Mud evaluation system and mud evaluation method

Abstract

To continuously measure properties of mud in a chamber of a shield drilling machine.SOLUTION: A mud evaluation system comprises: a storage unit that, on the basis of the results measured for a flow property in a condition in which a wetting density and a water content of a sample to be measured are adjusted, stores evaluation data representing a relation between a combination of the wetting density and the water content, and the measured flow property; a first acquisition unit for acquiring the wetting density and the water content measured by an instrument that measures the wetting density and the water content of mud in a chamber of a shield drilling machine; and a second acquisition unit for acquiring flow properties corresponding to the acquired combination of wetting density and water content from the evaluation data stored in the storage unit.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a mud evaluation system and a mud evaluation method. [Background technology]

[0002] When excavating a tunnel or the like in the natural ground using the earth pressure shield method, the cutter head of the shield machine rotates to excavate the ground, and the excavated soil is piled up in the chamber. The piled up excavated soil is discharged from the chamber by a screw conveyor or the like. In addition, in the case of large-diameter shields, if the mud in the chamber separates over time while the shield is stopped, settles, and becomes compacted, the cutter head may become unable to rotate when excavation is resumed. One of the causes of this phenomenon is that the excavated mud in the chamber settles while the shield is stopped, causing a decrease in plastic fluidity. In order to avoid such an event, it is possible to understand the properties of the mud in the chamber and take measures according to those properties. To check the properties of the mud in the chamber, for example, there is a method of qualitatively managing the properties of the mud discharged from the screw conveyor through empirical judgment such as visual observation or palpation. Patent Document 1 discloses an earth pressure type shield machine in which density and moisture measuring devices are provided on the outer periphery of the face and on the soil discharge pipe, respectively, to grasp the properties of the excavated soil and the discharged soil. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 2533811 Summary of the Invention [Problem to be solved by the invention]

[0004] However, the method of checking the mud discharged from the chamber requires waiting for the completion of visual observation and palpation of the discharged mud, so the properties can only be measured and evaluated intermittently. Therefore, it is desirable to be able to grasp the properties of the mud in the chamber more accurately while the shield is stopped. Although Patent Document 1 is capable of grasping the outer periphery of the tunnel face and the characteristics of the soil being discharged, it is not capable of grasping the characteristics of the mud inside the chamber.

[0005] The present invention has been made in consideration of the above circumstances, and its object is to provide a mud evaluation system and a mud evaluation method that can continuously measure the properties of mud inside the chamber of a shield excavator. [Means for solving the problem]

[0006] In order to solve the above-mentioned problems, one aspect of the present invention is a mud evaluation system having a memory unit that stores evaluation data representing the relationship between a combination of wet density and moisture content and the measured flow characteristics based on results of measurements of the flow characteristics when the wet density and moisture content of the sample to be measured are adjusted, a first acquisition unit that acquires the wet density and moisture content measured by a measuring instrument that measures the wet density and moisture content of mud in a chamber of a shield excavator, and a second acquisition unit that acquires the flow characteristics corresponding to the acquired combination of wet density and moisture content from the evaluation data stored in the memory unit.

[0007] Another aspect of the present invention is a mud evaluation method that has a computer perform the following steps: storing evaluation data in a memory unit that represents the relationship between a combination of wet density and moisture content and the measured flow characteristics based on the results of measurements of the flow characteristics when the wet density and moisture content of the sample to be measured are adjusted; acquiring the wet density and moisture content measured by a measuring instrument that measures the wet density and moisture content of mud in the chamber of a shield excavator; and acquiring the flow characteristics corresponding to the acquired combination of wet density and moisture content from the evaluation data stored in the memory unit. Effect of the Invention

[0008] As described above, according to the present invention, the properties of mud inside the chamber of a shield machine can be continuously measured. [Brief description of the drawings]

