JP2002097630A - Construction condition determining method for soil cement improved body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a construction condition determining method for a soil cement improved body capable of determining proper soil cement improved body construction conditions easily, speedily, and accurately and constructing the proper soil cement improved body in a ground improving construction method. SOLUTION: At least either of excavation speed of a rod provided with a digging blade, a stirring blade, and a solidifying agent liquid discharge port and addition amount of solidifying agent is changed to construct a soil cement column as a test in the ground for construction, a sample which is not hardened yet is sampled from the soil cement column, the sampled sample is observed visually to confirm a degree of mixture of the solidifying agent and ground soil, the sample is cured by promoting it to estimate compressing strength in 28 days after at least one day, and these results of observation and the results of estimated strength in 28 day are comprehensively judged to determine soil cement column construction conditions satisfying the required strength.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for determining the construction conditions for improving the quality of an improved soil cement constructed by a soil improvement method.

[0002]

2. Description of the Related Art Excavated ground soil and a solidified material are stirred and mixed in the ground to determine the conditions for building a soil cement improvement body for building a soil cement improvement body. The soil to be improved is collected, and in a test room, etc., the solidifying material such as cement is added to the collected soil to be improved in various mixing ratios (for example, the ratio of the amount of solidifying material such as cement to the amount of water, and By changing the mixing ratio with the target soil), a test specimen was prepared, and its compressive strength was measured to determine the construction conditions of the improved soil cement. Regarding the preparation of such a specimen, for example, a specimen preparation apparatus for ground improvement work disclosed in Japanese Patent Application Laid-Open No. 9-3866 has been proposed.

[0003] After the conditions for constructing the improved soil cement are determined in a test room or the like, an improved soil cement is constructed at a construction site in accordance with the conditions. Then, in order to confirm the stirring and mixing state of the solidified material and the soil of the soil cement improved body built at the construction site in this way, for example, as described in JP-A-2000-1844, the uncured state A method has been applied in which a sample is collected from the improved soil cement and the state of stirring and mixing of the solidified material and the soil is visually confirmed.

However, only the stirring and mixing state is confirmed by this method, and if the stirring and mixing state of the solidified material and the soil is determined to be poor, the only change is to construct an improved soil cement. The excavation speed and rotation speed of the device. Since the state of strength development is not known, the ratio between the amount of solidified material such as cement and the amount of water and the mixing ratio between the solidified material and the soil to be improved were not changed.

[0005]

A conventional system for collecting soil to be improved on the ground to be constructed and determining the construction conditions of the improved soil cement in a test room or the like is disclosed in JP-A-9-38.
As disclosed in Japanese Patent Publication No. 66, there is a variation due to the compaction method or the like at the time of preparing a test specimen,
Between the test room and the ground in the site, the restraint conditions, temperature, drainage conditions, etc. when creating the improved soil cement are different,
The construction conditions in this construction were not always reproduced correctly, and the construction conditions for the improved soil cement were not always determined. In addition, the strength of the conventional improved body was confirmed by waiting for the built soil cement improved body to solidify after a certain curing period, collecting the specimen by core boring, etc., and performing a compressive strength test to confirm the strength. I was If it is determined that the strength is insufficient, the construction has already been completed, and much labor such as additional construction and reinforcement work is required.

[0006] The present invention is also applicable to the case where the examination of the construction conditions of the improved soil cement in the above-mentioned test room was conducted preliminary, and the examination of the construction conditions of the improved soil cement in the test room was also conducted preliminary. Even if it is not performed, the appropriate construction conditions for the soil cement improved body can be easily, quickly and accurately determined at the site immediately before the execution of this work, and the soil cement improved body with the appropriate strength compensated. The present invention provides a method for determining construction conditions of a soil cement improved body capable of constructing a soil.

[0007]

A first aspect of the present invention is a method for determining a construction condition for constructing a ground improvement body by stirring and mixing ground soil and a solidified material in the ground. In the ground, using a rod having at least a drilling wing, a stirring wing, and a solidifying material liquid discharge port at a tip end, changing a construction condition, experimentally constructing a soil cement column, and the test construction process Collecting a sample in an uncured state from the uncured soil cement column built in the step (preferably collecting the entire length), and visually observing the sample collected in the sample collecting step,
A visual check step of checking the degree of mixing of the solidified material and the ground soil, and an accelerated curing of the sample collected in the sample collecting step, and a strength estimating step of estimating the compressive strength after 28 days after at least one day, Observation results of the degree of mixing of the visual confirmation step, and comprehensive determination of the estimated strength results 28 days after the strength estimation step, a determination step of determining the construction conditions of the soil cement column satisfying the required strength, This is a method for determining construction conditions for an improved soil cement, characterized by at least having.

