JP6979814B2 - Strength estimation method for root compaction, compressive strength estimation device, compressive strength determination device - Google Patents

Description

INDUSTRIAL APPLICABILITY According to the present invention, regardless of the amount of excavated sediment contained in the sample, it is possible to more accurately determine whether the compaction portion can estimate the compressive strength or more accurately determine whether the compaction portion satisfies the required compressive strength. It relates to a method for estimating the strength of a solidified portion, a compressive strength estimation device, and a compressive strength determination device.

Conventionally, as a method of constructing a foundation pile, there is a method of excavating a pile hole up to a support layer and installing a ready-made pile or a reinforcing bar cage in the pile hole. In this method, a rooting liquid is injected into the bottom of the pile hole and solidified to form a rooting portion. Since the formation of the solidified part is performed deep in the ground, it is difficult to measure the strength. Therefore, a method for estimating the strength of the solidified portion has been proposed (see, for example, Patent Document 1). In this strength estimation method, the N value and ground properties of the construction site are measured in advance, and a correspondence table of specific gravity-compressive strength is created. Then, a sample is taken from the root compaction portion before solidification, and the specific gravity is measured. From this specific gravity and the correspondence table, the compressive strength after solidification of the root compaction part is obtained.

Japanese Unexamined Patent Publication No. 2010-22799

When the compressive strength is obtained from the specific gravity, it is necessary that the root compaction liquid and the excavated earth and sand are uniformly mixed in the root compaction portion. However, it is difficult to confirm whether or not the excavated earth and sand are uniformly mixed at the bottom of the pile hole. When the excavated soil is not uniformly mixed in the root consolidation portion, the amount of excavated soil contained in the sample varies depending on the place where the sample is collected. Since the specific gravity of the sample changes according to the amount of excavated earth and sand contained in the sample, the compressive strength obtained from the specific gravity also changes depending on the sampling location of the sample. Then, there is a problem that the error of the estimation of the strength becomes large. Further, when it is determined whether or not the compacted portion satisfies the required compressive strength based on the strength estimated by such a method, there is a problem that the accuracy thereof is doubtful.

The present invention has been made in view of the above, and the compressive strength can be estimated more accurately or more accurately regardless of the amount of excavated earth and sand contained in the sample. It is an object of the present invention to provide a method for estimating the strength of a solidified portion, an apparatus for estimating the compressive strength, and an apparatus for determining the compressive strength, which can determine whether or not the required compressive strength is satisfied.

In order to solve the above-mentioned problems and achieve the object, the method for estimating the strength of the solidified portion according to the present invention is formed by injecting a liquid containing cement milk into the bottom of a pile hole excavated from the ground and solidifying it. This is a method for estimating the strength of a cemented portion, which is a method of estimating the strength of a cemented portion. A plurality of types of cement milk containing the above samples were generated and solidified, and a correlation derivation processing step for obtaining a correlation between the mass ratio of the cement and water of the cement milk and the compression strength after solidification and excavation were performed. Cement milk is injected into the bottom of the pile hole, and a mixture of the cement milk after injection and the ground material such as excavated earth and sand is collected as a second sample, and the amount of water contained in the second sample is determined. The measurement processing step, the cement amount measurement processing step for determining the mass of the cement contained in the second sample, and the mass ratio of the cement of the second sample to water from the mass of the water and the mass of the cement. The cement amount measurement processing step includes a compression strength estimation processing step of estimating the compression strength of the root compaction portion from the mass ratio of cement and water of the second sample and the correlation. An acid addition treatment step of adding an acidic aqueous solution necessary and sufficient for melting cement having a mass obtained by subtracting the mass of water from the mass of the second sample into the second sample, and a second step after adding the acidic aqueous solution. The second is based on the neutralization titration process in which neutralization titration is performed using an alkaline aqueous solution on the sample, the amount of the acidic aqueous solution charged into the second sample, and the amount of the alkaline aqueous solution dropped in the neutralization titration. It is characterized by including a cement amount calculation processing step for obtaining the mass of cement contained in a sample.

The compressive strength estimation device according to the present invention is a compressive strength estimation device that estimates the compressive strength after solidification of the solidified portion from a sample of soil cement collected from the solidified portion before solidification, and is contained in the sample. Cement of soil cement containing a water amount measuring means for determining the mass of water, a cement amount measuring means for determining the mass of cement contained in the sample, and a layer component in which the solidified portion is formed, which is determined in advance. Display the compression strength estimation means for estimating the compressive strength of the sample after solidification from the correlation between the mass ratio of and water and the compressive strength, the mass of the water, and the mass of the cement, and the estimation result. It is preferable to provide a display means.

