How to manage the stabilizer

Abstract

To properly manage wall-forming property of a stabilizing liquid that is circulated to be utilized, in a simple and economical manner.SOLUTION: A management method of a stabilizing liquid that is circulated to be utilized in a construction work of constructing a concrete structure by utilizing an underground hole comprises a polymer material management step of managing a proper quantity of a polymer material contained in the stabilizing liquid based on a calculation value of a polymer ratio S / P in the stabilizing liquid pumped from the underground hole and a preset management threshold value T of a polymer ratio. The polymer ratio S / P is a weight ratio of soil particles to a polymer material contained in the stabilizing liquid. The management threshold value T is set based on a relation between the polymer ratio S / P and a water-filtering quantity Fi, and is the upper limit value of the polymer ratio S / P in a range where the water-filtering quantity Fi is equal to or less than a management reference value managing a wall-forming property of the stabilizing liquid.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present invention relates to a method for managing a stabilizing solution that is recycled when constructing a concrete structure using an underground hole. [Background technology]

[0002] Conventionally, in construction of concrete structures such as cast-in-place concrete piles and diaphragm walls in underground holes, stabilizing fluid has been used mainly for the purposes of protecting the walls of the underground hole, transporting excavated soil, and using it as a replacement fluid when pouring underwater concrete. The stabilizing fluid is a muddy water made mainly 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, and then it is supplied to the underground hole again.

[0003] It is known that the properties of the stabilizer that is recycled in this way change over time due to residual fine particles, consumption of polymer materials, chemical deterioration caused by contact with concrete, etc., even after recycling. For this reason, quality control of the stabilizer is periodically carried out, with specific gravity, viscosity, sand content, wall-forming properties, etc. as control items. However, the drainage test to measure the amount of filtered water required for controlling wall-forming properties is often not carried out because it takes a long time to perform and the work is complicated.

[0004] In this situation, Patent Document 1 discloses a method for measuring the apparent viscosity, which has a correlation with the filtrate amount, and managing the deterioration state of the stabilizing liquid. Specifically, the relationship between the filtrate amount and the apparent viscosity when a Ca component is mixed into the stabilizing liquid is grasped in advance. In addition, the apparent viscosity corresponding to the quality control standard value specified by the filtrate amount is set as the apparent viscosity control value. Then, the actual measured apparent viscosity value of the stabilizing liquid is compared with the apparent viscosity control value to manage the deterioration state of the stabilizing liquid caused by aggregation. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2018-150689 A Summary of the Invention [Problem to be solved by the invention]

[0006] According to Patent Document 1, it is possible to quickly and economically manage the deterioration state caused by the aggregation of the stabilizing solution when Ca components are mixed into the stabilizing solution. However, the deterioration of the stabilizing solution 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 appropriately managing the wall-forming properties of the stabilizing solution is desired.

[0007] The present invention has been made in view of the above problems, and a main object of the present invention is to simply, economically and appropriately control the wall-forming property of a stabilizing solution to be recycled. [Means for solving the problem]

[0008] In order to achieve this object, 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 a polymer ratio in the stabilizing solution pumped up from the underground hole and a predetermined management threshold value for the polymer ratio, wherein the polymer ratio is the weight ratio of soil particles to the polymer material contained in the stabilizing solution, and the management threshold value is set based on the relationship between the polymer ratio and the amount of filtrate, and is an upper limit value of the polymer ratio in a range in which the amount of filtrate is equal to or less than the management standard value for managing the wall-forming ability of the stabilizing solution.

[0009] According to the method for controlling the stabilizing solution of the present invention, a control threshold value is set for the polymer ratio based on the control standard value of the filtered water volume, and this control threshold value for the polymer ratio is used to judge 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 carrying out a drainage test that requires complicated equipment and a long measurement time.

[0010] In addition, the stabilizing solution management method of the present invention includes a health evaluation step of evaluating the health of the stabilizing solution, which is determined in the polymer material management step to contain less than an appropriate amount of polymer material, based on an actual measured value of the B-type viscosity and a predetermined healthy region of the B-type viscosity, and is characterized in that the healthy region is a range in which the filtrate volume is equal to or less than the management standard value, which is set based on the relationship between the filtrate volume and the B-type viscosity.

[0011] According to the method for managing a stabilizing solution of the present invention, for a stabilizing solution determined in the polymer material management step to have an insufficient amount of polymer material in the stabilizing solution, the health of the stabilizing solution is further evaluated using the B-type viscosity, which indicates a sign of deterioration in the stabilizing solution. This makes it possible to determine whether the stabilizing solution has not deteriorated and maintains its wall-forming ability, even if the amount of polymer material is less than the appropriate amount. This makes it possible to manage the wall-forming ability of the stabilizing solution with high accuracy.

