Shield tunneling machine and calibration method for measurement values ​​in shield tunneling machine

Abstract

To provide a shield machine and a method for calibrating measured values in the shield machine, which can precisely specify at least the density of soil removed in the shield machine, and can suppress excessive uptake of excavated soil and subsidence (or depression) of the ground surface caused by this.SOLUTION: The present invention pertains to a shield machine 100 in which a screw conveyor 30 formed by a screw 32 including a rotating shaft 33 and a spiral blade 34 attached around the rotating shaft 33, and a cylinder 31 that rotatably accommodates the screw 32 communicates with a chamber 13 that takes in excavated soil and generates waste soil. An RI density measuring device 40 that measures the density and water content of waste soil using a radioisotope is provided on an outer periphery of the cylinder 31.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a shield tunneling machine and a method for calibrating measured values in a shield tunneling machine.

Background Art

[0002] In the earth pressure balance shield method, it is important to carry out the excavation of the shield tunneling machine while stabilizing the face and preventing settlement and subsidence on the ground surface within the affected area. For this purpose, it is essential to suppress the excessive intake of excavated soil and grasp the amount of deviation of the additive added to the excavated soil taken into the chamber of the shield tunneling machine. In a shield tunneling machine, a screw conveyor formed by a screw and a cylinder that rotatably houses the screw communicates with the chamber, and the muck generated by stirring the excavated soil together with the additive in the chamber is discharged to the screw conveyor and conveyed to the rear of the shield tunneling machine via the screw conveyor. The above-mentioned excessive intake of excavated soil depends on the fact that the volume of the excavated soil or muck has not been precisely specified. Since the volume of the muck is calculated by dividing its mass by the density, it is extremely important to precisely specify the density of the excavated soil or muck.

[0003] Here, Patent Documents 1 and 2 disclose a technique for measuring the density and water content of excavated soil using radioisotopes (RI: Radioisotope, radioactive isotopes) and managing the muck taken into a shield tunneling machine (here, a shield machine). The shield machine described in Patent Document 1 is a shield machine provided with a partition wall at the front of the shield cylinder, a face chamber provided through this partition wall, an excavation tool provided in front of this face chamber, and a muck discharging device connected to the rear of the face chamber. A density and moisture measuring device using radioisotopes for measuring the density and water content of the soil and sand in the face chamber is provided on the partition wall.

[0004] On the other hand, the shield machine described in Patent Document 2 is a shield machine equipped with a plastic fluidization measuring device consisting of a rotating shaft that rotates in the mud and measures rotational torque, and a drive device that drives the rotating shaft, and an RI density / moisture meter source sealed inside the rotating body, so that in addition to rotational torque the density and water content of the mud can be measured. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 5-263584 [Patent Document 2] Japanese Patent Publication No. 2003-97181 [Overview of the project] [Problems that the invention aims to solve]

[0006] The shielding machines described in Patent Documents 1 and 2 both employ a technology that involves installing a density and moisture content measuring device using a radioisotope inside the chamber to measure the density and moisture content of the excavated soil being agitated inside the chamber. More specifically, there is a cutter spoke in front of the chamber, and a working face (natural ground) in front of the cutter spoke. Radiation (gamma rays and neutrons) is emitted from a radiation source installed in the chamber's partition wall, and the radiation reflected by the cutter spoke and the working face in front of it is detected by a detector. Therefore, the effects of the working face and cutter spokes are reflected in the measurements, and since the density of the excavated soil being agitated in the chamber is not stable, it is difficult to say that the density of the excavated soil can be accurately measured.

[0007] The present invention aims to provide a shield tunneling machine and a method for calibrating measurements in the shield tunneling machine that can precisely determine at least the density of excavated soil and suppress excessive intake of excavated soil and the resulting ground surface settlement. [Means for solving the problem]

[0008] To achieve the above objective, one embodiment of the shield tunneling machine according to the present invention is: A shield tunneling machine comprising a screw conveyor formed by a screw having a rotating shaft and helical blades mounted around the rotating shaft, and a cylindrical body that rotatably houses the screw, the screw conveyor is connected to a chamber that takes in excavated soil and generates discharged soil, Using radioisotopes to reduce the density of the excavated soil degree The RI density measuring device is characterized by being provided on the outer circumference of the cylindrical body.

[0009] According to this embodiment, since the RI density meter, which measures the density of excavated soil using radioisotopes, is installed on the outer circumference of the cylindrical body constituting the screw conveyor, it is possible to measure the density of excavated soil with a stable (constant) density passing through the screw conveyor, thereby suppressing excessive intake of excavated soil and the resulting subsidence of the ground surface. Since a rotating screw is present inside a screw conveyor, when measuring the density of excavated soil by installing an RI density meter on the outer circumference of the screw conveyor's cylinder, the rotating screw may interfere with the density measurement. In this regard, verification by the inventors has demonstrated that the density of excavated soil can be measured with high accuracy in both cases, whether the screw is rotating or stationary. In the prior art, it is presumed that the presence of the screw was a concern for interfering with the measurement of the density of excavated soil, and therefore the density of the excavated soil being agitated in the chamber was measured. However, in the present invention, based on the verification results by the inventors, for example, the density of excavated soil passing through a screw conveyor with a rotating screw inside is measured.