In the compression strength estimation device according to the present invention, the cement amount measuring means measures a dropping mechanism for dropping an acidic aqueous solution and an alkaline aqueous solution on the sample, and the pH of the sample on which the acidic aqueous solution and the alkaline aqueous solution are dropped. The pH measurement mechanism and the acidic aqueous solution in an amount necessary and sufficient to dissolve the cement in the amount obtained by subtracting the mass of the water from the mass of the sample are added to the sample, and the alkaline aqueous solution is added to the sample into which the acidic aqueous solution is added. The amount of the acidic aqueous solution dropped and the amount of the alkaline aqueous solution dropped when the sample to which the alkaline aqueous solution was dropped was neutralized was determined by referring to the pH measured by the dropping and the pH measuring mechanism. It is preferable to provide a cement amount measurement control unit for obtaining the mass of the cement in the sample based on the dropping amount of the alkaline aqueous solution.

In the compression strength estimation device according to the present invention, the water amount measuring means has a coarse material removing mechanism for removing particles having a particle size larger than the average particle size of the cement in the sample by a predetermined amount or more, and a coarse material removing mechanism in the sample. The sample from the heating mechanism for evaporating the water content of the sample, the mass measurement mechanism for measuring the mass of the sample, the mass of the sample before water evaporation and the mass of the sample after water evaporation measured by the mass measurement mechanism. It is preferable to provide a water amount measurement control unit for obtaining the mass of water contained in the water.

The compressive strength determination device according to the present invention determines whether the compressive strength after solidification of the solidified portion satisfies the required compressive strength from the sample of soil cement collected from the solidified portion before solidification. The method includes a water amount measuring means for determining the mass of water contained in the sample, an input means for inputting the required compressive strength, and a layer component in which the previously determined cemented portion is formed. The above is the case where the sample after solidification satisfies the required compressive strength from the correlation between the mass ratio of the cement of the soil cement to water and the compressive strength, the mass of the water, and the required compressive strength. The cement amount calculation means for determining the required cement amount to be contained in the sample, the determination means for determining whether or not the required cement amount of cement is contained in the sample, and the determination result by the determination means are displayed. It is characterized by comprising a display means.

In the compression strength determination device according to the present invention, the determination means includes a dropping mechanism for charging an acidic aqueous solution and an indicator into the sample, an imaging mechanism for imaging a sample into which the acidic aqueous solution and the indicator are charged, and the indicator. And an acidic aqueous solution in an amount necessary and sufficient to dissolve the required amount of cement are put into the sample via the dropping mechanism, and based on the color of the image imaged by the imaging mechanism, the sample is filled with the required amount of cement. It is preferable to include a cement amount determining unit for determining whether or not the required cement amount of cement is contained.

In the compression strength determination device according to the present invention, the water amount measuring means has a coarse material removing mechanism for removing particles having a particle size larger than the average particle size of the cement in the sample by a predetermined amount or more, and a coarse material removing mechanism in the sample. The sample from the heating mechanism for evaporating the water content of the sample, the mass measurement mechanism for measuring the mass of the sample, the mass of the sample before water evaporation and the mass of the sample after water evaporation measured by the mass measurement mechanism. It is preferable to provide a water amount measurement control unit for obtaining the mass of water contained in the sample.

According to the above configuration, the compressive strength of the root compaction is estimated from the relationship between the cement water ratio and the compressive strength. The strength can be estimated, and the compressive strength of the cemented portion can be estimated more accurately.

According to the above configuration, the amount of cement to be contained in the sample satisfying the required compressive strength is obtained from the relationship between the cement water ratio and the compressive strength, and whether the amount of cement contained in the sample satisfies the obtained cement amount. The strength of the cemented portion is determined by determining whether or not it is. Therefore, regardless of the amount of excavated earth and sand contained in the second sample, the strength of the root compaction portion can be determined, and the strength of the root compaction portion can be determined more accurately.

FIG. 1 is a vertical sectional view showing a construction procedure according to an embodiment of the present invention. FIG. 2 is a diagram showing the relationship between the compressive strength and the cement water ratio of various ground materials according to the embodiment of the present invention. FIG. 3 is a schematic diagram showing an outline of the compressive strength estimation device according to the embodiment of the present invention. FIG. 4 is a flowchart showing the contents of processing performed by the control measurement mechanism of the compressive strength estimation device shown in FIG. FIG. 5 is a flowchart showing the contents of the cement amount measuring process shown in FIG. FIG. 6 is a schematic diagram showing an outline of a compressive strength determination device according to a modified example of the embodiment of the present invention.

<Outline of strength estimation method for root compaction>
Hereinafter, a preferred embodiment of the method for estimating the strength of the root compaction portion according to the present invention will be described in detail with reference to the accompanying drawings with reference to FIGS. 1 and 2. This method for estimating the strength of the solidified part estimates the compressive strength of the solidified part formed by injecting a liquid containing cement milk into the bottom of the excavated pile hole during the construction of the foundation pile. be.

