Additive selection system and additive selection method

Abstract

To select an additive effective for the plastic fluidization of excavated soil.SOLUTION: An additive selection system comprises: an acceleration sensor 14 that measures the vibration acceleration during excavation of a cutter head 13 at a working face; a vibration-acceleration-data-displaying part 22 that displays the vibration acceleration data measured with the acceleration sensor 14 as a vibration acceleration distribution being distributed on the circumferential direction of a circle; and a vibration-acceleration-data-processing part 31 that estimates soil property at the working face according to the vibration-acceleration-data-displaying-part 22 and selects an additive suitable for the estimated soil property. When there are change points 23a in the vibration waveform of the vibration acceleration distribution, the soil property in the area marked off with boarder lines 23b that are straight lines connecting the change points 23a is estimated, and an additive suitable for the dominating soil property that is determined by obtaining each area size is selected. When there is no change point 23a, an additive suitable for the soil property estimated from the vibration waveform of the vibration acceleration data is selected.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a system and method for selecting an additive, and in particular to a technology for managing the plastic fluidity of soil and sand that has been excavated at a tunnel face and taken into a chamber. [Background technology]

[0002] A shield tunneling machine is a machine that forms an excavation hole in the ground by pressing a cutter plate attached to the front of the machine body against the face of the ground and rotating it while moving forward. The earth and sand excavated by the cutter plate is stirred and mixed with additives in a chamber attached to the rear of the cutter plate, and then discharged from the rear of the machine body.

[0003] In recent years, tunnel construction work, especially in urban areas, has become significantly longer in distance. Although the general distribution of the ground to be excavated by a shield machine is known through prior boring surveys and other methods (soil columnar diagrams), there is a possibility that unexpected changes or unanticipated ground conditions may occur during the actual excavation work.

[0004] Here, the shield tunneling machine resists the earth pressure from the face with the pressure of the excavated soil taken into the chamber, and stabilizing the plastic fluidity allows the pressure inside the chamber to be kept constant, stabilizing the ground. Therefore, in shield tunneling, stabilizing the plastic fluidity of the excavated soil is important for efficient excavation work. If the excavated soil becomes too plastic, it will adhere to the inner walls and clog, slowing the excavation speed. Conversely, if the excavated soil becomes too fluid, it will erupt on the screw conveyor and reduce the pressure inside the chamber.

[0005] Additives are used to stabilize the plastic flow of excavated soil, but the type of additive that is effective varies depending on the soil type, so it is important to understand the type of soil that has been taken into the chamber.Today, before shield construction, ground surveys are conducted and the condition of the ground is predicted from soil columnar diagrams, and during excavation work, the condition of the ground at the current location is estimated.

[0006] This type of work does not allow for real-time changes in the soil layers, and it is difficult to grasp the soil quality and stabilize the plastic flow properties of the excavated soil.

[0007] The present applicant has proposed a technique for measuring vibration acceleration occurring on the outer periphery of a cutter during excavation and estimating the soil quality of the working face from the measured vibration acceleration data (Patent Documents 1 and 2). [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-003429 [Patent Document 2] Japanese Patent Application Laid-Open No. 2016-003430 Summary of the Invention [Problem to be solved by the invention]

[0009] According to the techniques described in the above-mentioned Patent Documents 1 and 2, it is believed that it is possible to estimate the soil quality of the face currently being excavated by the cutter and select an effective additive based on the estimated soil quality.

[0010] However, the soil quality of the ground at the face is not always the same across the entire surface, and there are also cases where the soil quality differs in parts of the face (for example, above and below). In such cases, it is necessary to use additives that are effective for each type of soil.

[0011] The present invention has been made in light of the above-mentioned technical background, and aims to provide a technology that enables the selection of an effective additive for plastically fluidizing the soil and sand that has been taken into the chamber by excavating the face. [Means for solving the problem]

[0012] In order to solve the above-mentioned problems, the system for selecting additives according to the invention of claim 1 is a system for selecting additives for excavating a face by rotating a cutter board on which a plurality of cutters are attached and plastically fluidizing the soil and sand taken into a chamber, and includes: an acceleration measuring means that is installed on the cutter board or the cutter and that measures vibration acceleration when the face is excavated by the cutter board; a vibration acceleration data display unit that displays vibration acceleration data measured by the acceleration measuring means for each rotation angle of the cutter board as a vibration acceleration distribution distributed in the circumferential direction of a circle that imitates the face cross section; and a vibration acceleration data processing unit that estimates the soil quality of the face from the vibration acceleration data display unit and selects additives according to the estimated soil quality, and The processing unit is characterized in that, if there is a change point in the state of the vibration waveform in the vibration acceleration distribution displayed on the vibration acceleration data display unit, it sets a boundary line connecting the change points with a straight line, estimates the soil quality of each area separated by the boundary line from the vibration waveform of the vibration acceleration data, calculates the area of each area, determines a dominant soil quality, which is the soil quality that has a large impact on the plastic flow rate of the excavated soil, from the ratio of the soil quality and area of each area, and executes a first process to select an additive material according to the determined dominant soil quality, and if there is no change point in the state of the vibration waveform in the vibration acceleration distribution displayed on the vibration acceleration data display unit, it executes a second process to estimate the soil quality of the face from the vibration waveform of the vibration acceleration data, and selects an additive material according to the estimated soil quality.

[0013] The additive selection system of the invention described in claim 2 is characterized in that, in the invention described in claim 1, the vibration acceleration data processing unit determines the dominant soil type to be gravelly soil if the proportion of the area of soil estimated to be gravelly soil in the first processing exceeds a predetermined proportion, and selects an additive appropriate for the gravelly soil.

[0014] The system for selecting an additive according to the invention described in claim 3 is characterized in that, in the invention described in claim 2, the predetermined ratio is 30%.