[0010] Furthermore, another embodiment of the shield tunneling machine according to the present invention is: A radioisotope moisture meter, which measures the water content of the excavated soil using a radioisotope, is further provided on the outer circumference of the cylindrical body.

[0011] According to this embodiment, since an RI moisture meter for measuring the water content of the excavated soil is further provided on the outer circumference of the cylindrical body, it becomes possible to determine the properties of the excavated soil with higher accuracy.

[0012] Furthermore, another embodiment of the shield tunneling machine according to the present invention is: The aforementioned RI density meter and the aforementioned RI moisture meter each include a radiation source and a radiation detector. The cylindrical body is characterized in that the radiation source and radiation detector constituting the RI density measuring device are provided at two points other than the two points on the straight line passing through the rotation axis of the screw.

[0013] According to this embodiment, the radiation source (gamma-ray source) and radiation detector (gamma-ray detector) constituting the RI density measuring instrument are provided on the outer circumference of the cylindrical body at two points other than the two points on the straight line passing through the rotation axis of the screw. This makes it possible to suppress obstruction of the rotation axis of the screw by the gamma rays emitted from the radiation source as they reach the radiation detector. Here, "two points other than the two points on the straight line passing through the screw's axis of rotation" includes two points other than the two points on the diameter in the same cross-section perpendicular to the axis of the cylinder (screw's axis of rotation) (for example, positions that are at an angle of 90 degrees and 120 degrees to each other), and two points that are separated in the axial direction of the cylinder and whose straight line does not intersect the axis of rotation when the two points are connected.

[0014] Furthermore, even if gamma rays pass through the screw's rotation axis on their way to the gamma-ray detector, it is presumed that the density of the excavated soil can be measured with high accuracy. However, by preventing gamma rays from interfering with the screw's rotation axis, the accuracy of density measurement can be further improved. Furthermore, with regard to RI moisture meters, since it is not necessary to install the radiation source (neutron source) and radiation detector (neutron detector) on the outer circumference of the cylindrical body while keeping them separate from each other, the installation techniques required for RI density meters are unnecessary.

[0015] Furthermore, in another embodiment of the shield tunneling machine according to the present invention, The shield tunneling machine further includes a measurement value calibration device, The measurement value calibration device, stores a calibration formula for calibrating the measurement values obtained by the RI density measuring device and the RI moisture measuring device, and has a storage unit, and during actual construction, applies the measurement values to the calibration formula to obtain calibration values related to the density and water content of the excavated soil, and is characterized by having a calibration unit.

[0016] According to this aspect, in the measurement value calibration device, by applying the measurement values obtained by the RI density measuring device and the RI moisture measuring device to the calibration formula to obtain calibration values related to the density and water content of the excavated soil, for the measurement values related to the intensity (counting rate) of radiation, the calibration values (density and water content of the excavated soil) specified by performing correction for the attenuation of the radiation intensity can be obtained. Since the RI measuring device is an indirect measuring device that uses radiation emitted from radioisotopes, it is necessary to perform comparative calibration with a substance whose density and water content are known in advance, obtain the relational expression of the radiation intensity with respect to the density and water content, that is, the calibration formula, and apply the actual measurement values to the calibration formula to obtain the density and water content.

[0017] Also, one aspect of the measurement value calibration method in the shield tunneling machine according to the present invention is, a measurement value calibration method for calibrating measurement values in the shield tunneling machine, applies the RI density measuring device and the RI moisture measuring device to a simulated screw conveyor having the same specifications as the screw conveyor, and based on both the test measurement values measured by the RI density measuring device and the RI moisture measuring device when discharging soil experimentally and the actual measurement values related to the density and water content of the discharged soil during the test, sets the calibration formula.

[0018] According to this aspect, for a simulated screw conveyor with the same specifications as the screw conveyor applied in actual construction, a RI density measuring device and a RI moisture measuring device are applied to obtain test measurement values, and a calibration formula is set based on both these test measurement values and the measured values regarding the density and water content of the muck during the test, so that based on a high-precision calibration formula corresponding to the screw conveyor of the shield tunneling machine applied in actual construction, it becomes possible to accurately obtain the density and water content of the muck during actual construction.

[0019] Here, "the same specifications as the screw conveyor applied in actual construction" means that the diameter (dimensions) and wall thickness of the cylinder body, the shape and dimensions of the screw rotation axis and the spiral blades, etc. are the same. Since a RI density measuring device and a RI moisture measuring device are installed on the outer circumference of the cylinder body to measure the density and water content of the muck passing through the inside of the cylinder body, the diameter and wall thickness of the cylinder body are particularly important factors. Also, "the measured values regarding the density and water content of the muck during the test" means the values when the muck passing through the screw conveyor during the test is separately put into a mold or the like and its wet density and water content (or water content ratio) are measured.

[0020] Moreover, another aspect of the measurement value calibration method in the shield tunneling machine according to the present invention is characterized in that the RI density measuring device and the RI moisture measuring device are installed at the same position as the installation position of the screw conveyor during actual construction with respect to the simulated screw conveyor.

[0021] According to this aspect, by installing the RI density measuring device and the RI moisture measuring device at the same position as the installation position of the screw conveyor during actual construction with respect to the simulated screw conveyor, in addition to the screw conveyor applied in actual construction, based on a more highly accurate calibration formula corresponding to the installation positions of the RI density measuring device and the RI moisture measuring device during actual construction, it becomes possible to more accurately obtain the density and water content of the muck during actual construction. Furthermore, preliminary measurements can be taken using full-scale models, in advance at machine manufacturing plants, and during machine assembly at workshops. These preliminary measurements can be taken when the screw casing is hollow, filled with water, or filled with bentonite solution or simulated soil, thereby improving the accuracy of the calibration formula.