In the above-mentioned “construction ground”, a soil cement column is experimentally constructed by using a rod provided with at least a drilling wing, a stirring wing, and a solidified material liquid discharge port at a tip end, and changing construction conditions. The construction conditions to be changed in the “test construction process” include any of the number of kneading (mixing times) with the excavating blade and the stirring blade, the number of rotations of the rod, the excavating speed of the rod, the amount of the solidified material added, and the amount of the solidified material discharged. However, if the same rod is used, the number of stirring blades is the same, and if the rotation speed of the rod is the same, the number of kneadings is defined by the excavation speed of the rod, The amount of the solidified material added per unit volume of the ground soil is determined by the discharge amount of the solidified material liquid and the excavating speed of the rod, so that at least one or both of the excavating speed of the rod and the added amount of the solidified material can be changed. Ba It is possible to change the construction conditions. Of course, conditions such as the number of rotations of the rod and the discharge amount of the solidifying material liquid may be changed.

In the case where it is determined that the desired strength can be obtained under a certain condition, or when it is specified in a special specification, etc., the test construction is performed without changing the building condition. Then, a sample may be taken from the soil cement column immediately after the construction, and after performing the mixing degree confirmation step (visual confirmation step) and the strength estimation step 28 days later, the present construction may be performed. However, if a bad result is obtained under the test construction conditions, the test construction must be performed again. Therefore, in the present invention, the soil cement columns are experimentally constructed by changing the construction conditions as described above. The merit of experimentally constructing a soil cement column by changing the construction conditions in this way is great.

[0010] A second aspect of the present invention is a method for determining a construction condition for constructing a ground improvement body by stirring and mixing ground soil and a solidified material in the ground. A test construction step of experimentally constructing a soil cement column using a rod having at least a drilling blade, a stirring blade, and a solidified material liquid discharge port, and changing at least one of the excavating speed and the solidified material addition amount of the rod. And collecting a sample in an uncured state from the uncured soil cement column built in the test building step (preferably collected over the entire length); and collecting a sample collected in the sample collecting step. A visual confirmation step of visually observing and confirming the degree of mixing of the solidified material and the ground soil, and accelerating curing of the sample collected in the sample collection step, and estimating the compressive strength after 28 days at least one day later. And strength estimation step of the observations of the degree of mixing of the visual check step, the intensity estimating step 28
And a determination step of determining the construction conditions of the soil cement columns satisfying the required strength, and a construction condition determination method of a soil cement improved body having at least .

According to a third aspect of the present invention, there is provided a method of determining construction conditions according to the first or second aspect, further comprising a photographing step of photographing a sample taken in the sample taking step with a camera. This is a method for determining the building conditions of the body.

According to a fourth aspect of the present invention, there is provided a method for determining a construction condition for constructing a ground improvement body by stirring and mixing ground soil and a solidified material in the ground. Using a rod having at least a drilling wing, a stirring blade, and a solidified material liquid discharge port, at least changing the excavating speed and the solidified material addition amount of the rod, and a test construction step of experimentally constructing a soil cement column. Collecting a sample in an uncured state (preferably collected over the entire length) from the uncured soil cement pillar built in the test building step, and visually observing the sample collected in the sample collecting step. Observed by, a visual confirmation step of confirming the degree of mixing of the solidified material and the ground soil, a photographing step of photographing the sample collected in the sample collection step with a camera, and a sample taken in the sample collection step After the sample has been accelerated and cured, at least one day later, a strength estimation step for estimating the compression strength after 28 days, the estimated strength result after 28 days of the strength estimation step, and the video taken in the photography step are comprehensively determined. And determining a construction condition of the soil cement column that satisfies the required strength.

According to a fifth aspect of the present invention, in the construction condition determining method according to the first, second, third or fourth aspect, a transmitting step of transmitting a trial construction condition of a test construction step to a construction management section; A soil having a transmission step of transmitting an estimated strength result 28 days after the estimation step to the construction management section, and a transmission step of transmitting the construction conditions determined in the decision step performed by the construction management section to the construction site. This is a method for determining the construction conditions of a cement improved body. That is, the determination of the construction conditions is not limited to the construction site, and may be performed by a construction management department in a remote place.

