JP4748570B2 - Mud improvement method and mud improvement material addition rate evaluation method - Google Patents

Description

  The present invention relates to a mud improvement technique for improving a mud without curing time by adding and mixing a water-absorbing mud improving material that absorbs the excess water into the mud.

  Excavation mud is discharged by excavation work by the mud pressure pressurizing shield method, and dredged mud is discharged by civil engineering construction work. Since these mud and other construction sludge have a high water content and flow easily, pulp sludge (PS) incineration ash, that is, paper sludge ash, is added to the mud as a mud improvement agent to improve soil quality. Technology has been studied.

  Conventionally, cement-based, lime-based and polymer-based improving materials have been used as existing soil-improving materials for improving soft mud. The cement-based improving material is an improvement for increasing the strength of the mud by the hydration / solidification action of the cement, and has the drawbacks of anxiety about elution of heavy metals and high pH. The lime-based improving material is a physical property improvement that lowers the moisture content of the mud due to water absorption and heat generation, but has the disadvantages that attention is required for reforming work due to heat generation during the improvement and the pH is high. In addition, the cement-based and lime-based improvement materials require a curing period to obtain a predetermined improvement effect, and thus have a drawback that the construction must be interrupted for a certain period or a curing yard must be provided. . On the other hand, the polymer-based improving material acts on free water and is improved by moisture adsorption, immobilization, and coating of the soil surface, and can be improved instantaneously, but has the disadvantage of low improvement strength.

  As described above, the existing improvement materials based on the chemical improvement principle have problems as described above. Therefore, as an improvement function, only the physical action of absorbing the moisture in the mud is used regardless of the chemical action. In order to improve the quality, mud improvement technology using a water-absorbing mud improvement material has been researched and developed. However, with this physical water-absorbing function, it is clear that the improved material has a water-absorbing function that affects the improvement effect of the mud, that is, how much of the improved material needs to be added per unit amount of mud to be improved. Therefore, establishment of a mud improvement method that clearly evaluates the water absorption performance is desired.

  Conventionally, as a test method for measuring water absorption of an improved material having the same shape and particle size as the water-absorbing mud improvement material, there is a “fine aggregate density and water absorption rate test method” defined in JISA1109. The test method is as follows.

  [1]. Collect a representative sample and reduce it to a specified volume by the quadrant method or sample collector. The mass is about 2 kg, and this is divided into 2 minutes every 2 kg.

  [2]. The sample is allowed to absorb water for 24 hours. The water temperature is kept at 20 ± 5 ° C. for at least 20 hours of water absorption.

  [3]. Spread the sample of [2] thinly on a flat surface, and stir occasionally to dry evenly while gently sending warm air.

  [4]. When there is still some surface water on the surface of the fine aggregate, loosely stuff the fine aggregate into the flow cone, flatten the upper surface, and then tap gently 25 times with a cue stick without applying force. After tamping, the remaining space must not be refilled. Next, gently raise the flow cone vertically. When the sample is dried little by little, the above method is repeated, and when the flow cone is pulled up, the fine aggregate cone is scrambling for the first time, and the surface is in a dry state.

  [5]. After measuring the mass (m1) of the water absorption test sample to 0.1 g, it is dried to a constant mass at 105 ± 5 ° C., cooled to room temperature in a desiccator, and the mass (m2) is reduced to 0. .Measure up to 1g.

[6]. Here, the water absorption Q (mass percentage) is defined by the following equation.
Q = (m1-m2) / m2 × 100 (%)
m1: Mass (g) of the sample for water absorption test in a surface dry saturated water state
m2: Mass (g) of the sample for water absorption test after drying

  In addition to this regulation, JISA1110 “Coarse Aggregate Density and Water Absorption Test Method” is defined in JIS as a method for measuring the water absorption rate. According to this test method, a coarse aggregate sample is stipulated that after a 24-hour sample absorption, it is rolled on an absorbent cloth and wiped off the visible water film, resulting in a dry surface. The mass of the sample at this time is m1, and the water absorption Q (%) is calculated by the same formula as in the case of fine aggregate.