[0022] Furthermore, another aspect of the measurement calibration method for a shield tunneling machine according to the present invention is: The method is characterized by making the angle between the radiation source and the radiation detector acute, depending on the size of the cylindrical body and the screw, thereby shortening the distance between them.

[0023] According to this embodiment, by making the angle between the radiation source and the radiation detector acute according to the scale of the cylindrical body and the screw, and shortening the distance between them, it is possible to determine the density and water content of the excavated soil with high precision, even in the case of a large-scale screw conveyor. [Effects of the Invention]

[0024] According to the shield tunneling machine and measurement calibration method for the shield tunneling machine of the present invention, at least the density of excavated soil in the shield tunneling machine can be precisely determined, and excessive intake of excavated soil and the resulting ground surface settlement can be suppressed. [Brief explanation of the drawing]

[0025] [Figure 1] This is a longitudinal cross-sectional view of an example of a shield tunneling machine according to an embodiment. [Figure 2] This is a perspective view showing an example of how RI density meters and RI moisture meters are installed on the outer circumference of a screw conveyor cylinder. [Figure 3] This figure shows an example of the hardware configuration of a measurement calibration device. [Figure 4] This figure shows an example of the functional configuration of a measurement value calibration device. [Figure 5]This table shows the experimental results of measuring the density and water content of excavated soil with a predetermined mix during a calibration formula identification experiment. [Figure 6A] This figure shows a graph corresponding to the calibration formula set by an RI density meter installed on the outer circumference of a screwless cylindrical body during a calibration formula identification experiment. [Figure 6B] This graph shows the correlation between measured values ​​and actual values ​​obtained using an RI density meter installed on the outer circumference of a screwless cylindrical body during a calibration formula identification experiment. [Figure 7A] This figure shows a graph corresponding to the calibration formula set by an RI density meter installed on the outer circumference of a cylindrical screw conveyor equipped with a non-rotating screw, as part of a calibration formula identification experiment. [Figure 7B] This graph shows the correlation between measured values ​​and actual values ​​obtained using an RI density meter installed on the outer circumference of a cylindrical screw conveyor equipped with a non-rotating screw, as part of a calibration formula identification experiment. [Figure 8A] This figure shows a graph corresponding to the calibration formula set by an RI density meter installed on the outer circumference of a cylindrical screw conveyor equipped with a rotating screw, as part of a calibration formula identification experiment. [Figure 8B] This graph shows the correlation between measured values ​​and actual values ​​obtained using an RI density meter installed on the outer circumference of a cylindrical screw conveyor equipped with a rotating screw, as part of a calibration formula identification experiment. [Figure 9A] This figure shows graphs corresponding to the calibration formulas set by RI moisture meters installed on the outer circumference of a cylindrical body without a screw, the outer circumference of a cylindrical body of a screw conveyor equipped with a non-rotating screw, and the outer circumference of a cylindrical body of a screw conveyor equipped with a rotating screw, as part of a calibration formula identification experiment. [Figure 9B] This graph shows the correlation between measured values ​​and actual values ​​obtained from RI moisture meters installed on the outer circumference of a cylindrical body without a screw, the outer circumference of a cylindrical body of a screw conveyor equipped with a non-rotating screw, and the outer circumference of a cylindrical body of a screw conveyor equipped with a rotating screw, during an indoor experiment. [Modes for carrying out the invention]

[0026] The shield tunneling machine and the measurement calibration method for the shield tunneling machine according to the embodiment will be described below with reference to the attached drawings. In this specification and drawings, substantially identical components may be denoted by the same reference numerals to avoid redundant explanations.

[0027] [Shield tunneling machine according to an embodiment and method for calibrating measured values ​​in the shield tunneling machine] First, an example of a shield tunneling machine and a measurement calibration method in the shield tunneling machine according to an embodiment will be described with reference to Figures 1 to 4. Here, Figure 1 is a longitudinal cross-sectional view of an example of a shield tunneling machine according to an embodiment, and Figure 2 is a perspective view showing an example of the installation configuration of the RI density meter and RI moisture meter on the outer circumference of the screw conveyor cylinder.

[0028] The illustrated shield tunneling machine 100 is an earth pressure balance type shield tunneling machine (including a mud pressure balance type shield tunneling machine) having a shield body 10 and a cutter head 20 rotatably mounted on the front of the shield body 10 in the direction of excavation, the cutter head 20 having a plurality of cutter spokes 22. Here, the shield tunneling machine may be a slurry type shield tunneling machine equipped with a faceplate-shaped cutter head. Furthermore, the shield tunneling machine may be a folding type shield tunneling machine equipped with a front body and a rear body. In addition, the illustrated example shield tunneling machine 100 may be a shield tunneling machine of various sizes and diameters.

