JP6804739B2 - Estimating method of strength characteristics of soil cement, estimation device, quality control method of rooted part during pile construction, quality control device - Google Patents

Description

The present invention relates to a method for estimating the strength characteristics of soil cement, an estimation device, a quality control method for a solidified portion at the time of pile construction, and a quality control device.

Conventionally, soil cement, which is a mixture of cement-based material and in-situ soil, has been widely used in ground improvement work and pile work. For example, one of the pile construction methods is an embedded pile construction method in which an enlarged root compaction made of high-strength soil cement is constructed at the tip of a ready-made pile to obtain high bearing capacity.

In this construction method, the soil cement after consolidation of the root consolidation portion must satisfy the strength required for structural design. The strength is usually confirmed by conducting a construction test in a hole separate from the main pile, collecting an unconsolidated sample of the root consolidation part by boring, etc., and conducting a compression test at the age of 28 days to confirm the strength. The compression test is performed at a material age of 3 to 7 days to estimate the strength of the material age at 28 days.

On the other hand, regarding a method for estimating the strength of improved soil made of soil cement, the applicant for this patent has already proposed a method as shown in Patent Documents 1 to 3, for example. In the method of Patent Document 1, the correlation between the water content and the strength of the soil cement is obtained in advance by a laboratory test, and then the water content of the sample collected from the improved ground is calculated, and the strength corresponding to the calculated water content is calculated. Is estimated from the above correlation.

The method of Patent Document 2 utilizes the fact that the relational curve between the uniaxial compressive strength q _u and the shear wave velocity V _s (hereinafter referred to as the q _{u to} V _s curve) is uniquely determined according to the soil to be improved. Is. More specifically, the q _{u to} V _s curve is obtained in advance by a laboratory test, and then the shear wave velocity V _s of the improved ground is measured by an in-situ test, and the uniaxial compressive strength q corresponding to this measured value is obtained. _u is estimated from the q _{u to} V _s curve as the intensity at the time of measurement.

The method of Patent Document 3 utilizes the fact that the above q _{u to} V _s curve can be determined by the dry density of the improved soil. More specifically, the q _{u to} V _s curve for each dry density category is obtained in advance by a laboratory test, and then the dry density and shear wave velocity V _s of the improved ground are measured to correspond to the measured dry density. The uniaxial compressive strength q _u is estimated from the shear wave velocity V _s using a curve from q _{u to} V _s .

Japanese Unexamined Patent Publication No. 4-244939 Japanese Unexamined Patent Publication No. 2004-53586 Japanese Unexamined Patent Publication No. 2006-329809

However, in the above-mentioned conventional method for estimating the strength of soil cement, the strength can usually be confirmed after 28 days, and there is a problem that it takes a long time to develop the strength, and the place where the unconsolidated sample is collected is the main pile. There is a problem that it is not.

If the unconsolidated sample of this pile is collected immediately before the pile is built and the developed strength can be estimated at that time, it is possible to judge whether or not the construction is possible in real time, and highly reliable construction management is possible. Against this background, a method has been desired that can estimate the expression strength after consolidation from an unconsolidated sample of soil cement at an early stage.

On the other hand, the present inventor considers that the elastic wave velocity (shear wave velocity V _s , consolidation wave velocity V _p ) of soil cement is closely related to the target soil quality, the amount of cement to be added, and the amount of water. , We conducted diligent research on the method of estimating the expression intensity from unconsolidated samples at an early stage. As a result, the following invention has been reached, in which the future developmental strength can be estimated at an early stage from the formulation of an unconsolidated sample of soil cement.

The present invention has been made in view of the above, and is a method for estimating the strength characteristics of soil cement, which can estimate the future development strength from the composition of soil cement at an early stage, an estimation device, and consolidation at the time of pile construction. The purpose is to provide quality control methods and quality control equipment for departments.

In order to solve the above-mentioned problems and achieve the object, the method for estimating the strength characteristics of a soil cement according to the present invention is a method for estimating the strength characteristics of a soil cement according to a predetermined age of a soil cement obtained by mixing a soil material, a soil material and water. A method for estimating strength characteristics, in which a soil-based material, a soil material, and water are mixed to prepare a sample of soil cement in which the mass ratio of cement and water is a predetermined value, and at a predetermined age. The step of finding the correlation between the elastic wave velocity of the specimen and the mass ratio, the step of measuring the mass ratio of cement and water contained in the sample of unsolidified soil cement to be estimated, and the measured mass. It is characterized by including a step of obtaining an elastic wave velocity corresponding to the ratio from the correlation and a step of estimating the strength characteristics of soil cement at a predetermined age based on the determined elastic wave velocity.

In addition, the method for estimating the strength characteristics of other soil cements according to the present invention is the step of obtaining the relationship between the elastic wave velocity of the specimen and the age of the material based on the above-mentioned correlation, and the obtained elasticity. It is characterized by further including a step of estimating the strength characteristics of the soil cement at an arbitrary material age based on the relationship between the wave velocity and the material age.

Further, in the method for estimating the strength characteristics of other soil cements according to the present invention, in the above-mentioned invention, the step of preparing the specimen for each soil material having a different particle size distribution and obtaining the correlation, and the step of obtaining the correlation and the estimation target have not yet been performed. The step of selecting the correlation based on the particle size distribution of the soil material contained in the sample of the consolidated soil cement and the step of obtaining the elastic wave velocity corresponding to the measured mass ratio from the selected correlation are performed. It is characterized by further preparation.

