Shield tunneling machine and measurement value calibration method for shield tunneling machine

Abstract

To provide a shield tunneling machine and a measurement value calibration method for the shield tunneling machine, which can precisely specify at least the density of excavated soil in the shield tunneling machine and can suppress excessive intake of excavated soil and the resulting subsidence (or collapse) of the ground surface.SOLUTION: A shield tunneling machine 100 has a screw conveyor 30 formed by a screw 32 comprising a rotating shaft 33, and a spiral blade 34 attached around the rotating shaft 33, and a cylindrical body 31 that rotatably houses the screw 32, and the screw conveyor is connected to a chamber 13 that takes in excavated soil and produces discharged soil, and an RI density meter 40 that measures the density and moisture content of the discharged soil using radioisotopes is provided in recesses 31c, 31d with a thin wall on the outer periphery 31a of the cylindrical body 31.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a shield tunneling machine and a method for calibrating measurement values ​​in the shield tunneling machine. [Background technology]

[0002] In earth pressure shield tunneling, it is important to stabilize the face and prevent the ground surface in the affected area from sinking or collapsing while the shield machine excavates, and for this reason it is essential to prevent excessive intake of excavated soil and to grasp the deviation amount of additives added to the excavated soil taken into the chamber of the shield machine. In the shield machine, a screw conveyor formed by a screw and a cylinder that rotatably houses the screw is connected to the chamber, and the excavated soil generated by mixing the excavated soil with additives in the chamber is discharged to the screw conveyor and transported to the rear of the shield machine via the screw conveyor. The above-mentioned excessive intake of excavated soil is due to the inability to precisely specify the volume of the excavated soil or discharged soil. However, since the volume of discharged soil is calculated by dividing its mass by its density, it is extremely important to precisely specify the density of the excavated soil or discharged soil.

[0003] Here, Patent Documents 1 and 2 disclose a technology for measuring the density and moisture content of excavated soil using radioisotopes (RI, radioactive isotopes) and managing the disposal of soil taken into a shield tunneling machine (here, a shield machine). The shield machine described in Patent Document 1 has a partition wall at the front of the shield cylinder, a face chamber is provided through this partition wall, an excavation tool is provided in front of the face chamber, and an earth removal device is connected to the rear of the face chamber. In this shield machine, a density and moisture meter using a radioisotope that measures the density and moisture content of soil in the face chamber is provided in the partition wall.

[0004] On the other hand, the shield machine described in Patent Document 2 is equipped with a plastic fluidization measuring device consisting of a rotating shaft installed in a chamber that rotates in the mud to measure the rotational torque, and a drive unit that drives the rotating shaft.An RI density / moisture meter source is enclosed inside the rotor so that in addition to the rotational torque, the density and moisture content of the mud are measured. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 5-263584 [Patent Document 2] JP 2003-97181 A Summary of the Invention [Problem to be solved by the invention]

[0006] The shield machines described in Patent Documents 1 and 2 are both based on technology in which a density / moisture measuring device using radioisotopes is installed in a chamber to measure the density and moisture content of the excavated soil being stirred in the chamber. More specifically, there are cutter spokes in front of the chamber, and in front of the cutter spokes there is a face (natural ground), and radiation (gamma rays and neutrons) is emitted from a radiation source installed in the partition wall of the chamber, and the radiation reflected by the cutter spokes and the face in front of them is detected by a detector. Therefore, the influence of the face and cutter spokes is reflected in the measured values, and since the density of the excavated soil being stirred in the chamber is not stable, it is difficult to say that the density of the discharged soil can be measured accurately.

[0007] The present invention aims to provide a shield tunneling machine and a measurement value calibration method for a shield tunneling machine that can precisely determine at least the density of soil discharged by the shield tunneling machine, and can suppress excessive intake of excavated soil and the resulting subsidence of the ground surface. [Means for solving the problem]

[0008] In order to achieve the above object, one aspect of the shield tunneling machine according to the present invention is to A shield tunneling machine, comprising: a screw having a rotating shaft and a spiral blade attached around the rotating shaft; and a cylindrical body rotatably housing the screw; a screw conveyor connected to a chamber that takes in excavated soil and generates excavated soil; The present invention is characterized in that an RI density meter that uses radioisotopes to measure the density of the discharged soil is provided in a recess in the outer periphery of the cylindrical body where the wall thickness is reduced.

[0009] According to the present embodiment, an RI density meter that uses radioisotopes to measure the density of discharged soil is provided on the outer periphery of the cylindrical body that constitutes the screw conveyor, making it possible to measure the density of discharged soil that has a stable (constant) density as it passes through the screw conveyor, thereby making it possible to suppress excessive intake of excavated soil and the resulting subsidence of the ground surface. Furthermore, by providing an RI density meter in a recess where the thickness of the outer periphery of the cylindrical body is thinned, it is possible to suppress large measurement errors caused by the thick thickness of the cylindrical body, and to prevent the cylindrical body from being unable to ensure sufficient rigidity due to the thin overall thickness of the cylindrical body. For example, one embodiment may be one in which the overall thickness is in the range of about 30 mm to 50 mm, for example about 40 mm, while the thickness of the recess is about 10 mm to 20 mm.