[0029] The shield body 10 is equipped with a bulkhead 11 behind the cutter head 20, and a chamber 13 for taking in excavated soil between the bulkhead 11 and the cutter head 20. Multiple fixed blades 12 are provided on the side of the bulkhead 11 facing the chamber 13, and a stirring blade 25 is provided on the back of the cutter head 20 facing the chamber 13. A mud additive is supplied to the excavated soil taken into the chamber 13, and the stirring blade 25 is rotated in accordance with the rotation of the cutter head 20, causing the excavated soil to plastically flow due to the fixed blades 12 and the rotating stirring blade 25, thereby generating excavated soil.

[0030] Multiple hydraulic motors 14 for driving cutter heads are provided near the center of the back of the bulkhead 11. A screw conveyor 30, which communicates with the chamber 13, extends in an inclined position from below the back of the bulkhead 11 to the rear of the shield body 10. The excavated soil generated by plastic fluidization inside the chamber 13 is transported to the rear of the shield tunneling machine 100 by the screw conveyor 30.

[0031] Multiple shield jacks 16 are attached to the inner circumferential surface of the shield body 10 (only two shield jacks are shown in Figure 1). By extending the shield jacks 16 and pressing against the segment ring, which is assembled in a ring shape by an erector device 17 located at the rear of the shield body 10, the shield tunneling machine 100 is advanced in the tunneling direction. In addition, multiple tail seals (not shown) are provided at multiple locations on the rear inner side of the shield body 10, and the watertightness of the shield body 10 is ensured by the constant sliding contact of the tail seals with the installed segment ring.

[0032] The cutter head 20 is equipped with multiple cutter spokes 22 that extend radially from a central boss member 24. Multiple cutter bits 23 are attached to the central fishtail 21 and the cutter spokes 22, and copy cutters 23A are retractably mounted on the outer ends of the cutter spokes 22.

[0033] The screw conveyor 30, which receives the excavated soil generated in the chamber 13 and discharges it to the rear of the shield tunneling machine 100, is formed by a screw 32 having a rotating shaft 33 and spiral blades 34 mounted around the rotating shaft 33, a cylindrical body 31 that houses the screw 32 so as to be rotatable in the X1 direction, and a drive source (drive motor) not shown that rotates the screw 32.

[0034] On the outer circumference of the cylindrical body 31, an RI density meter 40 and an RI moisture meter 50 are installed to measure the density and water content of the excavated soil that is transported in the X2 direction to the rear of the cylindrical body 31 in accordance with the rotation of the screw 32 in the X1 direction, using radioisotopes. In other words, in the shield tunneling machine 100, the excavated soil being transported inside the screw conveyor 30 is the target of measurement when measuring the density and water content of the excavated soil.

[0035] The RI density meter 40 has a radiation source 46 that emits gamma rays and a radiation detector 41 that detects the emitted gamma rays to measure the density of the excavated soil. On the other hand, the RI moisture meter 50 has a radiation source 53 that emits neutrons and a radiation detector 52 that detects the emitted neutrons to measure the moisture content of the excavated soil. Here, since the actual measurement of the density and moisture content of the excavated soil at the site is generally performed when the screw conveyor is filled with soil, the installation positions of the radiation sources 46 and 53 on the outer circumference of the cylindrical body 31 are selected based on the assumption that the screw conveyor is filled with soil, and the positions are such that measurements can be performed. The RI density meter 40 and the RI moisture meter 50 will be explained in detail below.

[0036] A measurement calibration device 60 is installed inside the shield body 10. The measurement calibration device 60 is a computer that determines the density and water content of excavated soil by applying the respective measurement values ​​from the RI density meter 40 and the RI moisture meter 50 to a calibration formula and obtaining calibration values ​​for the density and water content of the excavated soil. Hereinafter, the measurement calibration device 60 will be described as being installed inside the shield tunneling machine 100, but the measurement calibration device 60 may also be installed in an unillustrated control building on the ground, or it may be installed in both the shield tunneling machine 100 and the control building, and both measurement calibration devices 60 may be connected to enable data transmission and reception.

[0037] As shown in Figure 2, an RI density meter 40 and an RI moisture meter 50 are installed on the outer circumference of the cylindrical body 31 of the screw conveyor 30 at positions separated along the axial direction L of the rotation axis 33.

[0038] The radiation detector 41, which constitutes the RI density meter 40, has a stainless steel shield 43, a gamma-ray detector 44, and a high-voltage power supply 45 inside a case 42. On the other hand, the radiation source 46, which constitutes the RI density meter 40, has a gamma-ray source 48 inside a case 47. The radioactive material emitted from the gamma-ray source 48 can be, for example, cobalt 60 (Co·60).

[0039] For example, the PIRICA-S1 (PIRICA is a registered trademark), manufactured by Soil & Rock Engineering Co., Ltd., can be used with this RI density meter 40.

[0040] On the other hand, the RI moisture detector 50 houses a neutron detector 52 and a neutron source 53 together inside the case 51. The radioactive material emitted from the neutron source 53 can be, for example, californium-252 (cf-252).

[0041] For example, the CONG-II (SRM CONG is a registered trademark) manufactured by Soil & Rock Engineering Co., Ltd. can be used with this RI moisture meter 50.

[0042] Since the RI density meter 40 has a radiation detector 41 and a radiation source 46 that are separated from each other, it can be installed, for example, at two points on any cross section of the outer circumference of the cylindrical body 31 that is perpendicular to the axial direction L of the rotation axis 33. If, due to the relationship with other equipment in the shield body 10, it is not possible to install the radiation detector 41 and the radiation source 46 at two points on the same cross section, they may be installed at two points offset in the axial direction L.