Further, the device for estimating the strength characteristics of soil cement according to the present invention is a device for estimating the strength characteristics of soil cement obtained by mixing a cement-based material, a soil material, and water at a predetermined age, and is based on cement. Correlation between the elastic wave velocity at a predetermined age and the mass ratio of a soil cement specimen prepared by mixing a material, a soil material, and water and having a mass ratio of cement and water having a predetermined value. A means for measuring the mass ratio of cement and water contained in a sample of unsolidified soil cement to be estimated, and a means for obtaining an elastic wave velocity corresponding to the measured mass ratio from the above correlation. It is characterized by providing a means for estimating the strength characteristics of soil cement at a predetermined age based on the obtained elastic wave velocity.

Further, another device for estimating the strength characteristics of the soil cement according to the present invention is a means for obtaining the relationship between the elastic wave velocity of the specimen and the age of the material based on the above-mentioned correlation, and the obtained elasticity. It is further provided with a means for estimating the strength characteristics of soil cement at an arbitrary material age based on the relationship between the wave velocity and the material age.

Further, the device for estimating the strength characteristics of other soil cements according to the present invention is the means for obtaining the correlation between the specimens prepared for each soil material having a different particle size distribution and the consolidation of the estimation target in the above-mentioned invention. Further, a means for selecting the correlation based on the particle size distribution of the soil material contained in the soil cement sample in a consolidated state and a means for obtaining the elastic wave velocity corresponding to the measured mass ratio from the selected correlation. It is characterized by being prepared.

Further, the quality control method of the root compaction portion during pile construction according to the present invention is based on the strength characteristics estimated by using the above-mentioned method for estimating the strength characteristics of soil cement, and the soil cement of the root compaction portion during pile construction. It is characterized by having a step of controlling the quality of the soil.

Further, the quality control device for the root compaction portion during pile construction according to the present invention is based on the strength characteristics estimated by using the above-mentioned soil cement strength characteristic estimation device, and the soil cement for the root compaction portion during pile construction. It is characterized by providing a means for controlling the quality of the soil.

According to the method for estimating the strength characteristics of soil cement according to the present invention, it is a method for estimating the strength characteristics of soil cement obtained by mixing a cement-based material, a soil material, and water at a predetermined age, and is based on cement. The material, soil material, and water are mixed to prepare a specimen of soil cement in which the mass ratio of cement and water is a predetermined value, and the elastic wave velocity of the specimen at a predetermined age and the mass ratio From the above correlation, the step of finding the correlation between the above, the step of measuring the mass ratio of cement and water contained in the sample of unconsolidated soil cement to be estimated, and the step of measuring the elastic wave velocity corresponding to the measured mass ratio. Since it includes a step to obtain and a step to estimate the strength characteristics of the soil cement at a predetermined age based on the obtained elastic wave velocity, for example, it is predetermined from the cement water ratio C / W of the unconsolidated sample of the soil cement. It has the effect that the strength characteristics of soil cement at the age of the material (for example, 3 days, 7 days, 28 days) can be estimated at an early stage.

Further, according to another method for estimating the strength characteristics of soil cement according to the present invention, a step of obtaining a relationship between an elastic wave velocity of a specimen and a material age based on the correlation, and a obtained elastic wave velocity. Since it further includes a step of estimating the strength characteristics of soil cement at any age based on the relationship with the age, the effect that the strength characteristics of soil cement at any age can be estimated at an early stage. Play.

Further, according to another method for estimating the strength characteristics of soil cement according to the present invention, the step of preparing the specimen for each soil material having a different particle size distribution and obtaining the correlation and the unconsolidated state of the estimation target. Since the step of selecting the correlation based on the particle size distribution of the soil material contained in the soil cement sample and the step of obtaining the elastic wave velocity corresponding to the measured mass ratio from the selected correlation are further provided. , It is effective that the strength characteristics of the soil cement can be estimated accurately and early by using the correlation suitable for the soil material contained in the soil cement.

Further, according to the equipment for estimating the strength characteristics of soil cement according to the present invention, it is an apparatus for estimating the strength characteristics of soil cement obtained by mixing a cement-based material, a soil material and water at a predetermined age. For a soil cement specimen produced by mixing a cement-based material, a soil material, and water and having a mass ratio of cement and water having a predetermined value, the elastic wave velocity at a predetermined age and the mass ratio The means for obtaining the correlation, the means for measuring the mass ratio of cement and water contained in the sample of unconsolidated soil cement to be estimated, and the elastic wave velocity corresponding to the measured mass ratio are obtained from the above correlation. Since the means and the means for estimating the strength characteristics of the soil cement at a predetermined age based on the obtained elastic wave velocity are provided, for example, a predetermined value is obtained from the cement water ratio C / W of the unconsolidated sample of the soil cement. It has the effect that the strength characteristics of soil cement at the age of the material (for example, 3 days, 7 days, 28 days) can be estimated at an early stage.