[0010] Another aspect of the shield tunneling machine according to the present invention is The present invention is characterized in that an RI moisture meter that measures the moisture content of the discharged soil using a radioisotope is further provided on the outer periphery of the cylindrical body.

[0011] According to this embodiment, an RI moisture meter for measuring the moisture content of the discharged soil is further provided on the outer periphery of the cylindrical body, so that the properties of the discharged soil can be identified with higher accuracy.

[0012] Another aspect of the shield tunneling machine according to the present invention is The RI density meter and the RI moisture meter each include a radiation source and a radiation detector; The present invention is characterized in that the radiation source and the radiation detector constituting the RI density measuring device are provided in respective unique recesses on the outer periphery of the cylindrical body at two points other than the two points on a 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) that constitute the RI density measuring device are provided in their own unique recesses on the outer periphery of the cylindrical body at two points other than the two points on the line passing through the rotation axis of the screw, thereby preventing the gamma rays emitted from the radiation source from being blocked by the rotation axis of the screw on their way to the radiation detector. Here, "two points other than two points on a line passing through the rotation axis of the screw" refers to, for example, two points other than two points on a diameter in the same cross section perpendicular to the axis of the cylinder (rotation axis of the screw) (for example, positions with a relative angle of about 30 degrees to 90 degrees, e.g., an angular relationship of 60 degrees).

[0014] Furthermore, even if the gamma rays pass through the rotating shaft of the screw on the way to the gamma ray detector, it is assumed that the density of the discharged soil can be measured with high accuracy. However, since the gamma rays do not interfere with the rotating shaft of the screw, it is possible to further improve the accuracy of the density measurement. Furthermore, with regard to RI moisture meters, since there is no need to install the radiation source (neutron source) and radiation detector (neutron detector) on the outer periphery of the cylinder at a distance from each other, there is no need for special installation techniques like with RI density meters. However, while this "special installation technique is not necessary," it is necessary to "machine the thickness of the recess (make it thin)" with moisture meters as well, and to "ensure sufficient separation from the radiation source detection part of the density meter" so that they are not affected by each other's RI.

[0015] Another aspect of the shield tunneling machine according to the present invention is The recess is provided above the upper half of the cylindrical body.

[0016] According to the present embodiment, the radiation source and radiation detector constituting the RI density measuring device are housed in their own respective recesses provided above the upper half of the cylinder. As a result, with regard to wear associated with the transport of discharged soil in the cylinder of the screw conveyor, the area further above the upper half is relatively less worn than the lower half, and the effect of strength reduction in the recess areas where the wall thickness is relatively thin can be reduced. Here, "above the upper half" means that the radiation source and radiation detector are placed at a position of ±15 degrees to ±45 degrees (a relative angle of 30 degrees to 90 degrees) centered on the vertical line connecting the axis of the cylinder and the top of the cylinder, for example at a position of about ±30 degrees (a relative angle of 60 degrees).

[0017] Another aspect of the shield tunneling machine according to the present invention is The present invention is characterized in that a lead shield is provided on the outer periphery of the cylindrical body between the radiation source and the radiation detector that constitute the RI density measuring device.

[0018] According to this embodiment, a lead shield is provided between the radiation source and the radiation detector that constitute the RI density measuring device, so that leakage radiation from the radiation source on the outer periphery of the cylindrical body can be blocked, leading to improved measurement accuracy.

[0019] In another aspect of the shield tunneling machine according to the present invention, The shield tunneling machine further includes a measurement calibration device, The measurement value calibration device includes: A storage unit that stores a calibration formula for calibrating the measurement values ​​obtained by the RI density measuring device and / or the RI moisture measuring device; The present invention is characterized in that it has a calibration unit that applies the measured value to the calibration formula during actual construction to obtain a calibration value for the density and / or moisture content of the discharged soil.

[0020] According to this aspect, in the measurement calibration device, the measured values ​​from the RI density meter and / or the RI moisture meter are applied to the calibration formula to obtain a calibration value for the density and / or moisture content of the discharged soil, and thus it is possible to obtain a calibration value (density or moisture content of the discharged soil) specified by correcting for attenuation of radiation intensity for a measured value related to radiation intensity (counting rate).Since the RI meter is an indirect measurement device that uses radiation emitted from a radioisotope, it is necessary to carry out comparative calibration with a substance whose density or moisture content is known in advance, obtain a relational equation of the radiation intensity with respect to the density or moisture content, i.e., a calibration equation, and apply the actual measured value to the calibration equation to obtain the density or moisture content.

[0021] In addition, one aspect of a measurement value calibration method for a shield tunneling machine according to the present invention is to A measurement value calibration method for calibrating a measurement value in the shield tunneling machine, comprising: The present invention is characterized in that the calibration formula is set based on both test measurement values ​​measured by the RI density meter and / or the RI moisture meter when test soil is discharged by applying the RI density meter and / or the RI moisture meter to a simulated screw conveyor having the same specifications as the screw conveyor, and actual measurement values ​​regarding the density and / or moisture content of the discharged soil during the test.

