JP3986328B2 - Ground liquefaction prevention method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
TECHNICAL FIELD The present invention relates to a ground liquefaction prevention method, and in particular, a steelmaking slag before aging treatment and / or a steelmaking after aging treatment, surrounded by an outer peripheral wall constructed in a soft ground where liquefaction is likely to occur. The present invention relates to a ground liquefaction prevention method that improves the ground by utilizing the property of expanding the slag by absorbing water by filling with slag (hereinafter sometimes referred to simply as “slag”).
[0002]
[Prior art]
Conventionally, converter slag is used as the ground improvement material, and piles are driven into the soft ground layer by a pile body placing machine, and the ground is improved by utilizing the water absorption and expansion action of the slag (for example, JP-A-6-116937).
[0003]
[Problems to be solved by the invention]
By the way, in the countermeasures for the conventional soft ground, the converter slag is used to improve the ground by its water absorption expansion action, but this converter slag is directly placed in the soft ground by the pile body placing machine. Since it is laid, it has a ground compaction effect by pile driving, a dehydration compaction effect of soft ground by capillary action of slag, and a ground compaction effect by water absorption expansion action. However, because this converter slag is directly piled on soft ground, the ground improvement area for the load is limited to the periphery of the pile, and a large number of piles are placed for wide-ranging improvements. There is a problem that it takes a lot of time and money to improve the ground.
[0004]
In view of the problems of the conventional ground improvement measures described above, the present invention introduces and fills the slag produced during steelmaking into the inner periphery of the outer peripheral wall that surrounds a predetermined range of the sand ground where liquefaction is likely to occur. Accordingly, an object of the present invention is to provide a ground liquefaction prevention method that can easily and inexpensively improve the ground over a wide range and cope with an overload.
[0005]
[Means for Solving the Problems]
In order to achieve this object, the ground liquefaction prevention method according to the present invention constructs an outer peripheral wall in the ground using concrete so as to surround the periphery, and the entire ground for constructing the upper structure from the surface layer. Liquefaction of the ground that has been excavated to the ground that can support the structure, slag is filled and filled inside the outer peripheral wall, and the ground is improved by utilizing the expansion and solidification properties due to water absorption of the slag This is a preventive measure method, in which the outer peripheral wall has a circular shape, and a plurality of PC steel wires are spanned between the opposing outer peripheral walls on the inner side surrounded by the outer peripheral wall, and at substantially equal intervals in the circumferential direction of the outer peripheral wall. The slag is filled up to above the stretched position of the PC steel wire, and the PC steel wire embedded in the slag is expanded by the expansion of the filled slag. Pre-stress, It is characterized in.
[0006]
This ground liquefaction prevention construction method uses concrete to surround the surroundings and constructs an outer peripheral wall in the ground, and excavates the entire ground for constructing the upper structure from the surface layer to the ground that can support the upper structure. Since the slag is introduced and filled inside the outer peripheral wall and the ground is improved by utilizing the expansion and solidification properties due to the slag absorbing water, the slag absorbs water in the ground. Excess pore water can be drained smoothly using the characteristics of the slag, and liquefaction of the ground can be prevented in advance, and after the ground is strengthened by the expansion and hardening action of the slag, it can respond to the overload Therefore, it is possible to easily and reliably improve sand ground and the like that are liable to be liquefied.
In addition, even if excess pore water in the unmodified ground is fluidized outside the outer peripheral wall due to an earthquake or the like, the outer peripheral wall acts as a blocking wall and entry into the improved ground is prevented by the outer peripheral wall. Therefore, it can be made difficult to be affected by the fluidization of the surrounding ground.
[0007]
Then, the outer peripheral wall is circular, and a plurality of PC steel wires are spanned between the opposing outer peripheral walls inwardly surrounded by the outer peripheral wall, and are arranged at substantially equal intervals in the circumferential direction of the outer peripheral wall. After changing the installation position, the slag is filled up to the upper part of the PC steel wire, and the PC steel wire embedded in the slag is prestressed by the expansion of the filled slag. When the slag filled inwardly surrounded by the outer peripheral wall is expanded and hardened, the peripheral expansion is restrained by the outer peripheral wall, prestressing is naturally applied to the PC steel wire, and the tensile force of the ground is increased. It can be strengthened, and the entire ground can be made strong.
[0008]
Moreover, the slag filled inwardly surrounded by the outer peripheral wall can have a low peripheral portion and a central portion that rises and swells.