  Furthermore, as a method for measuring the water absorption rate of materials such as clay roof tiles, there is a method using the “water absorption rate measuring device” described in Patent Document 1, and the water absorption rate of the foamed granular material used for the concrete lightweight aggregate is determined. As a method to obtain, there is “an evaluation method of water absorption characteristics of foamed particles” described in Patent Document 2.

  Patent Document 1 describes a method of obtaining a water absorption rate by measuring a decrease amount of water in a liquid tank when the material is immersed in a liquid tank filled with water. Place two liquid tanks in the same state with water in it and hang a basket in it. Thereafter, the sample is put into one of the cages and immersed, so that the sample absorbs water in the liquid tank and a difference in weight is developed between the two liquid tanks. By measuring this, the amount of water decrease due to water absorption in the liquid tank is obtained over time.

In the evaluation method described in Patent Document 2, after a predetermined amount of foamed particles and water before water absorption is put into a container whose capacity can be adjusted strictly, and the inside of the container is filled to a predetermined level with these, Immediately measure the total weight, and after a predetermined time has elapsed, add water again to measure the total weight in a state where the container is filled to the predetermined level, and the difference between the two is the amount of water absorbed by the foam particles. As a method for evaluating water absorption characteristics.
JP-A-6-186153 JP 2001-83061 A

  The conventional water absorption test method described above is not for examining the water absorption function of the mud improvement material based on the water absorption function, and the test method described in JIS is usually a method for testing the water absorption coefficient of aggregate for concrete. Patent Document 1 describes a test method and apparatus for evaluating water absorption of clay roof tiles, and Patent Document 2 describes a test method for confirming the water absorption performance of concrete lightweight fine aggregate. ing. According to the above-mentioned JISA1109 “Method for testing fine aggregate density and water absorption”, it is difficult to determine when the sample cone is scrambled for the first time. However, there is a problem that a large variation occurs in the water absorption test results. Similarly, in JISA1110 “Coarse Aggregate Density and Water Absorption Test Method”, a sample that has been infiltrated with water for a certain period of time is taken out, and the method of wiping off the water on the surface of the specimen tends to cause a difference. There is a defect that causes an error in the measured water absorption. Furthermore, the mud improvement material based on the water absorption function is not suitable for the method for coarse aggregate because it has almost the fine aggregate level shape and particle size.

  Patent Document 2 is intended to have a shape similar to that of the water absorption improving material in terms of shape, but for a material that instantaneously exhibits a water absorption function, the weight immediately after charging the material cannot be measured. Inappropriate. Patent Document 1 is a test method and apparatus for evaluating water absorption of clay tiles and the like, and as such is not suitable for a fine aggregate-shaped mud improvement material. It seems that the test itself can be carried out by devising a basket etc., but this method also considers all the free water present between each particle of the water absorbent material, and surplus water in the mud It is considered difficult to evaluate the water absorption function as an improved material that absorbs water.

  In the method based on the chemical improvement principle such as cement-based solidified material and lime-based solidified material, the components of the mud such as the organic content in the mud greatly affect the blending. From the information, it is difficult to design an accurate blending amount, and a prior indoor blending test is indispensable. On the other hand, the principle of the water-absorbing mud improvement material is to absorb the excess moisture of the mud, so there is no need to examine the factors that impede chemical improvement, such as cement-based solidification materials. It is necessary to carry out a blending design from the relationship between the excess moisture of the mud and the water absorption performance of the target mud improvement material. However, it is unclear whether the modified soil will have the required strength even if it is simply mixed with mud without considering the material that will have a water absorption function. There is a possibility of adding mud improvement material. Also, since the absorption function of the mud improvement material varies depending on its type, to use it as an actual mud improvement technology, it should be possible to uniquely determine the formulation from the state of the mud and the water absorption function of the improvement material. Is essential.

  An object of the present invention is to provide a mud improvement method for improving mud using a water-absorbing mud improvement material.

  Another object of the present invention is to provide a method for evaluating the rate of addition of a water-absorbing mud improvement material.