[0022] According to this embodiment, an RI density meter and / or an RI moisture meter are applied to a simulated screw conveyor of the same specifications as the screw conveyor to be used in the actual construction to obtain test measurement values, and a calibration formula is set based on both the test measurement values ​​and the actual measured values ​​for the density and / or moisture content of the soil discharged during the test.This makes it possible to obtain with high accuracy the density and / or moisture content of the soil discharged during the actual construction based on the high-precision calibration formula corresponding to the screw conveyor of the shield machine to be used in the actual construction.

[0023] Here, "same specifications as the screw conveyor to be used in the actual construction" means that the diameter (dimensions) and thickness of the cylinder, the shape and dimensions of the screw's rotating shaft and spiral blades, etc. are the same. Since an RI density meter and / or an RI moisture meter are installed on the outer periphery of the cylinder to measure the density and moisture content of the waste soil passing through the inside of the cylinder, the diameter of the cylinder (related to the distance between the radiation source and the radiation detector) and the thickness are particularly important factors. In addition, "actual measured values ​​of the density and / or moisture content of the discharged soil during the test" means the values ​​obtained when the discharged soil passing through the screw conveyor during the test is placed in a separate mold or the like and its wet density and / or moisture content (or moisture ratio) is measured. Effect of the Invention

[0024] The shield tunneling machine and measurement value calibration method for the shield tunneling machine of the present invention make it possible to precisely determine at least the density of the soil discharged by the shield tunneling machine, thereby suppressing excessive intake of excavated soil and the resulting subsidence of the ground surface. [Brief description of the drawings]

[0025] [Figure 1] FIG. 2 is a vertical cross-sectional view of an example of a shield machine according to an embodiment. [Diagram 2] FIG. 2 is a perspective view showing an example of an installation form of an RI density meter and an RI moisture meter relative to the outer periphery of a cylindrical body of a screw conveyor. [Diagram 3] 1 is a perspective view showing a recess on the outer periphery of a cylindrical body in which a radiation source and a radiation detector of an RI density measuring device are installed. [Figure 4] FIG. 2 is a perspective view showing a state in which a radiation source and a radiation detector of an RI density measuring device are installed in each recess. [Diagram 5] This is a perspective view showing the state in which the radiation source and radiation detector of the RI density measuring device are installed in each recess, and the periphery of the recess is reinforced. [Figure 6] FIG. 2 is a diagram illustrating an example of a hardware configuration of a measurement value calibration device. [Figure 7] FIG. 2 is a diagram illustrating an example of a functional configuration of a measurement value calibration device. [Figure 8] This is a graph showing the experimental results in a calibration accuracy verification experiment in which the diameter and thickness of the cylinder were changed to determine the relationship between wet density and decay fluctuation error, when there was a lead shield between the radiation source and the RI density measuring device. [Figure 9] This is a graph showing the experimental results in a calibration accuracy verification experiment in which the diameter and thickness of the cylinder were changed to determine the relationship between wet density and decay fluctuation error, when there was no lead shielding between the radiation source and the RI density measuring device. [Figure 10] This is a graph showing the correlation between the measured values ​​and the actual values ​​measured by an RI density meter installed on the outer periphery of a cylinder in a calibration accuracy verification experiment, where a lead shield is present between the radiation source and the RI density meter. [Figure 11] This is a graph showing the correlation between the measured values ​​and the actual values ​​measured by an RI density meter installed on the outer periphery of the cylinder in a calibration accuracy verification experiment, where there is no lead shielding between the radiation source and the RI density meter. [Figure 12] 1 is a graph showing the correlation between measured values ​​and actual values ​​measured using an RI moisture meter installed on the outer periphery of a cylindrical body in a laboratory experiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0026] Hereinafter, a shield machine and a method for calibrating measured values ​​in a shield machine according to an embodiment will be described with reference to the accompanying drawings. In this specification and the drawings, substantially identical components are designated by the same reference numerals, and duplicated explanations may be omitted.

[0027] [Shield tunneling machine according to the embodiment and measurement value calibration method for the shield tunneling machine] First, an example of a shield machine and a method of calibrating measurement values ​​in the shield machine according to an embodiment will be described with reference to Figs. 1 to 7 . Here, Fig. 1 is a vertical cross-sectional view of an example of a shield tunneling machine according to an embodiment, Fig. 2 is a perspective view showing an example of an installation form of an RI density meter and an RI moisture meter relative to the outer periphery of a cylindrical body of a screw conveyor, Fig. 3 is a perspective view showing recesses on the outer periphery of the cylindrical body in which the radiation source and radiation detector of the RI density meter are installed, Fig. 4 is a perspective view showing a state in which the radiation source and radiation detector of the RI density meter are installed in each recess, and Fig. 5 is a perspective view showing a state in which the radiation source and radiation detector of the RI density meter are installed in each recess and the periphery of the recess is reinforced.

