JP7643249B2 - How to manage the stabilizer - Google Patents

Description

The present invention relates to a method for managing the stabilizing solution that is recycled when constructing a concrete structure using an underground hole.

Conventionally, in construction work for constructing concrete structures such as cast-in-place concrete piles and continuous underground walls in underground holes, stabilizing fluid has been used primarily for the purposes of protecting the walls of the underground hole, transporting excavated soil, and serving as a replacement fluid when pouring underwater concrete. The stabilizing fluid is a muddy water made primarily from polymer materials such as CMC and bentonite, and is pumped out of the underground hole together with the excavated soil. After that, it is subjected to physical processing to separate the stabilizing fluid from the sand, and regeneration processing such as regeneration mixing is carried out, before being supplied to the underground hole again.

It is known that the properties of the stabilizing solution that is recycled in this way change over time, even after recycling, due to residual fine particles, consumption of polymer materials, and chemical deterioration caused by contact with concrete. For this reason, quality control of the stabilizing solution is regularly carried out, with specific gravity, viscosity, sand content, wall-forming properties, etc. as control items. However, filtration tests to measure the amount of filtrate required for controlling wall-forming properties are often not carried out because the tests take a long time and are complicated to carry out.

In this context, Patent Document 1 discloses a method for measuring the apparent viscosity, which has a correlation with the amount of filtered water, and managing the deterioration state of the stabilizing liquid. Specifically, the relationship between the amount of filtered water and the apparent viscosity when Ca components are mixed into the stabilizing liquid is grasped in advance. In addition, the apparent viscosity corresponding to the quality control standard value specified by the amount of filtered water is set as the apparent viscosity control value. Then, the actual measured value of the apparent viscosity of the stabilizing liquid is compared with the apparent viscosity control value, thereby managing the deterioration state of the stabilizing liquid caused by aggregation.

JP 2018-150689 A

According to Patent Document 1, it is possible to quickly and economically manage the deterioration state caused by the aggregation of the stabilizing liquid when Ca components are mixed into the stabilizing liquid. However, deterioration of the stabilizing liquid can occur due to various factors other than contact with Ca components. If deterioration occurs and the wall-forming properties cannot be maintained, problems such as the collapse of the hole wall in the ground and poor pouring of concrete may occur, so a method for properly managing the wall-forming properties of the stabilizing liquid is desired.

The present invention was developed in consideration of these problems, and its main objective is to simply, economically, and appropriately manage the wall-forming properties of the stabilizing solution that is recycled.

In order to achieve this objective, the stabilizing solution management method of the present invention is a method for managing stabilizing solution that is recycled in construction work to build a concrete structure using an underground hole, and includes a polymer material management process for managing the appropriate amount of polymer material contained in the stabilizing solution based on a calculated value of the polymer ratio in the stabilizing solution pumped up from the underground hole and a preset management threshold value for the polymer ratio, the polymer ratio being the weight ratio of soil particles to the polymer material contained in the stabilizing solution, the management threshold being set based on the relationship between the polymer ratio and the amount of filtered water, and being the upper limit of the polymer ratio in a range in which the amount of filtered water is equal to or less than the management standard value that manages the wall-forming properties of the stabilizing solution.

According to the stabilizing solution control method of the present invention, a control threshold is set for the polymer ratio based on the control standard value of the filtered water volume, and this control threshold is used to determine whether the polymer material contained in the stabilizing solution satisfies the appropriate amount. This makes it possible to evaluate the wall-forming ability of the stabilizing solution without conducting a filtered water test, which requires complicated equipment and a long measurement time.

The method for managing the stabilizing solution of the present invention further includes a health evaluation step for evaluating the health of the stabilizing solution determined in the polymer material management step to contain less than the appropriate amount of polymer material, based on the actual measured value of the B-type viscosity and a predetermined healthy range of the B-type viscosity, and the healthy range is a range in which the amount of filtrate is equal to or less than the management reference value, which is set based on the relationship between the amount of filtrate and the B-type viscosity.

According to the stabilizing solution management method of the present invention, for stabilizing solutions that are determined in the polymer material management process to have less than the appropriate amount of polymer material, the health of the stabilizing solution is further evaluated using the B-type viscosity, which indicates signs of deterioration in the stabilizing solution. This makes it possible to determine whether the stabilizing solution has not deteriorated and maintains its wall-forming properties, even if the amount of polymer material is less than the appropriate amount. This makes it possible to manage the wall-forming properties of the stabilizing solution with high accuracy.