The mud improvement method of the present invention is a mud improvement method for improving the mud by adding and mixing a water-absorbing mud improvement material to the mud, and the liquid limit of the mud is determined from the water content ratio of the mud to be improved . A surplus moisture measurement step of subtracting the water content ratio to measure the excess moisture of the mud , and the dried mud improvement material and water are poured into a container having a constant inner diameter to restrain the moisture in the vessel. In order to set the improved soil to a predetermined strength based on the water absorption ratio measuring step of measuring the water absorption ratio of the mud improvement material by the difference between the height and the water level, the water absorption ratio of the mud improvement material and the excess moisture of the mud An addition rate calculation step for calculating the addition rate of the mud improvement material with respect to the necessary mud, and an addition step of adding the amount of the mud improvement material based on the calculated addition rate to the mud and stirring and mixing. Special to have To.

  The mud improvement method of the present invention calculates the improvement rate of the reference mud improvement material relative to the reference mud necessary for setting the improved soil at a predetermined strength in advance, and the water absorption ratio of the mud improvement material and the excess moisture of the mud are calculated as the improvement rate. The addition rate is calculated by integrating the above.

  The mud improvement method of the present invention is characterized in that the mud improvement material is incinerated ash of pulp sludge.

The method for evaluating the rate of addition of the mud improvement material according to the present invention is a method for evaluating the rate of addition of the mud improvement material to obtain the required rate of addition of the mud improvement material when the mud is improved by adding a water-absorbing mud improvement material to the mud. The excess moisture measurement step of measuring the excess moisture of the mud by subtracting the moisture content of the liquid limit of the mud from the moisture content of the mud to be improved; A water absorption ratio measuring step of measuring a water absorption ratio of the mud improvement material by a difference between a height and a water level of the mud improvement material which is injected into a certain container and restrains moisture; and a water absorption ratio of the mud improvement material and based on the excess moisture of the mud, and having an additive ratio calculation step of calculating the addition ratio of the mud modifying material for the mud required to set the modified soil to a predetermined intensity.

  The method for evaluating the rate of addition of the mud improvement material according to the present invention is to calculate in advance the improvement rate of the reference mud improvement material relative to the reference mud necessary for setting the improved soil at a predetermined strength, and the improvement rate and the water absorption ratio of the mud improvement material The addition rate is calculated by integrating the excess moisture of the mud.

  The method for evaluating the rate of addition of the mud improvement material of the present invention is characterized in that the mud improvement material is incinerated ash of pulp sludge.

  According to the present invention, if the surplus moisture of the mud to be improved is measured and the water absorption ratio of the mud improving material added thereto is measured, the improvement is based on the surplus moisture of the mud and the water absorption ratio of the mud improving material. Since the rate of addition of the mud improvement material added to the target mud can be evaluated, the mud can be improved to the improved soil having the desired strength using the mud improvement material, and the variation in strength is reduced. High quality improved soil can be obtained. By using a water-absorbing mud improvement material, mud can be improved instantly without curing time.

  According to the present invention, since the addition amount is calculated based on the excess moisture of the mud and the water absorption of the mud improving material added to the mud, the chemical improvement is not a chemical improvement like a cement-based solidifying material. It is not necessary to examine the factors that inhibit the above.

Excess moisture mud can be readily determined by subtracting the water content ratio w _L of the liquid limit of the mud from the water content w of mud. The water absorption ratio W _ab of the mud improvement material can be easily measured by putting a predetermined amount of water and a dry mud improvement material into a container having a constant cross-sectional area, and by measuring the difference between the water level and the improved soil height.

By obtaining the improvement rate ε of the reference mud improvement material relative to the reference mud so that the strength of the improved soil after the improvement of the mud to be improved becomes a predetermined strength, the improvement rate ε and the water absorption ratio W _ab The addition rate η can be easily obtained from the excess water w-w _L.

  According to the present invention, since a water-absorbing mud improvement material is used, a lime-based improvement material requires a curing period of several days for solidification, but can be improved instantaneously, and no curing period is required. The workability of reforming is excellent. Since it can be improved in the neutral range, it is not toxic and will not cause soil contamination even if left for a long time. Since it is a physical modification, there is no change in strength even when transported again. Even when there is a portion where the mud improvement material does not spread when the mud and the mud improvement material are agitated, the effect of water absorption is achieved. The target mud is not limited to mud generated in civil engineering construction work, but can also be applied to soil containing moisture such as cohesive soil, sandy soil, and corroded soil.

