JP3756728B2 - Control method of deformation characteristics of soil - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The invention of this application relates to a method for improving soil strength, and relates to a method for controlling the deformation characteristics of soil.
[0002]
[Prior art]
Soil is an aggregate of grains with relatively small particle size, which is mainly formed by the weathering of rock. “Soil” in geotechnical engineering contains all the materials that make up the ground. The size of the particles is wide, and the materials of the materials include various kinds from pure minerals to industrial waste. For example, dredged landfills modified by the addition of solidified materials such as sludge and cement deposited in rivers, lakes, canals, and sea areas with high organic matter content are also included. Therefore, its behavior is extremely complex and varied.
[0003]
Usually, when performing embankment or road construction, it is not easy to test the compaction characteristics of a large amount of soil material and its suitability as a roadbed. Therefore, the soil classification name is examined from the results of simple tests such as a grain size test and a consistency test, and the soil is classified based on many materials so that the engineering properties of the soil can be roughly determined. The classification name is given.
[0004]
The soil consists of soil particles and gaps, and water and air exist in the gaps. Soil exhibits properties as liquids, plastics, semi-solids, and solids as the moisture content decreases, and the moisture content that indicates the boundary of this state is called the consistency limit. Each boundary is a liquid limit, a plastic limit. , Defined as the shrinkage limit. In the hydrous state below the plastic limit, the soil shows high shear strength but is inelastic. When the water content is below the shrinkage limit, the volume does not decrease even if the water content decreases.
[0005]
For example, for the purpose of environmental conservation, main structures such as embankments and structures, or temporary structures, based on the knowledge and experience of the soil obtained so far, including the above knowledge Attempts have been made to improve soil strength. For example, in ground improvement work made of various soils to be treated, shallow layer improvement is known in which an improved layer is formed by adding and mixing a cecent solidified material to the surface layer portion.
[0006]
[Problems to be solved by the invention]
However, in the conventional construction method, the characteristics such as the deformation coefficient and fracture strain of the soil to be treated cannot be freely controlled according to the application. For example, in ordinary soil having uniaxial compressive strength, there has been no known method for reducing the deformation coefficient and increasing the fracture strain while maintaining the original uniaxial compressive strength. Solidified soil obtained by solidifying sludge that does not have uniaxial compressive strength with cement-based solidification material has high compressive strength but low fracture strain (that is, a large deformation coefficient), and its properties are significantly different from ordinary soil. Therefore, it is necessary to improve the deformation characteristics by crushing and loosening, but the characteristics cannot be freely controlled according to the purpose.
[0007]
Here, the uniaxial compressive strength can be expressed by the maximum compressive stress q _u of the specimen in the uniaxial compression test.
[0008]
The uniaxial compression test for determining the uniaxial compressive strength of soil is a test for compressing and destroying a self-supporting soil cylindrical specimen in the axial direction without applying side pressure, and is defined in JIS A 1216. This is a non-consolidation and non-drainage test for viscous soils with low water permeability and is widely used as the simplest soil shear test.
[0009]
Saturated clay that is not very hard has an internal friction angle φ _u = 0 under non-consolidated and non-drained conditions, and exhibits a constant undrained shear strength (C _u ) regardless of the total stress. In particular, with soft clay, C _u = q _u / 2 is the adhesive strength, and φ _u = 0 is widely used for stability analysis. The inclination of the shear plane in the uniaxial compression test, but there is a factor to overestimate C _u as compared to conditions of creep and strength anisotropy such practical problems, whereas inevitably disturbed due to sampling and shaping, which is the It is believed to give reasonable results, offset by the factors.
[0010]
Although knowledge about uniaxial compressive strength has been deepened as described above, and the test method has been established, in actual construction, the deformation characteristics of the soil are freely controlled as described above. However, it was not easy to reduce the burden, shorten the construction period, reduce the cost, and improve and stabilize the construction quality.
[0011]
Therefore, the invention of this application was made to solve the conventional practical problems as described above, and the characteristics such as the deformation coefficient and fracture strain of the soil to be treated depend on the purpose and application. It is an issue to be able to control freely.