Further, according to another device for estimating the strength characteristics of soil cement according to the present invention, a means for obtaining a relationship between an elastic wave velocity of a specimen and a material age based on the above correlation, and a obtained elastic wave velocity. Since it is further provided with a means for estimating the strength characteristics of the soil cement at an arbitrary material age based on the relationship with the material age, the effect that the strength characteristics of the soil cement at an arbitrary material age can be estimated at an early stage. Play.

Further, according to another soil cement strength property estimation device according to the present invention, there is a means for obtaining the correlation between the specimens prepared for each soil material having a different particle size distribution and an unconsolidated state of the estimation target. Since the means for selecting the correlation based on the particle size distribution of the soil material contained in the soil cement sample and the means for obtaining the elastic wave velocity corresponding to the measured mass ratio from the selected correlation are further provided. By using the correlation suitable for the soil material contained in the soil cement, the strength characteristics of the soil cement can be estimated accurately and at an early stage.

Further, according to the quality control method of the root compaction portion at the time of pile construction according to the present invention, the root compaction portion at the time of pile construction is based on the strength characteristics estimated by using the above-mentioned method for estimating the strength characteristics of soil cement. Since it is equipped with a step to control the quality of soil cement, it is easy to judge the pass / fail of the construction quality of the solidified part by estimating the strength characteristics of the soil cement of the rooted part at an early stage from the collection of the unconsolidated sample of the soil cement. Moreover, it has the effect of being able to be implemented at an early stage.

Further, according to the quality control device for the root compaction portion during pile construction according to the present invention, the root compaction portion during pile construction is based on the strength characteristics estimated by using the above-mentioned soil cement strength characteristic estimation device. Since it is equipped with a means to control the quality of soil cement, it is easy to judge the pass / fail of the construction quality of the root consolidation part by estimating the strength characteristics of the soil cement in the root consolidation part at an early stage from the collection of unconsolidated samples of soil cement. Moreover, it has the effect of being able to be implemented at an early stage.

FIG. 1 is a flowchart showing a method for estimating the strength characteristics of soil cement and an embodiment of an estimation device according to the present invention. FIG. 2 is a diagram showing a particle size addition curve of the soil material used for producing soil cement. FIG. 3 is a diagram showing the V _{s to} C / W relationship of soil cement, in which (1) is sand, (2) is clay, (3) is clay, and (4) is gravel. .. FIG. 4 is a diagram showing a list of coefficients used in the approximate expression of the V _{s to} C / W relationship. FIG. 5 is a diagram showing the V _{p to} C / W relationship of soil cement, in which (1) is sand, (2) is clay, (3) is clay, and (4) is gravel. FIG. 6 is a diagram showing a list of coefficients used in the approximate expression of the V _{p to} C / W relationship. FIG. 7 is a diagram showing the relationship between V _s and age of soil cement, in which (1) is sand and (2) is clay. FIG. 8 is a diagram showing an estimation chart of expression V _s , in which (1) is sand and (2) is clay. FIG. 9 is a side sectional view showing an example of a root compaction portion during pile construction. FIG. 10 is a flowchart showing a quality control method of a rooted portion and an embodiment of a quality control device at the time of pile construction according to the present invention.

Hereinafter, a method for estimating the strength characteristics of the soil cement according to the present invention, an estimation device, a quality control method for a solidified portion at the time of pile construction, and an embodiment of the quality control device will be described in detail with reference to the drawings. The present invention is not limited to this embodiment.

(Estimation method of strength characteristics of soil cement)
First, an embodiment of a method for estimating the strength characteristics of soil cement according to the present invention will be described.

As shown in FIG. 1, the method for estimating the strength characteristics of soil cement according to the present embodiment estimates the strength characteristics of soil cement obtained by mixing a cement-based material, a soil material, and water at a predetermined age. The method comprises the steps S1 to S4.

In step S1, a cement-based material, a soil material, and water are mixed to prepare a sample of soil cement at a predetermined cement water ratio C / W (mass ratio), and a predetermined material age (for example, material age 3 days) is prepared. , 7th, 28th), the correlation between the elastic wave velocity V of the specimen and C / W (V to C / W relationship) is acquired in advance. Here, the elastic wave velocity V is a shear wave velocity V _s or a sparse wave velocity V _p , C is the amount of cement contained in 1 m ³ of soil cement (kg / m ³ ), and W is contained in 1 m ³ of soil cement. Moisture content (kg / m ³ ). The soil material used for the specimen is preferably the same as the soil material of the improved soil to be estimated, or a soil material having a similar particle size distribution. The material age for which the correlation is to be obtained may be a material age other than the material ages of 3, 7, and 28 days.

In step S2, an unconsolidated sample of soil cement is collected from the improved soil to be estimated, and the C / W of this sample is measured. Here, in order to calculate the amount of water W in the sample when measuring C / W, for example, a method of diverging water using an infrared moisture meter or a microwave oven can be used. Further, for the calculation of the cement amount C, for example, a method of dissolving the sample after measuring the water content W in a predetermined amount of hydrochloric acid and titrating with sodium hydroxide, or calculating the heat of solution when dissolved in an acid. Can be used as determined by. C / W can be obtained from the water content W and the cement content C calculated in this way.

In step S3, the elastic wave velocity V corresponding to the C / W measured in step S2 is estimated from the above correlation (V to C / W relationship).