[0015] The additive selection system according to the invention described in claim 4 is characterized in that, in the invention described in claim 2, the vibration acceleration data processing unit, when the area proportion of the soil estimated to be gravelly soil in the first processing is equal to or less than a predetermined proportion, determines the soil estimated to be clayey soil or sandy soil, whichever has the larger area proportion, as the dominant soil quality, and selects an additive according to the determined dominant soil quality.

[0016] The additive selection system of the invention described in claim 5 is characterized in that, in the invention described in claim 1, the acceleration measuring means measures vibration acceleration every one ring width or every half ring width in the annular segment assembly.

[0017] In order to solve the above problem, the method for selecting an additive according to the invention described in claim 6 is a method for selecting an additive for excavating a face by rotating a cutter plate equipped with multiple cutters and plastically fluidizing the soil and sand taken into a chamber, the method comprising the steps of: measuring the vibration acceleration of the cutter plate when the face is excavated with the cutter plate; displaying the vibration acceleration data for each rotation angle of the cutter plate as a vibration acceleration distribution distributed in the circumferential direction of a circle simulating the face cross section; if there is a change point in the state of the vibration waveform in the vibration acceleration distribution, setting boundaries connecting the change points with straight lines; estimating the soil quality of each region separated by the boundaries from the vibration waveform of the vibration acceleration data and calculating the area of each region; determining a dominant soil quality, which is the soil quality that has a large impact on the plastic flowability of the excavated soil, from the ratio of the soil quality and area of each region; and performing a first process of selecting an additive according to the determined dominant soil quality; and if there is no change point in the state of the vibration waveform in the vibration acceleration distribution, performing a second process of estimating the soil quality of the face from the vibration waveform of the vibration acceleration data and selecting an additive according to the estimated soil quality. [Effects of the Invention]

[0018] According to the present invention, it is possible to select an additive that is effective in plastically fluidizing the excavated soil and sand taken into the chamber, not only when the soil quality of the ground at the face excavated by the cutter is the same across the entire surface, but also when the soil quality is different in parts of the face. [Brief explanation of the drawings]

[0019] [Figure 1] 1 is an explanatory diagram showing an additive selection system according to an embodiment of the present invention; [Figure 2] FIG. 1 is a front view of a cutter head attached to the front of a shield machine. [Figure 3] 3A is an enlarged cross-sectional view taken along line AA in FIG. 2, and FIG. 3B is an enlarged cross-sectional view taken along line BB in FIG. [Figure 4] FIG. 3(b) is an enlarged side view of part B in FIG. [Figure 5] FIG. 10 is an explanatory diagram showing the measurement direction of cutting vibration data by an acceleration sensor. [Figure 6] (a) is an explanatory diagram of the display screen with the vibration acceleration data display section and boundary line display section, and (b) is an explanatory diagram of the screen that predicts the soil distribution of the ground ahead of the face in the excavation direction. [Figure 7] 1 is a flowchart showing a procedure for selecting an additive according to an embodiment of the present invention. [Figure 8] 8 is a flowchart showing the procedure for determining the controlling soil quality in the selection procedure of FIG. 7. DETAILED DESCRIPTION OF THE INVENTION

[0020] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. In the drawings for explaining the embodiment, the same components are generally designated by the same reference numerals, and repeated description thereof will be omitted.

[0021] Figure 1 shows an additive selection system 10 according to one embodiment of the present invention. The additive selection system 10 shown in Figure 1 is used in shield construction, for example, to build a shield tunnel using an earth pressure type shield machine 11. The additive selection system 10 shown in Figure 1 is used to select an additive that is effective for plastically fluidizing the excavated soil and sand that has been taken into a chamber 19 formed behind the cutter head 13 by understanding in real time the condition of the ground 12a, 12b, 12c at the working face 12 that is being excavated by the rotation of a cutter head (cutter machine) 13 equipped with multiple cutters 16.

[0022] For example, in urban areas, construction of long-distance shield tunnels is desired not only with large-diameter shield machines but also with small- and medium-diameter shield machines due to issues such as shaft space constraints and the congestion of the ground and underground buried objects. Furthermore, when constructing long-distance shield tunnels, it is expected that the shield machine will often excavate not only ground consisting of a single soil type, but also the boundary areas of layered soils 12a, 12b, and 12c of different soil types. Therefore, the additive selection system 10 of this embodiment has a function to accurately identify the soil types (e.g., gravel, sand, and clay) of the grounds 12a, 12b, and 12c even when different soil types appear simultaneously at the excavation face 12. This enables the selection of an additive effective for plastic fluidizing the excavated soil and sand taken into the chamber 19 formed behind the cutter head 13.

[0023] The additive selection system 10 of this embodiment measures the vibration acceleration (ground response acceleration during excavation) when the cutter 16 is used to excavate the face, using an acceleration sensor (acceleration measuring means) 14 attached to the cutter head 13 or the cutter 16 (near the roller cutter 16a, inside the cutter bit 16c, which is the leading bit), so that the soil quality of the ground 12a, 12b, 12c at the face 12 during excavation can be accurately grasped in real time and across the entire surface, while (preferably) referring to a columnar diagram of the surrounding ground and the properties of the excavated soil and sand, as necessary.

[0024] In the present application, the cutter 16 is a general term for the roller cutter 16a and the cutter bit 16c. The shapes of the roller cutter 16a and the cutter bit 16c are not particularly limited.

[0025] More specifically, the system 10 for selecting an additive according to this embodiment includes an acceleration sensor 14 attached to the outer periphery of the cutter head 13 and a computer 20 connected to the acceleration sensor 14 .

[0026] The computer 20 is equipped with a vibration acceleration data storage unit 21 that stores vibration acceleration data measured by the acceleration sensor 14 (vibration acceleration data when the cutting face 12 is excavated by the cutter 16 provided on the cutter head 13) for each predetermined rotation angle of the cutter head 13, a vibration acceleration data display unit 22 that displays the vibration acceleration data for each rotation angle stored in the vibration acceleration data storage unit 21 as a vibration acceleration distribution 23 distributed in the circumferential direction of a circle that resembles the cutting face cross section, and a vibration acceleration data processing unit 31 that estimates the soil quality of the cutting face from the vibration acceleration data display unit 22 and selects an additive material according to the estimated soil quality.