[0012]
[Means for Solving the Problems]
The invention of this application, as to solve the above problem, in the first, 30 to a thickness of 0.1mm or less of waste paper to the target soil 1 m ³ at 1cm square below the soil having a uniaxial compressive strength By adding 1 kg or more of a polymer improver to 90 kg and 1 m ^{3 of the} target soil , the deformation coefficient is made higher than the original deformation coefficient while maintaining the uniaxial compression strength equivalent to the original uniaxial compression strength. Providing a method for controlling the deformation characteristics of soil for embankment to existing ground or for improving shallow layers of soft ground, characterized by reducing and controlling the fracture strain to be larger than the original fracture strain, secondly, the soil having an axial compressive strength, 1 kg or more high for 30~90kg and the target soil 1 m ³ to the target soil 1 m ³ the thickness 0.1mm or less wastepaper in 1cm square or less Original uniaxial pressure by adding molecular system improver While maintaining the strength and equivalent uniaxial compressive strength, characterized in that than when added alone fiber維質material only or the polymeric modifying material, which reduce the modulus of deformation is controlled so as to increase the strain fracture A method for controlling the deformation characteristics of soil for embankment on existing ground or for improving the shallow layer of soft ground is provided.
[0013]
The invention of this application, the first 3, 30～90Kg the target soil 1 m ³ to the target soil 1 m ³ the thickness 0.1mm or less wastepaper in 1cm square below soil no uniaxial compressive strength After adding 1 kg or more of the polymer-based improving material to the solid, this is solidified to maintain the uniaxial compressive strength equivalent to that obtained by solidifying the soil that does not have uniaxial compressive strength. However, the deformation coefficient is made smaller than the deformation coefficient of soil obtained by solidifying soil without uniaxial compressive strength, and the fracture strain is obtained by solidifying soil without uniaxial compressive strength. Provide a method for controlling the deformation characteristics of soil for embankment to an existing ground or for improving the shallow layer of soft ground, characterized in that the soil is controlled to be larger than the fracture strain of the soil, Less than 1cm square and 0.1mm thick on soil without uniaxial compressive strength The following used paper has ³⁰ to 90 kg of 1 m ^{3 of the} target soil and 1 kg or more of the polymer improving material to 1 m ^{3 of the} target soil , and then solidifies it so that it does not have uniaxial compressive strength. while maintaining the soil solidification treated is soil equivalent uniaxial compressive strength obtained, fiber維質material only or than when added alone the polymeric modifying material, to reduce the modulus of deformation, the strain fracture Provided is a method for controlling the deformation characteristics of soil for embankment on existing ground or for improving shallow layers of soft ground, which is characterized by being controlled to increase.
[0014]
The invention of this application, the fifth, pre Symbol solidification process, dewatering, drying, and embankment or soft to existing ground, characterized in that it is carried out as at least one process of addition of the solidified material A method for controlling the deformation characteristics of the soil for improving the shallow ground layer , and sixth , in any one of the above-described methods for controlling the deformation characteristics of the soil, the soil added with a fibrous material and a new polymer-based improvement material Provided is a method for controlling deformation characteristics of soil for embankment on existing ground or for improving shallow layers of soft ground, wherein the soil is aggregated by applying mechanical shear stress.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
The invention of this application has the features as described above, and an embodiment thereof will be described below.
[0016]
The method for controlling the deformation characteristics of soil according to the invention of this application is intended to improve the deformation characteristics of all soils, but the applicable soils include soil that can measure uniaxial compressive strength, uniaxial compressive strength, and so on. Can be divided into two types of soil that cannot be measured.
[0017]
(1) In the case of soil capable of measuring uniaxial compressive strength Fig. 1 shows that 1.0 kg / m ³ of polymer-based improving material is added to the soil to be treated having the uniaxial compressive strength having the characteristics shown in (1-1). The relationship between the compressive strain and the compressive stress in the case (1-2) and the case where the fibrous substance is further added (1-3) is shown.
[0018]
By adding the fibrous material and the polymer-based improving material (1-3), the uniaxial compressive strength is the same as that of the original soil (1-1) or the soil containing only the polymer-based improving material (1- 2), and the deformation coefficient (represented by the slope of the tangent of each graph in FIG. 1) becomes smaller. That is, it can be said that the characteristics of the soil to which the fibrous material and the polymer-based improving material are added are difficult to break, the residual strength can be maintained, and it is very useful in constructing a strong soil structure.
[0019]
The soil in which the deformation characteristics of the soil are controlled in this way is suitable for various uses that are used by embankment on the existing ground, and is also suitable for the improvement of the shallow layer of the soft ground. In addition, in this case, compared to the case where only the solidification treatment such as addition of the solidification material is performed, the particles are aggregated from the beginning, so that they are crushed and loosened to improve the characteristics as described in the prior art. There is no need.