[0012] In addition, since only filtration tests need to be conducted on stabilizing fluid that has deviated from the healthy range and shows signs of deterioration, management is easy and economical, and stabilizing fluid management work carried out during construction can be made more efficient. This makes it possible to detect deterioration of circulating stabilizing fluid at an early stage and implement appropriate regeneration treatment to improve the properties of the stabilizing fluid, thereby extending the life of the stabilizing fluid and reducing the amount of waste disposal. Effect of the Invention

[0013] According to the present invention, the soundness of the stabilizing solution is evaluated by combining the polymer ratio and the B-type viscosity, and then a drainage test is performed only on the stabilizing solution showing signs of deterioration, thereby making it possible to simply, economically, and appropriately manage the wall-forming property of the stabilizing solution to be recycled. [Brief description of the drawings]

[0014] [Figure 1] 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. [Diagram 2] 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. [Diagram 3] FIG. 1 is a diagram showing a stable test liquid and a B-type viscometer according to an embodiment of the present invention. [Figure 4] FIG. 2 is a diagram showing the relationship between Brookfield viscosity and drainage amount in an embodiment of the present invention. [Diagram 5] FIG. 4 is a diagram showing a procedure for managing a stabilizing solution according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] The present invention relates to a method for managing a stabilizing solution that is recycled in construction work for constructing concrete structures such as cast-in-place concrete piles and continuous underground walls using underground holes, and is particularly intended to properly manage the wall-forming properties of the stabilizing solution.

[0016] Below, we will explain in detail the method of managing the stabilizing liquid, using as an example the construction of cast-in-place concrete piles using the recycled CMC-based stabilizing liquid, which uses CMC, a polymer material known for its wall-building properties, as its main material, with reference to Figures 1 to 5.

[0017] As shown in Figure 1, when an underground hole 1 is constructed while supplying stabilizing liquid 3 in a construction area where a cast-in-place concrete pile is to be constructed, the CMC in the stabilizing liquid 3 binds 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 causes clogging of the hole wall, and the liquid pressure of the stabilizing liquid 3 is applied to the hole wall. As a result, the stabilizing liquid 3 resists the earth pressure and water pressure of the ground side 7, preventing the collapse of the hole wall and ensuring the stability of the hole wall.

[0018] <<<<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.

[0019] The recycling treatment facility 5 generally includes a soil 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 mixing device 53 that regenerates and mixes the stabilizing solution 3 from which the excavated soil has been separated, and supplies it back to the underground hole 1 for circulation.

[0020] The sediment separation device 51 is equipped with, for example, a sand settling tank 511 which allows the excavated sediment to settle by gravity, and a sediment separator 512 such as a vibrating mud screen, a cyclone, or a screw decanter which mechanically separates the excavated sediment. The blending device 53 is equipped with a mud preparation tank 531 which prepares the blending mud 33 to be replenished to the stabilizing liquid 3, and a circulation tank 532 which mixes and stirs the blending mud 33 and the stabilizing liquid 3 stored in the sand settling tank 511.

[0021] 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 a dispersant, etc., and then regeneration processing such as regeneration mixing is carried out 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 loss of water of the stabilizing solution 3 due to an increase in the number of circulations, consumption of CMC due to adsorption to the excavated soil, and aggregation of bentonite and clay colloid particles due to the mixing of cement (Ca component).

[0022] <<<<<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 managing the stabilizer, the wall-forming function of the recycled stabilizer 3 is managed 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.

[0023] The polymer ratio (S / P) is an index for determining whether the CMC contained in the stabilizing liquid 3 is adequate (the appropriate CMC amount 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 and signs of deterioration of the stabilizing liquid 3. The polymer ratio (S / P) and the B-type viscosity are explained below.

[0024] <<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.

[0025] As shown in Figure 1, the stabilizing solution 3 exhibits a wall-forming effect on the borehole 1 due to the CMC contained in the solution having the ability to form a mud film 2 on the wall of the borehole 1. In order for the stabilizing solution 3 to stably exhibit this hole-wall protecting effect even after repeated recycling, it is necessary to ensure that the CMC concentration in relation to the soil particle concentration is at the same level as when the solution was made.

[0026] Therefore, by calculating the polymer ratio (S / P) of the pumped stabilizing liquid 3, it is confirmed that the necessary amount of CMC is secured for the amount of soil particles in the recycled stabilizing liquid 3. The polymer ratio (S / P) can be calculated using the following formula (1).