[0043] Figure 2 illustrates three specific installation configurations when the radiation detector 41 and radiation source 46 are installed at two points on an arbitrary cross-section perpendicular to the axial direction L. One installation configuration has a relative angle θ1 of 90 degrees, while the other configurations have relative angles θ2 of 120 degrees and θ3 of 180 degrees. Here, the positions of the radiation detector 41 and radiation source 46 in Figure 2 may be swapped. Furthermore, if the relative angle θ between the radiation detector 41 and radiation source 46 is, for example, about 60 degrees, radiation shielding material such as lead can be installed between the radiation detector 41 and radiation source 46 to prevent leakage radiation and improve measurement accuracy.

[0044] In the installation configurations with angles θ1 and θ2, the radiation source 46 and radiation detector 41 are positioned at two points on the outer circumference of the cylindrical body 31, excluding two points on the straight line passing through the rotation axis 33 of the screw 32. On the other hand, in the installation configuration with angle θ3, the radiation source 46 and radiation detector 41 are positioned at two points on the straight line passing through the rotation axis 33 of the screw 32 (intersecting the rotation axis 33).

[0045] The verification results by the inventors are described in detail below. According to this verification, it has been determined that the density of excavated soil can be measured with high accuracy when the radiation source 46 and radiation detector 41 are installed at two points other than the two points on the straight line passing through the rotation axis 33 of the screw 32. It has also been determined that the distance between the radiation source 46 and the radiation detector 41 affects the accuracy of the measurement of the density of excavated soil. Furthermore, from these verification results, it can be inferred that even in the case of an installation configuration where the radiation source 46 and radiation detector 41 are installed at two points on the straight line passing through the rotation axis 33 of the screw 32 (an installation configuration with an angle θ3), the density of excavated soil can be measured with high accuracy.

[0046] Furthermore, regarding the measurement of the water content of the excavated soil using the RI moisture meter 50, fast neutrons emitted from the neutron source 53 collide with the water contained in the excavated soil, and the reflected thermal neutrons are detected by the neutron detector 52, which is attached to the neutron source 53. Therefore, the detector can be installed at any position on the outer circumference of the cylindrical body 31.

[0047] The gamma-ray detector 44 and the neutron detector 52 measure the amount of radiation that has passed through the excavated soil, thereby obtaining measurements regarding the density and water content of the excavated soil. The measurement data obtained by the gamma-ray detector 44 and the neutron detector 52 are converted into electrical signals and input to the measurement calibration device 60 via a cable (not shown). Here, the measurement data converted into electrical signals may be transmitted to the measurement calibration device 60 wirelessly.

[0048] Here, the measurement value calibration device 60 will be described with reference to Figures 3 and 4. Figure 3 is a diagram showing an example of the hardware configuration of the measurement value calibration device, and Figure 4 is a diagram showing an example of the functional configuration of the measurement value calibration device.

[0049] As shown in Figure 3, the measurement calibration device 60 is composed of an information processing device (computer) such as a personal computer (PC). The computer comprising the measurement calibration device 60 includes a CPU (Central Processing Unit) 61, main memory 62, auxiliary storage 63, input / output IF (interface) 64, and communication IF 65, which are interconnected by a connection bus 66. The main memory 62 and auxiliary storage 63 are recording media that can be read by the computer. Note that each of the above components may be provided individually, or some of the components may be omitted.

[0050] The CPU 61, also known as an MPU (Microprocessor) or processor, may be a single processor or a multiprocessor. The CPU 61 is a central processing unit that controls the entire measurement calibration device 60, which consists of a computer. For example, the CPU 61 expands a program stored in the auxiliary storage device 63 into an executable format in the working area of ​​the main memory device 62, and controls peripheral devices through the execution of the program, thereby providing a function that matches a predetermined purpose.

[0051] The main memory 62 stores computer programs executed by the CPU 61 and data processed by the CPU 61. The main memory 62 includes, for example, flash memory, RAM (Random Access Memory), and ROM (Read Only Memory). The auxiliary storage device 63 stores various programs and various data on a recording medium that can be read and written freely, and is also called an external storage device. The auxiliary storage device 63 stores, for example, the OS (Operating System), various programs, various tables, etc. The OS includes, for example, a communication interface program that exchanges data with external devices connected via the communication IF 65. External devices include, for example, a gamma-ray detector 44 and a neutron detector 52, as well as, for example, a personal computer (not shown) for construction management located in the management building connected to the network.

[0052] The auxiliary storage device 63 is used, for example, as a storage area that assists the main memory 62, and stores computer programs executed by the CPU 61, data processed by the CPU 61, etc. The auxiliary storage device 63 is a silicon disk containing non-volatile semiconductor memory (flash memory, EPROM (Erasable Programmable ROM)), a hard disk drive (HDD), a solid-state drive, etc. Examples of auxiliary storage devices 63 include drives for removable recording media such as CD drives, DVD drives, and BD drives, and examples of removable recording media include CDs, DVDs, BDs, USB (Universal Serial Bus) memory, SD (Secure Digital) memory cards, etc.

[0053] The input / output IF64 is an interface for inputting and outputting data between the measurement calibration device 60 and the connected equipment. For example, keyboards, pointing devices such as touch panels and mice, and input devices such as microphones can be connected to the input / output IF64. The measurement calibration device 60 receives operation instructions from the operator operating the input device via the input / output IF64.