[0028] The illustrated shield machine 100 is an earth pressure type shield machine (including a mud pressure type shield machine) that has a shield body 10 and a cutter head 20 that is rotatably attached to the front of the shield body 10 in the excavation direction, the cutter head 20 having a plurality of cutter spokes 22. Here, the shield machine may be a muddy water type shield machine that is equipped with a face plate-shaped cutter head. The shield machine may also be a center-bending type shield machine that has a front body and a rear body. Furthermore, the illustrated example shield machine 100 may be a shield machine of various diameters, large and small.

[0029] The shield body 10 has a partition wall 11 (bulkhead) behind the cutter head 20, and a chamber 13 for taking in the excavated soil (excavated soil) between the partition wall 11 and the cutter head 20, with multiple fixed blades 12 provided on the side of the partition wall 11 facing the chamber 13, and an agitator blade 25 provided on the back of the cutter head 20 facing the chamber 13. A mud-adding agent is supplied to the excavated soil taken into the chamber 13, and by rotating the agitator blade 25 in response to the rotation of the cutter head 20, the excavated soil is plastically fluidized by the fixed blades 12 and the rotating agitator blade 25, and soil is generated.

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

[0031] A number of shield jacks 16 are attached to the inner peripheral surface of the shield body 10 (only two shield jacks are shown in Fig. 1), and an erector device 17 at the rear of the shield body 10 extends the shield jacks 16 against a segment ring, which is made up of a number of segments S assembled into a ring shape, and presses the segment ring, causing the shield tunneling machine 100 to excavate in the excavation direction. In addition, tail seals (not shown) are provided in multiple locations on the inside rear of the shield body 10, extending in the circumferential direction, and the tail seals are constantly in sliding contact with the installed segment rings, thereby ensuring the waterproofing of the shield body 10.

[0032] The cutter head 20 has a plurality of cutter spokes 22 extending in a radial direction (radially) from a central boss member 24. A plurality of cutter bits 23 are attached to the central fishtail 21 and the cutter spokes 22, and a copy cutter 23A is attached to the outer circumferential end of the cutter spokes 22 so as to be freely retractable.

[0033] The screw conveyor 30, which receives the waste 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 a spiral blade 34 mounted around the rotating shaft 33, a cylindrical body 31 that houses the screw 32 so that it can rotate freely in the X1 direction, and a drive source (drive motor) (not shown) that drives and rotates the screw 32.

[0034] An RI density meter 40 and an RI moisture meter 50 are installed on the outer periphery of the cylindrical body 31, which use radioisotopes to measure the density and moisture content of the discharged soil transported in the X2 direction to the rear of the cylindrical body 31 in response to the rotation of the screw 32 in the X1 direction. That is, in the shield tunneling machine 100, when measuring the density and moisture content of the discharged soil, the discharged soil transported inside the screw conveyor 30 is the measurement target.

[0035] The RI density measuring device 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 discharged soil. On the other hand, the RI moisture measuring device 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 discharged soil. Here, since the density and moisture content of the actual discharged soil at the site are generally measured in a state where the screw conveyor is filled with soil and sand, the positions of the radiation sources 46 and 53 on the outer periphery of the cylindrical body 31 are set so that they can be measured on the assumption that the screw conveyor is filled with soil and sand. The RI density measuring device 40 and the RI moisture measuring device 50 will be described in detail below.

[0036] 3 to 5, the installation structure of the radiation source 46 and the radiation detector 41 on the outer periphery 31a of the cylindrical body 31 will be described. Note that Figs. 3 and 4 show a cross section of the cylindrical body 31 cut vertically at the midpoint of the recesses 31c and 31d provided on the outer periphery 31a of the cylindrical body 31. Also, although the recess for the RI moisture measuring device 50 is omitted in Fig. 3 etc., a recess specific to the RI moisture measuring device 50 is also provided on the outer periphery 31a of the cylindrical body 31.

[0037] As shown in FIG. 3, in a cylindrical body 31 having an inner diameter φ, two recesses 31c, 31b are provided on the left and right sides at an angle θ2 with respect to a line L2 that runs along the longitudinal direction at the top of the body. The relative angle between the two recesses 31c, 31d is θ1, which is twice θ2.

[0038] As shown in FIG. 4, the lower part of the radiation source 46 is housed and installed in one recess 31c, and the lower part of the radiation detector 41 is housed and installed in the other recess 31d.

[0039] Returning to FIG. 3, when the diameter φ of the cylindrical body 31 is 400 mm or more, the thickness (wall thickness) t1 of the general portion is set to about 40 mm or more, thereby ensuring the strength of the cylindrical body 31.

[0040] Thus, when the wall thickness t1 of the cylindrical body 31 is thick, there is a risk that highly accurate measurements cannot be achieved even if the RI density meter 40 or the RI moisture meter 50 is simply attached to the outer periphery 31a of the cylindrical body 31 and the density and moisture content of the discharged soil moving inside the cylindrical body 31 are measured. Although the shield tunneling machine 100 calibrates the measurements using a measurement calibration device as described below, it is essential that the measurements before calibration are highly accurate.