In step S4, the strength characteristics of the soil cement at a predetermined material age (for example, 3 days, 7 days, 28 days) are estimated based on the elastic wave velocity V obtained in step S3. Here, it is known that the elastic wave velocity V of soil cement and the uniaxial compressive strength q _u have a unique relationship. Therefore, the strength of the soil cement can be estimated by using this relationship to obtain the uniaxial compressive strength q _u corresponding to the estimated V.

By doing so, the strength characteristics of the soil cement at a predetermined material age (for example, 3 days, 7 days, 28 days) can be quickly determined from the cement water ratio C / W of the unconsolidated sample of the soil cement. Can be estimated.

It is also possible to estimate the strength characteristics of soil cement at any age other than, for example, 3, 7, and 28 days, using the above estimation method. In this case, the relationship between the elastic wave velocity V of the specimen and the material age (material age 3 days, 7 days, 28 days) is obtained in advance based on the above correlation (V to C / W relationship). .. In this way, based on this relationship, the strength characteristics of soil cement at any age other than 3, 7, and 28 days (for example, 20 days) can be estimated at an early stage. ..

Further, a specimen may be prepared for each soil material having a different particle size distribution, and the above correlation may be obtained in advance for each specimen. In this case, the above correlation (V to C / W relationship) is selected based on the particle size distribution of the soil material contained in the unconsolidated sample of the soil cement to be estimated. Then, the elastic wave velocity V corresponding to the C / W measured from the unconsolidated sample is estimated from the selected correlation (V to C / W relationship). In this way, the strength characteristics of the soil cement can be estimated accurately and early by using the correlation suitable for the soil material contained in the soil cement.

(Example)
Next, an example of the method for estimating the strength characteristics of the soil cement according to the present invention will be described. In the following, the method of estimating the intensity characteristic using the shear wave velocity V _s as the elastic wave velocity V and the method of estimating the intensity characteristic using the sparse wave velocity V _p will be described separately, and further, optionally. The method of estimating the strength characteristics of the material at the age of the material will also be described. The shear wave velocity V _s and the sparse and dense wave velocity V _p are also used when grasping the ground characteristics (Young's modulus, shear elastic modulus) of the improved soil by soil cement.

[Estimation method using shear wave velocity]
First, an example of a method of estimating the strength characteristics using the shear wave velocity will be described.

In this example, for four types of soil materials (sand, clay, clay, and gravel) with different particle size distributions, soil cement specimens are prepared with different cement water ratio C / W, and the specimens are used. The correlation between the shear wave velocity V _s and the cement water ratio C / W was investigated using. In each C / W, the blending amount of the soil material was set to 3 cases of 10%, 25%, and 40% by mass ratio.

FIG. 2 shows the particle size distribution of the soil material used. FIGS. 3 (1) to 3 (4) show the V _{s to} C / W relationship of the soil cement obtained in this laboratory test for each soil material. In each figure of FIG. 3, the measured values of the shear wave velocity V _s of the specimen at the ages of 3, 7, and 28 days are plotted according to the C / W at the time of preparing the specimen. For the plot of each material age, the following approximation formula can be set so as to pass through the origin.

Here, a, b, and c are fitting parameters. In FIGS. 3 (1) to 3 (4), the results approximated by the above equation (1) are shown by solid lines. FIG. 4 shows a list of coefficients a, b, and c used for the approximation in Eq. (1).

As shown in FIGS. 3 and 4, by keeping the coefficients c constant and changing the coefficients a and b, the V _{s to} C / W relationship of any soil cement can be expressed by the equation (1). That is, sand, earthenware, clay, and gravel were used from the C / W of the unconsolidated sample in the soil cement for an arbitrary composition (however, in this example, C / W ≦ 2.5). an age of 3 days of soil cement, 7 days, V _s of the 28 days it is possible to estimate.

For example, the shear wave velocity V _s of soil cement (C / W = 1.5) using sand as a soil material at the age of 28 days is 1500 m / s from the relationship of V _{s to} C / W in FIG. 3 (1). It can be read as a degree.

As described above, it is known that the shear wave velocity V _s of soil cement and the uniaxial compressive strength q _u have a unique relationship. Therefore, using this relationship, the strength of soil cement is estimated by obtaining the uniaxial compressive strength q _u corresponding to the read V _s . By doing so, the strength at 28 days of age can be estimated from the C / W of the unconsolidated sample of soil cement.

Therefore, according to this example, the strength of the soil cement using sand, earthenware, clay, and gravel at the ages of 3, 7, and 28 days is determined from the C / W of the unconsolidated sample in the soil cement. It can be estimated early.

In this embodiment, a case of soil cement using any of the soil materials (sand, clay, clay, gravel) having a particle size distribution as shown in FIG. 2 is used as an example so that it can be easily estimated at the construction site. I explained to him. At the construction site, after determining whether the particle size distribution of the soil material to be improved obtained by the soil survey before construction is closer to sand, clay, clay, or gravel using FIG. 2, the determined soil material The V _{s to} C / W relationship corresponding to is selected from FIG. 3 and V _s may be estimated. If the particle size distributions of the soil materials are close, it is presumed that the same correlation holds, so the approximate value of V _s can be grasped.

[Estimation method using sparse wave velocity]
Next, an example of a method of estimating the intensity characteristic using the sparse and dense wave velocity will be described.