[0009]
As a result, the improved ground can be integrated and the excess ground can be supported over the entire ground, making it suitable for foundations of structures that support loads in large areas such as oil storage tanks, and the improved ground Penetration into the ground at the time of oil leakage can be prevented by water permeability.
[0010]
The slag includes steelmaking slag before aging treatment and / or slag of steelmaking slag after aging treatment alone, or steelmaking slag before aging treatment and / or steelmaking slag after aging treatment, blast furnace slag, ferroalloy slag, water Crushed slag, copper smelting slag, red mud, fly ash, incineration slag, incineration ash, sludge slag, crushed glass, waste gypsum, concrete waste, etc., industrial waste, gypsum, quicklime, cement, crushed stone, earth and sand, clay The material which can utilize the expansion and solidification property of steelmaking slag which mixed 1 type, or 2 or more types of building materials, artificial materials, minerals, etc. can be used.
Here, “steel slag” means converter slag and / or electric furnace slag (oxidized slag and / or reduced slag).
[0011]
Thereby, due to the expansion and solidification of the steelmaking slag, a stronger slag layer ground can be obtained, and a low-cost steelmaking slag can be used, and further effective use of the steelmaking slag can be achieved. .
[0012]
Furthermore, the reduction | restoration slag of electric furnace slag can be used for slag.
[0013]
Thereby, an even stronger slag layer ground can be obtained by further improving the expansibility.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the ground liquefaction prevention method according to the present invention will be described below with reference to the drawings.
[0015]
Fig. 1 shows a reference example of the ground liquefaction prevention method .
When building superstructures such as buildings 4 and oil storage tanks 5 on soft ground such as sand geology, the ground has been improved to prevent liquefaction of soft ground that is likely to occur due to the occurrence of earthquakes and to withstand overloads. There is a need to.
[0016]
For this reason, in order to improve the ground of a preset area, the outer peripheral wall 1 is constructed in the ground using concrete so as to surround the place where the predetermined upper structure is constructed, and the upper structure is constructed. The entire ground is excavated from the surface layer to the ground that can support the upper structure, and the slag 2 is introduced and filled inside the outer peripheral wall 1.
[0017]
In this case, as the slag to be charged and filled in the inner wall of the outer peripheral wall 1, those having expansion and solidification characteristics can be suitably used. Specifically, aging treatment (after slag is crushed to a predetermined particle size) , Treatment for holding and reacting in steam at about 100 ° C. for about 100 hours) before making steelmaking slag and / or slag after aging treatment alone, or after making aging treatment and / or aging treatment Slag, blast furnace slag, ferroalloy slag, granulated slag, copper smelting slag, red mud, fly ash, garbage incineration slag, garbage incineration ash, sludge slag, glass fragments, waste gypsum, concrete waste, and other industrial waste, gypsum , Quick lime, cement, crushed stone, earth and sand, clay and other building materials, artificial materials, and one or a mixture of two or more .
[0018]
Furthermore, by using the reduced slag of the electric furnace slag as the slag, the expandability is further improved, so that a stronger slag layer ground can be obtained.
[0019]
Moreover, by using the earth and sand of the ground layer to be replaced with slag and the like within a range not losing the object of the present invention, the generation amount of residual soil can be suppressed and the construction cost can be reduced.
[0020]
In this way, the slag 2 charged and filled inwardly of the outer peripheral wall 1 expands when free lime (free lime) remaining in the slag reacts with water and expands. When the main purpose is to use, it is desirable to use the one before aging.
This slag, especially granulated slag, has countless bubbles and has an angular shape, so it has light weight, large shear resistance, and water permeability. As a result, the filled slag itself drains excess pore water in the ground, and the slag itself absorbs water by a part of the excess pore water contained in the ground to be improved, and expands and solidifies with this water absorption. To be able to.
And the influence of the unimproved surrounding ground which has water impermeability after hardening can be suppressed, and a ground can be improved firmly.
In addition, it is also possible to perform the water absorption expansion | swelling of this slag by appropriate addition.
[0021]
By the way, when the slag 2 filled inside the outer peripheral wall 1 expands due to water absorption, it is restrained by the outer peripheral wall 1 by the expansion force in the lateral direction (horizontal direction) in the outer peripheral wall 1 and from the surrounding ground. A pressing force is applied, the compression and bending rigidity of the outer peripheral wall 1 is increased, and an expansion force is also applied in the vertical direction. This expansion force is applied to the ground load and bending strength. The soft ground can be improved easily and reliably over a wide range.