[0054] Furthermore, the input / output IF64 is connected to display devices such as liquid crystal displays (LCDs) and electroluminescent (EL) panels, as well as output devices such as printers and speakers. For example, measurement data regarding density and water content transmitted via cables from gamma-ray detectors 44 and neutron detectors 52 is acquired and displayed. In addition, calibration values ​​(specific values) regarding the density and water content of the excavated soil, obtained by the measurement value calibration device 60, are also displayed on the same screen.

[0055] Communication IF65 is the interface between the measurement calibration device 60 and the cables and networks to which it is connected. Communication IF65 transmits calibration data regarding the density and water content of excavated soil to a personal computer used for construction management in the administration building via various networks, including public networks such as the internet, wireless networks such as mobile phone networks, dedicated networks such as VPNs (Virtual Private Networks), and LANs (Local Area Networks).

[0056] As shown in Figure 4, the measurement value calibration device 60 provides various functions, at least the acquisition unit 602, calibration unit 604, display unit 606, and storage unit 608, through the execution of a program by the CPU 61. Here, at least a portion of the above processing functions may be provided by a DSP (Digital Signal Processor), GPU (Graphics Processing Unit), etc. Similarly, at least a portion of the above processing functions may be provided by a dedicated LSI (large scale integration) such as an FPGA (Field-Programmable Gate Array), numerical arithmetic processor, image processing processor, or other digital circuits.

[0057] The acquisition unit 602 receives measurement data regarding density and water content transmitted via cables, etc., from the gamma-ray detector 44 and the neutron-ray detector 52, and the acquired measurement data is stored (remembered) in the storage unit 608.

[0058] The storage unit 608 stores calibration formulas for calibrating measured values ​​related to density and water content.

[0059] Since the RI density meter 40 and the RI moisture meter 50 are indirect measuring instruments that utilize radiation from radioisotopes, it is necessary to perform a comparative calibration in advance by comparing them with a substance whose density and moisture content are known, and to determine the relationship between the intensity of radiation and density and water content (moisture content), i.e., the calibration formula. In measuring instruments that utilize radiation, regardless of the type of radiation source, the intensity (counting rate) of the radiation is not constant and has the property of decaying over time.

[0060] Therefore, when determining the relationship between radiation intensity (count rate) and density or water content, the absolute value of the radiation intensity (count rate) cannot be used directly, and a correction for the attenuation of radiation intensity is necessary. The calibration formulas for the RI density meter 40 and the RI moisture meter 50 are values ​​unique to each meter. Prior to actual construction, a test is conducted to determine the calibration formula, and the calibration value is determined from the measured values ​​of density and water content using the calibration formula identified in the test.

[0061] Here, the radiation intensity is expressed not as an absolute value, but as a relative value (count rate ratio) of the measurement relative to a certain reference substance. That is, the count rate ratio = measurement value of the excavated soil being measured (count rate (cpm), cpm: counts per minute) / count rate (cpm) measured using the reference substance.

[0062] If the count rate ratio is not used, for example, when the count rate during the creation of the calibration formula is 500 cpm, the wet density: ρt is 2.0 g / cm³. 3 Let's assume that was the case. After some time has passed, ρt remains at 2.0 g / cm³. 3When measuring materials of the same density, the radiation attenuation can result in values ​​of, for example, 250 cpm, meaning that even though the materials are of the same density, the radiation count (cpm) will differ.

[0063] To avoid such situations, the counting rate ratio is used to take into account the passage of time (radiation decay).

[0064] More specifically, since radiation exists in nature, it is desirable to use the count rate ratio Rρ, which is obtained by subtracting the background (BG) count rate Nρ from the measured count rate Nρ and dividing the result by the standard count rate Sρ, in order to eliminate the influence of this naturally occurring radiation, background (BG). That is, Rρ is given by the following equation (1).

[0065]

number

[0066] From the count rate ratio Rρ calculated by equation (1), the calibration value is calculated from the measured value using the calibration formula shown in equation (2) below.

[0067]

number

[0068] Since the standard calibration constants A and B have unique values ​​depending on the diameter (outer diameter), wall thickness, and specifications of the cylindrical body (pipe) used when measuring the density of excavated soil, it is desirable that values ​​corresponding to the diameter and wall thickness of the cylindrical body of the screw conveyor to be used in the actual construction be entered at the time of factory shipment. In other words, in the calibration formula determination experiment, it is desirable to set the calibration formula using a simulated screw conveyor with the same specifications as the screw conveyor to be used in the actual construction, and furthermore, using the RI density meter and RI moisture meter appropriate for the actual construction.

[0069] In this process, by installing the RI density meter and RI moisture meter on the simulated screw conveyor at the same locations as they would be installed on the actual screw conveyor, a more accurate calibration formula can be identified.

[0070] In the calibration formula determination experiment, an RI density meter and an RI moisture meter are applied to a simulated screw conveyor with the same specifications as the actual screw conveyor. The calibration formula is then established based on both the test measurements taken with these RI density and RI moisture meters during the experimental soil discharge, and the actual measured values ​​of the density and moisture content of the soil discharged during the test.

[0071] In the calibration experiment, a prototype of the excavated soil (simulated excavated soil) expected during actual construction is created, and measurements are taken using an RI density meter, etc., when the simulated excavated soil is passed through a simulated screw conveyor. Furthermore, actual values ​​are determined based on wet density measurements and moisture content measurements of the prototyped excavated soil.