In this embodiment, in the same manner as the above-mentioned "estimation method using shear wave velocity", four types of soil materials (sand, clay, clay, gravel) having different particle size distributions as shown in FIG. Specimens of soil cement were prepared with different formulations of cement water ratio C / W, and the correlation between the sparse and dense wave velocity V _p and the cement water ratio C / W was investigated using this specimen. In each C / W, the blending amount of the soil material was set to 3 cases of 10%, 25%, and 40% by mass ratio.

FIGS. 5 (1) to 5 (4) show the V _{p to} C / W relationship of the soil cement obtained in this laboratory test for each soil material. In each figure of FIG. 5, the measured values of the sparse density velocity V _p of the specimen at the ages of 3, 7, and 28 days are plotted according to the C / W at the time of preparing the specimen. For the plot of each material age, the following approximation formula can be set so as to pass through the origin.

Here, a, b, and c are fitting parameters. In FIGS. 5 (1) to 5 (4), the results approximated by the above equation (2) are shown by solid lines. FIG. 6 shows a list of coefficients a, b, and c used for the approximation in Eq. (2).

As shown in FIGS. 5 and 6, by keeping the coefficients c constant and changing the coefficients a and b, the V _{p to} C / W relationship of any soil cement can be expressed by the equation (2). That is, sand, earthenware, clay, and gravel were used from the C / W of the unconsolidated sample in the soil cement for an arbitrary composition (however, in this example, C / W ≦ 2.5). V _p can be estimated at the ages of 3, 7, and 28 days for soil cement.

For example, the sparse wave velocity V _p of soil cement (C / W = 1.5) using sand as a soil material at the age of 28 days is 2700 m / s from the relationship of V _{p to} C / W in FIG. 5 (1). It can be read as a degree.

It is known that the sparse wave velocity V _p of soil cement and the uniaxial compressive strength q _u have a unique relationship. Therefore, using this relationship, the strength of the soil cement is estimated by obtaining the uniaxial compressive strength q _u corresponding to the read V _p . By doing so, the strength at 28 days of age can be estimated from the C / W of the unconsolidated sample of soil cement.

Therefore, according to this example, the strength of the soil cement using sand, earthenware, clay, and gravel at the ages of 3, 7, and 28 days is determined from the C / W of the unconsolidated sample in the soil cement. It can be estimated early.

In this embodiment, a case of soil cement using any of the soil materials (sand, clay, clay, gravel) having a particle size distribution as shown in FIG. 2 is used as an example so that it can be easily estimated at the construction site. I explained to him. At the construction site, after determining whether the particle size distribution of the soil material to be improved obtained by the soil survey before construction is closer to sand, clay, clay, or gravel using FIG. 2, the determined soil material The V _{p to} C / W relationship corresponding to is selected from FIG. 5 and V _p may be estimated. If the particle size distributions of the soil materials are close, it is presumed that the same correlation holds, so the approximate value of V _p can be grasped.

[Estimation method at any age]
Next, an estimation method at an arbitrary age will be described. In the following description, the case of estimating the strength at an arbitrary material age by using the above-mentioned "estimation method using shear wave velocity" will be described as an example, but the present invention is not limited to this. The intensity at any age may be estimated by using the above-mentioned "estimation method using sparse wave velocity".

In the above-mentioned "estimation method using shear wave velocity", the relationship between the cement water ratio C / W of the unconsolidated sample in soil cement and the shear wave velocity V _s is used, and the shear wave velocity in an arbitrary composition of soil cement is used. The above equation (1) was set as an approximate equation for estimating V _s . However, since this equation (1) is formulated using the results of laboratory tests on specimens of 3 days, 7 days, and 28 days of age, the shear wave velocity V _{s at} any age. Cannot be estimated.

Therefore, as described below, the developmental strength of soil cement at an arbitrary material age is estimated from the relationship between the shear wave velocity V _s of the unconsolidated sample in soil cement and the material age.

In this example, a sample of soil cement was prepared for sand and clay among the soil materials shown in FIG. 2, and the correlation between V _s and age was investigated. FIG. 7 shows the relationship between V _s and age of soil cement obtained in a laboratory test. The plot, age of 3 days, 7 days, represents the V _s of the 28 days.

Hereinafter, the notation V _s of age of 3 days V _{s, 3d} and the V _s of age of 28 days shall be denoted as V _{s, d28.} FIG. 8 shows the rate of increase of V _s with respect to the increment of V _{s , d 28} to V _{s, 3 d} at any age.

The expression V _s of soil cement at any age can be estimated, for example, by the following procedure.
(1) A sample of soil cement is prepared using the soil material to be improved, and the V _{s to} C / W relationship is obtained.
(2) Based on the test results, for example, the fitting parameters a, b, and c of the approximate formula (1) for the material age of 3 days and the material age of 28 days are obtained.
(3) Collect an unconsolidated sample of soil cement at the in-situ position and determine the C / W.
(4) Using the approximate formula (1), V _s of 3 days old and 28 days old is obtained.
(5) Using the correlation shown in FIG. 8, V _s at an arbitrary age is obtained.

As an example of this estimation method, a case of estimating the expression V _s of soil cement (C / W = 1.25) using sand at the age of 20 days will be described as an example. First, the shear wave velocities V _{s at} the age of 3 days and 28 days of the soil cement are V _{s, 3d} = 660 m / s and V _{s, d28} = 1400 m / s from FIG. 7 (1).