[0027] The vibration acceleration data processing unit 31 then collects the vibration acceleration data for each rotation angle stored in the vibration acceleration data memory unit 21 for an excavation span equivalent to one ring width in the annular segment assembly that makes up the shield tunnel, and from the vibration change point 23a, which is the point where the state of the vibration waveform in the circumferential vibration acceleration distribution of the circle that resembles the face cross section displayed on the vibration acceleration data display unit 22 clearly changes, estimates the soil quality of each layer in the layer structure by distinguishing the boundary parts of different soil qualities and the vibration waveform on the face 12, and selects an additive that is effective for plastically fluidizing the excavated soil and sand taken into the chamber 19.

[0028] The vibration acceleration data processing unit 31 includes a boundary line display unit 32a, a soil quality estimation unit 32b, and an additive selection unit 32c.

[0029] When there is a change point 23a in each of the vibration acceleration distributions 23 in the circumferential direction of the circles simulating the multiple face cross sections displayed by the vibration acceleration data display unit 22, the boundary display unit 32a sets a boundary line 23b connecting a pair of change points 23a with a straight line, and displays the boundary line 23b as a boundary portion of different soil types at the face cross section of the ground 12a, 12b, 12c of the face 12 (see FIG. 6(a)). Next, the soil quality estimation unit 32b estimates the soil quality of each region separated by the boundary lines 23b in this manner from the vibration waveform of the vibration acceleration data measured by the acceleration sensor 14. Then, the additive material selection unit 32c determines a controlling soil quality, which is a soil quality that has a large influence on the plastic flow rate of the excavated soil, based on the soil quality of each region estimated by the soil quality estimation unit 32b and the area ratio of each region separated by the boundary lines 23b, and performs a process (first process) of selecting an additive material according to the determined controlling soil quality.

[0030] On the other hand, if there is no change point 23a in each vibration acceleration distribution 23 in the circumferential direction of the circle simulating a plurality of face cross sections displayed by the vibration acceleration data display unit 22, processing (display as a soil boundary portion) is not performed by the boundary display unit 32a. The soil quality estimation unit 32b estimates the soil quality of the face from the vibration waveform of the vibration acceleration data. Then, the additive material selection unit 32c executes processing (second processing) to select an additive material according to the soil quality estimated by the soil quality estimation unit 32b.

[0031] In this embodiment, the additive selected by the vibration acceleration data processing unit 31 (additive selected according to the estimated soil quality) is used. However, the additive does not have to be an additive selected in this manner. For example, the vibration acceleration data processing unit 31 may adjust the proportion of the additive according to the area ratio based on the soil quality of each region estimated by the soil quality estimation unit 32b and the area ratio of each region separated by the boundary line 23b. Alternatively, the additive may be selected according to the soil quality expected from a columnar diagram of the surrounding ground, the properties of the excavated soil, etc.

[0032] The vibration acceleration data processing unit 31 further includes a forward soil distribution prediction unit 32d. This forward soil distribution prediction unit 32d predicts the soil distribution of the ground 12a, 12b, 12c ahead of the working face 12 in the excavation direction from the tendency for the position of the vibration change point 23a in the vibration acceleration distribution 23 displayed on the vibration acceleration data display unit 22 to displace in the excavation direction at multiple excavation spans on the leading edge side of the excavation direction (see Figure 6(b)).

[0033] In this embodiment, an auxiliary acceleration sensor 18 connected to a computer 20 is attached to the back of a partition wall 17 provided on the main body 15 of the shield machine 11. The vibration acceleration data display unit 22 uses the vibration data of the main body 15 sent from the auxiliary acceleration sensor 18 to remove noise and mechanical vibrations, and then displays the vibration acceleration data for each rotation angle as a circumferential vibration acceleration distribution 23.

[0034] As shown in Figure 1, the shield machine 11 is a mud pressure type shield machine, which is a sealed type shield machine. In the mud pressure type shield machine 11, a partition wall 17 is provided behind the cutter head 13 at the tip of the main body 15 to form a chamber 19 into which excavated earth and sand is taken in, and a center shaft 13a is provided to rotate the cutter head 13, supported by this partition wall 17. Inside the main body 15, a mud discharge mechanism, a rotary drive motor, a shield jack, an erector (none of which are shown), etc. are also provided.

[0035] The computer 20 constituting the additive selection system 10 functions as a database server, and can be, for example, a personal computer. The database server as the computer 20 is equipped with a CPU, ROM, RAM, I / F, storage means, input means, display means, output means, etc. The CPU of the database server controls the overall operation of the database server using the RAM as a work area in accordance with a control program stored in the ROM. Furthermore, by storing various computer programs in the ROM, the CPU functions as storage means, input means, display means, output means, etc., and also stores vibration acceleration data sent from the acceleration sensor 14 together with the rotation angle of the cutter head 13 in a vibration acceleration data storage unit 21, displays the vibration acceleration data stored in the vibration acceleration data storage unit 21 on a display 24 as a vibration acceleration distribution 23 distributed in the circumferential direction by a vibration acceleration data display unit 22, and displays the complex data displayed by the vibration acceleration data display unit 22. A boundary line 23b is set by connecting pairs of change points 23a of each vibration acceleration distribution 23 in the circumferential direction of a circle simulating the cross section of several tunnel face, and the boundary line display unit 32a displays the boundary line 23b on the display 24. The soil quality is estimated by the soil quality estimation unit 32b from the vibration waveform of the vibration acceleration data measured by the acceleration sensor 14. The additive material selection unit 32c executes a process to select an additive material from the soil quality estimated by the soil quality estimation unit 32b. The soil quality distribution of the ground 12a, 12b, 12c ahead of the tunnel face 12 in the excavation direction is predicted by the forward soil quality distribution prediction unit 32d.