[0072] In creating the simulated excavated soil, the target site for the actual construction is assumed, and gravel, sand, and soil are mixed in predetermined proportions. Furthermore, the thickening agent (mud thickener) used in the actual construction is added at this stage.

[0073] Furthermore, according to the inventors, the properties (type) of the excavated soil have almost no effect on the accuracy of the calibration formula; it has been determined that only the density and water content of the excavated soil affect the accuracy of the calibration formula.

[0074] The storage unit 608 stores the calibration formulas for the RI density meter 40 and the RI moisture meter 50, which are set in the calibration formula identification experiment and are suitable for use in the actual construction.

[0075] During actual construction, measured data regarding the density and water content of the excavated soil are stored in the storage unit 608 as needed. The calibration unit 604 then applies the measured data to the calibration formulas for density and water content stored in the storage unit 608 to determine the calibration values ​​for density and water content. The above describes the measurement calibration method for the shield tunneling machine according to this embodiment.

[0076] According to the inventors, the outer diameter (size) and wall thickness of the cylindrical body and the size of the screw have a significant impact on the calibration. Therefore, depending on the size of the cylindrical body and the screw, it is preferable to set the angle between the radiation source 46 and the radiation detector 41 of the RI density measuring instrument 40 to an acute angle (for example, 90 degrees or less) to shorten the distance between them.

[0077] The display unit 606 displays calibration values ​​for the specified density and water content on the screen, identifies the volume of excavated soil calculated based on the calibration values, and displays the basis for verification regarding whether or not excessive excavated soil has been taken into the chamber 13. In addition, the appropriate range for the amount of excavated soil to be taken is stored in the storage unit 608, and a determination unit (not shown) may periodically compare the amount of excavated soil to be taken, calculated from the density of the specified excavated soil (and thus the excavated soil), with the appropriate range for taking the soil, and display the determination result on the display unit 606.

[0078] According to the shield tunneling machine 100 and the measurement calibration method, the density of excavated soil and water content in the shield tunneling machine 100 can be precisely determined, making it possible to effectively suppress excessive intake of excavated soil and the resulting ground surface settlement.

[0079] [Experiment to identify the calibration formula and its results] The inventors created a simulated soil excavation sample with a predetermined composition, and then manufactured a simulated screw conveyor. They conducted an indoor experiment to verify the effect of the presence or absence of a screw conveyor and the rotation of the screw conveyor on the accuracy of the calibration formula.

[0080] Here, for the simulated excavated soil with a predetermined mix, several types of simulated excavated soil were created using various mixes, including one with 40% gravel, 40% sand, and 20% soil. After dry mixing in a mixer, water was added to achieve the predetermined moisture content and mixed further. Finally, a biodegradable polymer thickener was added and mixed to create simulated excavated soil with the desired wet density and moisture content.

[0081] In this experiment, calibration formulas for the density and water content of excavated soil were determined for each of the following cases: a cylindrical body without a screw, a screw with a non-rotating screw, and a screw with a rotating screw. Furthermore, to verify whether the presence or absence of a screw and whether or not it rotates affects the accuracy of the calibration formulas, calibration formulas were determined for the RI density meter in each of the following cases: when the gamma-ray source was set at an angle of 90 degrees relative to the gamma-ray detector, at 120 degrees, and at 150 degrees.

[0082] Figure 5 is a table showing the experimental results of measuring the density and water content of excavated soil of a predetermined mix in the calibration formula determination experiment. Figures 6A, 7A, and 8A are graphs corresponding to the calibration formula determined by an RI density meter installed on the outer circumference of a cylindrical body without a screw, a graph corresponding to the calibration formula determined by an RI density meter installed on the outer circumference of a cylindrical body of a screw conveyor equipped with a non-rotating screw, and a graph corresponding to the calibration formula determined by an RI density meter installed on the outer circumference of a cylindrical body of a screw conveyor equipped with a rotating screw, respectively. Furthermore, Figures 6B, 7B, and 8B are graphs showing the correlation between measured values ​​and actual values ​​obtained in the calibration formula identification experiment, specifically: a graph showing the correlation between measured values ​​and actual values ​​obtained in the calibration formula identification experiment, Furthermore, Figure 9A shows a graph corresponding to the calibration formula set by RI moisture meters installed on the outer circumference of a cylindrical body without a screw, the outer circumference of a cylindrical body of a screw conveyor equipped with a non-rotating screw, and the outer circumference of a cylindrical body of a screw conveyor equipped with a rotating screw, in the calibration formula determination experiment. Figure 9B shows a graph showing the correlation between the measured values ​​and actual values ​​measured by RI moisture meters installed on the outer circumference of a cylindrical body without a screw, the outer circumference of a cylindrical body of a screw conveyor equipped with a non-rotating screw, and the outer circumference of a cylindrical body of a screw conveyor equipped with a rotating screw, in the laboratory experiment.

[0083] Figure 5 shows that, regardless of the presence or absence of a screw or whether the screw is rotating, there was no significant difference in the measured values ​​in any of the cases where the gamma-ray source was positioned at an angle of 90 degrees, 120 degrees, or 150 degrees relative to the gamma-ray detector.