[0027] TIFF0007643249000001.tif44170

[0028] TIFF0007643249000002.tif20170

[0029] TIFF0007643249000003.tif25170

[0030] TIFF0007643249000004.tif21170

[0031] <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 stabilized liquid 3 collected on-site, the CMC concentration p is estimated from the mass balance (quantitative relationship between the inflow and outflow of substances).

[0032] First, as shown in Fig. 1, the stabilizing solution 3 to be recycled is stored in an underground hole 1, a sand settling tank 511, and a circulation tank 532. The stabilizing solution 3 in the underground hole 1 contains CMC with a content A, and the stabilizing solution 3 in the sand settling tank 511 and the circulation tank 532 contains CMC with a content B, which is the sum of both.

[0033] Next, the lost stabilizing solution 31 that leaks out from the wall of the underground hole 1 and the waste stabilizing solution 32 that is disposed of due to deterioration are losses of the recycled stabilizing solution 3. The lost stabilizing solution 31, the waste stabilizing solution 32, and the waste soil 6 stored in the waste sand tank 52 all contain a CMC of output D, which corresponds to the output amount of the substance in the mass balance.

[0034] On the other hand, the muddy water for blending 33 prepared in the preparation tank 531 is added to the stabilizing solution 3 in the circulation tank 532, and this is an additional amount of the stabilizing solution 3 that is recycled. The muddy water for blending 33 contains an input amount C of CMC, which corresponds to the input amount of the substance in the mass balance.

[0035] In this way, 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 sampling) can be calculated by the following formula (5). The content A, content B, inflow amount C, outflow amount D, on-site retention amount and loss amount are calculated by the following formulas (6) to (11), respectively. Note that the pile hole volume, grit tank volume, circulation tank volume and septic tank volume are all the volumes of septic tank 3 stored in the underground hole 1, grit tank 511, circulation tank 532 and septic tank 531, as shown in Figure 1.

[0036] TIFF0007643249000005.tif55170

[0037] << 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).

[0038] The control threshold T is set by the following procedure. First, a number of test stabilizing solutions 3' with various properties are prepared by appropriately changing the specific gravity, CMC concentration, cement addition rate, etc. (The preparation method will be described later). Next, for each test stabilizing solution 3' prepared, the filtrate volume is measured and the polymer ratio (S / P) is calculated. The measurement of the filtrate volume may be performed by a filtrate volume test using a filtrate volume tester, which has been conventionally performed.

[0039] 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) that corresponds to the upper limit of the range where the filtered water volume does not exceed 30 ml is extracted and set as the control threshold value T.

[0040] The filtered water volume is an index generally used in evaluating wall-forming properties in the control method of the stabilizing solution 3, and the control standard value of the filtered water volume is set at 30 ml. In other words, when the filtered water volume measured from the stabilizing solution 3 exceeds 30 ml, the stabilizing solution 3 is determined to have lost its wall-forming properties. Therefore, the control threshold value T is set to the polymer ratio (S / P) that corresponds to the upper limit of the range of the filtered water volume below 30 ml, which is the control standard value.

[0041] 2(a), it can be seen that the filtrate volume of all the test stabilizing solutions 3' does not exceed 30 ml when the polymer ratio (S / P) is equal to or less than 40. Therefore, in this embodiment, the control threshold T is set to 40, and when the polymer ratio (S / P) is equal to or less than 40, it is determined that the CMC contained in the stabilizing solution 3 satisfies the appropriate amount, and the stabilizing solution 3 is sound.

[0042] As shown in Figure 2(b), two cases of test stabilizing solution 3', whose data is plotted in the graph of Figure 2(a) above, were prepared: one with and one without the addition of cement. Test stabilizing solution 3' without the addition of cement was prepared by appropriately changing the specific gravity and CMC concentration, and 125 types with specific gravity in the range of 1.002 to 1.150 and CMC addition rate in the range of 0.01 to 0.4% were used.

[0043] Meanwhile, the test stabilizing solution 3' with added cement was prepared by appropriately changing the cement addition rate, CMC addition rate and specific gravity, and 54 types were adopted, with the cement addition rate in the range of 0.4-0.8%, the CMC addition rate in the range of 0.05-0.3%, and the specific gravity in the range of 1.049-1.153. In preparing the test stabilizing solution 3', the soil for adjusting the specific gravity was a homogenized mixture of bentonite, Kasaoka clay, tochi clay, alluvial clay and tsutan.