[0020]
(2) Soil in which uniaxial compressive strength cannot be measured As an example of soil in which uniaxial compressive strength cannot be measured, for example, unmodified soil having a high water content ratio can be considered. In the case of the invention of this application, first, a fibrous material and a polymer-based improving material are added to the unmodified soil. Next, a solidification process is performed. Specifically, cement-based solidifying material is added. As a result, control of the characteristics not conventionally known in the stress-strain diagram is performed, and aggregated improved soil is obtained.
[0021]
(1) Comparison with soil prepared with a uniaxial compressive strength of 50 kN / m ² Figure 2 shows the uniaxial compressive strength obtained by adding a solidifying material such as cement to the unmodified soil where the uniaxial compressive strength cannot be measured. The relationship between the compressive strain and the compressive stress in the case of the prepared soil (2-1) prepared to 50 kN / m ² is shown.
[0022]
In addition, in FIG. 2, in comparison with this, when 1.0 kg / m ³ of a polymer-based improving material is added to the unmodified soil and stirred, and then a solidifying material is added (2-2) Furthermore, the case (2-3) where a solidifying material is added after adding a fibrous substance and stirring is shown.
[0023]
By adding the fibrous material and the polymer-based improving material, the uniaxial compressive strength is in the case of the prepared soil (2-1), and further in the case of the prepared soil (2-2) to which the polymer-based improving material is added. The deformation coefficient is smaller than that of the prepared soil (2-1), while maintaining the uniaxial compressive strength equivalent to the above, and the fracture strain is added to the prepared soil (2-1) and the polymer-based improving material. It becomes larger than the fracture strain of the prepared soil (2-2). That is, the characteristics of the soil are difficult to break, and the residual strength can be maintained, which is very useful in constructing a sticky and strong earth structure.
[0024]
(2) Comparison with soil prepared with a uniaxial compressive strength of 100 kN / m ² Figure 3 shows the uniaxial compressive strength by adding a solidifying material such as cement to the unmodified soil where the uniaxial compressive strength cannot be measured. The relationship between the compressive strain and the compressive stress in the case of the prepared soil (3-1) prepared to 100 kN / m ² is shown.
[0025]
In addition, in FIG. 3, in comparison with this, when 1.0 kg / m ³ of the polymer-based improving material is added to the unmodified soil and stirred, and then a solidifying material is added (3-2) Furthermore, (3-3) is shown in the case where a solidifying material is added after adding a fibrous substance and stirring.
[0026]
By adding the fibrous material and the polymer-based improving material, the uniaxial compressive strength is in the case of the prepared soil (3-1), and further in the case of the prepared soil (3-2) to which the polymer-based improving material is added. The deformation coefficient is smaller than that of the prepared soil (3-1) while maintaining the uniaxial compressive strength equivalent to that of the prepared soil (3-1) (3-2). growing. That is, the characteristics of the soil are difficult to break, and the residual strength can be maintained, which is very useful in constructing a sticky and strong earth structure.
[0027]
(3) Comparison with soil prepared with uniaxial compressive strength of 200 kN / m ² Figure 4 shows the uniaxial compressive strength by adding a solidifying material such as cement to the unmodified soil where uniaxial compressive strength cannot be measured. The relationship between the compressive strain and the compressive stress in the case of the prepared soil (4-1) prepared at 200 kN / m ² is shown.
[0028]
In addition, in FIG. 4, in comparison with this, when 1.0 kg / m ³ of the polymer-based improving material is added to the unmodified soil and stirred, and then a solidifying material is added (4-2) Furthermore, after adding a fibrous substance and stirring, the case (4-3) when a solidification material is added is shown.
[0029]
By adding the fibrous material and the polymer-based improving material, the uniaxial compressive strength is equivalent to that of the prepared soil (4-1), and further, the prepared soil (4-2) to which the polymer-based improving material is added. While maintaining the uniaxial compressive strength, the deformation coefficient becomes smaller than that of the prepared soil (4-1), and the fracture strain becomes larger than that of the prepared soil (4-1) (4-2). . That is, the characteristics of the soil are difficult to break, and the residual strength can be maintained, which is very useful in constructing a sticky and strong earth structure.
[0030]
In the above, three examples have been presented for soils where uniaxial compressive strength cannot be measured. The soil obtained by controlling the deformation characteristics of such soil is used by embedding it on the existing ground. It is suitable for reinforced earth embankment, and it is also suitable for shallow layer improvement of soft ground. Moreover, compared to the case where only the solidification process such as adding the solidification material is performed, the agglomeration is performed from the beginning, so that it is not necessary to crush and loosen as described in the prior art, and therefore the strength by crushing is increased. There is no decline. Therefore, it is not necessary to increase the cement-based solidified material in anticipation of a decrease in strength.