[0009] [Figure 1] FIG. 2 is a configuration diagram of a shield tunneling machine 10 as seen from the side. [Figure 2A] 4 is a cross-sectional view showing the configuration of the measuring unit 20 when the cutter device 15 is performing excavation. FIG. [Figure 2B] 4 is a cross-sectional view showing the configuration of the measuring unit 20 when measuring the wet density and moisture content while the shield is stopped. FIG. [Diagram 3] FIG. 2 is a schematic functional block diagram showing the configuration of the mud evaluation system S. [Figure 4] 1 is a flowchart illustrating the operation of the mud evaluation system S. [Figure 5A] FIG. 1 is a contour diagram showing an example of evaluation of a measurement sample (clay soil) based on table flow values. [Figure 5B] FIG. 1 is a contour diagram showing an example of evaluation of a measurement sample (sandy soil) based on table flow values. [Figure 6] FIG. 1 is a graph showing a particle size accumulation curve of a measurement sample. [Figure 7A] 1 is a graph showing the relationship between gamma ray count rate ratio and wet density measurement results. [Figure 7B] 1 is a graph showing the relationship between the neutron count rate ratio and the measurement results of the water content. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, a mud evaluation system according to an embodiment of the present invention will be described with reference to the drawings. Fig. 1 is a schematic diagram showing an example of the configuration of a shield excavator using an earth pressure shield method in which a mud evaluation system is used. Fig. 1 is a configuration diagram of a shield excavator 10 as seen from the side.

[0011] In the shield excavator 10, a chamber 13 for taking in excavated soil is provided by partitioning the tip of the skin plate 11 with a partition wall 12. Excavated soil resulting from excavating the face with a cutter device 15 is taken into the inside of the chamber 13. An agitator blade 14 is provided on the side of the cutter device 15 facing the partition wall 12. The shield excavator 10 is configured to add chemicals such as hydrated bentonite or polymeric material or air bubbles to the excavated soil in the chamber 13 by supplying them from an injection pipe, agitate the excavated soil with the agitator blade 14 to give the excavated soil a predetermined plastic fluidity, turn it into mud, and apply the earth pressure to the face to stabilize the face while excavating.

[0012] The screw conveyor 16 discharges the mud inside the chamber 13 through a discharge gate onto the conveyor 17. The conveyor 17 discharges the mud discharged from the screw conveyor 16 to a subsequent stage.

[0013] The measuring unit 20 is inserted into the chamber 13 through the partition 12 from the side opposite to the side facing the cutter device 15, and measures the wet density and moisture content of the mud in the chamber 13. The measuring unit 20 measures the wet density and moisture content of the mud in the chamber 13 by directly inserting a portable single-hole density meter / moisture meter into the chamber 13. The measuring section 20 is provided above the center in the height direction of the partition wall 12, but may be provided below the center. The scaler 21 supplies power to the probe, performs counting based on the detection signal obtained from the measuring unit 20, and outputs the measurement result.

[0014] FIG. 2 is a cross-sectional view showing an example of the configuration of the measuring unit 20. As shown in FIG. FIG. 2A is a cross-sectional view showing the configuration of the measurement unit 20 when the cutter device 15 is performing excavation, and FIG. 2B is a cross-sectional view showing the configuration of the measurement unit 20 when measuring the wet density and moisture content while the shield is stopped.

[0015] In FIG. 2A, the case portion 201 is attached to the partition wall 12. 2A, guide pipe 204 has been pulled out from the opening of case part 201. A screw is formed on the inner periphery of the end of mounting jig 203 opposite to the end attached to partition wall 12, and sealing part 202 is attached and closed. This prevents mud or moisture in chamber 13 from flowing out from chamber 13 to the front side of partition wall 12 during excavation. 2B, when the shielding is stopped, the sealing part 202 is removed and a mounting jig 203 is attached. A screw is formed at the end of the mounting jig 203 that is attached to the partition wall 12, so that the mounting jig 203 can be attached to the case part 201. A guide tube 204 is inserted from the opening at the other end of the mounting jig 203 so as to reach the inside of the chamber 13. An RI (radioisotope) device 210 is inserted into the inner circumference of the guide tube 204.

[0016] The guide tube 204 has a cylindrical shape. One end of the guide tube 204 is closed so as to be continuous with the outer periphery, and the other end is open. The thickness of the guide pipe 204 is about several mm (for example, about 3 to 6 mm). Here, the guide pipe 204 is configured as a separate member from the partition wall, so that the thickness can be set to a thickness different from that of the partition wall. In addition, a water-stop rubber 205 is provided on the inner circumference of the mounting jig 203, and when the guide pipe 204 is inserted into the mounting jig 203 from the closed end, the mounting jig 203 and the guide pipe 204 are tightly fitted together so that no gap is generated between them. This makes it possible to completely stop water from leaking out from between the mounting jig 203 and the guide pipe 204. The water-stop rubber 205 may be made of a flexible material other than rubber as long as it is a water-stop mechanism that can ensure water-stopping between the guide pipe 204 and the mounting jig 203.