In the present embodiment, as shown in FIG. 1F, a foundation pile 31 is arranged in the pile hole 1 after the consolidation portion 32 is constructed at the bottom of the pile hole 1 excavated from the ground surface to the support layer 12 in the ground 11. In this case, a method of estimating the strength of the consolidation portion 32 before arranging the foundation pile 31 will be exemplified. As shown in FIG. 1A, the excavator used when excavating the pile hole 1 is provided with an excavation head 3 at the tip of the excavation rod 2. When the excavation head 3 is rotated in the forward direction, the excavation teeth are closed. On the other hand, when it is rotated in the opposite direction, the excavated teeth expand and expanded digging is possible.

First step: In this method of estimating the strength of the root compaction portion 32, the constituents thereof are first collected as a sample (first sample) from the support layer 12 on which the root compaction portion 32 is formed. When collecting a sample, for example, it may be carried out by boring.

Second step: Cement containing the first sample is produced by producing multiple types of cement milk containing the sample collected in the first step, and measuring the cement water ratio and the compressive strength of the solidified product. Obtain the correlation between the cement water ratio of milk and the compressive strength. Correlation is represented by graphs and relational expressions. More specifically, cement milk as a test body containing the first sample is produced, for example, 12 patterns (at least 2 patterns) by changing the amount of aggregate, the amount of cement, and the amount of water. Then, the cement water ratio thereof is calculated, and they are solidified, and the compressive strength at the age of 28 days is measured. From the result, as shown in FIG. 2, the relational expression (regression expression) between the cement water ratio and the compressive strength is calculated. The regression equation is a straight line. The square of R represents the coefficient of determination. FIG. 2 shows the case where the first sample is gravel sand (FIG. 2A), sand-mixed clay (FIG. 2B), sandy clay (FIG. 2C), and sand-mixed gravel (FIG. 2D). In this case, an example of the relationship between the cement water ratio and the compression strength of the cement milk containing the first sample is shown. As shown in FIG. 2, the relational expression between the cement water ratio and the compressive strength differs depending on the material of the first sample. The first step and the second step are combined to form a correlation derivation processing step.

Third step: As shown in FIG. 1A, the pile hole 1 is excavated by the excavation rod 2 while injecting water (excavation liquid) at the construction site of the foundation pile 31. When excavating the pile hole 1, as shown in FIG. 1B, it is preferable to excavate while leveling the side wall of the pile hole 1 with the kneading drum 4. The excavated pile hole 1 will be filled with muddy water 13 in which the injected water and the excavated earth and sand (ground material) are mixed. After excavating until the support layer 12 is reached, the excavation rod 2 is reversed and the excavation head 3 which is the tip of the excavation rod 2 is expanded. In that state, as shown in FIG. 1B, the support layer 12 is expanded and excavated with a diameter larger than that of the other portion of the pile hole 1 by the excavation rod 2 to form the enlarged portion 1A. Then, as shown in FIG. 1C, cement milk (root hardening liquid) is injected into the enlarged portion 1A, and the muddy water 13 and the excavated earth and sand are stirred and mixed. The cement milk becomes soil cement 21. After filling with cement milk, the excavation rod 2 is pulled up from the pile hole 1, and in the state of FIG. 1D, a sample (second sample) is taken from the soil cement 21 (cement milk containing excavated earth and sand) before the soil cement 21 solidifies. ) Is collected. As a method for collecting a sample, for example, a sampling device is attached to the tip of the excavation rod 2 to collect a sample. The amount of sample collected may be about 100 g. Before collecting the second sample, the cement milk, the muddy water 13, and the excavated earth and sand were stirred and mixed by the excavation rod 2 of the excavator, but they do not have to be agitated.

Fourth step: A test piece is prepared from the second sample collected in the third step, and the water content of the test piece is determined. As a method for measuring the water content of the test piece, for example, a method of using an infrared moisture meter or a microwave oven to dissipate the water, a method of heating with a frying pan to dissipate the water, a method of using an organic solvent, or the like. Can be used. Further, a water amount measuring mechanism described later may be used. Further, it is preferable to measure the water content in a state where the temperature is 200 ° C. or lower. This is because clay may be denatured by heat and become a component that dissolves in acid. The third step and the fourth step are combined to form a water amount measurement processing step.

Fifth step: Obtaining the mass of cement contained in the test piece (cement amount measurement processing step). For that purpose, first, an acidic aqueous solution necessary and sufficient for dissolving cement having a mass obtained by subtracting the mass of water from the mass of the test piece is added to the test piece (acid charging treatment step). After adding an acidic aqueous solution to the test piece, neutralization titration using an alkaline aqueous solution is performed (neutralization titration treatment). The mass of cement contained in the test piece is obtained from the amount of acid charged into the test piece and the amount of alkaline aqueous solution dropped in the neutralization titration (cement amount calculation processing step).

Sixth step: The cement water ratio of the test piece is calculated from the mass of water contained in the test piece obtained in the fourth step and the mass of cement contained in the test piece obtained in the fifth step. The compressive strength of the solidified portion 32 is estimated from the cement water ratio of the test piece and the above-mentioned correlation (compressive strength estimation processing step).