Next, _{with respect} to an increment of 740 m / s from V _{s, d 28} to V _{s, 3 d} , the expression of about 80% of V _s can be read from FIG. 8 (1) at the age of 20 days (480 hours). Therefore, the shear wave velocity V _{s at} the age of 20 days is V _{s, 3d} + (740 × 0.8) = 660 + 592 = 1252, and can be estimated to be about 1250 m / s.

As described above, it is known that the shear wave velocity V _s of soil cement and the uniaxial compressive strength q _u have a unique relationship. Therefore, using this relationship, the strength of soil cement is estimated by obtaining the uniaxial compressive strength q _u corresponding to the estimated V _s . In this way, the C / W and age of 3 days and age of 28 days of V _s of unconsolidated samples soil cement, it is possible to estimate the strength at the age of 20 days.

In the above embodiment, the case of soil cement using sand and soil cement using clay has been described as an example, but the present invention is not limited to this, and soil cement and gravel using clay are not limited to this. It may be the case of soil cement using. Also, the V _s of 3 days and age of 28 days an age has been described taking as an example the case of estimating the intensity of any wood age, of the present invention is not limited to this, another different wood age V The strength of any material age may be estimated from _s .

(Estimator of strength characteristics of soil cement)
Next, an embodiment of an apparatus for estimating the strength characteristics of soil cement according to the present invention will be described.

The device for estimating the strength characteristics of soil cement according to the present invention is a device for estimating the strength characteristics of soil cement obtained by mixing a cement-based material, a soil material, and water at a predetermined age, and is used for providing soil cement. For the specimen, a means for obtaining the correlation (V to C / W relationship) between the elastic wave velocity V (shear wave velocity V _s or the sparse wave velocity V _p ) and C / W at a predetermined age, and an estimation target. Based on the means for measuring the C / W of the unsolidified sample of soil cement, the means for obtaining the elastic wave velocity V corresponding to the measured C / W from the V to C / W relationship, and the obtained elastic wave velocity V. , A means for estimating the strength characteristics of soil cement at a predetermined age.

Here, since each of the above means corresponds to each step of the method for estimating the strength characteristics of the soil cement according to the present invention, in the following description, the contents overlapping with the contents described in the above estimation method will be described. The explanation is omitted.

As a means for measuring the C / W of the unconsolidated sample, for example, various measuring devices for measuring and calculating the cement amount C and the water content W by the above method can be used.

As a means for obtaining the above V to C / W relationship, a means for obtaining an elastic wave velocity V corresponding to C / W from the V to C / W relationship, and a means for estimating the strength characteristics of soil cement, for example, a compounding of a sample is used. more resulting C / W, acoustic wave velocity V, measured from the specimen, unconsolidated measured C / W from sintered sample (such as V _s) q _u ~V curve, database information about the stored such an age or It can be configured by a memory and a computer having an arithmetic processing unit that reads out the above information stored in the database or the memory and estimates the strength characteristics of the soil cement at a predetermined age.

According to the device for estimating the strength characteristics of the soil cement configured in this way, a predetermined material age (for example, material age 3) is obtained from the cement water ratio C / W of the unconsolidated sample of the soil cement in the same manner as in the above estimation method. The strength characteristics of soil cement at (7th, 7th, 28th) can be estimated at an early stage.

In the above embodiment, the means for obtaining the relationship between the elastic wave velocity V and the material age of the specimen based on the V to C / W relationship and the relationship between the obtained elastic wave velocity V and the material age are obtained. Based on this, a means for estimating the strength characteristics of the soil cement at any age may be further provided. As a result, the strength characteristics of soil cement at any age can be estimated at an early stage.

In the above embodiment, the means for obtaining the V to C / W relationship for the specimens prepared for each soil material having a different particle size distribution and the V to C / W based on the particle size distribution of the soil material contained in the unconsolidated sample. A means for selecting the W relationship and a means for obtaining the elastic wave velocity V corresponding to the measured C / W from the selected V to C / W relationship may be further provided. Thereby, the strength characteristics of the soil cement can be estimated accurately and early by using the V to C / W relationship suitable for the soil material contained in the soil cement.

(Quality control method for root consolidation during pile construction)
Next, an embodiment of a quality control method for a rooted portion at the time of pile construction according to the present invention will be described by taking as an example a case where it is applied to a high bearing capacity embedded pile construction method for obtaining a high bearing capacity.

First, the construction method of the root consolidation portion will be outlined. As shown in FIG. 9, a pile hole 2 is excavated up to the supporting ground 1 at the time of pile construction, and a ready-made pile 3 is installed in the pile hole 2. By injecting cement milk properly mixed in the above-ground plant into the enlarged pile hole 4 at the tip of the ready-made pile 3 and stirring and mixing, the tip of the ready-made pile 3 is solidified with high-strength soil cement. Build part 5. Soil cement consists of in-situ soil, cement-based materials and water. The construction quality of this soil cement is appropriately controlled by using the above estimation method.

More specifically, as shown in FIG. 10, first, in-situ soil is collected (step S11) and a particle size test is performed (step S12) to obtain a particle size distribution of the in-situ soil. The particle size distribution described in the ground survey report conducted before construction may be used. In this case, steps S11 and S12 can be omitted. Based on the particle size distribution of the obtained in-situ soil, the soil materials are roughly systematized using FIG.