According to a sixth aspect of the present invention, in the construction condition determining method according to the third or fourth aspect, a transmission step of transmitting test construction conditions of a test construction step to a construction management section, and a camera in a photographing step. The transmission process of transmitting images to the construction management department using a digital camera, the transmission process of transmitting the estimated strength result 28 days after the strength estimation process to the construction management department, and the construction process determined by the decision process performed by the construction management department And a transmitting step of transmitting the conditions to a construction site. That is,
The determination of the construction conditions is not limited to the construction site, and may be performed by a construction management department in a remote place.

[0015] Claim 7 of the present invention is Claims 1, 2, 3,
The construction condition determining method according to 4, 5, or 6, wherein accelerated curing in the strength estimation step is hot water curing.

Claim 8 of the present invention is Claims 1, 2, 3,
The construction condition determination method according to 4, 5, 6, or 7, wherein the compression strength in the strength estimation step is measured by a uniaxial compression test.

According to a ninth aspect of the present invention, there is provided a method for determining a construction condition of an improved soil cement according to the seventh or eighth aspect, wherein the strength estimating step is performed at a construction site. is there.

In the present invention, when a rod having at least the excavating blade, the stirring blade, and the solidified material discharge port at the tip is used, the ground is excavated by the excavating blade at the tip by rotating and excavating the rod. The ground soil and the solidified material liquid (solidified material liquid such as cement milk) supplied from the discharge port can be stirred and mixed by the stirring blade.

Using this rod, the excavation speed of the rod, for example, the excavation length per hour (unit: m / min), the amount of solidifying material added, for example, the solidifying material (eg, cement) per volume of excavated soil A soil cement column is experimentally constructed on the construction target ground by changing at least one of the weight (unit: kg / m ³ ). Of course, the soil cement columns may be experimentally constructed on the construction target ground by changing at least both the excavation speed and the amount of the solidifying material added. If both are changed, the condition can be largely changed.

At this time, the amount of the solidifying material added is determined by experimentally constructing a soil cement column in which the amount of the solidifying material is changed so as to supply the solidifying material liquid having a different concentration of the solidifying material contained in the solidifying material liquid. By changing the flow rate discharged from the solidified material liquid outlet without changing the solidified material concentration, a soil cement column with a different amount of solidified material added may be experimentally constructed. The soil cement column with the added amount of the solidifying material may be experimentally constructed by changing the solidification material amount and changing the flow rate discharged from the solidifying material liquid discharge port.

With respect to the excavating speed of the rod, for example, when the rod is rotated at the same rotational speed per minute, if the excavating speed is high, the degree of agitation by the agitating blade (the number of agitations per depth) is high. If the excavation speed is low (as would be clear if the ground is hard and the excavation speed is low even if the rod is rotated at the same number of revolutions per minute)
The degree of agitation (the number of agitation per depth) by the agitation blade increases.

As described above, the number of times of stirring of the stirring blade is defined by the excavation speed, and the ratio of the solidified material to the soil in the soil cement column is determined by the amount of the solidified material (for example, the weight of the solidified material per volume of the excavated soil). Is defined, and a test body in which the ratio of the solidified material and the soil in the soil cement column and the degree of mixing thereof can be changed by the test execution of the soil cement column at the construction site.

At the time of preparing the test specimen on the construction ground, preliminary examination of the construction conditions of the improved soil cement in the test room was performed, and the result was used to construct a test soil cement column on the construction ground. May be used as a reference sample, and without conducting preliminary examination of the construction conditions of the improved soil cement in the test room, based on past knowledge, Creation may be performed.

In the present invention, an uncured sample over the entire length is collected from the uncured soil cement column immediately after the trial construction at the construction site. The degree of mixing of the solidified material (for example, cement) and the ground soil is confirmed by visual observation of the collected sample. In this case, for example, a phenolphthalein reaction may be used to make it easier to determine the degree of mixing of the solidified material (for example, cement) and the ground soil by visual observation.

In order to record the result of this visual judgment as an image, it is preferable to photograph an uncured sample over the entire length with a camera. When a digital camera is used as a camera, it is convenient to transmit the digital signal.

Further, from the uncured sample taken over the entire length taken from the uncured soil cement columns experimentally built at the construction site, at least a deep position, an intermediate position, and a shallow position for each soil cement column. A test specimen for measuring the compressive strength is taken at at least three places, and the compressive strength after 28 days is estimated at least one day after accelerated curing.