Seventh step: If it is estimated that the compressive strength is insufficient compared to the construction target, repairs such as further filling with cement milk are performed. When it is presumed that the compressive strength is sufficient, as shown in FIG. 1E, the pile circumference fixing liquid 22 is injected into the portion 1B above the enlarged portion 1A in the pile hole 1 to the vicinity of the ground surface. At that time, the muddy water 13 overflowing to the ground may be solidified by adding, for example, a cement-based solidifying material, and may be disposed of as industrial waste having a viscosity sufficient to be transported by a truck. After that, as shown in FIG. 1F, the foundation pile 31 is sunk until it reaches the enlarged portion 1A.

As described above, a sample is collected in advance from the portion of the foundation pile 31 that becomes the support layer 12, and the relational expression between the cement water ratio of the cement milk containing the sample and the compressive strength of the solidified product is obtained. Then, a sample is taken from the cement milk (soil cement) before solidification injected into the enlarged portion 1A when the root hardening portion 32 is constructed, the cement water ratio of the sample is obtained, and the compressive strength is obtained from the above-mentioned relational expression. I'm trying to ask. The cement-water ratio is an amount determined only by the amount of cement and the amount of water. Therefore, the compressive strength can be estimated regardless of the amount of excavated soil contained in the sample.

<Compressive strength estimation device>
Subsequently, the compressive strength estimation device 40 of the root compaction portion 32 will be described with reference to FIG. The compressive strength estimation device 40 includes a control measuring mechanism 50, a water amount measuring mechanism 60, a cement amount measuring mechanism 70, a tank portion 80, and a sample moving mechanism 90.

The control measurement mechanism 50 includes a control unit 51, a water amount measurement control unit 52, a cement amount measurement control unit 53, a compressive strength estimation unit (compressive strength estimation means) 54, a storage unit 55, and an operation input unit (input means). ) 56 and a display unit (display means) 57. The control measurement mechanism 50 may be configured by, for example, a personal computer.

The control unit 51 is a unit that controls the entire device. The water amount measurement control unit 52 is a part that controls the water amount measurement mechanism 60 and calculates the mass of water contained in the sample SP1. The cement amount measurement control unit 53 is a part that controls the cement amount measurement mechanism 70 and calculates the amount of cement contained in the samples SP1 and SP2. The compressive strength estimation unit 54 is a portion that estimates the compressive strength of the sample SP1 after solidification, that is, the compressive strength of the root compaction portion 32 after solidification, for example, the compressive strength of 28 days of age. The storage unit 55 is a portion in which the correlation information D, which is information on the correlation between the cement water ratio of the cement milk containing the first sample obtained in the second step and the compressive strength, is stored. The operation input unit 56 is a unit for inputting to the control unit 51. The display unit 57 is a unit that displays the strength estimation result and the like of the root consolidation unit 32.

The water amount measuring mechanism 60 is a mechanism for measuring the mass of water contained in the sample SP1, and includes a mass measuring mechanism 61, a heating mechanism 62, a heating container 63, and a coarse material removing mechanism 64. The mass measuring mechanism 61 sequentially measures the mass of the sample SP1 placed in the heating container 63. The measurement result is sent to the water amount measurement control unit 52 via the control unit 51 one by one. The heating mechanism 62 heats the sample SP1 via the heating container 63 and evaporates the water content in the sample SP1. The heating container 63 is a container capable of heating the sample SP1 contained therein from the outside. The water amount measuring mechanism 60 and the water amount measuring control unit 52 constitute a water amount measuring means. The coarse material removing mechanism 64 removes coarse materials, for example, excavated earth and sand having a particle size of more than 1 mm contained in the sample SP0. Here, the coarse material has a particle size larger than the average particle size of the cement particles by a predetermined diameter or more. The predetermined diameter is, for example, twice the standard deviation of the grain size distribution of cement. The sample SP1 from which the coarse material has been removed by the coarse material removing mechanism 64 becomes an aggregate of particles substantially equal to or smaller than the cement particles. The coarse material removing mechanism 64 is, for example, a mechanism using a sieve.

The cement amount measuring mechanism 70 is a mechanism for measuring the mass of cement contained in the samples SP1 and SP2, and includes a titration container 71, a dropping mechanism 72, a stirring mechanism 73, a stirrer 74, a pH measuring mechanism 75, and the like. It is equipped with. The titration container 71 is a container for performing neutralization titration. The dropping mechanism 72 has a function of dropping a desired amount of an acidic aqueous solution and a function of dropping a desired amount of an alkaline aqueous solution per unit time. The dropping mechanism 72 has a flow rate measuring function for measuring the flow rate of the dropping liquid. The stirring mechanism 73 rotates the stirrer 74 to mix the substances in the titration container 71. The stir bar 74 is placed in the titration container 71. The pH measuring mechanism 75 is a sensor for measuring pH, and transmits the measured pH to the control unit 51. The cement amount measuring mechanism 70 and the cement amount measuring control unit 53 constitute a cement amount measuring means.