[0017] Also, the guide pipe 204 is attached so as to penetrate the partition wall 12 by being attached so as to penetrate the case part 201 and the attachment jig 203, but it may be attached without using the case part 201 and the attachment jig 203. In this case, it is preferable to provide a water stop mechanism so that mud and water in the chamber 13 do not flow out from between the partition wall 12 and the guide pipe 204.

[0018] The RI device 210 is inserted into the inner circumference of the guide tube 204. A density meter / moisture meter source unit 211 is arranged at the tip of the RI device, a density meter / moisture meter probe 212 is arranged next to the tip, and an extension rod 213 is arranged after the density meter / moisture meter probe 212. A signal indicating the result of measurement by the RI device 210 is output to the scaler 21 via a cable 215.

[0019] FIG. 3 is a schematic functional block diagram showing the configuration of the mud evaluation system S. The mud evaluation system S includes an RI device 210, a scaler 21, and an evaluation device 100. The RI device 210 is connected to the scaler 21 , measures the wet density and water content of the mud present in the chamber 13 , and outputs the measurement results to the scaler 21 . The scaler 21 is connected to the RI device 210 and the evaluation device 100 , acquires measurement results from the RI device 210 , and outputs them to the evaluation device 100 . The evaluation device 100 is connected to the scaler 21. The evaluation device 100 includes a storage unit 101, an input unit 102, a first acquisition unit 104, a second acquisition unit 105, and an output unit 106. The memory unit 101 stores evaluation data representing the relationship between the combination of wet density and moisture content and the measured flow characteristics based on the results of measurement of the flow characteristics when the wet density and moisture content of the sample to be measured are adjusted. The evaluation data is data representing a contour diagram generated according to a distribution of values ​​representing flow characteristics based on the relationship between wet density and moisture content. A table flow value may be used as a value representing the flow characteristics. Moreover, a mini-slump value may be used as a value representing the flow characteristics.

[0020] The input unit 102 receives input of a table flow value or a mini-slump value based on the operation contents from an operator such as an engineer. When obtaining a table flow value, the input unit 102 obtains data of a combination of the table flow value, wet density, and moisture content. When obtaining a mini-slump value, the input unit 102 obtains data of a combination of the mini-slump value, wet density, and moisture content. The input unit 102 may be at least one of an input device such as a mouse, a keyboard, a touch panel, etc., and may acquire the table flow value or the mini-slump value by accepting an operation from an operator. The input unit 102 may also accept an input by receiving the table flow value or the mini-slump value transmitted from an external device of the evaluation device 100 via a communication line.

[0021] The data processing unit 103 generates a contour diagram based on the data input from the input unit 102. For example, the data processing unit 103 generates a contour diagram by generating two-dimensional distribution data for the table flow value corresponding to the wet density and moisture content based on the table flow value, wet density, and moisture content input from the input unit 102. The data processing unit 103 may also generate a contour diagram by generating two-dimensional distribution data for the mini-slump value corresponding to the wet density and moisture content based on the mini-slump value, wet density, and moisture content input from the input unit 102.

[0022] The first acquisition unit 104 acquires the wet density and moisture content measured by a measuring instrument that measures the wet density and moisture content of mud in a chamber of the shield excavator SE. The first acquisition section 104 sequentially acquires the measurement results in response to sequential measurements made by the RI device 210 during the period when the shield excavator SE is halting excavation.

[0023] The second acquisition unit 105 acquires, from the evaluation data stored in the storage unit 101, flow characteristics corresponding to the acquired combination of wet density and moisture content. When the first acquisition unit 104 obtains a measurement result, the second acquisition unit 105 obtains a flow characteristic according to the obtained measurement result.

[0024] The output unit 106 outputs the evaluation data acquired by the second acquisition unit 105. The output unit 106 can be communicatively connected to an external device by wire or wirelessly, and may output the evaluation data to the connected external device. The external device may be any of a computer, a smartphone, and the like. These external devices may be used by engineers, workers, and the like involved in construction at a construction site where excavation is performed by the shield excavator 10. This allows the engineers and workers to understand the properties of the mud in the chamber 13 by checking the evaluation data displayed on the display screen of the external device. Furthermore, the output unit 106 may be any unit that outputs the evaluation data. For example, the output unit 106 may be a display device, and the evaluation data may be output by being displayed on a display screen of the display device.