[0041] On the other hand, if the overall wall thickness t1 of the cylindrical body 31 is reduced in order to increase the measurement accuracy, the strength of the cylindrical body 31 will not be ensured sufficiently, which is undesirable.

[0042] Therefore, as shown in FIG. 3, the overall thickness t1 of the cylindrical body 31 is set to a thickness that ensures sufficient strength (for example, about 40 mm), and unique recesses 31c, 31d (and a recess unique to the RI moisture meter 50, not shown) are provided at the installation locations of the RI density meter 40 (radiation source 46, radiation detector 41) and the RI moisture meter 50, and the thickness t2 of each recess 31c, 31d is made relatively thin.

[0043] From the viewpoint of measurement accuracy, the thickness t2 can be set to about 10 mm to 20 mm.

[0044] On the other hand, the present inventors have determined that the measurement error increases as the distance (clearance) between the radiation source 46 and the radiation detector 41 increases. For this reason, θ2 shown in Fig. 3 is set to about 30 degrees or less, and the relative angle between them is set to about 60 degrees or less.

[0045] In this way, measurement errors can be suppressed by making the distance (relative angle) between the radiation source 46 and the radiation detector 41 as small as possible. However, if the radiation source 46 and the radiation detector 41 are too close, there is a risk that the measurement accuracy will decrease due to the radiation detector 41 detecting leakage radiation from the radiation source 46.

[0046] Therefore, as shown in Figs. 3 and 4, a lead shield 35 having a size that does not interfere with the screw 32 is installed between the two recesses 31c, 31d on the outer periphery 31a of the cylindrical body 31.

[0047] As shown in the figure, the respective unique recesses 31c, 31d for housing the radiation source 46 and the radiation detector 41 are provided above the upper half of the cylindrical body 31. As a result, with regard to wear associated with the transport of discharged soil in the cylindrical body 31 of the screw conveyor 30, the area further above the upper half is relatively less worn than the lower half, so that the effect of reduction in strength in the areas of the recesses 31c, 31d, which are relatively thin, can be reduced.

[0048] However, since the recesses 31c and 31d are relatively thin compared to other general parts, there is a risk of a decrease in strength of the regions of the recesses 31c and 31d and the surrounding regions. Therefore, as shown in Fig. 5, frame-shaped steel reinforcing members 36 and 37 are fixed by welding or the like to the periphery of the recesses 31c and 31d on the outer periphery 31a of the cylindrical body 31, respectively, to reinforce the strength of the periphery of the recesses 31c and 31d.

[0049] Similarly, as shown in FIG. 2, a steel frame-shaped reinforcing member 38 is fixed around a recess (not shown) in which the RI moisture meter 50 is installed on the outer periphery 31a of the cylindrical body 31 to reinforce the strength around the recess.

[0050] There are various other methods of reinforcing strength in addition to the illustrated reinforcing members 36, 37, and 38. If there is no risk of a decrease in strength of the regions of the recesses 31c and 31d and the surrounding regions, it is not necessary to install reinforcing members.

[0051] According to the installation structure of the cylindrical body 31 and the RI density meter 40 and the RI moisture meter 50 shown in the figure, a predetermined thickness of the cylindrical body 31 is ensured to maintain its overall rigidity, while high measurement accuracy can be enjoyed by the RI density meter 40 and the RI moisture meter 50 installed on the outer periphery 31a of the cylindrical body 31.

[0052] A measurement value calibration device 60 is provided inside the shield body 10. The measurement value calibration device 60 is a computer that applies the respective measurement values ​​from the RI density meter 40 and the RI moisture meter 50 to a calibration formula to determine calibration values ​​related to the density and moisture content of the discharged soil, thereby specifying the density and moisture content of the discharged soil. Here, the measurement value calibration device 60 will be described below as being provided inside the shield tunneling machine 100, but the measurement value calibration device 60 may be provided in a management building (not shown) on the ground, or may be provided in both the shield tunneling machine 100 and the management building, with both measurement value calibration devices 60 connected to enable data transmission and reception.

[0053] As shown in FIG. 2, on the outer periphery 31a of the cylinder 31 of the screw conveyor 30, an RI density meter 40 and an RI moisture meter 50 are disposed at positions separated from each other along the axial direction L1 of the rotation shaft 33.

[0054] Radiation detector 41 constituting RI density measuring instrument 40 has, inside case 42, stainless steel shield 43, gamma ray detector 44, and high voltage power supply 45. Meanwhile, radiation source 46 constituting RI density measuring instrument 40 has gamma ray source 48 inside case 47. The radioactive material emitted from gamma ray source 48 can be, for example, cobalt 60 (Co 60), etc.

[0055] For example, PIRICA-S1 (PIRICA S-One, PIRICA densitometer for piping, PIRICA is a registered trademark) manufactured by Soil and Rock Engineering Co., Ltd. can be used as the RI density measuring instrument 40.

[0056] On the other hand, the RI moisture measuring instrument 50 has a neutron detector 52 and a neutron source 53 housed side by side inside a case 51. The radioactive material emitted from the neutron source 53 may be, for example, californium 252 (cf-252).