The tank portion 80 includes an acid liquid tank 81 and an alkaline liquid tank 82. The acid liquid tank 81 is a container containing an acidic aqueous solution, and supplies the acidic aqueous solution to the dropping mechanism 72. The alkaline liquid tank 82 is a container containing an alkaline aqueous solution, and supplies the alkaline aqueous solution to the dropping mechanism 72.

In order to estimate the compressive strength of the root compaction portion 32 by the compressive strength estimation device 40 configured in this way, first, the sample SP0 collected in the third step is charged into the water amount measuring mechanism 60. Then, the coarse material removing mechanism 64 removes the coarse material contained in the sample SP0, for example, the excavated earth and sand having a particle size larger than 1 mm. The sample SP1 from which the coarse material has been removed is charged into the heating container 63. Then, the mass of the sample SP1 is measured by the mass measuring mechanism 61. The measurement result is sent to the water amount measurement control unit 52 via the control unit 51. When the mass of the sample SP1 is sent, the water amount measurement control unit 52 causes the heating mechanism 62 to start heating. The water amount measurement control unit 52 stops heating by the heating mechanism 62 when the sample SP1 is dried and its mass becomes constant. The water amount measurement control unit 52 obtains the mass of water contained in the sample SP1 from the mass of the sample SP1 before the water evaporation and the mass of the sample SP1 after the water evaporation. The water amount measurement control unit 52 sends the obtained mass of water to the compressive strength estimation unit 54. The water amount measurement control unit 52 sends the mass of the sample SP2 after drying to the cement amount measurement control unit 53. When the heating by the heating mechanism 62 is stopped, the control unit 51 causes the sample moving mechanism 90 to move the sample SP2 after drying. The sample moving mechanism 90 moves the sample SP2 into the titration container 71. When the sample moving mechanism 90 moves the sample SP2, the sample moving mechanism 90 notifies the cement amount measurement control unit 53 via the control unit 51 to that effect.

The cement amount measurement control unit 53 calculates the required amount of an acidic aqueous solution (for example, hydrochloric acid) necessary and sufficient to dissolve the cement corresponding to the mass of the sample SP2 after drying. When the cement amount measurement control unit 53 is notified that the movement of the sample SP2 is completed, the cement amount measurement control unit 53 charges the required amount of the acidic aqueous solution into the sample SP2 via the dropping mechanism 72. The cement amount measurement control unit 53 puts the acidic aqueous solution into the sample SP2, and then agitates and mixes the sample SP2 and the acidic aqueous solution via the stirring mechanism 73. When the pH is 7 or less, the cement amount measurement control unit 53 drops an alkaline aqueous solution (for example, sodium hydroxide aqueous solution) from the alkaline liquid tank 82 via the dropping mechanism 72 to perform neutralization titration. Neutralization titration is performed with reference to the measurement results of the pH measuring mechanism 75 at any time. When the pH reaches 7, the cement amount measurement control unit 53 stops dropping the alkaline aqueous solution. The cement amount measurement control unit 53 calculates the mass of cement contained in the sample SP2 from the amount of the alkaline aqueous solution dropped until the pH reaches 7 and the amount of the acidic aqueous solution charged into the sample SP2. The calculated mass of cement is sent to the compressive strength estimation unit 54.

The compressive strength estimation unit 54 calculates the cement-water ratio from the obtained mass of water and the mass of cement. The compressive strength estimation unit 54 is information on the correlation between the calculated cement water ratio and the cement water ratio of the cement milk containing the first sample obtained in the second step stored in the storage unit 55 and the compressive strength. From a certain correlation information D, the compressive strength of the cemented portion 32 after solidification is estimated.

<Compressive strength estimation process by the compressive strength estimation device 40>
Next, the compressive strength estimation processing procedure by the compressive strength estimation device 40 will be described. FIG. 4 is a flowchart showing a compressive strength estimation processing procedure by the control measurement mechanism 50 of the compressive strength estimation device 40. As shown in FIG. 4, first, a correlation input process is performed in which the correlation information D, which is the information on the correlation between the cement water ratio of the cement milk containing the first sample and the compressive strength, is stored in the storage unit 55 ( Step S101).

After that, the water amount measurement control unit 52 performs a water amount measurement process for measuring the mass of water contained in the sample SP1 by using the water amount measurement mechanism 60 (step S102). The water amount measurement result is stored in the storage unit 55. After that, the cement amount measurement control unit 53 performs a cement amount measurement process for measuring the mass of the cement contained in the sample SP2 by using the cement amount measurement mechanism 70 (step S103). The cement amount measurement result is stored in the storage unit 55.