[0025] The above-mentioned evaluation device 100 may be configured by one computer, or may be configured by a cloud server. The storage unit 101 is configured with a storage medium, for example, a hard disk drive (HDD), a flash memory, an electrically erasable programmable read only memory (EEPROM), a random access read / write memory (RAM), a read only memory (ROM), or any combination of these storage media. The storage unit 101 may be, for example, a non-volatile memory. The input unit 102, data processing unit 103, first acquisition unit 104, second acquisition unit 105, and output unit 106 may be configured, for example, as a processing unit such as a CPU (Central Processing Unit) or a dedicated electronic circuit.

[0026] FIG. 4 is a flowchart illustrating the operation of the mud evaluation system S. The input unit 102 of the evaluation device 100 receives an input of a table flow value measured for a target sample after the density and moisture content of the target sample have been adjusted in advance. The target sample is mud obtained from the chamber 13. When obtaining the mud in the chamber 13, the mud may be obtained by transporting the mud by the screw conveyor 16 while the shield of the shield excavator 10 is stopped. A plurality of lumps are taken out from the mud obtained in this manner, and each lump is adjusted to have a different wet density and moisture content. Then, a table flow test is performed for each adjusted mud lump to obtain a table flow value. When different types of mud are obtained from the chamber 13, such an experiment to obtain a table flow value is performed for each type of mud. The table flow value can be used as a value representing the flow characteristics of the mud in the chamber 13, and can also be used as a main required performance related to the plastic flow characteristics of the mud. The table flow value thus obtained, and the wet density and water content of the mud lump from which the table flow value was obtained, can be used as values ​​for evaluating the mud properties in the chamber. Here, a guideline for judging the table flow value that can ensure the plastic flow characteristics of the mud is, for example, 105 mm to 160 mm. The table flow test is carried out by vibrating the target sample (here, mud obtained from inside the chamber 13) on a flow table. Here, the maximum diameter (mm) of the spread of the target sample after a prescribed number of vibrations is used as the table flow value. Here, the same or different table flow values ​​can be obtained depending on the combination of wet density and moisture content of the mud lump. The operator inputs multiple combinations of wet density, moisture content, and table flow value obtained in this way for each type of mud through the input unit 102.

[0027] When a plurality of combinations of wet density, moisture content, and table flow value are input from the input unit 102, the data processing unit 103 generates two-dimensional distribution data for the table flow value corresponding to the wet density and moisture content for each mud type based on the wet density, moisture content, and table flow value (step S102), and stores the generated two-dimensional distribution data in the storage unit 101 (step S103). The data processing unit 103 may display a contour diagram on the display screen by the output unit 106 based on the two-dimensional distribution data generated in this way.

[0028] FIG. 5 is a diagram showing an example of a contour diagram generated by the data processing unit 103. As shown in FIG. Fig. 5A is a contour diagram showing an example of evaluation of a measurement target sample (clay soil) based on the table flow value, and Fig. 5B is a contour diagram showing an example of evaluation of a measurement target sample (sandy soil) based on the table flow value. Thus, when the type of mud is different, the two-dimensional distribution data (contour diagram) is also different.

[0029] Here, the case where the flow characteristics of mud are evaluated using the table flow value has been described, but the flow characteristics of mud may also be evaluated using the mini-slump value. That is, the mini-slump value may be measured by carrying out a mini-slump test on the mud obtained from inside the chamber 13. The mini-slump value is measured by filling the mini-slump cone with the target sample and then gently and continuously pulling the mini-slump cone up vertically. Thereafter, the sagging of the target sample is measured at the center, and this is taken as the mini-slump value. Here, either the table flow value or the mini-slump value may be used to evaluate the fluidity characteristics of the mud, or the table flow value and mini-slump value may be used in combination to evaluate the fluidity characteristics of the mud.

[0030] In this way, by storing the mud in chamber 13 by type as a value for evaluating the flow characteristics, when a new face is excavated by the shield tunneling machine SE and the same type of mud is obtained, the two-dimensional distribution data stored in memory unit 101 can be referenced.

[0031] Fig. 6 is a diagram showing the grain size accumulation curves of the measurement target sample. Fig. 6 shows the grain size accumulation curve for clayey soil, which is the type of the measurement target sample shown in Fig. 5A, and the grain size accumulation curve for sandy soil.