In addition, since the filtration rate test only needs to be carried out on stabilizing fluid that has deviated from the healthy range and is showing signs of deterioration, management is easy and economical, and the management work of stabilizing fluid carried out during construction can be made more efficient. This makes it possible to detect deterioration of circulated stabilizing fluid at an early stage and carry out appropriate regeneration treatment to improve the properties of the stabilizing fluid, thereby extending the lifespan of the stabilizing fluid and reducing the amount of waste.

According to the present invention, the soundness of the stabilizing solution is evaluated by combining the polymer ratio and B-type viscosity, and then a drainage test is performed only on the stabilizing solution that shows signs of deterioration, making it possible to simply, economically, and appropriately manage the wall-forming properties of the stabilizing solution to be recycled.

FIG. 1 is a diagram showing a state in which a stabilizing solution is recycled at a construction site in an embodiment of the present invention. FIG. 2 is a diagram showing the relationship between the polymer ratio and the amount of drainage water in an embodiment of the present invention. FIG. 1 is a diagram showing a test stabilizing liquid and a B-type viscometer according to an embodiment of the present invention. FIG. 2 is a diagram showing the relationship between B-type viscosity and drainage amount in an embodiment of the present invention. FIG. 4 is a diagram showing a procedure for managing a stabilizing solution according to an embodiment of the present invention.

The present invention is a method for managing the stabilizing solution that is recycled in construction work to build concrete structures such as cast-in-place concrete piles and continuous underground walls using underground holes, and in particular aims to properly manage the wall-forming properties of the stabilizing solution.

The following describes in detail the method of managing the stabilizing solution, taking as an example the construction of cast-in-place concrete piles using recycled CMC-based stabilizing solution, which uses CMC, a polymer material known for its ability to contribute to wall construction, as its main material, with reference to Figures 1 to 5.

As shown in Figure 1, when an underground hole 1 is constructed in a construction area where a cast-in-place concrete pile is planned to be constructed, while supplying stabilizing liquid 3, the CMC in the stabilizing liquid 3 bonds the clay particles, forming a mud film 2, which is a clay-CMC complex, on the hole wall. The formation of the mud film 2 in this way clogs the hole wall, allowing the liquid pressure of the stabilizing liquid 3 to act on the hole wall. As a result, the stabilizing liquid 3 resists the earth pressure and water pressure on the ground side 7, preventing the hole wall from collapsing, and ensuring the stability of the hole wall.

<<<<Recycling of stabilizing solution>>>>
The stabilizing solution 3 functions as a discharge medium for excavated soil and sand when the underground hole 1 is excavated, and is pumped up together with the excavated soil and sand generated by excavating the ground with the underground drilling machine 4. The pumped stabilizing solution 3 is supplied to a regeneration treatment facility 5, where it is regenerated and then supplied to the underground hole 1 again for recycling.

The regeneration treatment facility 5 generally includes a sediment separation device 51 that separates the excavated soil from the stabilizing solution 3, a waste sand tank 52 that stores the separated waste soil 6, and a regeneration mixer 53 that mixes the stabilizing solution 3 from which the excavated soil has been separated, and supplies it back to the underground hole 1 for circulation.

The soil separation device 51 is equipped with, for example, a sand settling tank 511 that allows the excavated soil to settle by gravity, and a soil separator 512 such as a vibrating mud screen, cyclone, or screw decanter that mechanically separates the excavated soil. The blending device 53 is equipped with a mud preparation tank 531 that prepares the blending mud 33 to be replenished to the stabilizing liquid 3, and a circulation tank 532 that mixes and stirs the blending mud 33 with the stabilizing liquid 3 stored in the sand settling tank 511.

Therefore, the stabilizing solution 3 pumped up from the underground hole 1 is subjected to physical processing to separate the mixed excavated soil in the soil separator 51, and chemical processing using dispersants, etc., before being subjected to regeneration processing such as regeneration mixing in the mixing device 53. By carrying out such regeneration processing, the recycled stabilizing solution 3 recovers its wall-forming function that may be lost for various reasons, such as the loss of water due to the increase in the number of circulations, the consumption of CMC due to adsorption to the excavated soil, and the aggregation of bentonite and clay colloid particles due to the mixing of cement (Ca component).