After that, the compressive strength estimation unit 54 calculates the cement water ratio from the mass of water and the mass of cement stored in the storage unit 55, and the calculated cement water ratio and the correlation stored in the storage unit 55. From the information D, a compressive strength estimation process for estimating the compressive strength of the cemented portion 32 after solidification is performed (step S104). After that, the control unit 51 performs a display process of the estimation result for displaying the compressive strength which is the estimation result on the display unit 57 (step S105), and ends this process.

FIG. 5 is a flowchart showing a detailed processing procedure of the cement amount measuring process according to step S103. As shown in FIG. 5, the cement amount measurement control unit 53 first calculates the required amount of an acidic aqueous solution necessary and sufficient to dissolve the cement corresponding to the mass of the sample SP2 after drying, and sets the dropping mechanism 72. An acid charging process is performed in which a required amount of an acidic aqueous solution is charged into the sample SP2 via the sample SP2 (step S201).

After that, the cement amount measurement control unit 53 stirs and mixes the sample SP2 and the acidic aqueous solution via the stirring mechanism 73, and when the pH is 7 or less, the neutralization titration treatment of dropping the alkaline aqueous solution via the dropping mechanism 72. (Step S202).

After that, when the pH becomes 7 during the dropping of the alkaline aqueous solution, the cement amount measurement control unit 53 stops the dropping of the alkaline aqueous solution, and the amount of the alkaline aqueous solution dropped until the pH reaches 7 and the sample SP2. A cement amount calculation process for calculating the mass of the cement contained in the sample SP2 is performed from the amount of the charged acidic aqueous solution (step S203), the mass of the cement is stored in the storage unit 55, and then the process returns to step S103.

As described above, the compressive strength estimation device 40 collects a sample from a portion of the foundation pile 31 that becomes the support layer 12 in advance, and the cement water ratio of the cement milk containing the sample and the compressive strength of the solidified product. The correlation information D with the above is obtained, and the correlation information D is stored in the storage unit 55. Then, a sample is taken from the cement milk (soil cement) before solidification injected into the enlarged portion 1A when the root hardening portion 32 is constructed, and the sample is charged into the compressive strength estimation device 40, whereby the compressive strength estimation device 40 is used. , The cement water ratio of the sample is obtained, and the compressive strength is obtained from the above-mentioned correlation. The cement-water ratio is an amount determined only by the amount of cement and the amount of water. Therefore, the compressive strength can be estimated regardless of the amount of excavated soil contained in the sample.

<Compressive strength judgment device>
Next, the compressive strength determination device 140 of the consolidation portion 32, which is a modification of the compressive strength estimation device 40, will be described with reference to FIG. The compressive strength determination device 140 is a replacement of a part of the configuration of the compressive strength estimation device 40. The compressive strength determination device 140 includes a control measurement mechanism 150, a water amount measurement mechanism 60, a cement amount determination mechanism 170, a tank portion 180, and a sample movement mechanism 90. The control measurement mechanism 150 eliminates the compressive strength estimation unit 54 of the control measurement mechanism 50, and uses the cement amount measurement control unit 53 as a cement amount determination unit (cement amount calculation means) 153. The cement amount determination mechanism 170 is provided with an image pickup mechanism 100 in place of the pH measurement mechanism 75 of the cement amount measurement mechanism 70. The tank portion 180 is provided with an indicator tank 83 in place of the alkaline liquid tank 82 of the tank portion 80. The cement amount determination unit 153 and the cement amount determination mechanism 170 constitute a determination means.

The cement amount determination unit 153 is a portion for determining whether or not a required amount of cement is contained in the sample SP1. The image pickup mechanism 100 images the sample SP2. The indicator tank 83 is a container containing the indicator, and supplies the indicator to the dropping mechanism 72.

In order to determine the compressive strength of the consolidation portion 32 by the compressive strength determination device 140 configured in this way, first, the required compressive strength is input via the operation input unit 56. The required compressive strength is the compressive strength required when the foundation pile 31 is arranged on the root compaction portion 32 and the foundation compaction portion 32 is solidified, and it is preferable that the safety factor is taken into consideration from the design standard strength.

Then, the sample SP0 collected in the third step is charged into the water amount measuring mechanism 60. Since the measurement of the mass of water is the same as that of the compressive strength estimation device 40, the description thereof will be omitted. The water amount measurement control unit 52 sends the obtained mass of water to the cement amount determination unit 153. When the heating by the heating mechanism 62 is stopped, the control unit 51 causes the sample moving mechanism 90 to move the sample SP2 after drying. The sample moving mechanism 90 moves the sample SP2 into the titration container 71. When the sample moving mechanism 90 moves the sample SP2, the sample moving mechanism 90 notifies the cement amount determination unit 153 via the control unit 51 to that effect.