  FIG. 1 is a schematic diagram showing the principle of improving mud by adding a water-absorbing mud improving material to the mud. As shown in FIG. 1 (A1), the mud M is in a state in which soil particles s1, moisture Q, and free air a1 are mixed. The mud M contains a large amount of moisture Q and cannot be compacted as it is. On the other hand, as shown in FIG. 1 (A2), the water-absorbing mud improvement material P is in a state where the improvement material particles s2, the restrained air b trapped in this, and the free air a2 are mixed in the dried state. ing. The improvement material particles s2 of the mud improvement material P in the dry state have a large number of projections microscopically capturing the restricted air b, as shown in FIG. Is captured between the parts.

  As the water-absorbing mud improvement material P, sludge ash such as papermaking sludge ash, that is, incineration ash of pulp sludge (PS), which has a particle size distribution from fine sand containing some silt to medium is used. Is done. FIG. 2 is a characteristic diagram showing the particle size distribution of the mud improvement material P used.

When this water-absorbing mud improvement material P is added to the mud M and mixed, the moisture Q contained in the mud M is captured by the improvement material particles a2 of the mud improvement material P as shown in FIG. The air b is replaced with the moisture Q and becomes the restricted water Q1. As a result, as shown in FIG. 1 (B1), improved soil MP ₀ consisting of the mud M and mud modifying material P is modified soil and particle matters of consisting of soil particles s1 and modifying material particles s2 mud M, free The restraint water Q1 corresponding to the air b, the free water Q2, and the air component a1 + a2 are mixed, and the restraint water Q1 is trapped by the improvement material particles s2. When compacting modified soil MP ₀ shown in FIG. 1 (B1), is released to the outside air partial Δ (a1 + a2) is partially shown in FIG. 1 (B2), compacted soil MP ₁ and mud M improvements The material P is mixed and compacted to include a part of free water.

In this way, the mud mud M is taken into the mud improvement material P as constrained water, and the mud particles with no excess water approach the optimum water content ratio and are mixed with the skeletal component of the improving material to be easily compacted. MP ₀ . However, the blending ratio of the mud improvement material P added to the mud M needs to be set appropriately according to the properties of the mud M and the water absorption performance of the mud improvement material P.

  Therefore, about the mud M to which the mud improvement material P is added, the property of the mud M is evaluated by measuring the excess moisture and using the excess moisture as an index.

(Excess water)
The surplus moisture of the mud M is obtained by a value (w−w _L ) obtained by subtracting the moisture content w _L of the soil liquid limit from the moisture content w of the mud M. The water content ratio w is determined by these ratios (Ws / Ww) when the dry mass of the soil is Ws and the moisture content is Ww, and is expressed as a percentage of the moisture with respect to the dry mass of the mud. When the liquid limit w _L which is the water content ratio when the soil becomes liquid is subtracted from the water content ratio w, the excess water of the improvement target mud soil is obtained from the value (w−w _L ). The water content ratio w of the improvement target mud and the liquid limit w _L of the water content ratio are measured in advance. However, as the excess moisture fine soil adopted w-w _L, coarse soil w _L is not required w _{L =} 0 for (sandy soil), i.e., was it excess moisture w .

(Water absorption ratio)
On the other hand, for the water absorption performance of the mud improvement material P, the water absorption ratio W _ab is obtained, and the water absorption performance is evaluated by the water absorption ratio W _ab .

The water absorption performance was measured from the ratio of moisture trapped in the mud improvement material P and moisture not trapped by adding water to the dry mud improvement material P. In order to easily measure and evaluate water absorption performance, a predetermined amount of water and a predetermined amount of dried mud improvement material P are poured into a container having a constant inner diameter, for example, a graduated cylinder, and left for a predetermined time, The water absorption ratio W _ab was measured from the difference between the height in the graduated cylinder of the mud improvement material P restrained by water and the water surface. As described above, when a container having a constant inner diameter is used, the water absorption ratio W _ab of the mud improvement material can be easily obtained from its height.