[0084] Furthermore, as shown in Figures 6A, 7A, and 8A, specific calibration formulas are identified for each case where the gamma-ray source is positioned at an angle of 90 degrees, 120 degrees, and 150 degrees relative to the gamma-ray detector. However, as shown in Figures 6B, 7B, and 8B, it is demonstrated that all of these calibration formulas exhibit good correlation.

[0085] Furthermore, as shown in Figures 9A and 9B, the same calibration formula was identified for all cases—the case without a screw, the case where the screw is not rotating, and the case where the screw is rotating—and it was demonstrated that all of these calibration formulas showed good correlation.

[0086] This laboratory experiment demonstrates that when measuring the density and water content of excavated soil by installing an RI density meter and an RI moisture meter on the outer circumference of a screw conveyor cylinder, the resulting calibration formula is independent of the presence or absence of a screw or the rotation of the screw.

[0087] Furthermore, other embodiments may be used in which other components are combined with the configurations listed in the above embodiments, and the present invention is not limited in any way to the configurations shown herein. In this regard, modifications can be made without departing from the spirit of the present invention, and can be appropriately determined according to the application form. [Explanation of Symbols]

[0088] 10: Shield body 11: Bulkhead 12:Fixed wing 13: Chamber 14: Hydraulic motor for driving the cutter head 16: Shield Jack 17: Erecta equipment 18: Folding jack 20: Cutter head 21: Fishtail 22: Cut Spoke 23: Cutter Bit 23A: Copy cutter 24: Boss component 30: Screw conveyor 31: Cylinder 32: Screw 33: Rotation axis 34: Spiral feather (feather) 40:RI density meter 41: Radiation detector 42: Case 43: Shield 44: Gamma-ray detector 45: Power supply 46: Line source 47: Case 48: Radiation source (gamma ray source) 50:RI moisture meter 51: Case 52: Radiation detector (neutron detector) 53: Radiation source (neutron source) 60: Measurement Calibration Device 61: Communications Department 62: Proofreading Department 63: Storage Unit 100: Shield tunneling machine L: Axis of the rotation axis

Claims

1. A shield tunneling machine comprising a screw conveyor formed by a screw having a rotating shaft and helical blades mounted around the rotating shaft, and a cylindrical body that rotatably houses the screw, the screw conveyor is connected to a chamber that takes in excavated soil and generates discharged soil, An RI density meter and an RI moisture meter, which measure the density and water content of the excavated soil using radioisotopes, are provided on the outer circumference of the cylindrical body. The RI density meter and the RI moisture meter each comprise a radiation source and a radiation detector. On the outer circumference of the cylindrical body, the radiation source and the radiation detector constituting the RI density measuring device are provided at two points other than the two points on the straight line passing through the rotation axis of the screw. The aforementioned shield tunneling machine further includes a measurement calibration device, The aforementioned measurement value calibration device is A storage unit for storing a calibration formula for calibrating the measured values ​​obtained from the RI density meter and the RI moisture meter, During the actual construction work, the system includes a calibration unit that applies the measured values ​​to the calibration formula to determine calibration values ​​for the density and water content of the excavated soil. The aforementioned calibration formula is: A shield tunneling machine characterized in that the machine is set based on both the test measurement values ​​obtained by applying the RI density meter and the RI moisture meter to a simulated screw conveyor having the same specifications as the screw conveyor, and the actual measured values ​​of the density and moisture content of the excavated soil during the test.

2. A shield tunneling machine comprising a screw having a rotating shaft and spiral blades mounted around the rotating shaft, and a cylindrical body that rotatably houses the screw, wherein the screw conveyor is connected to a chamber that takes in excavated soil and generates discharged soil, An RI density meter and an RI moisture meter, which measure the density and water content of the excavated soil using radioisotopes, are provided on the outer circumference of the cylindrical body. The RI density meter and the RI moisture meter each comprise a radiation source and a radiation detector. On the outer circumference of the cylindrical body, the radiation source and the radiation detector constituting the RI density measuring device are provided at two points other than the two points on the straight line passing through the rotation axis of the screw. The aforementioned shield tunneling machine further includes a measurement calibration device, The aforementioned measurement value calibration device is A storage unit for storing a calibration formula for calibrating the measured values ​​obtained from the RI density meter and the RI moisture meter, A method for calibrating measured values ​​in a shield tunneling machine having a calibration unit that, during actual construction, applies the measured values ​​to the calibration formula to obtain calibration values ​​for the density and water content of the excavated soil, wherein the measured values ​​are calibrated in the shield tunneling machine, A method for calibrating measurement values ​​in a shield tunneling machine, characterized in that the RI density meter and the RI moisture meter are applied to a simulated screw conveyor having the same specifications as the screw conveyor, and the calibration formula is set based on both the test measurement values ​​measured by the RI density meter and the RI moisture meter when soil is excavated experimentally, and the actual measured values ​​regarding the density and moisture content of the excavated soil at the time of the test.

3. A method for calibrating measured values ​​in a shield tunneling machine according to claim 2, characterized in that the RI density meter and the RI moisture meter are installed on the simulated screw conveyor at the same positions as they are installed on the screw conveyor during actual construction.

4. A method for calibrating a measurement value in a shield tunneling machine according to claim 3, characterized in that, depending on the size of the cylindrical body and the screw, the angle between the radiation source and the radiation detector is made acute to shorten the distance between them.

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