[0031]
As the polymer-based improving material used in each of the examples described above, polyacrylic acid, polyacrylic acid salt, polyacrylic acid ester, polyacrylamide, and combinations thereof, which are conventionally known as soil improving materials, are used. Various types of copolymers and their copolymers with polyalkylene glycol, maleic anhydride, epoxy compounds, and the like are considered. Among them, water-soluble polymers are preferable. For example, synthetic water-soluble polymer powder (PH 7-8, moisture 10 ± 2%, bulk specific gravity) whose main component is a polyacrylic polymer, which is also used in the examples of FIG. 1, FIG. 2, FIG. 3, and FIG. 0.6-0.7, true specific gravity 1.4-1.5) etc. are illustrated. In the invention of this application, it is desirable to add these polymer-based improving materials at a rate of 1 kg or more with respect to 1 m ³ of the target soil.
[0032]
Further, the fibrous material used in each of the above-described examples may be various natural or synthetic materials. For example, recycled newspaper paper, recycled vinyl for agriculture, polyethylene, polyester, and the like can be used. About these fibrous substances, the shape may be various shapes such as a strip shape, a small piece shape, a thread shape, and a cloth shape. For example, in waste paper, it is 1 cm square or less and a thickness of 0.1 mm or less. Can be added. The amount of addition can be determined experimentally as appropriate according to the type and properties of the target soil so that a synergistic effect with the amount of addition of the polymer-based improving material becomes large. For example, the amount added is preferably 30 kg or more, more preferably 50 kg to 90 kg in the case of waste paper with respect to 1 m ³ of the target soil.
[0033]
In addition, it is desirable to consider the use of a cement solidifying material in selecting the addition amount.
[0034]
Even if a small amount of the polymer-based improving material is added, the strength characteristics are improved, but it is necessary to add a fibrous substance in order to see a significant improvement in actual construction. In addition, those with a small amount of cement can retain the residual strength after breaking, and are characterized by stickiness. It can be seen that when the amount of cement is increased, the fracture strain is reduced and the effect of mixing the fibrous material and the polymer improving material is reduced.
[0035]
In this way, it is difficult to break, and it is possible to maintain the residual strength, and the manifestation of stickiness appears remarkably in the low-strength stabilized soil.
[0036]
In the method for controlling the deformation characteristics of the soil described above, when a mechanical shear stress is applied to the soil by means such as stirring with a spatula after adding a fibrous material and a polymer-based improving material to the soil, As described above, the soil properties are controlled in such a way that the soil properties are hard to break and become strong, and the soil aggregates.
[0037]
In general, when a mechanical shear stress such as stirring is applied to improved soil having a high uniaxial compressive strength, it becomes a crushed stone. Moreover, when it is improved soil with low uniaxial compressive strength, it becomes a paste.
[0038]
Thus, it is difficult to aggregate the improved soil.
[0039]
In order to aggregate, it is a necessary condition that the improved soil has an appropriate compressive strength and a large fracture strain. In the invention of this application, an appropriate compressive strength and a large fracture strain can be obtained by performing operations such as the addition of the fibrous material and the polymer-based improving material as described above. And if the dynamic pressure and rotational motion by a mechanical shear stress are given, the process soil which has a big compressive-strain stress will reduce the porosity. That is, the decrease in the porosity means that the distance between the particles constituting the treated soil is shortened.
[0040]
As a result, stickiness is generated due to an increase in the bonding force between particles, and aggregation is enabled.
[0041]
Explaining the results of the agglomeration test using the soil with the compressive stress adjusted to 100 kN / m ² as the test object, it is not agglomerated in the case of no addition of the polymer-based improving material, and becomes a paste. . On the other hand, the soil to which 1.0 kg / m ^{3 of} the polymer improving material is added aggregates. The particle size can be controlled by applying shear stress by mechanical stirring.
[0042]
For example, when mechanical stirring is performed for about 1 minute using a spatula moving in parallel and the speed of the spatula is changed to 25, 50, 75, 100 cm / sec, no aggregation occurs at the spatula speed of 25 cm / sec. When the speed is 50 cm / sec, the average particle diameter is 2.5 cm, when the speed is 75 cm / sec, the average particle diameter is 2.0 cm, and when the speed is 100 cm / sec, the average particle diameter is 1.0 cm. This is related to fracture strain. When a large mechanical shear stress is applied, it is finely divided, and when a small mechanical shear stress is applied, it becomes large.