Next, an unconsolidated sample of soil cement at the root consolidation portion of the main pile is collected (step S13), and the cement water ratio C / W of this sample is measured (step S14).

Next, the V _{s to} C / W relationship (or V _{p to} C / W relationship) corresponding to the systematized soil material is selected (step S15). Subsequently, using the selected V _{s to} C / W relationship, V _s at a predetermined material age corresponding to the measured C / W is estimated. Furthermore, the expression V _s at an arbitrary age is estimated (step S16). From the estimated V _s , the strength of the soil cement at the root consolidation part of the main pile at this age is estimated.

In this way, the future development strength of the soil cement in the root consolidation part is estimated early (for example, within 1 hour) from the collection of the unconsolidated sample of the soil cement, and the pass / fail judgment of the construction quality of the root consolidation part is made. It can be carried out easily and early. Since it is a particularly simple method, it can be easily carried out by a pile builder.

(Quality control device for root consolidation during pile construction)
Next, an embodiment of a quality control device for a root compaction portion at the time of pile construction according to the present invention will be described.

The quality control device for the soil cement at the time of pile construction according to the present invention is based on the strength characteristics estimated by using the above-mentioned device for estimating the strength characteristics of soil cement, and the quality of the soil cement at the time of pile construction. Provide means to manage.

As means for controlling the quality of the above soil cement, for example, C / W obtained from the formulation of the specimen, elastic wave velocity V measured from the specimen, C / W measured from the unsolidified sample, q _u to V. (V _s etc.) curve, the age, and the database or memory that contains information about such design strength, reads the information stored in the database or memory, the strength properties of the soil cement at a given age of It can be configured by a computer having an arithmetic processing unit that estimates and determines the pass / fail of the construction quality of the solidified portion based on the estimated strength characteristics.

According to the quality control device for the consolidation part at the time of pile construction configured in this way, the strength characteristics of the soil cement in the consolidation part are early from the collection of the unconsolidated sample of the soil cement, as in the above quality control method. By estimating, it is possible to easily and quickly determine whether or not the construction quality of the consolidation portion is acceptable.

As described above, according to the method for estimating the strength characteristics of soil cement according to the present invention, a method for estimating the strength characteristics of soil cement obtained by mixing a cement-based material, a soil material, and water at a predetermined age. Therefore, a soil-based material, a soil material, and water are mixed to prepare a soil cement specimen in which the mass ratio of cement and water is a predetermined value, and the elastic wave velocity of the specimen at a predetermined age. And the step of finding the correlation with the mass ratio, the step of measuring the mass ratio of cement and water contained in the sample of unconsolidated soil cement to be estimated, and the elastic wave corresponding to the measured mass ratio. Since it includes a step of obtaining the velocity from the correlation and a step of estimating the strength characteristics of the soil cement at a predetermined age based on the determined elastic wave velocity, for example, the cement water ratio of the unconsolidated sample of the soil cement. From the C / W, the strength characteristics of soil cement at a predetermined age (for example, 3 days, 7 days, 28 days) can be estimated at an early stage.

Further, according to the method for estimating the strength characteristics of other soil cements according to the present invention, the step of obtaining the relationship between the elastic wave velocity of the specimen and the age of the material based on the correlation, and the obtained elastic wave velocity. Since the step of estimating the strength characteristics of the soil cement at an arbitrary material age is further provided based on the relationship with the material age, the strength characteristics of the soil cement at an arbitrary material age can be estimated at an early stage.

Further, according to another method for estimating the strength characteristics of soil cement according to the present invention, the step of preparing the specimen for each soil material having a different particle size distribution and obtaining the correlation and the unconsolidated state of the estimation target. Since the step of selecting the correlation based on the particle size distribution of the soil material contained in the soil cement sample and the step of obtaining the elastic wave velocity corresponding to the measured mass ratio from the selected correlation are further provided. , The strength characteristics of soil cement can be estimated accurately and early by using the correlation suitable for the soil material contained in soil cement.

Further, according to the equipment for estimating the strength characteristics of soil cement according to the present invention, it is an apparatus for estimating the strength characteristics of soil cement obtained by mixing a cement-based material, a soil material and water at a predetermined age. For a soil cement specimen produced by mixing a cement-based material, a soil material, and water and having a mass ratio of cement and water having a predetermined value, the elastic wave velocity at a predetermined age and the mass ratio The means for obtaining the correlation, the means for measuring the mass ratio of cement and water contained in the sample of unconsolidated soil cement to be estimated, and the elastic wave velocity corresponding to the measured mass ratio are obtained from the above correlation. Since the means and the means for estimating the strength characteristics of the soil cement at a predetermined age based on the obtained elastic wave velocity are provided, for example, a predetermined value is obtained from the cement water ratio C / W of the unconsolidated sample of the soil cement. The strength characteristics of soil cement at the age of the material (for example, 3 days, 7 days, 28 days) can be estimated at an early stage.

Further, according to another device for estimating the strength characteristics of soil cement according to the present invention, a means for obtaining the relationship between the elastic wave velocity of the specimen and the age of the material based on the correlation, and the obtained elastic wave velocity. Since the means for estimating the strength characteristics of the soil cement at an arbitrary material age is further provided based on the relationship with the material age, the strength characteristics of the soil cement at an arbitrary material age can be estimated at an early stage.