The cement amount determination unit 153 determines the measured mass of water, the input required compressive strength, and the cement water ratio of the cement milk containing the first sample obtained in the second step stored in the storage unit 55. From the correlation information D, which is information on the correlation between the compressive strength and the compressive strength, the amount of cement (referred to as the required cement amount) to be contained in the sample SP1 when the required compressive strength is satisfied is obtained. When determining the required cement amount, for example, the required compressive strength is substituted into the relational expression calculated in the second step to obtain the cement water ratio. Since the cement water ratio = cement mass / water mass, the cement mass can be obtained from the obtained cement water ratio and the water content obtained in the fourth step. This is the required amount of cement. The cement amount determination unit 153 calculates a required amount, which is the mass of an acidic aqueous solution (for example, hydrochloric acid) necessary and sufficient to dissolve the required cement amount of cement.

When the cement amount determination unit 153 is notified that the movement of the sample SP2 is completed, the cement amount determination unit 153 charges the sample SP2 with the required amount of the acidic aqueous solution and the indicator via the dropping mechanism 72. The indicator is preferably a colored indicator with a pH of 7 or higher. The cement amount determination unit 153 puts the acidic aqueous solution into the sample SP2, and then agitates and mixes the indicator, the sample SP2, and the acidic aqueous solution via the stirring mechanism 73. The state of the sample SP2 within 10 minutes to 1 hour (preferably 30 minutes after the start of stirring) is imaged by the image pickup mechanism 100. The captured image is sent to the cement amount determination unit 153 and the display unit 57. The captured image is displayed on the display unit 57. The displayed image is the determination result. The cement amount determination unit 153 may analyze the color temperature of the sent image, store the result in the storage unit 55, and determine from the result whether or not the sample SP1 contains the required amount of cement. ..

As described above, a sample is taken in advance from a place to be the support layer 12 of the foundation pile 31, and the correlation between the cement water ratio of the cement milk containing the sample and the compressive strength of the solidified product is obtained. Then, a sample is taken from the cement milk (soil cement) before solidification injected into the enlarged portion 1A when the root compaction portion 32 is constructed, and the cement having the root compaction portion 32 satisfying the required compressive strength in the sample. It is determined whether or not the required amount of cement, which is the amount, is included. The required cement amount is obtained from the above-mentioned correlation. In this way, it is determined whether the root compaction portion 32 satisfies the required compressive strength. Therefore, the strength of the solidified portion 32 can be determined regardless of the amount of excavated soil contained in the sample. Since the number of days required for determining the compressive strength can be set within one day after the cement milk is placed in the enlarged portion 1A, the rooting portion 32 can be repaired at an early stage. According to the above-mentioned compressive strength estimation device 40 and compressive strength determination device 140, it is possible to quickly estimate the strength or determine the strength in the field.

In the above-described embodiment, the bottom of the pile hole 1 is expanded and dug to form the enlarged portion 1A, but the enlarged portion 1A is not formed and cement is formed on the bottom of the pile hole 1 having the same diameter as the other portions. Milk may be injected to form the cemented portion 32. Although the cement-water ratio is used in the above-described embodiment, the water-cement ratio may be used. It may be a mass ratio of the amount of cement to the amount of water. In the compression strength estimation method and the compression strength estimation device 40 of the root compaction portion 32 of the above-described embodiment, an acidic aqueous solution and an alkaline aqueous solution are used when determining the amount of cement, but a mixture of a sample and water is used. The amount of the acidic aqueous solution to be neutralized may be determined by dropping the acidic aqueous solution little by little, and then the amount of cement may be determined. The water amount measuring mechanism 60 is exemplified by a mechanism having a heating mechanism 62, but is not limited to this, and may be, for example, a mechanism for measuring electric conductivity and calculating the amount of water from the electric conductivity. .. The water amount measuring mechanism 60 and the cement amount measuring mechanism 70, or the water amount measuring mechanism 60 and the cement amount determining mechanism 170 may be integrated. In that case, the sample moving mechanism 90 becomes unnecessary.

32 Firming part 40 Compressive strength estimation device 52 Water amount measurement control unit 53 Cement amount measurement control unit 54 Compressive strength estimation unit 57 Display unit 60 Water amount measurement mechanism 70 Cement amount measurement mechanism

Claims (6)