[0022]
By the way, the outer peripheral wall 1 constructed so as to surround the place where the predetermined upper structure is constructed has an arbitrary shape according to the shape, type, etc. of the upper structure constructed on the ground, such as a square shape or a circular shape. be able to. Specifically, for example, in the case of an upper structure such as a building, it is desirable to have a square shape that matches the shape of the building, and in the case of an oil storage tank, it is desirable to have a circular shape. It is not limited.
When the outer peripheral wall 1 is, for example, a square, as shown in FIG. 2 (A), the outer peripheral wall 1 is constructed only at the outer peripheral portion, and as shown in FIG. It is also possible to construct the lattice wall body 11 integrally with the outer peripheral wall 1 so as to partition in a shape.
[0023]
Then, by forming the lattice wall body 11 integrally with the concrete inside the outer peripheral wall 1 like the outer peripheral wall, the geology in each section surrounded by the outer peripheral wall 1 and the lattice wall body 11 is different. Even in the case, the ground improvement corresponding to each geology can be performed. In particular, when a wide range of ground is improved at the same time, the geology is often different from place to place. It becomes an improvement method suitable for such a case, and the entire ground improvement can be performed on average.
Even in a construction area where construction cannot be performed at once, construction can be performed separately for each section.
[0024]
Moreover, when it is made to receive a load substantially in the whole upper structure like the tank 5 for oil reserves, etc. of one Example of the liquefaction prevention countermeasure method of the ground of this invention shown in FIGS. Thus, the outer peripheral wall 1 can be formed in a circle.
The circular outer peripheral wall 1 can be constructed in the same manner as the square outer peripheral wall 1.
[0025]
In this case, a section steel 6 such as an H-section steel is embedded in the outer peripheral wall 1, and a PC steel wire 3 is stretched between the section steels 6. This PC steel wire 3 is stretched between opposing wall surfaces of the outer peripheral wall 1 so as to pass through the center of the circular outer peripheral wall 1 or in the vicinity of the center, and is provided at predetermined intervals along the circumferential direction of the circular outer peripheral wall 1. Arrange and stretch each time.
Thereby, when the slag 2 filled inside the outer peripheral wall expands by water absorption, the expansion direction of the slag 2 acts in the radial direction and also in the vertical direction over the entire circumference of the outer peripheral wall. In particular, the expansion force acting in the radial direction over the entire circumference of the outer peripheral wall is restrained by the outer peripheral wall, so that tension is applied to the PC steel wire, and the tensile force of the ground can be strengthened. .
In the illustrated embodiment, the PC steel wire 3 is stretched in a flat shape, but the PC steel wire 3 can be stretched in two or more stages in the height direction. Thereby, the tensile force of the ground can be further strengthened. Further, since a uniform restraining force acts on the outer peripheral wall, it is possible to prevent the outer peripheral wall from being broken due to stress concentration.
[0026]
Moreover, the slag filled inside the outer peripheral wall 1 can be made into an arch type so that the side along the inner peripheral surface of the outer peripheral wall is low and the central portion of the outer peripheral wall is raised.
As a result, the center part is raised when the slag is filled, but when the slag expands due to water absorption, the expansion force of the slag acts on the outer peripheral wall side, and the surface of the improved ground is flat. The ground is integrated so that the upper load can be supported by the entire ground.
For this reason, it is suitable for the foundation of a structure that supports a load with a large area such as the oil storage tank 5 and the like, and further improved impermeability of the ground can prevent penetration into the ground when oil leaks. .
[0027]
Although the liquefaction prevention method of the ground of the present invention have been described based on the embodiments, the present invention is not limited to the configuration described in the above embodiments, as appropriate within a scope not departing from its gist The configuration can be changed.
[0028]
【The invention's effect】
According to the ground liquefaction prevention method according to the present invention, it is possible to construct the outer peripheral wall in the ground using concrete so as to surround the periphery, and to support the upper structure from the surface of the entire ground for constructing the upper structure. Excavating to the ground, filling and filling the slag inside the outer peripheral wall, and improving the ground by utilizing the expansion and solidification by the slag water absorption, so the slag absorbs water In addition, drainage of excess pore water in the ground can be performed smoothly using the characteristics of the slag, liquefaction of the ground can be prevented in advance, and after the ground is strengthened by the expansion and hardening action of the slag, Since the ground strength corresponding to the overload can be obtained, improvement of the sand ground or the like that is liable to be liquefied can be easily and reliably performed.