FIG. 3 is a schematic view showing a method for measuring the water absorption ratio W _ab . First, a predetermined volume, for example, 300 ml of distilled water is injected into a graduated cylinder 10 having an inner peripheral surface with a cross-sectional area of A and mud soil to be added. Improving the improvement material P. The amount of the mud improvement material P injected is, for example, 100 g, 150 g, and 200 g. Next, sufficient vibration is applied by the vibrator until no visible bubbles are generated for each graduated cylinder 10. The vibration frequency of the vibrator was about 3000 times / minute.

After leaving the graduated cylinder 10 after the vibration to stand for a day, the vibrator is sufficiently vibrated until a visible bubble disappears again. In this way, as shown in FIG. 3, the water level H1 and the height H2 of the mud improvement material P separated from the water are measured. Seeking water content ratio on the basis of the measurement results, defining a water content ratio and water absorption ratio W _ab, water ratio W _ab is represented by the following formula (1).
W _ab = [{300−A (H ₁ −H ₂ )} × ρ _W ] / W _ash × 100 (%) (1)
_{However, W ab:} water ratio (weight percentage) (%) _{H 1:} water (cm) _{H 2:} mud modifying material separate from the water height (cm) A: cross sectional area of the measuring cylinder 10 ^(cm 2) ρ _W : Density of distilled water (g / cm ³ ) W _ash : Dry weight (g) of mud improvement material to be charged

The water absorption ratio W _ab thus obtained indicates the water absorption weight per 1 g of the dried mud improvement material. Table 1 shows the water absorption ratios of various materials measured including the mud improvement material by the measuring method shown in FIG.

(Addition ratio of various improved materials to standard mud)
In order to add the mud improvement material to the mud to be improved and obtain the improved soil having the desired corn index, the degree of addition of the various mud improvement materials to each type of mud is determined. There is a need. First, Fujimori clay, which is the standard for mud, was used as the standard mud, and the relationship between the addition rate of various mud improvers and the corn index was calculated for the standard mud.

  The corn index was determined by a method of corn index test of degree of treatment in accordance with “Consolidated soil cone index test” (JGS T 716) of JGS (Geotechnical Society).

About 15 kinds of mud improvement materials were used in the experiment, and each was added to the reference mud to make improved soil, and a cone penetration test was conducted for each. The setting condition of the reference mud was adjusted at a water content ratio 1.1 times the liquid limit w _L (%) of Fujimori clay. The test results are as shown in FIG.

FIG. 4 is a characteristic diagram showing the relationship between the addition rate η ₀ satisfying a specific corn index and the water absorption ratio W _ab, and the muddy soil improvement material relative to the reference mud where the ordinate is corn index q _c = 200,400,800 kPa. The addition rate η ₀ (M _ash / M _mud ) is shown, and the horizontal axis shows the water absorption ratio W _ab of each mud improvement material. However, _Mash shows the dry weight of the added mud improvement material, _Mmud shows the dry weight of a reference | standard mud.

As shown in FIG. 4, there is a correlation between the water absorption ratio W _ab and the addition rate η ₀ of the mud improvement material, and if the addition rate η ₀ is changed according to the water absorption ratio W _ab , the reference mud It was confirmed that can be used as an improved soil having a desired corn index. If the relationship shown in FIG. 4 is linearly approximated to be a mathematical formula, there is the following relationship between the addition rate η ₀ of various mud improvement materials with respect to the reference mud and the water absorption ratio W _ab .
η ₀ = a × W _ab + b (2)
However,
η ₀ : [M _ash (various mud improvement materials) / M _mud (standard clay)]
a: [M _ash (various mud improvement materials) / M _mud (standard clay)]
b: [M _ash (various mud improvement materials) / M _mud (standard clay)]