[0036] The computer 20 also incorporates a shield tunneling management system that is capable of centrally managing measurement values collected from various measuring instruments used in the shield tunneling method and survey values entered via input means. The shield tunneling management system has functions such as centrally managing measurement values collected from various measuring instruments used in the shield tunneling method, organizing this information and providing it to engineers and workers to support on-site construction management, predicting the condition of the ground, the condition of excavated earth and sand, and the installation status of the shield tunneling machine based on changes over time and the results of statistical processing, and calculating the position of the shield tunneling machine and segments by inputting measurement results and determining the deviation from the baseline.

[0037] In this embodiment, computer 20 is installed in an operation control room 30 located on the ground, and computer 20 installed in operation control room 30 is connected to various measuring instruments, acceleration sensor 14, and auxiliary acceleration sensor 18, for example, via acceleration sensor amplifiers 25a and 25b, and via a transmission system 29 equipped with a control panel 26 made of PCL, a sequencer panel 27, a remote operation panel 28, etc.

[0038] Various types of acceleration sensors can be used for acceleration sensor 14 and auxiliary acceleration sensor 18 as sensors capable of measuring acceleration, which is the rate of change of velocity over time (time derivative). Acceleration sensors are used to measure the value of acceleration itself and detect the application of an external force, using the physical law that the acceleration acting on an object is proportional to the external force applied. Various types of acceleration sensors can be used for acceleration sensor 14 and auxiliary acceleration sensor 18, including those capable of detecting tilt, vibration, movement, impact, and fall, as well as for scientific experiments requiring high-precision measurements, gravity measurement, earthquake measurement, etc.

[0039] As shown in FIG. 3( a), the acceleration sensor 14 is attached to the cutter head 13 adjacent to, but spaced apart from, the roller cutter 16a, which is the cutter 16 located at the outermost periphery of the cutter head 13. That is, the acceleration sensor 14 is attached to the back surface of the roller cutter 16a located at the outermost periphery of the cutter head 13. By attaching the acceleration sensor 14 adjacent to, but spaced apart from, the roller cutter 16a located at the outermost periphery of the cutter head 13, it is possible to appropriately measure the ground response acceleration during excavation. This also simplifies maintenance of the acceleration sensor 14 and avoids interfering with the replacement of the roller cutter 16a. However, the attachment position of the acceleration sensor 14 is not limited to the present embodiment and may be other than the outer periphery of the cutter head 13. For example, as shown in FIG. 3(b), the acceleration sensor 14 can be attached to any position of the cutter 16 placed on the cutter head 13, such as by inserting and fixing it inside the cutter bit 16c (cutter 16) which is the leading bit.

[0040] In this embodiment, the acceleration sensor 14 is, for example, a triaxial piezoelectric acceleration measuring device, so that it can measure vibration acceleration data in three directions, preferably at least two directions perpendicular to each other. As shown in Figures 3 to 5, the acceleration sensor 14 is attached to the outer periphery of the cutter head 13 with the X direction, which is the first measurement direction, aligned with the circumferential direction R of the rotation of the cutter head 13 (see Figure 2), and the Y direction, which is the second measurement direction, aligned with the head surface of the cutter head 13 at the portion where the acceleration sensor 14 is attached, aligned with the rotation axis 16b (see Figure 3(a)) of the roller cutter 16a, which is, for example, a roller cutter, located at the outermost periphery of the cutter head 13. By aligning the first measurement direction X of the acceleration sensor 14 along the circumferential direction R of rotation of the cutter head 13 and the second measurement direction Y of the acceleration sensor 14 along a direction perpendicular to the head surface of the cutter head 13 where the acceleration sensor 14 is attached, it becomes possible to efficiently measure the ground response acceleration in the circumferential direction R of rotation using the first measurement direction X and the ground response acceleration in the excavation direction using the second measurement direction Y, and it becomes possible to obtain a more accurate vibration acceleration distribution 23 from these response accelerations. Note that the measurement directions X, Y, and Z are the same even when using the cutter bit 16c shown in Figure 3(b).

[0041] The acceleration sensor 14 is connected to an acceleration sensor amplifier 25a via a connection cable 14a (see FIG. 1). In this embodiment, the Z direction, which is the third measurement direction of the acceleration sensor 14, is a direction along the head surface of the cutter head 13 at the portion where the acceleration sensor 14 is attached, and is arranged in the direction of a rotation axis 16b (see FIG. 3(a)) of a roller cutter 16a, which is a roller cutter, arranged at the outermost portion of the cutter head 13.

[0042] Meanwhile, as shown in FIG. 1, auxiliary acceleration sensor 18 is attached to the back portion of partition wall 17, which separates chamber 19, as the inner wall surface of main body 15. Like acceleration sensor 14, auxiliary acceleration sensor 18 is a triaxial piezoelectric acceleration measuring device, and is attached to the back portion of partition wall 17 with its first measurement direction aligned with the excavation direction of shield machine 11 and its second measurement direction aligned with the circumferential direction R of rotation of cutter head 13. This makes it possible to efficiently and accurately measure and obtain specific vibration data caused by vibration of main body 15 when shield machine 11 is in operation. In addition, auxiliary acceleration sensor 18 is connected to acceleration sensor amplifier 25b via connection cable 18a. The main body vibration data from auxiliary acceleration sensor 18 is sent to computer 20 via acceleration sensor amplifier 25b and transmission system 29, and as described above, vibration acceleration data display unit 22 is able to display the vibration acceleration data for each rotation angle sent from acceleration sensor 14 as circumferential vibration acceleration distribution 23 with noise and mechanical vibrations removed.