[0032] Next, when the shield excavator SE excavates the face in a certain section and stops excavation, the first acquisition unit 40 acquires the measurement results measured by the RI device 210 during the period when excavation is stopped (step S104). Here, the RI device 210 performs measurements at a certain measurement interval and sequentially outputs the measurement results each time a measurement is performed. As a result, the measurement results of the RI device 210 are output to the evaluation device 100 via the scaler 21. The first acquisition unit 40 sequentially acquires the measurement results output each time a measurement is performed by the RI device 210. The measurement results obtained from the RI device 210 via the scaler 21 are the wet density and water content of the mud present in the chamber 13.

[0033] Here, Fig. 6 is a graph showing the grain size accumulation curves of the measurement target samples, with the horizontal axis representing grain size and the vertical axis representing the passing rate. Fig. 6 also shows grain size accumulation curves for each of the two types of samples (clay soil and sandy soil) shown in Fig. 5. The radiation (gamma ray and neutron ray) count rate is measured for the measurement sample shown in Figure 6, and the radiation count rate ratio (radiation count rate / standard count rate) is calculated. The radiation count rate is a value excluding the background. The standard count rate is a value that takes into account the measurement date (half-life) from the standard value of the radiation source.

[0034] 7A is a graph showing the relationship between the measurement results of the gamma ray count rate ratio and the wet density, and FIG. 7B is a graph showing the relationship between the measurement results of the neutron count rate ratio and the moisture content. As shown in these figures, the measurement results confirmed a very high correlation between the gamma ray count rate ratio and the wet density, and between the neutron count rate ratio and the moisture content. Therefore, it was found that the wet density and moisture content of the measurement target sample can be calculated from the measurement results of the radiation count rate. In this way, the RI device 210 can measure the wet density and moisture content.

[0035] The RI device 210 can also measure radiation in the mud inside the chamber 13, which is on the opposite side of the guide tube. The thickness of the guide tube is about several mm. Therefore, by measuring radiation through a guide tube of about several mm, there is an advantage in that the measurement accuracy of density and water content can be maintained.

[0036] Next, when the first acquisition unit 104 obtains the wet density and moisture content as the measurement results, the second acquisition unit 105 obtains the flow characteristics corresponding to the combination of the obtained wet density and moisture meter by reading out the evaluation data (two-dimensional distribution data) stored in the memory unit 101 (step S105). For example, the second acquisition unit 105 reads out the table flow value corresponding to the combination of the wet density and moisture meter. The output unit 106 displays the read out table flow value on the display screen. This allows engineers and workers at the construction site to understand the properties of the mud in the chamber 13 by checking the displayed table flow value. Here, the wet density and moisture content of the measurement target sample are adjusted in advance, the table flow value is measured, and a contour diagram for property evaluation is created and stored in the memory unit 101. Therefore, while shield tunneling is stopped, the wet density and moisture content are successively measured by the RI device 210, and it is possible to continuously measure and evaluate the properties of the mud in the chamber 13 based on the measured wet density and moisture content (step S106).

[0037] According to the embodiment described above, it is possible to continuously measure and evaluate the properties of the mud under pressure in the chamber 13 during the period when the shield excavation machine SE stops excavating, without sampling the mud in the chamber 13. Since it is possible to continuously measure and evaluate, even if the properties of the mud in the chamber 13 change over time, it is possible to grasp the tendency. For example, it is possible to grasp whether or not a situation is occurring in which the mud in the chamber 13 separates and settles over time.

[0038] Furthermore, according to the method for measuring and evaluating mud properties in the above-described embodiment, radiation measurements are performed through a guide tube with a thickness of approximately a few mm, which prevents a decrease in measurement accuracy and makes it possible to continuously measure and evaluate the mud properties under pressure within the chamber while shield excavation is halted.

[0039] Also, methods have been proposed for indirectly evaluating the properties of mud under pressure in a chamber as mechanical load (e.g., Patent Nos. 6905364 and 6678438), but these methods are unable to measure physical indicators that are directly related to the mud properties, such as the wet density and moisture content of the mud under pressure in a chamber. In contrast, according to this embodiment, physical indicators that are directly related to the mud properties, such as the wet density and moisture content, can be measured for mud under pressure in the chamber 13.

[0040] There are also devices (e.g., Patent No. 7066907) that use radiation (gamma rays or neutron rays) to measure the density and moisture properties of the soil filled in the chamber of a shield excavator, but these are used to grasp the soil density (e.g., the amount of mixed bubbles) and are not used to evaluate the soil properties (flow properties). In addition, the radiation measurement device measures the soil through a steel plate about 25 mm thick, which is thinner than the chamber partition wall, which is generally about 40 to 60 mm thick, and therefore the measurement accuracy is reduced. In contrast, in this embodiment, radiation measurement can be performed through a guide tube about several mm thick, making it possible to prevent the measurement accuracy from decreasing.