[0057] For example, CONG-II (SRM CONG is a registered trademark) manufactured by Soil and Rock Engineering Co., Ltd. can be used as the RI moisture meter 50.

[0058] Since the radiation detector 41 and the radiation source 46 are separated from each other, the RI density measurer 40 is installed, for example, at two points on any cross section perpendicular to the axial direction L1 of the rotation shaft 33 on the outer periphery of the cylindrical body 31. If the radiation detector 41 and the radiation source 46 cannot be installed at two points on the same cross section due to their relationship with other devices in the shield body 10, they may be installed at two points shifted in the axial direction L1.

[0059] 2, in the case where the radiation detector 41 and the radiation source 46 are installed at two points on an arbitrary cross section perpendicular to the axial direction L1, as already explained with reference to Fig. 3 etc., the radiation detector 41 and the radiation source 46 are installed at a position where the relative angle θ1 is about 60 degrees from the top of the cylindrical body 31. Note that Fig. 2 shows the top of the cylindrical body 31 shifted to an oblique position in order to make both the radiation detector 41 and the radiation source 46 easier to view.

[0060] In this way, the radiation source 46 and the radiation detector 41, which are in a positional relationship with a relative angle of θ1, are provided on the outer periphery 31a of the cylindrical body 31 at two points other than the two points on the straight line passing through the rotation axis 33 of the screw 32.

[0061] According to the inventors, it has been determined that an installation configuration in which the radiation source 46 and the radiation detector 41 are provided at two points other than the two points on a line passing through the rotation axis 33 of the screw 32 allows the density of the discharged soil to be measured with high accuracy.

[0062] Regarding the measurement of the moisture content of the waste soil using the RI moisture meter 50, fast neutrons emitted from the neutron source 53 collide with the moisture contained in the waste soil, and the reflected thermal neutrons are detected by the neutron detector 52 installed next to the neutron source 53, so the RI moisture meter 50 may be installed at any position on the outer periphery 31a of the cylindrical body 31.

[0063] The gamma ray detector 44 and the neutron ray detector 52 measure the amount of radiation that has passed through the discharged soil to obtain measurements related to the density and moisture content of the discharged soil. The measurement data obtained by the gamma ray detector 44 and the neutron ray 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.

[0064] That is, the shield tunneling machine 100 not only measures the density and moisture content of the discharged soil with high precision using the RI density meter 40 and the RI moisture meter 50, but also calibrates the measurement values, which may contain measurement errors to some extent, using the measurement calibration device 60, thereby further improving the accuracy of determining the density and moisture content of the discharged soil.

[0065] Next, the measurement value calibration device 60 will be described with reference to Fig. 6 and Fig. 7. Here, Fig. 6 is a diagram showing an example of the hardware configuration of the measurement value calibration device, and Fig. 7 is a diagram showing an example of the functional configuration of the measurement value calibration device.

[0066] As shown in Fig. 6, the measurement value calibration device 60 is configured with an information processing device (computer) such as a personal computer (PC). The computer that configures the measurement value calibration device 60 includes a CPU (Central Processing Unit) 61, a main memory device 62, an auxiliary memory device 63, an input / output IF (interface) 64, and a communication IF 65, which are interconnected by a connection bus 66. The main memory device 62 and the auxiliary memory device 63 are computer-readable recording media. The above components may be provided separately, or some of the components may not be provided.

[0067] The CPU 61 is also called an MPU (Microprocessor) or a processor, and may be a single processor or a multiprocessor. The CPU 61 is a central processing unit that performs overall control of the measurement calibration device 60, which is made up of a computer. The CPU 61, for example, develops a program stored in the auxiliary storage device 63 in an executable manner in the working area of ​​the main storage device 62, and controls peripheral devices through the execution of the program, thereby providing functions that meet a predetermined purpose.

[0068] The main storage device 62 stores computer programs executed by the CPU 61, data processed by the CPU 61, etc. The main storage device 62 includes, for example, a flash memory, a RAM (Random Access Memory), and a ROM (Read Only Memory). The auxiliary storage device 63 stores various programs and various data in a readable and writable recording medium, and is also called an external storage device. The auxiliary storage device 63 stores, for example, an OS (Operating System), various programs, various tables, etc. The OS includes, for example, a communication interface program that transfers data to and from external devices, etc. connected via the communication IF 65. The external devices, etc. include, for example, the gamma ray detector 44 and the neutron ray detector 52, as well as a personal computer (not shown) for construction management in a management building connected to a network.

[0069] The auxiliary storage device 63 is used, for example, as a storage area that assists the main storage device 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 including a non-volatile semiconductor memory (flash memory, EPROM (Erasable Programmable ROM)), a hard disk drive (HDD: Hard Disk Drive) device, a solid state drive device, etc. Examples of the auxiliary storage device 63 include drives for removable recording media such as a CD drive device, a DVD drive device, and a BD drive device, and examples of the removable recording media include a CD, a DVD, a BD, a USB (Universal Serial Bus) memory, and an SD (Secure Digital) memory card, etc.