[0043] Furthermore, in this embodiment, a tachometer (not shown), for example, made up of a rotary encoder, is attached to the center shaft 13a of the cutter head 13. The rotation angle measured by this tachometer is sent to the computer 20 via the transmission system 29, so that the vibration acceleration data measured by the acceleration sensor 14 when excavating the cutting face 12 can be stored in the vibration acceleration data storage unit 21 for each predetermined rotation angle.

[0044] According to this embodiment, the frequency Δθ of circumferential measurements by acceleration sensor 14 is determined by the formula Δθ=r / 60×Δt×360°, using the data collection time interval Δt and the rotational speed r (ppm) of cutter head 13. For example, if shield machine 11 is a small-diameter machine with an excavation outer diameter of about 2360 mm and has a fast rotational speed r=2.3 (ppm), the measurement frequency Δθ when the measurement time interval Δt is set to 0.1 seconds will be Δθ=2.3 / 60×0.1×360°, or 1.38°, and therefore acceleration sensor 14 will take a measurement every 1.38°.

[0045] In addition, in this embodiment, in order to grasp the circumferential position θ of the acceleration sensor 14 in the cutter head 13, a contact switch (not shown) is installed on the center shaft 13a of the cutter head 13, and for example, the top of the shield tunneling machine 11 can be set as the zero point, and a reset process can be performed every time this zero point is passed.

[0046] In this embodiment, the vibration acceleration data measured by the acceleration sensor 14 at each predetermined rotation angle is output via dedicated acceleration sensor amplifiers 25a, 25b together with main body vibration data measured by the auxiliary acceleration sensor 18 at the same timing as the measurement by the acceleration sensor 14. The output signals then pass through a control panel 26 and a sequencer panel 27, and are sent to the operation control room 30 via the same transmission system 29 as other excavation management data.

[0047] Now, the vibration acceleration data memory unit 21 stores the vibration acceleration data when the cutter 16 excavates the face 12, which is sent from the acceleration sensor 14 to the computer 20 during the excavation of each excavation span equivalent to one ring width in the annular segment assembly that makes up the shield tunnel, together with the ring number of each ring, for each predetermined rotation angle of the cutter head 13, corresponding to each excavation span.

[0048] In addition, when each excavation span equivalent to one ring width in the annular segment assembly that constitutes the shield tunnel is excavated, the vibration acceleration data memory unit 21 stores the main body vibration data caused by the main body 15 itself vibrating due to the drive of a rotary drive motor or the like when the cutter 16 excavates the face 12, which is sent from the auxiliary acceleration sensor 18 to the computer 20, along with the ring number of each ring, corresponding to each excavation span, for each predetermined rotation angle of the cutter head 13.

[0049] In this embodiment, for each excavation span equivalent to one ring width in the annular segment assembly that makes up the shield tunnel, measurement of this vibration acceleration data and main body vibration data begins, for example, when the jack stroke of the shield jack or thrust jack has progressed 100 mm from the start of excavation of the 1,000 mm excavation span equivalent to one ring width (more specifically, when the acceleration sensor 14 is positioned at the top of the cutter head 13 after progressing 100 mm), and continues while the cutter head 13 rotates five times, with the data obtained being the average of the measurements for the five rotations. This makes it possible to obtain measurement results for each one ring width in a more stable state.

[0050] In addition, these vibration acceleration data and main body vibration data are integrated in a chronological order with measurement values collected from various measuring instruments used in the shield tunneling method in a shield tunneling management system built into computer 20, and are stored as data linked to the ring number of each ring assembled using segments.

[0051] The vibration acceleration data display unit 22 displays the vibration acceleration data for each rotation angle stored in the vibration acceleration data storage unit 21 as a vibration acceleration distribution 23 distributed in the circumferential direction of a circle that resembles the cross section of the excavation face. That is, as shown in Fig. 6(a), the vibration acceleration data display unit 22 displays the distribution of magnitudes of vibration acceleration (ground response acceleration during excavation) for each rotation angle as vibration acceleration data for each rotation angle on the display 24 as a vibration acceleration distribution 23, with noise and mechanical vibrations removed using the main body vibration data sent from the auxiliary acceleration sensor 18. Furthermore, as shown in Fig. 6(b), the vibration acceleration data display unit 22 is capable of displaying multiple such circumferentially distributed vibration acceleration distributions 23 in succession for each excavation span equivalent to one ring width.

[0052] 6(a) is a display of the vibration acceleration distribution 23 on the display 24, which is a distribution of magnitudes of vibration acceleration based on vibration acceleration data in the X direction, which is the circumferential direction R of the rotation of the cutter head 13, as the measurement direction of the vibration acceleration data by the acceleration sensor 14, with noise and mechanical vibrations removed by the main body vibration data in the second measurement direction, which is the circumferential direction R of the rotation of the cutter head 13, measured by the auxiliary acceleration sensor 18. This makes it possible to display a vibration acceleration distribution 23 that more accurately reflects the condition of the ground 12a, 12b, 12c on the working face 12 being excavated by the cutter head 13.

[0053] In this embodiment, the boundary between different soil types in the ground at the working face 12 can be easily identified from the circumferential vibration acceleration distribution 23 shown in Figure 6(a) displayed by the vibration acceleration data display unit 22. That is, by observing the displayed circumferential vibration acceleration distribution 23, it is possible to identify vibration change points 23a, which are locations where the vibration distribution trend clearly changes. In the vibration acceleration distribution 23 in Figure 6(a), two vibration change points 23a can be identified on both the left and right sides. Then, by connecting the two change points 23a on each side, it is possible to identify the layer structure of the ground 12a, 12b, and 12c at the working face 12.

[0054] Furthermore, in this embodiment, a boundary line display unit 32a is provided that displays a boundary line 23b connecting each pair of vibration change points 23a on the left and right sides as a boundary portion between different soil types in the ground 12a, 12b, 12c of the working face 12. Therefore, by displaying the boundary line 23b by the boundary line display unit 32a, it becomes possible to more easily grasp the boundary portion between different soil types in the working face 12 and the layer structure of the ground 12a, 12b, 12c.