Further, according to another soil cement strength property estimation device according to the present invention, there is a means for obtaining the correlation between the specimens prepared for each soil material having a different particle size distribution and an unconsolidated state of the estimation target. Since the means for selecting the correlation based on the particle size distribution of the soil material contained in the soil cement sample and the means for obtaining the elastic wave velocity corresponding to the measured mass ratio from the selected correlation are further provided. The strength characteristics of the soil cement can be estimated accurately and early by using the correlation suitable for the soil material contained in the soil cement.

Further, according to the quality control method of the root compaction portion at the time of pile construction according to the present invention, the root compaction portion at the time of pile construction is based on the strength characteristics estimated by using the above-mentioned method for estimating the strength characteristics of soil cement. Since it is equipped with a step to control the quality of soil cement, it is easy to judge the pass / fail of the construction quality of the solidified part by estimating the strength characteristics of the soil cement of the rooted part at an early stage from the collection of the unconsolidated sample of the soil cement. And it can be implemented early.

Further, according to the quality control device for the root compaction portion during pile construction according to the present invention, the root compaction portion during pile construction is based on the strength characteristics estimated by using the above-mentioned soil cement strength characteristic estimation device. Since it is equipped with a means to control the quality of soil cement, it is easy to judge the pass / fail of the construction quality of the root consolidation part by estimating the strength characteristics of the soil cement in the root consolidation part at an early stage from the collection of unconsolidated samples of soil cement. And it can be implemented early.

As described above, the method for estimating the strength characteristics of soil cement, the estimation device, the quality control method for the consolidation portion at the time of pile construction, and the quality control device according to the present invention are soils used in ground improvement work and pile work. It is useful for determining the developmental strength of cement, and is particularly suitable for determining early in the unconsolidated stage.

1 Supporting ground 2, 4 Pile holes 3 Ready-made piles 5 Root consolidation part

Claims (8)

A method for estimating the strength characteristics of soil cement, which is a mixture of cement-based material, soil material, and water, at a predetermined age.
A cement-based material, a soil material, and water are mixed to prepare a specimen of soil cement in which the mass ratio of cement and water is a predetermined value, and the elastic wave velocity of the specimen at a predetermined age and the mass thereof. Steps to find the correlation with the ratio and
The step of measuring the mass ratio of cement and water contained in the sample of unconsolidated soil cement to be estimated, and
The step of obtaining the elastic wave velocity corresponding to the measured mass ratio from the above correlation, and
A method for estimating the strength characteristics of soil cement, which comprises a step of estimating the strength characteristics of soil cement at a predetermined age based on the obtained elastic wave velocity. Based on the above correlation, the step of finding the relationship between the elastic wave velocity of the specimen and the age of the material, and
The strength characteristic of the soil cement according to claim 1, further comprising a step of estimating the strength characteristic of the soil cement at an arbitrary material age based on the relationship between the obtained elastic wave velocity and the material age. Estimating method. The step of preparing the specimen for each soil material having a different particle size distribution and obtaining the correlation, and
The step of selecting the correlation based on the particle size distribution of the soil material contained in the sample of unconsolidated soil cement to be estimated, and
The method for estimating the strength characteristics of soil cement according to claim 1 or 2, further comprising a step of obtaining an elastic wave velocity corresponding to the measured mass ratio from the selected correlation. A device that estimates the strength characteristics of soil cement, which is a mixture of cement-based materials, soil materials, and water, at a predetermined age.
For a sample of soil cement, which is produced by mixing cement-based material, soil material, and water and has a mass ratio of cement and water of a predetermined value, the elastic wave velocity at a predetermined age and the mass ratio Means for finding correlation and
A means for measuring the mass ratio of cement and water contained in a sample of unconsolidated soil cement to be estimated, and
A means for obtaining the elastic wave velocity corresponding to the measured mass ratio from the above correlation, and
An apparatus for estimating the strength characteristics of soil cement, which comprises means for estimating the strength characteristics of soil cement at a predetermined age based on the obtained elastic wave velocity. A means for obtaining the relationship between the elastic wave velocity of the specimen and the age of the material based on the above correlation,
The strength characteristic of the soil cement according to claim 4, further comprising a means for estimating the strength characteristic of the soil cement at an arbitrary material age based on the relationship between the obtained elastic wave velocity and the material age. Estimator. A means for obtaining the correlation of the specimens prepared for each soil material having a different particle size distribution, and
A means for selecting the correlation based on the particle size distribution of the soil material contained in the sample of unconsolidated soil cement to be estimated, and
The device for estimating the strength characteristics of soil cement according to claim 4 or 5, further comprising means for obtaining an elastic wave velocity corresponding to the measured mass ratio from the selected correlation. A step of controlling the quality of the soil cement at the root compaction during pile construction is provided based on the strength characteristics estimated by using the method for estimating the strength characteristics of the soil cement according to any one of claims 1 to 3. A quality control method for cemented parts during pile construction, which is characterized by this. A means for controlling the quality of soil cement in a solidified portion at the time of pile construction is provided based on the strength characteristics estimated by using the soil cement strength characteristic estimation device according to any one of claims 4 to 6. A quality control device for cementing parts during pile construction.

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