Before the accelerated curing, the collection of the specimen for measuring the compressive strength from the soil cement column having a poor mixing degree based on the result of the visual judgment may be postponed. If only a part of the soil cement column is poorly mixed and the mixing is good in many parts, the variation can be used as a judgment material. Collect. By collecting specimens in combination with good parts and poorly mixed parts, the number of specimens for compressive strength measurement can be increased, and the degree of dispersion of the measured values of compressive strength can be accurately estimated. . Also,
When examining the construction conditions of the improved soil cement, it will be helpful in determining the construction conditions for avoiding the defective mixing part.

As described above, as a method of estimating the compressive strength of 28 days after at least one day after accelerating the test specimen for compressive strength measurement, the test specimen is put in a mold, and a cooler box or the like is used. 55 ° C with a heater equipped with an automatic temperature controller and a circulation pump etc. in a water tank with such a structure
The specimen is stored in a hot water curing tank at a temperature of 55 ° C and accelerated curing for a certain period of time (approximately 24 hours). After this warm water curing, the specimens reach room temperature and the compressive strength is measured. This compression strength can be measured, for example, with a simple uniaxial compression tester capable of performing a uniaxial compression test.

As a method for estimating the compressive strength after 28 days from the measured values, various test specimens were used in advance,
Compressive strength after accelerated curing for a certain period of time (approximately 24 hours) with hot water at ° C, and compressive strength (20 °
C Curing material age 28 days strength), a relational expression obtained in advance, for example, a certain time (approximately 24 hours
Use the method to estimate the compressive strength after 28 days by using the following relational expression obtained when the compressive strength after accelerated curing for about 30 hours) is Pd and the compressive strength after 28 days is Pm. Can be. Relational expression: Pm = a · (Pd) ^b where a and b are constants obtained by experiments using a large number of test pieces for obtaining the above relational expression.

FIG. 5 shows an example of this. FIG. 5 plots the compressive strength of a specimen on a number of grounds after being subjected to hot water curing at 55 ° C. for 24 hours, and the compressive strength of the same specimen at 20 ° C. on the age of 28 for the cured material, When the relationship is approximated by an exponential function, an approximate expression of the average intensity shown in FIG. 5 is obtained. On the other hand, the relationship between the strength after 24 hours of 55 ° C warm water curing and the 28-day strength can be regarded as equal variance, so that the 28-day strength can be obtained with a probability of 90% or more than the strength after 24 hours of 55 ° C warm water curing. The lower limit is shown in FIG. 5 as a formula for a one-sided 90% confidence limit. In the approximate expression of the average intensity, the correlation r is 0.96, and the correlation is very high, and the 28-day intensity can be estimated by this expression. When the number of measurements of the compressive strength is small, it is necessary to estimate the 28-day strength on the safe side in consideration of the variation. In this case, it is recommended to use the 90% limit equation. However, when measuring the compressive strength after 24 hours of 55 ° C hot water curing with a large number of test specimens for compressive strength measurement, variations can be taken into account. It is more appropriate to do. The approximate expression of the average intensity in FIG. 5 is as follows. Pm = a. (Pd) ^b , a = 22.05, b = 0.63 The 90% limit equation in FIG. 5 is as follows. Pm = a. (Pd) ^b , a = 16.52, b = 0.63

In this way, the compression strength after 28 days can be estimated one day later. In addition, the above-mentioned hot water curing tank has a simple structure, and a simple uniaxial compression tester can be used for measuring the compressive strength, so that the strength can be measured at the construction site.

It should be noted that the larger the number of specimens to be subjected to the compressive strength measurement test, the more the compressive strength can be estimated in the estimation value in consideration of the variation in strength. For this purpose, it is preferable to increase the number of specimens by taking the specimens for measuring the compressive strength not only at three places at a deep depth, at an intermediate position and at a shallow depth at each soil cement column but also at many places.

From the construction conditions of the soil cement columns that satisfy the estimated compressive strength after 28 days as described above on the soil cement columns that were experimentally constructed on the construction ground, Determine the construction conditions for construction.

At the time of this determination, it is more preferable to determine the construction conditions by comprehensively judging the image of the uncured sample taken by the camera taken over the entire length previously taken together with the result based on the compressive strength.