[0055] Then, the soil quality estimation unit 32b of the vibration acceleration data processing unit 31 estimates the soil quality of each layer of the identified layer structure by identifying the boundary portions of different soil qualities at the working face 12 and the vibration waveform.

[0056] Specifically, for example, when considering soil types such as gravelly soil (soil containing a large amount of gravel), sandy soil (soil with a large amount of sand), and clayey soil (fine-grained soil mainly composed of clay), when the cutter head 13 excavates the face, the gravelly soil experiences the greatest vibration, followed by the sandy soil and the clayey soil. Therefore, the vibration acceleration measured by the acceleration sensor 14 attached to the cutter head 13 is greatest for gravelly soil, and decreases in the order of sandy soil and clayey soil. Then, the vibration waveform in the vibration acceleration distribution 23 displayed by the vibration acceleration data display unit 22 is the largest amplitude waveform for gravelly soil, the next largest amplitude waveform for sandy soil, and the smallest amplitude waveform for clayey soil. Therefore, it is possible to estimate the soil type of each region from these characteristics of the vibration waveform in the vibration acceleration data measured by the acceleration sensor 14.

[0057] In FIGS. 1 and 6, the vibration waveform in the vibration acceleration data measured by the acceleration sensor 14 is a sawtooth wave, but it is not necessarily limited to a sawtooth wave, and for example, a waveform close to a sine wave is also possible.

[0058] Then, the additive material selection unit 32c of the vibration acceleration data processing unit 31 executes a first process in which the dominant soil quality, which is the soil quality that has a large influence on the plastic flow properties of the excavated soil, is determined based on the soil quality of each region estimated by the soil quality estimation unit 32b and the area ratio of each region separated by the boundary line 23b, and an additive material is selected according to the determined dominant soil quality.

[0059] As described above, if there is no change point 23a in each of the vibration acceleration distributions 23 in the circumferential direction of the circle simulating a plurality of face cross sections displayed by the vibration acceleration data display unit 22, the soil quality estimation unit 32b estimates the soil quality of the face from the vibration waveform of the vibration acceleration data.Then, the additive material selection unit 32c executes a second process of selecting an additive material according to the soil quality estimated by the soil quality estimation unit 32b.

[0060] Then, the additive selected in the first process or the second process is injected into the excavated soil taken into the chamber 19.

[0061] The additives used here include mineral-based additives (clay and bentonite), surfactant-based additives (foaming agents and penetrating agents), polymer-based additives (flocculants, composites, and dispersants), and natural polymer-based additives (thickeners). In this embodiment, bentonite is used to supplement the fine particles in the excavated soil, a foaming agent to ensure the fluidity of the excavated soil, and a dispersing agent to weaken the bonds between particles. The additives selected based on the soil type (determined dominant soil type and estimated soil type) are based on the injection rate (the injection ratio when the volume of excavated soil taken into chamber 19 is taken as 100%): for gravelly soil, 30% foaming agent and 15% bentonite; for sandy soil, 30% foaming agent and 8% bentonite; and for clayey soil, 30% foaming agent and 10% dispersant. Note that these additive types and injection rates are merely examples; in actual construction, they are selected based on the results of a preliminary survey of the ground to be excavated, and are not particularly limited. Furthermore, in this embodiment, a plurality of additives are used in combination, but a single additive may also be used.

[0062] Now, if there is a boundary where the soil type changes within the excavation range of the face, it is necessary to determine which soil type to use as an additive. Furthermore, the impact on the plastic flow of the excavated soil varies depending on the soil type. Therefore, in this embodiment, as described above, the soil type that has the greatest impact on the plastic flow of the excavated soil is determined as the dominant soil type, and an additive effective for this soil type is selected and the injection amount is adjusted. For example, if the area ratio of the region estimated to be gravelly soil exceeds 30%, the dominant soil type is determined to be gravelly soil, and an additive appropriate for the gravelly soil is selected. Furthermore, if the area ratio of the region estimated to be gravelly soil is 30% or less, the soil type with the larger area ratio of the remaining region is determined to be the dominant soil type, and an additive appropriate for sandy soil or clayey soil is selected.

[0063] It is advisable to estimate in advance based on columnar diagrams, etc., the combinations of soil types, the dominant soil type for each combination, and the proportion of the combination that is the dominant soil type, and adjust these in the early stages of construction.

[0064] Next, the procedure for selecting an additive in this embodiment will be described using the flowcharts of Figures 7 and 8. Here, Figure 7 is a flowchart showing the procedure for selecting an additive in one embodiment of the present invention, and Figure 8 is a flowchart showing the procedure for determining the controlling soil quality in the selection procedure of Figure 7.

[0065] In Figure 7, the shield tunneling machine 11 begins excavating (rotating the cutter head 13 to dig into the ground and injecting additives into the excavated soil taken into the chamber 19), and after the shield tunneling machine 11 has excavated one ring width of the segment assembly and then advanced a further 100 mm (step S01), the vibration acceleration when the cutter 16 attached to the rotating cutter head 13 excavates the face is measured by the acceleration sensor 14 (step S02).

[0066] Next, it is determined whether or not there is a change point in the vibration waveform in the circumferential vibration acceleration distribution of the circular vibration acceleration data displayed on the vibration acceleration data display unit 22 (step S03).

[0067] Then, in step S03, if it is determined that there are change points 23a in the vibration waveform (these are points where the soil quality changes, so there will be two or more change points), a boundary line 23b is drawn by connecting the pair of change points 23a with a straight line (step S04). As mentioned above, the boundary line 23b is a line that indicates the boundary portion of different soil quality at the face cross section of the ground 12a, 12b, 12c of the working face 12.

[0068] Next, for each region separated by boundary line 23b, the soil type is estimated from the vibration waveform of the vibration acceleration data measured by acceleration sensor 14 (step S05). As a specific example, the region with the largest amplitude waveform can be estimated as gravelly soil, the region with the next largest amplitude waveform as sandy soil, and the region with the smallest amplitude waveform as sandy soil. Next, the area ratio of each region is calculated (step S06). The area ratio of each soil type on the face is determined by the processing of steps S05 and S06.