<<<<<Indicators used in the management method of stabilizing solution>>>>
As described above, the stabilizer 3 that is recycled is periodically quality-controlled by taking a portion of the pumped mud as a sample and measuring the specific gravity, viscosity, and sand content, but there is no proper evaluation as to whether the wall-forming function is being maintained. Therefore, in the method of controlling the stabilizer, the wall-forming function of the recycled stabilizer 3 is controlled by combining the polymer ratio (S/P) and B-type viscosity in addition to the filtered water volume, which is known as an index for evaluating wall-forming function.

The polymer ratio (S/P) is an index for determining whether the CMC contained in the stabilizing liquid 3 is in the proper amount (the proper amount of CMC relative to the amount of soil particles contained in the stabilizing liquid 3), and the B-type viscosity is an index for determining the soundness of the stabilizing liquid 3 and signs of deterioration. The polymer ratio (S/P) and B-type viscosity are explained below.

<<Polymer ratio (S/P)>>
The polymer ratio (S/P) is the weight ratio of soil particles to CMC in the stabilizing solution 3. The soil particles refer to the sum of the bentonite added when preparing the stabilizing solution 3 and the fine particles in the excavated soil and sand.

As shown in Figure 1, the stabilizing solution 3 exhibits a wall-protecting effect on the underground hole 1 due to the wall-forming ability of the CMC contained in the solution, which functions to form a mud film 2 on the wall of the underground hole 1. In order for the stabilizing solution 3 to stably exhibit such wall-protecting effect even after repeated recycling, it is necessary to ensure that the CMC concentration is sufficient relative to the soil particle concentration, at the same level as when the solution was made.

Therefore, by calculating the polymer ratio (S/P) of the pumped stabilizing liquid 3, it is possible to confirm that the necessary amount of CMC is secured relative to the amount of soil particles in the circulating stabilizing liquid 3. The polymer ratio (S/P) can be calculated using the following formula (1).

<Mass P of CMC>
On the other hand, the mass P of CMC can be calculated from the CMC concentration p as shown in the above formula (1). However, since it is difficult to obtain the CMC concentration p of the stabilizing solution 3 collected on-site, the CMC concentration p is estimated from mass balance (quantitative relationship between the inflow and outflow of a substance).

First, as shown in Figure 1, the stabilizing solution 3 to be recycled is stored in the underground hole 1, the sand settling tank 511, and the circulation tank 532. The stabilizing solution 3 in the underground hole 1 contains CMC with a content of A, and the stabilizing solution 3 in the sand settling tank 511 and the circulation tank 532 contains CMC with a content of B, which is the sum of the two.

Next, the lost stabilizing liquid 31 that escapes from the wall of the underground hole 1 and the waste stabilizing liquid 32 that is disposed of due to deterioration are losses of the recycled stabilizing liquid 3. The lost stabilizing liquid 31, waste stabilizing liquid 32, and waste soil 6 stored in the waste sand tank 52 all contain a total of CMC with an output amount D, which corresponds to the output amount of material in mass balance.

On the other hand, the mixing mud 33 prepared in the preparation tank 531 is added to the stabilizing solution 3 in the circulation tank 532, so this is an additional amount of the stabilizing solution 3 that is recycled. The mixing mud 33 contains an input amount C of CMC, which corresponds to the input amount of the substance in mass balance.

The CMC concentration p at the time when a portion of the pumped stabilizing liquid 3 is taken as a sample (on the day of collection) can be calculated using the following formula (5). The content A, content B, input amount C, output amount D, on-site retention amount, and loss amount are calculated using the following formulas (6) to (11), respectively. Note that the pile hole volume, sand settling tank volume, circulation tank volume, and liquid production volume are all the volumes of stabilizing liquid 3 stored in the underground hole 1, sand settling tank 511, circulation tank 532, and liquid production tank 531, as shown in Figure 1.

<<<Setting the polymer ratio (S/P) threshold>>>
When using the above polymer ratio (S/P) to determine whether the CMC contained in the stabilizing solution 3 satisfies the appropriate amount, a control threshold value T is set in advance for the polymer ratio (S/P).

The control threshold T is set by the following procedure. First, multiple test stabilizing solutions 3' with various properties are prepared by appropriately changing the specific gravity, CMC concentration, cement addition rate, etc. (The preparation method is described later). Next, for each test stabilizing solution 3' prepared, the filtrate volume is measured and the polymer ratio (S/P) is calculated. The filtrate volume can be measured by a filtrate volume test using a filtrate volume tester, as has been conventionally done.