If the image from the camera is recorded as a digital image, a process of sending the image together with the strength result to the construction management department and determining the actual construction conditions in the construction management department is adopted. Even if the operator has little experience in determining the construction conditions, the construction management section having experience in determining a large number of construction conditions can properly determine the actual construction conditions to be constructed.

When the construction management section determines the construction conditions to be actually constructed, the determined construction conditions are transmitted to the construction site by a transmission means or other appropriate means.

[0037]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on an embodiment shown in the drawings. In this embodiment, the ground condition to be constructed is clay ground, and a column of the improved soil cement was experimentally constructed at one corner of the ground.

For the construction of the improved soil cement, a ground improvement machine 1 shown in FIG. 1 is used. As shown in FIG. 1, the ground improvement machine 1 has a driving part 4 of a rod 3 attached to a leader mast 2 provided on the front surface thereof so as to be able to move up and down by a guide rail, and is suspended and held by a wire 5. A stirring head 6 is provided in the section.

As shown in FIG. 2, the agitating head 6 includes a digging wing 7 serving as a digging wing for digging the ground in order from the tip end side.
, A co-rotation prevention blade 8, and a plurality of stirring blades 9 spaced vertically. Also, a solidified material liquid discharge port 13 is provided at the position of the excavation wing 7 of the rod 3. The co-rotation prevention wing 8 is for preventing a so-called co-rotation phenomenon of the soil, and is rotated by the rod 3 so that the tip protruding outside the excavation diameter penetrates the excavation hole wall and stops in the soil. Mounted freely. A detection magnet 18 that can monitor whether or not the anti-corotating blade 8 is in a stationary state relative to the stirring blade 9 is provided at a connection portion between the rod 3 and the anti-corotating blade 8.
a and a relative rotation detector 18 comprising a magnetic proximity switch 18b and the like.

On the other hand, as shown in FIG. 1, in a plant 10, water and a solidifying material (cement) are kneaded to produce a cement milk 11. The produced cement milk 11 is sent to the ground improvement machine 1 via a slurry pump 12 whose discharge amount can be controlled, passes through the inside of the rod 3, and is discharged from a discharge port 13 at the tip of the rod 3. The discharged cement milk 11 is efficiently stirred and mixed with the excavated ground soil by the excavating wing 7, the co-rotation preventing wing 8, and the stirring wing 9, thereby constructing an improved soil cement.

Further, the ground improvement machine 1 is provided with a depth detector 14 for detecting the depth from the movement amount of the rod 3, and the supply flow rate of the cement milk 11, that is, the discharge amount, is detected at the outlet side of the slurry pump 12. A discharge amount detector 17 is provided. That is, if the time is recorded from the depth measured by the depth detector 14, the excavation speed (excavation length per time) can be measured, and the volume of excavated soil can be measured from the depth and the excavation diameter. From the supplied amount of the solidified material liquid and the weight of the solidified material in the solidified material liquid, the amount of the solidified material added (the weight of cement as the solidified material per volume of excavated soil) can be measured.

In addition, the ground improvement machine 1 includes a rotation speed detector 15 for detecting the rotation speed of the rod 3 and a current for detecting the current value (or hydraulic pressure) of the electric motor (or hydraulic motor) of the drive unit 4. A detector (or hydraulic pressure detector) 16 is provided. Accordingly, the rotation speed of the rod 3 is also recorded, and the excavation length is determined from the number of the stirring blades 9 (in the present invention, the excavation blades 7 also act as the stirring blades, so that the number of the excavation blades 7 is counted) and the rod rotation speed and the excavation speed. And the number of rotations of the ground soil and the solidified material with respect to the unit length can be recorded, and the work amount of the apparatus can be recorded from the load (current value) applied to the motor for rotating the rod 3. It is possible to confirm that the excavation depth has reached the supporting ground due to the change in the work amount.

The data at the time of the above construction is recorded as a digital signal, and as shown in FIG. 3, the construction conditions of the soil cement column can be recorded.

Using a construction machine having the above-mentioned equipment, test soil cement columns were constructed at construction sites under various conditions shown in Table 1 below.

[0045]

[Table 1]

Immediately after being constructed under such conditions, the test soil cement column was still in an uncured state, and an uncured sample over the entire length of the soil cement column was taken. For this collection, a sample soil collection device 20 shown in FIG. 4 can be used. The sample soil collecting apparatus 20 is generally composed of an inner pipe 21 and an outer pipe 22 having a substantially semicircular shape, and a ground improvement machine is used in a state where the inner pipe 21 and the outer pipe 22 are overlapped in a semicircular shape. It is to be inserted into the uncured soil cement pillar after construction, and when it reaches a predetermined depth, the inner pipe 21 is rotated to collect a cylindrical sample soil, and to collect a sample soil without disturbance. Can be.