[0069] Then, based on the estimated soil properties of each region and the area ratio of each region, the dominant soil property, which is the soil property that has the greatest influence on the plastic flow property of the excavated soil, is determined (step S07).

[0070] Here, in determining the dominant soil type, because gravelly soil is a soil type that has a significant impact on the plastic flowability of excavated soil, first, it is determined whether the area proportion of the area estimated to be gravelly soil exceeds 30% (step S07-1). If it is determined in step S07-1 that the area proportion of the area estimated to be gravelly soil exceeds 30%, the dominant soil type is determined to be gravelly soil (step S07-2). On the other hand, if it is determined in step S07-1 that the area proportion of the area estimated to be gravelly soil does not exceed 30% (i.e., if it is determined that the area proportion of the area estimated to be gravelly soil is 30% or less), it is determined whether the area proportion of the remaining area estimated to be clayey soil is greater than the area proportion of the area estimated to be sandy soil (step S07-3). If it is determined in step S07-3 that the area proportion of the area estimated to be clayey soil is greater, the dominant soil type is determined to be clayey soil (step S07-4). Furthermore, if it is determined in step S07-3 that the area proportion of the area estimated to be clayey soil is not large (i.e., if it is determined that the area proportion of the area estimated to be sandy soil is large), the dominant soil type is determined to be sandy soil (step S07-5).

[0071] Once the dominant soil quality has been determined using the above procedure, an additive is selected according to the determined dominant soil quality (step S08). In this embodiment, if the soil is determined to be gravelly, an additive with a foaming agent injection rate of 30% and a bentonite injection rate of 15% is selected; if the soil is determined to be sandy, an additive with a foaming agent injection rate of 30% and a bentonite injection rate of 8% is selected; and if the soil is clayey, an additive with a foaming agent injection rate of 30% and a dispersant injection rate of 10% is selected.

[0072] Finally, the selected additive is injected into the excavated soil and sand taken into the chamber 19 (step S09).

[0073] Thereafter, it is determined whether the shield machine 11 has excavated the planned working length (step S10), and if it is determined that it has not excavated the planned working length, the process returns to step S01, and if it is determined that it has excavated the planned working length, the process ends.

[0074] If it is determined in step S03 that there is no change point 23a in the vibration waveform, the soil type is estimated from the vibration waveform of the vibration acceleration data measured by the acceleration sensor 14 (step S11). As explained in step S06, the soil type is estimated based on the magnitude of the amplitude of the vibration waveform. Once the soil type has been estimated in step S11, the process proceeds to step S08, where an additive is selected according to the estimated soil type, and then the process proceeds to step S09 described above.

[0075] In this way, according to the additive selection system 10 of this embodiment, it is possible to select an additive that is effective in plastically fluidizing the excavated soil and sand taken into the chamber not only when the ground at the face excavated by the cutter head 13 has the same soil quality across the entire surface, but also when the soil quality is different in parts of the face.

[0076] In this embodiment, as shown in Fig. 6(b), the vibration acceleration data display unit 22 is further capable of extracting vibration acceleration data for multiple excavation spans at predetermined locations from the vibration acceleration data stored in the vibration acceleration data storage unit 21 (vibration acceleration data measured during excavation of each excavation span equivalent to one ring width in the annular segment assembly that makes up the shield tunnel), and displaying multiple vibration acceleration distributions in the circumferential direction of a circle that resembles a face cross section based on this vibration acceleration data, along the excavation direction of the shield machine 11. Note that the display screen shown in Fig. 6(b) identifies a vibration change point 23a from the vibration acceleration distribution 23 (see Fig. 6(a)), displays a boundary line 23b using the boundary line display unit 32a, and then erases the vibration acceleration distribution 23, draws the boundary line 23b, and displays multiple circles that resemble the face cross section in succession.

[0077] The forward soil distribution prediction unit 32d predicts the soil distribution of the ground ahead of the working face 12 in the excavation direction from these multiple continuous vibration acceleration distributions and circles simulating the working face cross section.

[0078] The forward soil distribution prediction unit 32d incorporates various known mathematical formulas for performing statistical processing, etc., and is configured to predict the soil distribution of the ground ahead of the excavation face 12 in the excavation direction from the tendency for the position of the vibration change point 23a in the circumferential vibration acceleration distribution to displace in the excavation direction for multiple excavation spans at the front end of the excavation direction. That is, in this embodiment, the forward soil distribution prediction unit 32d is configured to specify multiple arbitrary vibration acceleration distributions, for example, from the vibration acceleration distributions of multiple excavation spans at the front end of the excavation direction or a circle simulating the face cross section, and to connect, for example, the positions of the vibration change point 23a between the specified arbitrary multiple vibration acceleration distributions, or to connect the rate of change of displacement when the vibration change point 23a displaces, and to predict the vibration change point 23a' in the circle simulating the face cross section of the ground ahead in the excavation direction from an extension of these. Furthermore, for example, by connecting the predicted vibration change point 23a' with a boundary line 23b' using the boundary line display unit 32a, it is possible to easily predict the soil distribution of the ground ahead of the working face 12 in the excavation direction.

[0079] As a result, when constructing a shield tunnel, a simple configuration can be used to accurately grasp the condition of the ground 12a, 12b, 12c at the face 12 being excavated by the cutter head 13 in real time and on a planar basis, and from the grasped condition of the ground 12a, 12b, 12c at the face 12, it becomes possible to easily predict the soil distribution of the ground 12a, 12b, 12c ahead of the face 12 in the excavation direction.