These are plotted on a graph with the filtered water volume on the vertical axis and the polymer ratio (S/P) on the horizontal axis, as shown in Figure 2 (a). From the graph showing the relationship between the polymer ratio (S/P) and the filtered water volume thus created, the polymer ratio (S/P) corresponding to the upper limit of the range in which the filtered water volume does not exceed 30 ml is extracted, and this is set as the control threshold value T.

The filtered water volume is an index commonly used in evaluating wall-forming properties in the management method of stabilizing liquid 3, and the management standard value for the filtered water volume is set at 30 ml. In other words, if the filtered water volume measured from stabilizing liquid 3 exceeds 30 ml, the stabilizing liquid 3 is determined to have lost its wall-forming properties. Therefore, the management threshold value T is set to the polymer ratio (S/P) that corresponds to the upper limit of the range in which the filtered water volume is 30 ml or less, which is the management standard value.

Looking at the example in Figure 2(a), it can be seen that when the polymer ratio (S/P) is 40 or less, the filtered water volume of all test stabilizing liquids 3' does not exceed 30 ml. Therefore, in this embodiment, the control threshold T is set to 40, and when the polymer ratio (S/P) is 40 or less, it is determined that the CMC contained in the stabilizing liquid 3 satisfies the appropriate amount, and the stabilizing liquid 3 is healthy.

As shown in Figure 2(b), two cases of test stabilizing liquid 3', whose data are plotted in the graph of Figure 2(a) above, were prepared: one with and one without the addition of cement. Test stabilizing liquid 3' without added cement was prepared by appropriately changing the specific gravity and CMC concentration, and 125 types with specific gravities in the range of 1.002 to 1.150 and CMC addition rates in the range of 0.01 to 0.4% were used.

Meanwhile, test stabilizing solution 3' with added cement was prepared by appropriately varying the cement addition rate, CMC addition rate and specific gravity, and 54 types were used, with cement addition rates in the range of 0.4-0.8%, CMC addition rates in the range of 0.05-0.3%, and specific gravities in the range of 1.049-1.153. In preparing test stabilizing solution 3', soil for adjusting specific gravity was prepared by mixing and homogenizing bentonite, Kasaoka clay, tochi clay, alluvial clay and red clay.

<<Method of preparing test stabilizing solution 3′ used when setting control threshold value T>>
In this way, it is advisable to prepare multiple types of test stabilizing solution 3' with different compositions, taking into consideration that the properties of the stabilizing solution 3 may change in various ways depending on the on-site environment, construction conditions, etc., during the process of recycling the stabilizing solution 3. The procedure for preparing the test stabilizing solution 3' will be described below with reference to Fig. 3(a).

First, soil 8 for adjusting specific gravity is collected from samples obtained by boring surveys conducted in the target construction area and homogenized. The bentonite concentration and CMC concentration are set from the initial concentration of the stabilizing liquid 3. The bentonite concentration is set to 0% to be on the safe side, and the addition rate is set within the range of 0 to the initial concentration as necessary. The CMC concentration is set to a maximum initial concentration and a minimum of 0.05%, and multiple cases with gradually decreasing concentrations are prepared (for example, if the initial concentration is 0.2%, the concentrations are 0.2, 0.1, 0.05%).

After this, for each CMC concentration for which multiple cases have been prepared, the specific gravity is set so that the polymer ratio (S/P) is in the range of approximately 1 to 150, and multiple patterns are set for the amount of soil 8 added to adjust the specific gravity. Furthermore, the addition rate of cement 9 to be added is set for these. Multiple patterns are set for the addition rate of cement 9 in the range of 0.4 to 0.8%.

Each of the formulations designed as above is stirred and mixed with water 10 to prepare multiple types of test stabilizing solutions 3'. In this way, various test stabilizing solutions 3' with different CMC concentrations, specific gravities, and cement 9 addition rates are prepared, and these are used to set the control threshold T of the polymer ratio (S/P) using the procedure described above.