(Addition rate of standard mud improvement material to various mud)
Add the specific mud improvement material to the standard mud improvement material A (trade name FT Mud Killer (product obtained by re-baking PS ash), Table-1 Sample A) to the actual mud that is to be improved, that is, various mud. The addition rate η ₁ of the reference mud improvement material A necessary for setting the obtained improved soil to a predetermined cone index was obtained by experiments. In order to obtain a predetermined corn index by adding and mixing the reference mud improving material A to mud of various types and water content, the addition rate η ₁ increases as the excess water contained in the mud increases. The excess water is considered as the amount exceeding the liquid limit w _L indicating the limit of liquid / solid (w−w _L ), and the relationship between the size and the required addition rate η ₁ Obtained by conducting a compaction test and a cone test. Tables 2a and 2b show the improvement results after adding the reference mud improvement material A to the various muds shown by reference numerals 1 to 25 that are actually required to be improved.

FIG. 5 is an experimental result showing the relationship between the surplus moisture of various mud actually improved and the addition rate η ₁ of the reference mud improving material A having a cone index of q _c = 200 kPa. In this case, w−w _L was employed, and w _L = 0, that is, w was employed for the coarse-grained soil. Among fine-grained soils, bentonite and highly organic soils are different, but other general mud soils have a proportional relationship indicated by a single straight line between the addition rate η ₁ and the excess water (w−w _L ). The coarse-grained soil was found to have a linear relationship parallel to it.

The experimental result shown in FIG. 5 is expressed by the following general formula (3). However, c and d have different values for fine-grained soil and coarse-grained soil.
η ₁ = c × (w−w _L ) + d (3)
However,
η ₁ : [M _ash (standard mud improvement material A) / M _mud (various muds)]
c: [M _ash (standard mud improvement material A) / M _mud (various muds)]
d: [M _ash (standard mud improvement material A) / M _mud (various muds)]

(Addition ratio of various improving materials to various mud)
The constants a to _{d in the} above formulas (2) and (3) indicate the case where the cone index q _c is 200 kPa, and are not for any mud improvement material and any kind and water-containing mud, but these constants Is considered to be applicable to all combinations of mud improvement materials and mud for q _c = 200 kPa. Therefore, when an addition rate η of an arbitrary mud improvement material to an arbitrary mud, that is, various muds is obtained, η ₀ = [M _ash (various mud improvement materials) / M _mud (reference clay)], and η ₁ = M _ash Since (standard mud improvement material A) / M _mud (various muds)], it is obtained by the following equation (4).

In the formula (4), the value of M _mud (standard mud) / M _ash (standard mud improvement material A)] is q _c = 200 kPa with respect to the reference clay. It is the reciprocal of the rate η and indicates the improvement rate ε.

Therefore, for example, when obtaining q _c = 200 kPa, since the improvement rate ε of the reference mud and the reference mud improvement material A in Formula (4) is a specific value and known, any excess water (w−w _L The addition rate η of the mud improvement material having an arbitrary water absorption ratio (W _ab ) to the mud is obtained by the above formula (4).

Fig. 6 shows the calculation formula and experimental value of the addition rate η of any mud improver for any mud of formula (4) in all the data in Fig. 3 and Fig. 4 (excluding bentonite and highly organic soil). This is a characteristic diagram plotted against a high correlation between the theoretical formula and the experimental value, which is almost 1: 1. It was confirmed that it is possible to design a combination of both when an arbitrary mud improvement material is added to an arbitrary mud. Similarly, in the case of obtaining, for example, q _c = 400, 800 kPa, if the improvement rate ε of each reference mud improvement material A and reference clay is obtained, each of the arbitrary excess water (w−w _L ) The addition rate η of the mud improvement material having an arbitrary water absorption ratio (W _ab ) with respect to the mud can be obtained in the same manner.

As described above, there is a proportional relationship between the required addition rate η of the mud improvement material and the excess moisture (w−w _L ) of the mud, and there is a relationship between the improvement effect of the mud improvement material and the water absorption ratio (W _ab ). It is confirmed that there is a correlation, and the performance of the mud improvement material can be evaluated by the value of the water absorption ratio (W _ab ). Therefore, if the reference mud and the standard mud improvement material A are set in advance and the improvement rate ε of the standard mud improvement material necessary for obtaining the set strength with respect to the standard mud is obtained, any mud for any mud is obtained. The required addition rate η in the case of adding and mixing the improving material is obtained.