[0080] Although the invention made by the inventor has been specifically described above based on the embodiments, the embodiments disclosed in this specification are illustrative in all respects and should not be considered to be limited to the disclosed technology. In other words, the technical scope of the present invention should not be interpreted restrictively based on the description of the above embodiments, but should be interpreted solely in accordance with the description of the claims, and includes technologies equivalent to the technologies described in the claims and all modifications within the scope of the claims.

[0081] For example, in this embodiment, the vibration acceleration data for each rotation angle stored by the vibration acceleration data storage unit 21 is collected for an excavation span equivalent to one ring width of the annular segment assembly, but the collection interval for the vibration acceleration data is not limited to this and can be set freely. However, if the collection interval is long, it is conceivable that the soil quality will change significantly during that time, so it is desirable to collect data every one ring width or half a ring width, as in this embodiment.

[0082] Furthermore, in this embodiment, a case where a ribbon screw type screw conveyor is used has been described, but this is not limited to this and various modifications are possible. For example, a screw conveyor that combines a ribbon type and a shaft type may also be used.

[0083] Furthermore, a plurality of cutter bits 16c may be provided in the radial direction of the cutter head 13. In this case, the cutter bits 16c do not necessarily have to be used in combination with the roller cutter 16a, and either the roller cutter 16a or the cutter bits 16c may be used alone. However, it is desirable that either one of them is disposed near the outer periphery of the cutter head 13.

[0084] Furthermore, the process of removing noise and mechanical vibrations using main body vibration data is not essential, and if removal is not performed, the auxiliary acceleration sensor 18 may be omitted. [Industrial Applicability]

[0085] The above explanation has been given of the application of the present invention to an intermediate support drive type mud pressure shield machine, but the present invention is not limited to this and can also be applied to various other shield machines, such as center shaft drive type or peripheral support drive type mud pressure shield machines, and mud water type shield machines. [Explanation of symbols]

[0086] 10 Additive selection system 11 Shield tunneling machine 12 Face 12a,12b,12c ground 13 Cutter head (cutter head) 14 Acceleration sensor (acceleration measuring means) 15 Main body 16 cutters 16a Roller cutter 16c cutter bit 17 Bulkhead 18 Auxiliary Acceleration Sensor 19 Chamber 20 Computer 21 Vibration acceleration data storage unit 22 Vibration acceleration data display section 23 Vibration acceleration distribution 23a Change points 23b Border 24 displays 29 Transmission Systems 30 Operation Control Room 31 Vibration acceleration data processing unit 32a Boundary line display area 32b Soil Estimation Department 32c Additive selection department 32d Forward soil distribution prediction section

Claims

1. A system for selecting an additive for plastically fluidizing soil and sand taken into a chamber by excavating a face by rotating a cutter board equipped with a plurality of cutters, an acceleration measuring means installed on the cutting board or the cutter, for measuring vibration acceleration when the cutting board excavates a face; a vibration acceleration data display unit that displays the vibration acceleration data measured by the acceleration measuring means for each rotation angle of the cutting board as a vibration acceleration distribution distributed in the circumferential direction of a circle that resembles a face cross section; a vibration acceleration data processing unit that estimates the soil quality of the face from the vibration acceleration data display unit and selects an additive material according to the estimated soil quality, The vibration acceleration data processing unit If there is a change point in the state of the vibration waveform in the vibration acceleration distribution displayed on the vibration acceleration data display unit, a boundary line is set by connecting the change points with a straight line, the soil quality of each region separated by the boundary line is estimated from the vibration waveform of the vibration acceleration data, and the area of each region is calculated, and a dominant soil quality, which is the soil quality that has a large impact on the plastic flow rate of the excavated soil and sand, is determined from the ratio of the soil quality and area of each region, and a first process is executed to select an additive material according to the determined dominant soil quality. If there is no change point in the state of the vibration waveform in the vibration acceleration distribution displayed on the vibration acceleration data display unit, a second process is executed to estimate the soil quality of the face from the vibration waveform of the vibration acceleration data and select an additive material according to the estimated soil quality. An additive selection system characterized by the above.

2. The vibration acceleration data processing unit In the first process, if the proportion of the area of the soil estimated to be gravelly soil exceeds a predetermined proportion, the dominant soil is determined to be gravelly soil, and an additive appropriate for the gravelly soil is selected.

2. The system for selecting an additive according to claim 1, wherein:

3. The predetermined percentage is 30%.

3. The system for selecting an additive according to claim 2.

4. The vibration acceleration data processing unit In the first process, if the proportion of the area of the soil estimated to be gravelly soil is equal to or less than a predetermined proportion, the soil estimated to be clayey soil or sandy soil, whichever has the larger proportion of area, is determined to be the dominant soil quality, and an additive material is selected according to the determined dominant soil quality.

3. The system for selecting an additive according to claim 2.

5. the acceleration measuring means measures vibration acceleration for each ring width or half ring width of the annular segment assembly; 2. The system for selecting an additive according to claim 1, wherein:

6. A method for selecting an additive for plastically fluidizing soil and sand taken into a chamber by excavating a face by rotating a cutter machine equipped with a plurality of cutters, comprising: Measure the vibration acceleration of the cutter when excavating a face with the cutter; The vibration acceleration data for each rotation angle of the cutter board is displayed as a vibration acceleration distribution distributed in the circumferential direction of a circle simulating a face cross section, If there is a change point in the state of the vibration waveform in the vibration acceleration distribution, a boundary line is set by connecting the change points with a straight line, the soil quality of each region separated by the boundary line is estimated from the vibration waveform of the vibration acceleration data, and the area of each region is calculated. A first process is executed to determine a dominant soil quality, which is a soil quality that has a large impact on the plastic flow rate of the excavated soil, based on the ratio of the soil quality and area of each region, and to select an additive material according to the determined dominant soil quality. If there is no change point in the state of the vibration waveform in the vibration acceleration distribution, a second process is executed to estimate the soil quality of the face from the vibration waveform of the vibration acceleration data and select an additive material according to the estimated soil quality. A method for selecting an additive, comprising:

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