[0070] The input / output IF 64 is an interface for inputting and outputting data between devices connected to the measurement value calibration device 60. For example, input devices such as a keyboard, a touch panel, a mouse, or other pointing device, and a microphone are connected to the input / output IF 64. The measurement value calibration device 60 receives operation instructions and the like from an operator who operates the input device via the input / output IF 64.

[0071] In addition, the input / output IF 64 is connected to display devices such as a liquid crystal panel (LCD: Liquid Crystal Display) or an organic EL panel (EL: Electroluminescence), as well as output devices such as a printer and a speaker. For example, measurement data relating to density and moisture content transmitted from the gamma ray detector 44, the neutron ray detector 52, etc. via a cable or the like is acquired and displayed. Also, calibrated values ​​(specific values) relating to the density and moisture content of the discharged soil, etc., obtained by the measurement value calibration device 60, are displayed on the same screen.

[0072] The communication IF 65 is an interface with a cable or network to which the measurement value calibration device 60 is connected. The communication IF 65 transmits calibration value data related to the density and moisture content of the discharged soil to a personal computer for construction management in a management building via various networks, such as a public network such as the Internet, a wireless network such as a mobile phone network, a dedicated network such as a VPN (Virtual Private Network), and a LAN (Local Area Network).

[0073] 7, the measurement value calibration device 60 provides various functions of at least an acquisition unit 602, a calibration unit 604, a display unit 606, and a storage unit 608 by executing a program by a CPU 61. Here, at least a part of the above processing functions may be provided by a DSP (Digital Signal Processor), a GPU (Graphics Processing Unit), or the like, and similarly, at least a part of the above processing functions may be a dedicated LSI (large scale integration) such as an FPGA (Field-Programmable Gate Array), a numerical calculation processor, an image processing processor, or other digital circuits, or the like.

[0074] The acquisition unit 602 acquires measurement data regarding density and water content transmitted via a cable or the like from the gamma ray detector 44 and the neutron ray detector 52, and the acquired measurement data is stored (memorized) in the storage unit 608.

[0075] Stored in storage 608 are calibration equations that calibrate the measurements for density and moisture content.

[0076] Because the RI density meter 40 and the RI moisture meter 50 are indirect measuring instruments that use radiation from radioisotopes, it is necessary to perform a comparative calibration with a substance whose density and moisture content are known in advance and determine the relational equation of radiation intensity with respect to density and moisture content (moisture content), i.e., the calibration equation. In measuring instruments that use radiation, regardless of the type of radiation source, the radiation intensity (counting rate) is not constant and has the property of decaying over time.

[0077] Therefore, when determining the relationship between radiation intensity (counting rate) and density or moisture content, the absolute value of radiation intensity (counting rate) cannot be used as is, and correction for attenuation of radiation intensity is required. The calibration formulas in the RI density meter 40 and the RI moisture meter 50 are unique to each meter, and a test to identify the calibration formula is carried out prior to construction, and the calibration value is identified from the measured values ​​related to density and moisture content using the calibration formula identified in the test.

[0078] Here, the radiation intensity is not an absolute value but a relative value (counting rate ratio) measured against a certain reference material. In other words, counting rate ratio = measured value of the discharged soil to be measured (counting rate (cpm), cpm: counts per minute)) / counting rate (cpm) measured using a reference material.

[0079] If the count rate ratio is not used, for example, the wet density ρt when the count rate at the time of creating the calibration formula is 500 cpm is 2.0 g / cm 3 As time passes, ρt becomes 2.0g / cm 3 When measuring something with the same density, the radiation will decay to, for example, 250 cpm, and the radiation count (cpm) will be different, even though the objects being measured are of the same density.

[0080] To avoid such a situation, the count rate ratio is used to take into account the passage of time (decay of radiation).

[0081] More specifically, since radiation also exists in nature, it is desirable to subtract the background (BG) count rate NB from the measured count rate Nρ and divide the result by the standard count rate Sρ to determine the count rate ratio Rρ, in order to eliminate the influence of background (BG) radiation that exists in nature. In other words, Rρ is given by the following formula (1).

[0082]

number

[0083] From the count rate ratio Rρ calculated by formula (1), a calibration value is calculated from the measured value using a calibration formula such as formula (2) below.

[0084]

number

[0085] Since the standard calibration constants A and B have unique values ​​depending on the diameter (outer diameter), thickness, and standards of the cylinder (pipe) used when measuring the density of discharged soil, it is desirable to input values ​​according to the diameter and thickness of the cylinder of the screw conveyor used in the actual construction, for example, at the time of shipment from the factory. In other words, in the calibration formula specification experiment, it is desirable to set the calibration formula using a simulated screw conveyor with the same specifications as the screw conveyor used in the actual construction, and further using an RI density meter and an RI moisture meter that are appropriate for the actual construction.

[0086] In this case, a more accurate calibration formula can be identified by installing an RI density meter and an RI moisture meter at the same positions on the simulated screw conveyor as they will be installed on the screw conveyor during actual construction.