[0044] <<How to prepare test stabilizing solution 3' used when setting the control threshold 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 recycling process of the stabilizing solution 3. The procedure for preparing the test stabilizing solution 3' is shown below with reference to Figure 3(a).

[0045] First, soil 8 for adjusting specific gravity is collected from samples obtained by boring surveys conducted in the target construction area and homogenized. In addition, the bentonite concentration and CMC concentration are set from the initial concentration of the stabilizing liquid 3. The bentonite concentration is set to 0% for safety reasons, and the addition rate is set within the range of 0 to the initial concentration as necessary. The CMC concentration is set to the maximum initial concentration and the minimum concentration to 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%).

[0046] After that, for each of the CMC concentrations 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 for adjusting 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%.

[0047] The mixtures designed as above are each stirred and mixed with water 10 to prepare a plurality of 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 value T of the polymer ratio (S / P) according to the above-mentioned procedure.

[0048] 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', by using the materials to be used during construction as the bentonite and CMC, and by using soil and sand collected in the target construction area as the soil and sand for adjusting the specific gravity, it becomes possible to evaluate the soundness of the stabilizing liquid 3 with higher accuracy.

[0049] ≪≪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).

[0050] 3(b), the B-type viscometer 11 includes an immersion mark 111, a rotor 112, and a guide rail 113, and in a B-type viscosity measurement test, first, the rotor 112 is inserted into the beaker until the guide rail 113 approaches the bottom of the beaker. Next, a test stabilizing liquid 3' is supplied into 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.

[0051] The B-type viscosity is a viscosity value converted based on this torque value and a predetermined 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 amount of drainage and can be used as an index for evaluating the deterioration of the stabilized liquid 3 caused by the inclusion of cement (Ca component). For details, see JP 2018-150689 A.

[0052] Therefore, the following test was conducted to verify that it is possible to evaluate not only the deterioration of stabilizer 3 caused by the inclusion of cement (Ca component) but also the deterioration of stabilizer 3 caused by a lack of CMC based on the relationship between B-type viscosity and drainage volume.

[0053] <<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.

[0054] 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 adopted, with specific gravity in the range of 1.002 to 1.160, cement addition rate in the range of 0 to 5.0%, and CMC addition rate in the range of 0.01 to 0.4%. The soil and sand used for adjusting the specific gravity in preparing the solution was a homogenized mixture of bentonite, Kasaoka clay, tochi clay, alluvial clay, and tsutan.

[0055] Next, the amount of filtrate and the B-type viscosity were measured for each of the prepared test stabilizing solutions 3'. The amount of filtrate was measured by a conventional filtrate test using a filtrate tester. The B-type viscosity was measured by the above-mentioned B-type viscosity measurement test.

[0056] Since the rotation speed of the rotor 112 of the B-type viscometer 11 can be changed stepwise between 6 and 60 rpm, tests were conducted at different rotation speeds and it was found that the optimal rotation speed was 6 rpm. For this reason, the rotation speed was set to 6 rpm for all of the above 238 types of test stabilizing solutions 3'.

[0057] These were plotted on a graph, with the filtrate volume on the vertical axis and the B-type viscosity on the horizontal axis, as shown in Figure 4(b). Looking at the graph showing the relationship between B-type viscosity and filtrate 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 filtrate 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.

[0058] On the other hand, when the value falls below 6 mPa·s, the amount of drainage 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 the CMC is insufficient.

[0059] It can also be seen that even when the B-type viscosity exceeds 100 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 high viscosity range where there is 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.

[0060] As described above, in the method for managing stabilizer, the range of B-type viscosity of 6 to 100 mPa s is defined as the healthy region, and stabilizer 3 that deviates from this healthy region is determined to show signs of deterioration. Furthermore, for stabilizer 3 that shows signs of deterioration, the B-type viscosity is used as supporting information to identify the cause of deterioration (cement contamination or insufficient CMC).

[0061] <<<<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 of the polymer ratio (S / P), B-type viscosity and drainage amount will be described below with reference to FIG.

[0062] <<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.

[0063] As a preliminary step, a 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 the bentonite and CMC, and soil collected at the construction site should be used as the 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 to measure the specific gravity, sand content, and viscosity.

[0064] TIFF0007643249000006.tif30170

[0065] TIFF0007643249000007.tif10170

[0066] The calculated value of the polymer ratio (S / P) is compared with the previously obtained control threshold value T of the polymer ratio (S / P), and if it is less than the control threshold value T, it can be assumed that the amount of CMC contained in the stabilizing liquid 3 being recycled meets the appropriate amount. Therefore, the stabilizing liquid 3 is judged 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 judged that the amount of CMC does not meet the appropriate amount, and proceed to STEP 2.