It is a method for estimating the strength of the solidified part, which estimates the strength of the solidified part formed by injecting a liquid containing cement milk into the bottom of a pile hole excavated in the ground and solidifying it.
The constituents of the layer are collected as a first sample from the layer on which the solidified portion of the ground is formed, and the amount of aggregate, the amount of cement, and the amount of water, which are the first sample, are determined. A correlation derivation process for producing and solidifying a plurality of different types of cement milk, and obtaining a correlation between the mass ratio of the cement and water of the cement milk and the compressive strength after solidification.
Cement milk is injected into the bottom of the excavated pile hole, a mixture of the cement milk after injection and the ground material such as excavated earth and sand is collected as a second sample, and a test piece is prepared from the second sample. A water amount measurement processing step for determining the mass of water contained in the test piece, and
A cement amount measurement processing step for determining the mass of cement contained in the test piece after the water amount measurement processing step, and a cement amount measurement processing step.
The mass ratio of the cement and the water in the specimen determined from said correlation between the mass ratio of the cement and the water in the specimen from the mass of the cement and the mass of the water, the compressive strength of the root hardened portion Compressive strength estimation processing step to estimate
Including
The cement amount measurement processing step is
And the acid-on processing step of introducing a necessary and sufficient aqueous acid to dissolve the mass of cement minus the mass of the water from the mass of the specimen in the specimen,
A neutralization titration treatment step of performing neutralization titration using an alkaline aqueous solution on the test piece after adding an acidic aqueous solution, and
A cement amount calculation processing step for obtaining the mass of cement contained in the test piece from the amount of the acidic aqueous solution charged into the test piece and the amount of the alkaline aqueous solution dropped in the neutralization titration.
A method for estimating the strength of a solidified portion, which comprises. It is a compressive strength estimation device that estimates the compressive strength after solidification of the root compaction part from the sample of soil cement collected from the root compaction part before solidification.
The constituents of the layer are collected from the layer on which the solidified portion is formed, and a plurality of types of cement milk in which the amount of aggregate, the amount of cement, and the amount of water, which are the constituents, are changed are generated. And solidified, the correlation between the mass ratio of the cement of the cement milk and water and the compressive strength after solidification is obtained in advance, and a storage unit that stores the correlation.
A water amount measuring means for determining the mass of water contained in the sample, and
A cement amount measuring means for determining the mass of cement contained in the sample after the mass of the water has been determined by the water amount measuring means, and a cement amount measuring means.
A compressive strength estimation means for estimating the compressive strength of the sample after solidification from the correlation, the mass of the water, and the mass of the cement.
A display means for displaying the estimation result and
A compressive strength estimation device characterized by comprising. The cement amount measuring means is
A dropping mechanism for dropping an acidic aqueous solution and an alkaline aqueous solution onto the sample,
A pH measuring mechanism for measuring the pH of the acidic aqueous solution and the sample dropped with the alkaline aqueous solution, and
An acidic aqueous solution necessary and sufficient for dissolving the cement in an amount obtained by subtracting the mass of the water from the mass of the sample is added to the sample, and the alkaline aqueous solution is dropped onto the sample into which the acidic aqueous solution is added, and the pH is measured. With reference to the pH according to the mechanism, the amount of the alkaline aqueous solution dropped when the acidic aqueous solution and the sample to which the alkaline aqueous solution was dropped is neutralized is determined, and the amount of the acidic aqueous solution charged into the sample and the drop of the alkaline aqueous solution are obtained. A cement amount measurement control unit that obtains the mass of the cement in the sample based on the amount and
2. The compressive strength estimation device according to claim 2. The water amount measuring means is
A coarse material removal mechanism that removes particles having a particle size larger than the average particle size of cement in the sample by a predetermined amount or more.
A heating mechanism that evaporates the water in the sample,
A mass measuring mechanism for measuring the mass of the sample and
A water amount measurement control unit that obtains the mass of water contained in the sample from the mass of the sample before water evaporation and the mass of the sample after water evaporation measured by the mass measuring mechanism.
The compressive strength estimation device according to claim 2 or 3, wherein the device is provided with. It is a compressive strength determination device for the root compaction that determines whether the compressive strength after solidification of the root compaction satisfies the required compressive strength from the sample of soil cement collected from the root compaction before solidification.
A water amount measuring means for determining the mass of water contained in the sample, and
An input means for inputting the required compressive strength and
From the correlation between the mass ratio of the cement and water of the soil cement containing the composition of the layer in which the solidified portion is formed and the compressive strength obtained in advance, the mass of the water, and the required compressive strength. A cement amount calculating means for obtaining the required cement amount to be contained in the sample when the solidified sample satisfies the required compressive strength.
A determination means for determining whether or not the required amount of cement is contained in the sample, and
A display means for displaying the determination result by the determination means, and a display means.
Equipped with
The determination means is
A dropping mechanism for adding an acidic aqueous solution and an indicator to the sample,
An imaging mechanism for imaging a sample containing the acidic aqueous solution and the indicator,
The indicator and an acidic aqueous solution in an amount necessary and sufficient to dissolve the required cement amount are charged into the sample via the dropping mechanism, and the sample is based on the color of the image imaged by the imaging mechanism. A cement amount determination unit for determining whether or not the required amount of cement is contained therein, and a cement amount determination unit.
A compressive strength determination device comprising. The water amount measuring means is
A coarse material removal mechanism that removes particles having a particle size larger than the average particle size of cement in the sample by a predetermined amount or more.
A heating mechanism that evaporates the water in the sample,
A mass measuring mechanism for measuring the mass of the sample and
A water amount measurement control unit that obtains the mass of water contained in the sample from the mass of the sample before water evaporation and the mass of the sample after water evaporation measured by the mass measuring mechanism.
5. The compressive strength determination device according to claim 5.

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