[0043]
However, when the shear stress is too small, no aggregation occurs. Thus, handling is improved when aggregated, and immediate transportation is possible after processing.
[0044]
【The invention's effect】
As described in detail above, according to the method for controlling the deformation characteristics of soil according to the invention of this application, by adding a fibrous material and a polymer-based improving material to soil having or without uniaxial compressive strength, The effect that characteristics, such as a deformation coefficient of a processing object soil and a fracture strain, can be freely controlled according to a use is acquired.
[Brief description of the drawings]
FIG. 1 is a diagram illustrating the relationship between compressive stress and compressive strain for soil having uniaxial compressive strength and soil according to an embodiment of the present invention.
FIG. 2 is a diagram exemplifying a relationship between compressive stress and compressive strain with respect to a soil that has been subjected to strength adjustment to a soil that does not have uniaxial compressive strength and a soil according to an embodiment of the present invention.
FIG. 3 is a diagram exemplifying a relationship between compressive stress and compressive strain with respect to a soil that has been subjected to strength adjustment to a soil that does not have uniaxial compressive strength and a soil according to an embodiment of the present invention.
FIG. 4 is a diagram exemplifying a relationship between compressive stress and compressive strain with respect to a soil that has been subjected to strength adjustment to a soil that does not have uniaxial compressive strength and a soil according to an embodiment of the present invention.

Claims (6)

Adding 1kg or more polymeric modifying material against 30~90kg and the target soil 1 m ³ the thickness 0.1mm or less wastepaper in 1cm square or less with respect to the target soil 1 m ³ soil having uniaxial compressive strength Therefore, while maintaining the uniaxial compressive strength equivalent to the original uniaxial compressive strength, the deformation coefficient is controlled to be smaller than the original deformation coefficient and the fracture strain is made larger than the original fracture strain. A method for controlling the deformation characteristics of soil for embankment on existing ground or for improving shallow layers of soft ground . Soil with an axial compression strength, 1 kg or more polymeric modifying material against 30~90kg and the target soil 1 m ³ to the target soil 1 m ³ the thickness 0.1mm or less wastepaper in 1cm square below by adding, while maintaining original uniaxial compressive strength comparable to uniaxial compressive strength, fiber維質material only or than when added alone the polymeric modifying material, to reduce the modulus of deformation, the strain fracture A method for controlling the deformation characteristics of soil for embankment on existing ground or for improving shallow layers of soft ground, characterized in that control is performed so as to increase. Added 1kg or more polymeric modifying material against 30~90kg and the target soil 1 m ³ the thickness 0.1mm or less of waste paper to the target soil 1 m ³ at 1cm square below soil no uniaxial compressive strength After that, by solidifying this, the deformation coefficient has a uniaxial compressive strength while maintaining a uniaxial compressive strength equivalent to that obtained by solidifying a soil that does not have a uniaxial compressive strength. Control so that the deformation coefficient of the soil obtained by solidifying the non-contaminated soil is smaller than that of the soil, and the fracture strain is larger than that of the soil obtained by solidifying the soil that does not have uniaxial compressive strength. A method for controlling the deformation characteristics of soil for embankment on existing ground or for improving shallow layers of soft ground . Added 1kg or more polymeric modifying material against 30~90kg and the target soil 1 m ³ the thickness 0.1mm or less of waste paper to the target soil 1 m ³ at 1cm square below soil no uniaxial compressive strength after, by solidification of this, while maintaining the uniaxial compressive strength comparable to soil obtained by solidification having no soil uniaxial compressive strength, fiber維質material or only the polymer system Control of deformation characteristics of soil for embankment on existing ground or for improvement of shallow layer of soft ground, which is controlled to reduce deformation coefficient and increase fracture strain than when only improved material is added Method. 5. The soil for embankment on existing ground or shallow ground improvement of soft ground according to claim 3, wherein the solidification treatment is performed as at least one kind of treatment of dehydration, drying, and addition of a solidifying material. Method of controlling the deformation characteristics. The method for controlling deformation characteristics of soil according to any one of claims 1 to 5 , wherein the soil is agglomerated by applying mechanical shear stress to the soil to which a fibrous material and a new polymeric material are added. A method for controlling the deformation characteristics of soil for embankment on existing ground or for improving shallow layers of soft ground .

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