In the sample soil collected, the soil cement column of No. 4 in Table 1 had a large amount of soil mass throughout, and the degree of mixing of cement and soil was poor. This is because the excavating speed of the rod was high and stirring was insufficient. Also,
In order to eliminate insufficient stirring during excavation, stirring when the rod is lifted can be used, but in No. 4, the pulling speed was also high, so that the stirring was insufficient as a whole. This is supported by the recording of the degree of ground relative to the unit length of the apparatus and the number of rotations of mixing with the solidified material.

Nos. 1 to 4 where the degree of mixing by visual observation was good.
For the No. 3 soil cement column, from the collected sample, for each soil cement column, the upper 3
The test specimen for compressive strength measurement was selected from three places, three places in the middle part and three places in the lower part by molding.

With a total of 27 (= 3 × 3 × 3) specimens in a mold, a heater with an automatic temperature control device and a circulation unit are circulated in a water tank of a cooler box type structure installed in the construction site. It was stored in a 55 ° C hot water curing tank equipped with a pump, etc., accelerated curing with the 55 ° C hot water for about 24 hours, and after the hot water curing, the compressive strength was measured after the specimen reached room temperature. The strength was measured at the construction site using a simple uniaxial compression tester to measure the compression strength.

From the measurement results, the 28-day intensity was estimated using a predetermined test line from which the 28-day intensity could be estimated.
As a result, the 28-day strength of the No. 1 soil cement column was 2.2 [N / mm ² ], and the variation of each specimen was small. On the other hand, in No. 2, 1.4 [N
/ Mm ² ], and in No. 3, 1.5 [N / mm ² ]
However, the variation in strength between the specimens was small.

As a result, the degree of mixing by visual observation is good, and considering the state of variation in strength, the solidified material is obtained from the building conditions of No. 1 which exceeds the required strength of 2.0 [N / mm ² ]. (The weight of the solidified material per volume of excavated soil) was determined to be 400 [kg / m ³ ].

No difference was observed between No. 2 and No. 3 in the result of visual observation and in the result of compressive strength. Therefore, even if the No. 1 excavation condition and the pulling condition are changed to the No. 3 condition with a high construction speed, the required amount of solidified material (weight of solidified material per volume of excavated soil) ) To 40
As long as it is 0 [kg / m ³ ], it is judged that there is no problem, and in the actual construction, the necessary addition amount of the solidifying material is 400 [kg / m 3].
³ ], it was decided that the excavating speed of the rod was 0.8 [m / min] and the pulling speed of the rod was 1.5 [m / min].

In the actual construction, a soil cement column was constructed while monitoring the addition amount of the solidifying material, the speed at the time of excavation, and the like, using the apparatus equipped with the above-described measuring device. To be on the safe side,
A sample was taken from the soil cement column, and the compressive strength was measured. The 28-day strength sufficiently satisfied the required strength.

Conventionally, the soil to be improved of the construction target ground is sampled, and a solidifying material such as cement is added to the collected soil to be improved at various mixing ratios in a test room (for example, a solidifying material such as cement). By changing the ratio of the amount of water to the amount of water and the mixing ratio of the solidified material and the soil to be improved), and preparing the test specimen, measuring its compressive strength, and determining the building conditions for the improved soil cement, The required amount of solidifying material is 300 [kg /
m ³ ], but under these conditions, the strength is unsatisfactory as described above. If the actual construction is performed with this amount of addition as in the past, an improved soil cement with insufficient strength is obtained.

The required addition amount of the solidifying material of 400 [kg / m ³ ] determined above is changed to 450 [kg / m ³ ] or 500 [kg / m ³ ].
Changing to [kg / m ³ ] results in an improved body with higher strength, but on the other hand results in expensive excess quality. That is, it is possible to provide a soil cement improved body whose quality is guaranteed by the soil cement improved body construction condition determination system of the present invention.

In the above example, the construction conditions of the improved soil cement were determined at the construction site. Of course, when the uncured sample taken from the soil cement column over the entire length was recorded as a digital image, the strength was increased. By adopting the process of sending to the construction management department with the results and determining the actual construction conditions to be executed by the construction management department, many construction conditions are determined even if the construction site workers have little experience in determining the construction conditions. It is possible to properly determine the construction conditions to be actually constructed by the construction management department having experience.
In this case, the determined construction conditions are transmitted to the construction site.