In the water absorption ratio (W _ab ) described above, water (free water) present in the gaps between the particles is counted in addition to the water absorbed in the material particles (restraint water). However, since a sufficiently compacted density state is set, it is determined that the amount of moisture is minimum and unique for each material. Therefore, the ratio of the constrained moisture absorbed inside the material can also be calculated by subtracting the free moisture from the water absorption ratio (W _ab ). Assuming free moisture from the minimum gap ratio e _min of the granular material, the amount absorbed in the particles of the material can be assumed by the following equation.
^{_{W ab * = W ab -13.2 =}} [{300-A (H1-H2)] × ρ w / W ash × 100-13.2 (%)

(Stirring method)
When improving the mud using a water-absorbing mud improving material, the influence of mixing unevenness is less likely to occur when compared with cement-based solidified materials and the like, so it is possible to cope with backhoe stirring. However, when the viscosity of the mud becomes high, it is desirable to use a dedicated stirring device. In addition, it is more advantageous to use a dedicated stirring device for large-scale construction and urban shield construction, but backhoe stirring is advantageous for small-scale construction in rural areas. In any case, the present invention can cope with various mud improvement, but in any method, the improvement rate ε is obtained in advance, and the addition rate η of the mud improvement material is determined based on the water absorption ratio. Calculate and set the amount of addition.

(Consolidation test)
The mud soil was improved using PS ash with high water absorption as a mud improvement material, and confirmation experiment of the compaction characteristics of the improved soil was conducted. In the experiment, a compaction test (Method A) of re-baked PS ash a, PS ash b, and PS ash c was mixed with Fujimori clay at a dry weight ratio of 20% and 40% respectively. did. The experimental results are shown in FIGS.

  FIG. 7 is a compacting characteristic diagram showing the relationship between the moisture content and the dry density when each PS ash is added to Fujimori clay and when it is not added at all. FIG. 8 is a static characteristic diagram for each improved soil. It is a characteristic diagram which shows the relationship between compaction pressure and compaction degree.

Compaction degree maximum dry density [rho _max obtained by compaction characteristic diagram shown in FIG. 7 as a reference _{(D c = ρ d / ρ} dmax) Defines, D _c in a mixture of each of the modified soil clogging sample = 90,95,100 (%) relationship between the compaction degree D _c and compacting pressure P ₀ when compacted manner by a static compaction method compaction degree is obtained of shown in FIG. 8 Yes. As shown in FIG. 8, any case where PS ash with, it can be seen that the predetermined degree of compaction D _c is obtained at a much smaller static pressure than the case of Fujimori clay alone. Therefore, when the actual mud is improved, even if the compaction energy of the mud is large, if the mud improver is added and mixed, considering the static compaction pressure, the pressure can be reduced to an order of magnitude by one order of magnitude. Since it can be compacted, the improved soil after stirring and mixing is taken out of the stirrer and statically compacted by the bucket load of the backhoe. It can be confirmed whether or not. In that case, the relationship between the static compaction pressure necessary to obtain the predetermined density and the predetermined compaction degree is obtained in advance and the bucket load of the heavy machinery is checked. Become.

(Muddy soil improvement procedure)
FIG. 9 is a process diagram showing a procedure in the case of performing improvement with mud by adding an optional mud improvement material to improve this with respect to an arbitrary mud. First, as shown in FIG. The surplus moisture (w−w _L ) of the target mud is measured (surplus moisture measuring step), and the water absorption ratio (W _ab ) of the mud improving material added to the mud is measured (water absorption ratio measuring step). Since the required addition rate η of the mud improvement material is proportional to the excess moisture (w−w _L ) of the mud and the water absorption ratio (W _ab ) of the mud improvement material, the water absorption ratio (W _ab ) and the excess water of the mud improvement material Based on (w−w _L ), as shown in the above equation (4), the addition rate η of the mud improvement material to the mud necessary for setting the improved soil to a predetermined strength is calculated (addition rate calculation step). . Through these steps, the addition rate of the mud improvement material added to the mud is calculated to evaluate the addition rate of the mud improvement material. When the addition rate η is obtained, a predetermined amount of the mud improvement material is added to the mud so that the mud improvement material for the mud becomes the obtained addition rate η (addition process). Thereby, the improved soil having a desired strength is obtained.