[0067] <<Stabilized solution integrity evaluation process: STEP 2>> In STEP 1, for the stabilized liquid 3 that is determined to contain an insufficient 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 stabilized liquid 3 is evaluated.

[0068] If the measured value Vi of the B-type viscosity falls within the above healthy region (range 6 to 100 mPa s), the stable solution 3 is judged to be healthy. On the other hand, if the measured value Vi of the B-type viscosity deviates from the healthy region, the stable solution 3 is treated as having signs of deterioration, and proceed to STEP 3 to identify the cause of deterioration.

[0069] In this way, by combining the polymer ratio (S / P) and the Brookfield viscosity, it is possible to determine whether the stabilizing solution 3 is not degraded 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 control the wall-forming properties of the stabilizing solution 3 with high accuracy.

[0070] <<Stabilizer deterioration determination process: STEP 3>> A filtration test is carried out on the stabilizing solution 3 that showed signs of deterioration in STEP 2, the actual filtrate volume Fi is obtained, and the deterioration of the stabilizing solution 3 is judged.

[0071] When the measured value of the 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 of the filtered water volume for evaluating wall-forming properties is set at 30 ml. On the other hand, when the measured value of the filtered water volume, Fi, exceeds 30 ml, it is judged as follows:

[0072] If the measured filtrate volume Fi exceeds 30 ml and the measured 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. If the measured filtrate volume Fi exceeds 30 ml and the measured 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.

[0073] In this way, since the filtered water volume test is carried out only on the stabilizer 3 that has deviated from the healthy region 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 grasp 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.

[0074] <<Countermeasures based on the cause of deterioration: STEP 4>> For the stabilizing solution 3 whose cause of deterioration has been identified, measures based on the cause of deterioration are implemented.

[0075] If it is determined that the cause of deterioration of stabilizing solution 3 is a lack of CMC, an investigation of the decay state will be conducted, and measures to prevent decay, the addition of CMC, and the dilution or disposal of stabilizing solution 3 will be considered. On the other hand, if it is determined that the cause of deterioration of stabilizing solution 3 is the inclusion of cement (Ca component), the addition of CMC, the addition of a dispersant, and the dilution or disposal of stabilizing solution 3 will be considered.

[0076] 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 adjusting the stabilizing liquid 3 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.

[0077] According to the method for managing the stabilizing solution of the present invention, the soundness of the stabilizing solution 3 is evaluated by combining the polymer ratio (S / P) and the Brookfield viscosity, and then a drainage test is carried out only on the stabilizing solution 3 showing signs of deterioration. This makes it possible to simply, economically, and appropriately manage the wall-forming property of the stabilizing solution 3 to be recycled.

[0078] The method for managing a stabilizing solution of the present invention is not limited to the above-described embodiment, and various modifications are possible without departing from the spirit and scope of the present invention.

[0079] For example, in the present embodiment, the method of managing the stabilizing liquid is described using the CMC-based stabilizing liquid as an example, but the present invention is not limited to this. For example, the method can be adopted for any stabilizing liquid 3 as long as it 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.

[0080] In addition, the polymer material to be used for the stabilizing liquid 3 may be any of SSD (Super Slurry D: a polycarboxylic acid-based mud film forming agent), SSC (Super Slurry C: a drilling mud material that combines the functions of dispersibility and mud film forming), and Sarari (mud adjuster), as long as it has the function of forming a mud film 2 on the wall of the underground hole 1.

[0081] Furthermore, in this embodiment, the method of managing the stabilizing liquid has been given as an example of its use in the construction of cast-in-place concrete piles, but this is not limited to this, and the method can be used in any construction work in which the stabilizing liquid 3 is recycled to build a cast-in-place concrete structure in an underground hole or trench. [Explanation of symbols]

[0082] 1 underground hole 2 mud film 3. Stabilizing solution 31 Water loss stabilizing solution 32 Disposal of stabilizing liquid 33 Muddy Water for Mixing 4. Underground Excavator 5. Recycling equipment 51 Soil separation device 511 Sand settling tank 512 Soil Separator 52 Waste sand tank 53 Mixing Equipment 531 Liquid 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

1. A method for managing a stabilizing solution that is recycled in a construction project for constructing a concrete structure using an underground hole, comprising the steps of: 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 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 solution.

2. 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 management standard value, which is set based on the relationship between the amount of filtered water and the B-type viscosity.

Images