundation pile of a house, the pile space | interval of a horizontal direction shall be about 1m-2m, for example.

  The target ground is composed of a non-liquefied layer 21, a liquefied layer 22, a top soil 23, and a drainage layer 24 from the lower layer to the upper layer. The non-liquefied layer 21 is a stable layer that does not liquefy even during an earthquake. When the liquefied layer 22 is present, the non-liquefied layer 21 is usually at a depth of 5 m or more from the ground surface. In order to secure the function as the foundation pile, the lower end portion of the pile 10 is placed in the non-liquefied layer 21 to be rooted. In the case of a foundation pile of a house, the length of the part to be embedded is, for example, about 1 m. If the length of the pile block 1 is 1 m, one pile block 1 will be installed in the non-liquefaction layer 21. The length of the penetration is appropriately set according to the purpose of the pile 10 and the construction conditions.

  The liquefied layer 22 is a range from the boundary with the non-liquefied layer 21 to the highest position of the groundwater level. There is a topsoil layer 23 on the liquefied layer 22. The surface of the topsoil layer 23 is the ground surface before construction. The drainage layer 24 is composed of a gravel layer formed in the final process of construction. The drainage layer 24 is also for covering the protruding head of the top pile block 1.

  When liquefaction occurs, the pile 10 absorbs groundwater in the liquefied layer 22 from its peripheral surface and drains it to the ground surface. As a result, an increase in excess pore water pressure in the liquefied layer 22 is suppressed, and the liquefied layer 22 is made non-liquefied.

  The shape of the pile block and the connection means between the upper and lower pile blocks are not limited to the examples described above. The pile block has a solid substantially columnar body and may have any shape that can be stacked in the vertical direction to form one pile. The shapes of the upper end portion and the lower end portion of the substantially cylindrical main body can be appropriately designed according to the connection means. The above-mentioned fitting convex part and fitting concave part are examples. For example, the upper and lower pile blocks may be joined with an adhesive.

  Drawing 4 is a figure which illustrated another embodiment of a pile block connected using a joint member. (A) is a schematic sectional view in which two pile blocks 1 ′ are stacked, (b) is a schematic sectional view of the joint member 6, and (c) is a schematic plan view of the joint member 6. The joint member 6 is a tubular member having a shape in which a thick tube and a thin tube are attached together. The upper and lower pile blocks 1 ′ and 1 ′ are connected to both ends of the joint member 6 by inserting them. The joint member 6 can be made of synthetic resin, for example, made of vinyl chloride. The shape of the end of the substantially cylindrical main body 2 ′ of the pile block 1 ′ is formed according to the joint member 6. The joint member 6 shown in FIG. 4 is an example, and a steel socket can also be used.

  FIG. 5 is a diagram schematically showing an example of a construction method for constructing the pile block shown in FIGS. 1 and 2 on the target ground.

  Manufacture pile blocks at factories before construction. The manufacturing method is a method in which the above-described blended materials are mixed, poured into a mold, and cured until sufficient strength is developed. The suspension ring, which is a steel material, causes the legs of the suspension ring to be embedded in a predetermined position when the compounded material is poured into the mold.

  The pile block manufactured in this way is carried into a construction site of a detached house, for example. Necessary work machines and plant equipment will be prepared at the construction site.

  In Fig.5 (a), first, the auger 30 which is a kind of excavator is set in a predetermined position. Subsequently, as shown in FIG. 5 (b), a hole 40 is formed in the target ground. It is preferable to excavate slowly while ensuring the verticality of the hole 40. The diameter of the drilling hole 40 is set to a size with a margin that allows the pile block 1 to be smoothly inserted. For example, when the diameter of the pile block 1 is 450 mm, the diameter of the hole 40 is 600 mm.

  In FIG.5 (c), formation of the drilling hole 40 of the depth as designed is completed. After the excavation is completed, the auger 30 is rotated for a while at the same depth so that no excavated soil remains. By measuring the remaining length of the auger 30, the depth of the hole 40 can be confirmed. Before pulling out the auger 30, a hole wall protective material for preventing the hole wall from collapsing is filled.

  In FIG. 5 (d), the root hardening material is filled to a height of about 1 m from the bottom of the drilling hole. Table 5 shows formulation examples of the root hardening material. The admixture of Table 5 is a special lignin sulfonate (trade name “Floric GR” manufactured by Floric Co., Ltd.). Thereafter, the auger 30 is slowly pulled out.

  In FIG.5 (e), the crane hook 60 of a crane and the suspension ring of the pile block 1 are connected with a rope, are suspended one by one in a drilling hole, and a required number is piled up.

  In FIG. 5F, the exposed head of the top pile block 1 is cured. Specifically, a drainage layer 24 having a predetermined thickness is provided on the ground surface so as to cover the head of the pile block 1. Then, move to the position of the next pile and perform construction in the same way.

DESCRIPTION OF SYMBOLS 1, 1 'pile block 2, 2' Cylindrical part 3 Fitting convex part 4 Fitting concave part 5 Suspension ring 6 Joint member 10 Pile (foundation pile)
21 Non-liquefied layer 22 Liquefied layer 23 Topsoil layer 24 Drainage layer 30 Excavator 40 Drilling hole 50 Root-setting liquid 60 Crane hook

Claims (8)

Forming a hole (40) in the ground;
A water-permeable pile block (1) comprising a solid, substantially cylindrical main body, which is a solidified product of a combination material containing at least cement, aggregate that is crushed tile, admixture and water, And a step of constructing a single pile (10) by stacking a plurality of piles in the liquefaction countermeasure method. The liquefaction countermeasure method according to claim 1, wherein the pile (10) is embedded in a non-liquefied layer (21) located below the liquefied layer (22) in the ground. The liquefaction countermeasure method according to claim 1 or 2, wherein the pile (10) constructed by a plurality of the pile blocks (1) is used as a foundation pile of a building structure or a civil engineering structure.   The liquefaction countermeasure method according to any one of claims 1 to 3, wherein in the blended material, the weight of the crushed roof tile is 3.5 to 4.5 with respect to the cement 1.   In the said compounding material, with respect to the cement 1, the crushing roof tiles are 3.5-4.5 and water are the weight compounding ratios of 0.5-0.6, In any one of Claims 1-3 characterized by the above-mentioned. The liquefaction countermeasure method described. A pile block (1) that is used in a liquefaction countermeasure construction method and builds up a single pile (10) by stacking a plurality of pieces in the vertical direction, comprising a solid substantially columnar body, A pile block, characterized in that the main body is a solidified material of cement, aggregates that are crushed tiles, an admixture and water.   The pile block according to claim 6, wherein the blended material has a weight blending ratio of 3.5 to 4.5 with respect to the cement 1.   The pile according to claim 6 or 7, wherein the blended material has a weight blending ratio of 3.5 to 4.5 for crushed tile and 0.5 to 0.6 for water with respect to cement 1. block.

Images