In addition, even if excess pore water in the unmodified ground is fluidized outside the outer peripheral wall due to an earthquake or the like, the outer peripheral wall acts as a blocking wall and entry into the improved ground is prevented by the outer peripheral wall. Therefore, it can be made difficult to be affected by the fluidization of the surrounding ground.
[0029]
Then, the outer peripheral wall is circular, and a plurality of PC steel wires are spanned between the opposing outer peripheral walls inwardly surrounded by the outer peripheral wall, and are arranged at substantially equal intervals in the circumferential direction of the outer peripheral wall. After changing the installation position, the slag is filled up to the upper part of the PC steel wire, and the PC steel wire embedded in the slag is prestressed by the expansion of the filled slag. When the slag filled inwardly surrounded by the outer peripheral wall is expanded and hardened, the peripheral expansion is restrained by the outer peripheral wall, prestressing is naturally applied to the PC steel wire, and the tensile force of the ground is increased. It can be strengthened, and the entire ground can be made strong.
[0030]
In addition, the slag that fills the inside surrounded by the outer peripheral wall has a low peripheral part and a central part that rises and swells, so that the improved ground is integrated, and the entire ground supports the overloading Therefore, it is suitable for the foundations of structures that support loads in large areas such as oil storage tanks, and further improved water impermeability can prevent penetration into the ground when oil leaks. .
[0031]
The slag includes steelmaking slag before aging treatment and / or slag of steelmaking slag after aging treatment alone, or steelmaking slag before aging treatment and / or steelmaking slag after aging treatment, blast furnace slag, ferroalloy slag, water Crushed slag, copper smelting slag, red mud, fly ash, incineration slag, incineration ash, sludge slag, crushed glass, waste gypsum, concrete waste, etc., industrial waste, gypsum, quicklime, cement, crushed stone, earth and sand, clay Building materials such as building materials, artificial materials, and minerals that can be used for the expansion and solidification of steelmaking slag mixed with one or more types of minerals can be made stronger by the expansion and solidification of steelmaking slag. Slag layer ground can be obtained, and low-cost steelmaking slag can be used. It is possible.
[0032]
Furthermore, by using the reduced slag of the electric furnace slag as the slag, the expandability is further improved, so that a stronger slag layer ground can be obtained.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view showing a reference example of a ground liquefaction prevention countermeasure method .
2A and 2B are cross-sectional plan views of the same reference example , in which FIG. 2A shows a case without a lattice wall body, and FIG. 2B shows a case where the lattice wall body is integrally formed.
FIG. 3 is a longitudinal sectional view showing an embodiment of the ground liquefaction prevention method according to the present invention.
FIG. 4 is a cross-sectional view of the same.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Outer wall 11 Lattice wall body 2 Slag 3 PC steel wire 4 Building (superstructure)
5 Oil storage tank (superstructure)
6 Shape steel

Claims (4)

In addition to constructing the outer peripheral wall in the ground using concrete so as to surround the periphery, the entire ground for constructing the upper structure is excavated from the surface layer to the ground that can support the upper structure, and the slag is inward of the outer peripheral wall. Is a ground liquefaction prevention method that improves the ground by utilizing the expansion and solidification properties of the slag that absorbs water, and has a circular outer peripheral wall surrounded by the outer peripheral wall. The PC steel wire is stretched so that a plurality of PC steel wires are stretched between the opposing outer peripheral walls and the arrangement positions thereof are mutually changed so as to be substantially equidistant in the circumferential direction of the outer peripheral wall. The ground liquefaction prevention construction method characterized by prestressing the PC steel wire embedded in the slag by filling the slag above the wire tensioning position and expanding the filled slag . 2. The ground liquefaction prevention method according to claim 1 , wherein the slag filled inwardly surrounded by the outer peripheral wall has a low peripheral part and a central part that rises and bulges. Slag is steelmaking slag before aging treatment and / or slag of steelmaking slag after aging treatment alone, or steelmaking slag before aging treatment and / or steelmaking slag after aging treatment, blast furnace slag, ferroalloy slag, granulated slag, Copper smelting slag, red mud, fly ash, incineration slag, incineration ash, sludge slag, crushed glass, waste gypsum, concrete waste, and other industrial waste, gypsum, quicklime, cement, crushed stone, earth and sand, clay, etc. The construction method of the foundation ground according to claim 1 or 2, wherein the expansion and solidification properties of steelmaking slag mixed with one or more of materials for use, artificial materials and minerals can be used. The foundation ground construction method according to claim 1 or 2, wherein the slag is reduced slag out of electric furnace slag.

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