In this manner, the variation in strength is also taken into consideration.
Improved soil cement with 28-day strength guaranteed can be constructed with good reproducibility.

At the time of actual construction, in order to confirm that the construction was carried out under the conditions determined above, Japanese Patent Laid-Open
What is necessary is just to use the apparatus which can manage the construction state disclosed by -220134 gazette. By using this management device, the determined working conditions (in the above example, the required addition amount of the solidifying material is 400 [kg / m ³ ], the excavation speed of the rod is 0.8 [m / min], The pulling speed is 1.5 [m /
Minutes].

[0059]

(1) In the present invention, a soil cement column is experimentally constructed by changing the excavation speed of the rod of the ground improvement machine and the amount of the solidifying agent added, and the uncured soil cement column is constructed from the constructed unhardened soil cement column. A sample in an uncured state is collected and visually observed, and after one day of accelerated curing, the compressive strength after 28 days is estimated, and these results are comprehensively judged to build soil cement columns that satisfy the required strength. The construction conditions of the appropriate soil cement improvement can be easily determined,
It can be determined quickly and accurately, and a proper soil cement improvement with 28-day strength guaranteed can be applied with good reproducibility.

(2) In particular, an uncured sample taken from the soil cement column, which has been experimentally constructed, is photographed with a camera, and the degree of mixing of the solidified material and the ground soil is determined by the camera. It helps to determine the excavation speed and the amount of solidified material discharged, so that the part other than the part where the compressive strength is measured is mixed uniformly, and the appropriate soil cement improved body whose overall compressive strength is guaranteed is reproducible. Can be constructed well.

(3) Further, when the camera is a digital camera, the image can be easily transmitted.
Even if construction site workers are not used to determining construction conditions,
The construction management department at a remote location can determine the construction conditions based on the images sent and the measurement results of the compressive strength, and if the determined excavation speed of the rod and the amount of solidified material discharged are managed at the construction site, 28 It is possible to construct a proper soil cement improved body whose day strength is guaranteed with good reproducibility.

(4) If the accelerated curing in the step of estimating the compressive strength at least 28 days after accelerated curing is warm water curing and the compressive strength is measured by a uniaxial compression test, Measurement at the construction site,
From the test results, it becomes possible to determine the construction conditions of this construction at the construction site at an early stage.

[Brief description of the drawings]

FIG. 1 is an apparatus configuration diagram showing an example of a ground improvement machine and a management apparatus used in a construction condition determining method of the present invention.

FIG. 2 is a stirring head part of the ground improvement machine of FIG. 1,
(a) is a side view, (b) is a partial cross-sectional view showing a sensor for detecting relative rotation of the co-rotation prevention wing.

FIG. 3 is a diagram showing an example of display display of data of the management device of FIG. 1;

FIG. 4 is an example of a sample soil collecting apparatus used in the method for determining construction conditions according to the present invention, wherein (a) is a front view and a cross-sectional view of an inner pipe, (b) is a front view and a cross-sectional view of an outer pipe, and (c). ) Is a front view and a sectional view at the time of penetration, (d) is a front view and a sectional view, and (e) is a sectional view of the upper part of the outer tube.

FIG. 5 shows the relationship between the compressive strength of a specimen on a number of grounds after being subjected to a 55 ° C. warm water curing for 24 hours and the compressive strength of the same specimen at 20 ° C. on 28 days of curing. It is a graph.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Ground improvement machine 2 ... Leader mast 3 ... Rod 4 ... Drive part 5 ... Wire 6 ... Agitation head 7 ... Excavation wing 8 ... Anti-rotation wing 9 ... Agitation wing 10 ... Plant 11 ... Cement milk 12 ... Slurry pump 13 ... Discharge port 14 ... Depth detector 15 ... Rotation number detector 16 ... Current detector 17 ... Discharge amount detector 18 ... Relative rotation detector 18a ... Detecting magnet 18b Magnetic proximity switch 20 Sample soil sampling device 21 Inner tube 22 Outer tube