This makes it possible to use the control threshold value T of the polymer ratio (S/P) to determine whether the CMC contained in the stabilizing liquid 3 satisfies the appropriate amount. Therefore, it becomes possible to evaluate the wall-forming properties of the stabilizing liquid 3 without conducting a drainage test, which requires complicated equipment and a long measurement time. In addition, when preparing the test stabilizing liquid 3', it is possible to use the materials to be used during construction as bentonite and CMC, and to use soil and sand collected in the construction area as soil and sand for adjusting the specific gravity, thereby making it possible to evaluate the soundness of the stabilizing liquid 3 with higher accuracy.

<<B-type viscosity>>
The Brookfield viscosity is obtained by a Brookfield viscosity measurement test using a Brookfield viscometer 11 (single cylindrical rotational viscometer: Brookfield type viscometer).

As shown in FIG. 3(b), the B-type viscometer 11 is equipped with an immersion mark 111, a rotor 112, and a guide rail 113. In a B-type viscosity measurement test, the rotor 112 is first inserted into the beaker until the guide rail 113 approaches the bottom of the beaker. Next, test stabilizing liquid 3' is supplied to the beaker until the liquid level reaches the immersion mark 111, and the rotor 112 is rotated. At this time, the viscous resistance torque of the test stabilizing liquid 3' acting on the rotor 112 is measured.

The B-type viscosity is converted into a viscosity value based on this torque value and a specified coefficient. In this way, the B-type viscosity measurement test can measure the B-type viscosity simply and quickly. It is known that the B-type viscosity has a correlation with the drainage amount, and can be used as an index for evaluating the deterioration of the stabilizing liquid 3 caused by the inclusion of cement (Ca component). For details, refer to JP 2018-150689 A.

Therefore, the following test was carried out to verify that it is possible to evaluate not only the deterioration of stabilizing solution 3 caused by the inclusion of cement (Ca component) but also the deterioration of stabilizing solution 3 caused by a lack of CMC, based on the relationship between B-type viscosity and drainage volume.

<<Evaluation test of stabilized liquid based on B-type viscosity and drainage volume>>
The evaluation test of the stabilizing solution is set up according to the following procedure: First, a number of test stabilizing solutions 3' are prepared assuming various conditions of the stabilizing solution 3.

As shown in Figure 4(a), the test stabilizing solution 3' was prepared by appropriately changing the specific gravity, cement addition rate, and CMC addition rate, and 238 types were used, with specific gravity ranging from 1.002 to 1.160, cement addition rate ranging from 0 to 5.0%, and CMC addition rate ranging from 0.01 to 0.4%. The soil and sand used to adjust the specific gravity in preparing the solution was a homogenized mixture of bentonite, Kasaoka clay, tochi clay, alluvial clay, and red clay.

Next, the filtrate volume and B-type viscosity were measured for each test stabilizing solution 3' that was prepared. The filtrate volume was measured using a conventional filtrate volume tester. The B-type viscosity was measured using the B-type viscosity measurement test described above.

The rotation speed of the rotor 112 of the B-type viscometer 11 can be changed in stages between 6 and 60 rpm, so tests were conducted at different rotation speeds and it was found that the optimal rotation speed was 6 rpm. For this reason, tests were conducted with the rotation speed set to 6 rpm for all 238 types of test stabilizing liquids 3' mentioned above.

These were plotted on a graph, as shown in Figure 4(b), with the filtered water volume on the vertical axis and the B-type viscosity on the horizontal axis. Looking at the graph showing the relationship between B-type viscosity and filtered water volume in Figure 4(b), it can be seen that when the B-type viscosity is in the range of 6 to 100 mPa·s, the filtered water volume is generally below 30 ml. In other words, test stabilizing solution 3' in this range can be said to be in a healthy state with wall-forming properties.

On the other hand, when the viscosity falls below 6 mPa·s, the amount of filtered water gradually increases, and the number of cases where it exceeds 30 ml increases. This means that the test stabilizing solution 3' is in a low viscosity region where it does not have sufficient viscosity. In other words, it is in a state where there is a shortage of CMC.

It can also be seen that even when the B-type viscosity exceeds 100 mPa·s, the amount of drained water gradually increases, and the number of cases where it exceeds 30 ml increases. This means that the test stabilizing solution 3' is in a high viscosity range where it has high resistance to the rotation of the rotor 112. In other words, it can be said that the added cement (Ca component) is causing the aggregation of bentonite and clay colloid particles.