[0041] The evaluation device 100 in the above-described embodiment may be realized by a computer. In that case, a program for realizing this function may be recorded in a computer-readable recording medium, and the program recorded in the recording medium may be read into a computer system and executed to realize the function. The term "computer system" as used herein includes hardware such as an OS and peripheral devices. The term "computer-readable recording medium" refers to portable media such as flexible disks, optical magnetic disks, ROMs, and CD-ROMs, and storage devices such as hard disks built into a computer system. The term "computer-readable recording medium" may also include a medium that dynamically holds a program for a short period of time, such as a communication line when a program is transmitted via a network such as the Internet or a communication line such as a telephone line, and a medium that holds a program for a certain period of time, such as a volatile memory inside a computer system that is a server or client in that case. The above-described program may be a program for realizing a part of the above-described function, or may be a program that can realize the above-described function in combination with a program already recorded in the computer system, or may be a program that is realized using a programmable logic device such as an FPGA (Field Programmable Gate Array).

[0042] The "Sustainable Development Goals (SDGs)" are 17 international goals that were adopted at the United Nations Summit in September 2015. The mud evaluation system according to this embodiment can contribute to the achievement of one of the 17 SDGs, for example goal 9 "Build resilient infrastructure, promote industry, innovation and infrastructure."

[0043] Although an embodiment of the present invention has been described in detail above with reference to the drawings, the specific configuration is not limited to this embodiment, and designs that do not deviate from the gist of the present invention are also included. [Explanation of symbols]

[0044] 10...Shield drilling machine, 11...Skin plate, 12...Bulkhead, 13...Chamber, 14...Agitator, 15...Cutter device, 16...Screw conveyor, 17...Conveyor, 20...Measurement unit, 21...Scaler, 40...First acquisition unit, 100...Evaluation device, 101...Memory unit, 102...Input unit, 103...Data processing unit, 104...First acquisition unit, 105...Second acquisition unit, 106...Output unit, 201...Case unit, 202...Sealing unit, 203...Jig, 204...Guide tube, 205...Waterstop rubber, 210...RI equipment, 211...Density meter / moisture meter source unit, 212...Density meter / moisture meter probe, 213...Extension road, 215...Cable, S...Mud evaluation system

Claims

1. a storage unit that stores evaluation data representing a relationship between a combination of a wet density and a moisture content of a sample to be measured and the measured flow characteristics, based on a result of measurement of the flow characteristics in a state in which the wet density and moisture content of the sample are adjusted; A first acquisition unit that acquires the wet density and the moisture content measured by a measuring device that measures the wet density and the moisture content of the mud in the chamber of the shield excavator; A second acquisition unit that acquires flow characteristics corresponding to the combination of the acquired wet density and moisture content from the evaluation data stored in the storage unit; A mud evaluation system having:

2. The evaluation data is data representing a contour diagram generated according to a distribution of values ​​representing flow characteristics based on a relationship between wet density and moisture content. The mud evaluation system according to claim 1 .

3. The table flow value is used as the value representing the flow characteristics. The mud evaluation system according to claim 2 .

4. The mini-slump value is used as a value representing the flow characteristics. The mud evaluation system according to claim 2 .

5. The first acquisition unit sequentially acquires measurement results in response to sequential measurements by the measuring instrument during a period when the shield excavator is stopped excavating, When the measurement result is obtained by the first acquisition unit, the second acquisition unit acquires a flow characteristic according to the obtained measurement result. The mud evaluation system according to any one of claims 1 to 4.

6. A guide tube is attached to penetrate the partition that forms the chamber, and the measuring device is inserted into the guide tube. The mud evaluation system according to claim 5.

7. On the computer, A step of storing evaluation data in a storage unit, the evaluation data representing a relationship between a combination of the wet density and the moisture content of the sample to be measured and the measured flow characteristics, based on the results of the measurement of the flow characteristics in a state in which the wet density and the moisture content of the sample to be measured are adjusted; Obtaining the wet density and moisture content of the mud in the chamber of the shield machine by a measuring device for measuring the wet density and moisture content of the mud; Obtaining flow characteristics corresponding to the combination of the obtained wet density and moisture content from the evaluation data stored in the memory unit; A mud evaluation method that performs the above.

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