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Atsushi Murayama 6-13-7 Akasaka, Minato-ku, Tokyo Tenox Corporation (72) Inventor Tomio Soma 6-13-7 Akasaka, Minato-ku, Tokyo Tenox Corporation (72) Inventor Toshiaki Yamane 6-13-7 Akasaka, Minato-ku, Tokyo Tenox Co., Ltd. (72) Inventor Yuji Kazari 6-13-7 Akasaka, Minato-ku, Tokyo Tenox Co., Ltd. F-term (reference 2D040 AB05 BA08 BD05 CA01 CB03 FA04 GA01

Claims (9)

[Claims] 1. A method for determining a construction condition for constructing a ground improvement body by stirring and mixing a ground soil and a solidified material in a ground, comprising: Using a rod having at least a solidifying material liquid discharge port, changing the construction conditions, and experimentally constructing a soil cement column, and an uncured soil cement column constructed in the test construction process A sample collecting step of collecting an uncured sample from the sample, a visual check step of visually observing the sample collected in the sample collecting step, and checking a degree of mixing of the solidified material and the ground soil, and the sample collecting step. A step of estimating the compressive strength of 28 days after at least one day by accelerating the sample collected in the above, an observation result of the degree of mixing in the visual confirmation step, and an estimation of 28 days after the strength estimating step strength And determining a construction condition of the soil cement column that satisfies the required strength by comprehensively judging the degree results and a construction condition determination method of the improved soil cement body. 2. A method for deciding construction conditions for constructing a ground improvement body by stirring and mixing ground soil and solidified material in the ground, comprising: Using a rod having at least a solidifying material liquid discharge port, changing at least one of the excavating speed of the rod and the amount of solidifying material added, to test-build a soil cement column, and the test building step. A sample collection step of collecting an uncured state sample from the uncured soil cement column built in, and visually observing the sample collected in the sample collection step, to determine the degree of mixing of the solidified material and the ground soil. A visual confirmation step of confirming, a strength estimating step of accelerating and curing the sample collected in the sample collecting step, and estimating a compressive strength of 28 days after at least one day; And a determination step of comprehensively judging the result and the estimated strength result 28 days after the strength estimation step, and determining a construction condition of the soil cement column that satisfies the required strength. How to determine the construction conditions for the improved body. 3. The construction condition determining method according to claim 1, further comprising a photographing step of photographing a sample taken in the sample taking step with a camera. . 4. A method for deciding construction conditions for constructing a ground improvement body by stirring and mixing ground soil and a solidified material in the ground, comprising: Using a rod having at least a solidifying material liquid discharge port, at least changing the excavating speed of the rod and the amount of solidifying material added, a test construction step of experimentally constructing a soil cement column, A sample collection step of collecting an uncured state sample from the built uncured soil cement column, and visually observing the sample collected in the sample collection step to confirm the degree of mixing of the solidified material and the ground soil. A visual confirmation step to perform, a photographing step of photographing the sample collected in the sample collection step by a camera, and accelerating curing of the sample collected in the sample collection step, and compressing the sample after 28 days after at least one day. The strength estimation step of estimating the degree, the estimated strength result 28 days after the strength estimation step, and comprehensively judging the video taken in the shooting step, the construction conditions of the soil cement pillar that satisfies the required strength A method for determining construction conditions for an improved soil cement, comprising: at least a determining step of determining. 5. The construction condition determining method according to claim 1, wherein the transmitting step includes transmitting a trial construction condition of the test construction process to the construction management section, and a step of transmitting the test condition 28 days after the strength estimating process. Construction conditions of an improved soil cement body having a transmission step of transmitting the estimated strength result to the construction management section and a transmission step of transmitting the construction conditions determined in the decision step performed by the construction management section to the construction site. Decision method. 6. The construction condition determination method according to claim 3, wherein a transmission step of transmitting test construction conditions of the test construction step to a construction management section, and an image using a digital camera as a camera in the photographing step. Transmission to the construction management department, transmission of the estimated strength result 28 days after the strength estimation process to the construction management department, and construction conditions determined by the decision process performed by the construction management department to the construction site A method for determining construction conditions for an improved soil cement, comprising: 7. The building condition determining method according to claim 1, 2, 3, 4, 5, or 6, wherein accelerated curing in the strength estimation step is hot water curing. Decision method. 8. The method of claim 1, 2, 3, 4, 5, 6, or 7.
3. The method for determining construction conditions of an improved soil cement according to claim 1, wherein the compressive strength in the strength estimating step is measured by a uniaxial compression test. 9. The method according to claim 7, wherein the strength estimating step is performed at a construction site.