It is a schematic diagram which shows the mud improvement principle by adding a water absorbing mud improvement material to mud. It is a characteristic diagram which shows the particle size distribution of a mud improvement material. It is the schematic which shows the measuring method of water absorption ratio. It is a characteristic diagram which shows the relationship between the addition rate which satisfy | fills a specific corn index | exponent, and a water absorption ratio. And excess moisture various mud is a characteristic diagram showing the relationship between the mixing ratio of the reference mud modifying material cone index is q _{c =} 200 kPa. It is a characteristic diagram which compares the experimental value and calculated value of the required addition rate of a mud improvement material. It is a compaction characteristic diagram which shows the relationship between the moisture content and the dry density when each PS ash is added to Fujimori clay and when it is not added at all. It is a characteristic diagram which shows the relationship between the static compaction pressure and the compaction degree about each improved soil. It is process drawing which shows the procedure in the case of adding an arbitrary mud improvement material and improving mud with respect to arbitrary mud.

Explanation of symbols

ε Improvement rate η ₀ Addition rate of various mud improvement materials to ₀ standard mud η ₁ Addition rate of reference mud improvement material to various mud η ₂ Addition rate of various mud improvement materials to various mud ww _L surplus water W _ab water absorption ratio

Claims (6)

A mud improvement method for improving the mud by adding and mixing a water-absorbing mud improvement material to the mud,
A surplus moisture measurement step of subtracting the moisture content of the liquid limit of the mud from the moisture content of the mud to be improved to measure the excess moisture of the mud ,
Water absorption ratio for measuring the water absorption ratio of the mud improvement material according to the difference between the height and the water level of the mud improvement material in which the dried mud improvement material and water are poured into a container having a constant inner diameter to restrain moisture. Measuring process;
Based on the water absorption ratio of the mud improvement material and the excess moisture of the mud, an addition rate calculation step of calculating the addition rate of the mud improvement material to the mud necessary for setting the improved soil to a predetermined strength;
A mud improvement method, comprising: adding an amount of the mud improvement material based on the calculated addition rate to the mud and stirring and mixing. In the mud improvement method of Claim 1, the improvement rate of the reference mud improvement material with respect to the reference mud necessary for setting the improvement soil to a predetermined strength is calculated in advance, and the water absorption ratio of the mud improvement material and the mud A mud improvement method characterized by calculating an addition rate by integrating surplus moisture. The mud improvement method according to claim 1 or 2 , wherein the mud improvement material is incinerated ash of pulp sludge. A method for evaluating an addition rate of a mud improvement material to obtain a necessary addition rate of the mud improvement material when improving the mud by adding a water-absorbing mud improvement material to the mud,
A surplus moisture measurement step of subtracting the moisture content of the liquid limit of the mud from the moisture content of the mud to be improved to measure the excess moisture of the mud ,
Water absorption ratio for measuring the water absorption ratio of the mud improvement material according to the difference between the height and the water level of the mud improvement material in which the dried mud improvement material and water are poured into a container having a constant inner diameter to restrain moisture. Measuring process;
Based on the excess moisture water ratio and the mud of the mud modifying material, having an additive ratio calculation step of calculating the addition ratio of the mud modifying material for the mud required to set the modified soil to a predetermined intensity A method for evaluating the rate of addition of mud improvement material. 5. The method for evaluating the rate of addition of the mud improvement material according to claim 4 , wherein the improvement rate of the reference mud improvement material relative to the reference mud necessary for setting the improvement soil to a predetermined strength is calculated in advance, and the water absorption of the mud improvement material is calculated as the improvement rate. An addition rate evaluation method for a mud improvement material, wherein the addition rate is calculated by integrating the ratio and the excess moisture of the mud. 6. The method for evaluating the rate of addition of a mud improvement material according to claim 4 or 5 , wherein the mud improvement material is incinerated ash of pulp sludge.

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