As described above, in the stabilizing solution management method, the range of B-type viscosity of 6 to 100 mPa·s is defined as the healthy region, and stabilizing solution 3 that deviates from this healthy region is determined to show signs of deterioration. Furthermore, for stabilizing solution 3 that shows signs of deterioration, the B-type viscosity is used as support information to identify the cause of deterioration (cement contamination or insufficient CMC).

<<<<How to manage stabilizing solution>>>>
The procedure for evaluating the wall-forming ability of the recycled stabilizing solution 3 by combining the above three indexes, the polymer ratio (S/P), the Brookfield viscosity and the drainage amount, will be described below with reference to FIG.

<<Stabilizer polymer material management process: STEP 1>>
The polymer ratio (S/P) of the stabilizing solution 3 pumped up from the underground hole 1 is calculated, and it is confirmed that the amount of CMC contained in the stabilizing solution 3 is appropriate for the amount of soil particles.

As a preliminary step, the control threshold value T for the polymer ratio (S/P) is set. The setting method and the method for preparing the test stabilizing solution 3' are as described above. When preparing the test stabilizing solution 3', the materials to be used during construction should be used as bentonite and CMC, and soil collected at the construction site should be used as soil for adjusting the specific gravity. Next, a portion of the stabilizing solution 3 pumped up from the underground hole 1 is taken as a sample, and the specific gravity, sand content, and viscosity are measured.

The calculated value of the polymer ratio (S/P) is compared with the control threshold value T of the polymer ratio (S/P) obtained in advance. If it is less than the control threshold value T, it can be assumed that the amount of CMC contained in the stabilizing solution 3 being recycled meets the appropriate amount. Therefore, the stabilizing solution 3 is determined to be good. On the other hand, if the calculated value of the polymer ratio (S/P) is equal to or greater than the control threshold value T, it is determined that the amount of CMC does not meet the appropriate amount, and proceed to STEP 2.

<<Stabilized solution integrity evaluation process: STEP 2>>
In STEP 1, for the stabilizing solution 3 that is determined to contain less than the appropriate amount of CMC, the actual measured value Vi of the B-type viscosity is obtained using a B-type viscometer 11, and the soundness of the stabilizing solution 3 is evaluated.

If the measured value Vi of the B-type viscosity falls within the above-mentioned healthy region (range of 6 to 100 mPa·s), the stabilizing solution 3 is determined to be healthy. On the other hand, if the measured value Vi of the B-type viscosity deviates from the healthy region, the stabilizing solution 3 is treated as having signs of deterioration, and the process proceeds to STEP 3 to identify the cause of deterioration.

In this way, by combining the polymer ratio (S/P) and B-type viscosity, it is possible to determine whether the stabilizing solution 3 has not deteriorated and maintains its wall-forming properties, even if the CMC content in the stabilizing solution 3 is less than the appropriate amount. This makes it possible to manage the wall-forming properties of the stabilizing solution 3 with high accuracy.

<<Stabilizer deterioration determination process: STEP 3>>
A drainage test is carried out on the stabilizer 3 which shows signs of deterioration in STEP 2 to obtain the actual filtered water volume Fi, and the deterioration of the stabilizer 3 is judged.

If the measured filtered water volume Fi is 30 ml or less, the stabilized liquid 3 is evaluated as sound. This is because, as mentioned above, the control standard value for the filtered water volume used to evaluate wall-forming properties is set at 30 ml. On the other hand, if the measured filtered water volume Fi exceeds 30 ml, it is judged as follows:

If the measured value of the filtrate volume Fi exceeds 30 ml and the measured value of the B-type viscosity Vi is lower than the lower limit of the healthy region (6 mPa·s), it is determined that deterioration has occurred due to a lack of polymer in the stabilizing liquid 3. In addition, if the measured value of the filtrate volume Fi exceeds 30 ml and the measured value of the B-type viscosity Vi exceeds the upper limit of the healthy region (100 mPa·s), it is determined that deterioration has occurred due to the inclusion of cement (Ca component) in the stabilizing liquid 3.

In this way, since the filtered water volume test is only performed on the stabilizer 3 that has deviated from the healthy range and shows signs of deterioration, management is easy and economical, and the management work of the stabilizer 3 carried out during construction can be made more efficient. This makes it possible to identify the deterioration of the stabilizer 3 that is recycled at an early stage and to carry out appropriate regeneration treatment to improve the properties of the stabilizer 3, thereby making it possible to extend the life of the stabilizer 3 and reduce the amount of waste disposal.

<<<Measures based on the cause of deterioration: STEP 4>>>
For the stabilizing solution 3 whose deterioration cause has been identified, measures based on the deterioration cause are implemented.

If it is determined that the cause of deterioration of Stabilizer 3 is a lack of CMC, the decay state will be investigated and measures to prevent decay, the addition of CMC, and dilution or disposal of Stabilizer 3 will be considered. On the other hand, if it is determined that the cause of deterioration of Stabilizer 3 is the inclusion of cement (Ca component), the addition of CMC, the addition of dispersant, dilution or disposal of Stabilizer 3 will be considered.

As long as wall-building properties are ensured, it is preferable that the stabilizing liquid 3 has a low specific gravity and low viscosity. Therefore, if wall-building properties are ensured by implementing the above measures, and then the stabilizing liquid 3 is adjusted to an appropriate specific gravity and viscosity, it will be possible to contribute to improving the quality of the cast-in-place concrete piles constructed in the underground hole 1.

According to the stabilizing solution management method of the present invention, the integrity of the stabilizing solution 3 is evaluated by combining the polymer ratio (S/P) and the B-type viscosity, and then a drainage test is performed only on the stabilizing solution 3 that shows signs of deterioration. This makes it possible to simply, economically, and appropriately manage the wall-forming properties of the stabilizing solution 3 that is recycled.

The method for managing the stabilizing solution of the present invention is not limited to the above embodiment, and various modifications are possible without departing from the spirit of the present invention.

For example, in this embodiment, a CMC-based stabilizing liquid is used as an example to explain the method of managing the stabilizing liquid, but the present invention is not limited to this. For example, any stabilizing liquid 3 that contains bentonite and a polymer material that contributes to wall-forming properties, such as a bentonite-based stabilizing liquid that contains a large amount of bentonite or a polymer-based stabilizing liquid that contains a large amount of a polymer material that has the same function as CMC, can be used.

The polymer material used for the stabilizing liquid 3 can be anything that has the function of forming a mud film 2 on the wall of the underground borehole 1, such as SSD (Super Slurry D: a polycarboxylic acid-based mud film former), SSC (Super Slurry C: a drilling mud material that combines the functions of dispersibility and mud film formation), or Sarari (a mud adjuster).

In addition, in this embodiment, the method of managing the stabilizing solution is used in the construction of cast-in-place concrete piles, but the present invention is not limited to this, and can be used in any construction work in which the stabilizing solution 3 is recycled to build a cast-in-place concrete structure in an underground hole or trench.

1 underground hole 2 mud film 3 stabilizing liquid 31 lost water stabilizing liquid 32 waste stabilizing liquid 33 mixing mud 4 underground excavator 5 recycling treatment device 51 soil separation device 511 sand settling tank 512 soil separator 52 waste sand tank 53 mixing device 531 soil preparation tank 532 circulation tank 6 waste soil 7 ground side 8 soil 9 cement 10 water 11 B type viscometer 111 immersion mark 112 rotor 113 guide rail A content (CMC)
B Content (CMC)
C content (CMC)
D Output (CMC)
T Control threshold (polymer ratio)
Vi measured value (B-type viscosity)
Fi Actual value (filtered water volume)

Claims (2)

A method for managing a stabilizing solution that is recycled in a construction project for constructing a concrete structure using an underground hole, comprising:
A polymer material management step of managing an appropriate amount of polymer material contained in the stabilizing solution based on a calculated value of a polymer ratio in the stabilizing solution pumped up from the underground hole and a preset management threshold value of the polymer ratio,
the polymer ratio is a weight ratio of soil particles to the polymer material contained in the stabilizing solution;
The control threshold is set based on the relationship between the polymer ratio and the drainage volume, and is an upper limit value of the polymer ratio in a range in which the drainage volume is equal to or less than a control standard value for controlling the wall-forming property of the stabilizing liquid. The method for managing a stabilizing solution according to claim 1,
a soundness evaluation step of evaluating the soundness of the stabilizing liquid based on an actual measurement value of the B-type viscosity of the stabilizing liquid determined in the polymer material management step to contain an amount of the polymer material that is less than the appropriate amount and a preset sound region of the B-type viscosity,
A method for managing a stabilizing solution, characterized in that the healthy region is a range in which the amount of filtered water is below the control standard value, which is set based on the relationship between the amount of filtered water and the B-type viscosity.

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