[0087] In the calibration equation specification experiment, an RI density meter and an RI moisture meter are applied to a simulated screw conveyor of the same specifications as the screw conveyor, and a calibration equation is set based on both the test measurement values ​​measured with the RI density meter and the RI moisture meter when test soil is discharged, and the actual measured values ​​for the density and moisture content of the discharged soil during the test.

[0088] In the calibration specific experiment, a prototype of the soil discharge (simulated soil discharge) expected during the actual construction work is prepared, and measurement values ​​are obtained using an RI density meter or the like when the simulated soil is passed through a simulated screw conveyor. Furthermore, actual measurement values ​​are obtained based on the wet density and moisture content measurements of the prototype soil discharge.

[0089] In creating the simulated soil removal, gravel, sand, and soil are mixed in a specified ratio, assuming the target ground for the actual construction. In addition, the mud-adding material (thickening material) to be used in the actual construction is added.

[0090] Incidentally, according to the present inventors, it has been determined that the accuracy of the calibration formula is hardly affected by the properties (type) of discharged soil, and that it is the density and moisture content of the discharged soil that affect the accuracy of the calibration formula.

[0091] The storage section 608 stores the calibration equations for the RI density meter 40 and the RI moisture meter 50 that are set in the calibration equation specification experiment and that are to be applied in the actual work.

[0092] In actual construction, measurement data relating to the density and moisture content of the discharged soil is stored in storage unit 608 as needed, and calibration unit 604 specifies calibration values ​​for density and moisture content by applying each measurement data to the calibration equations for density and moisture content stored in storage unit 608. This completes the measurement calibration method for the shield tunneling machine according to the embodiment.

[0093] According to the inventors, it has been determined that the outer diameter (size) and wall thickness of the cylinder and the size of the screw have a large effect on the calibration result. Therefore, it is preferable to set the relative angle θ1 between the radiation source 46 of the RI density meter 40 and the radiation detector 41 to an acute angle (e.g., about 60 degrees) and to set the distance between the two short, depending on the size of the cylinder and the screw.

[0094] Furthermore, as already explained, in order to prevent a decrease in measurement accuracy caused by the radiation detector 41 detecting leakage radiation from the radiation source 46, which is a concern when the distance between the radiation source 46 and the radiation detector 41 is shortened, it is preferable to install a lead shield 35 of a size that does not interfere with the screw 32 between the two recesses 31c, 31d on the outer periphery 31a of the cylindrical body 31.

[0095] The display unit 606 displays the calibration values ​​for the specified density and water content on a screen, specifies the volume of discharged soil calculated based on the calibration values, and displays the verification basis for whether or not an excessive amount of excavated soil is being taken into the chamber 13. In addition, an appropriate range for the amount of excavated soil to be taken in is stored in the storage unit 608, and a determination unit (not shown) or the like may compare the amount of excavated soil to be taken in calculated from the specified density of the discharged soil (and thus the excavated soil) with the appropriate range of the amount of take-in at any time, and display the determination result on the display unit 606.

[0096] The shield tunneling machine 100 and the measurement value calibration method make it possible to precisely determine the density of soil discharged and water content by the shield tunneling machine 100, thereby making it possible to effectively suppress excessive intake of excavated soil and the resulting subsidence of the ground surface.

[0097] [Calibration accuracy verification experiment and its results] The inventors constructed a simulated screw conveyor and conducted a calibration equation accuracy verification experiment to verify the effects on the accuracy of the calibration equation of installing an RI density meter and an RI moisture meter in recesses on the outer periphery of the cylinder, and of installing a lead shield between the radiation source and radiation detector that make up the RI density meter.

[0098] Here, the simulated casings simulating the cylindrical body were φ600mm, φ800mm, φ1000mm, and φ1200mm in size, and had a wall thickness of 12mm (only φ800mm had 12mm and 19mm). The relative angle between the radiation source and the radiation detector constituting the RI density meter was set to 60 degrees. This thickness simulates the thickness of a recess with a wall thickness of about 10mm to 20mm formed in a normal cylindrical body with a wall thickness of about 40mm.

[0099] In this experiment, the density was measured when the simulated casing was filled with water, when it was filled with sand and water (wet sand), and when it was filled with red soil and water (wet clayey soil), and RI density measurements were also performed.

[0100] Figures 8 and 9 are graphs showing the experimental results when there is a lead shield between the radiation source and the RI density meter, and when there is no lead shield between the radiation source and the RI density meter, in the calibration accuracy verification experiment, in which the diameter and thickness of the cylinder are changed to specify the relationship between the wet density and the decay fluctuation error. Figures 10 and 11 are graphs showing the correlation between the measured values ​​and the actual values ​​measured by the RI density meter installed on the outer periphery of the cylinder, respectively, in the calibration accuracy verification experiment, in which there is a lead shield between the radiation source and the RI density meter, and when there is no lead shield between the radiation source and the RI density meter. Figure 12 is a graph showing the correlation between the measured values ​​and the actual values ​​measured by the RI moisture meter installed on the outer periphery of the cylinder in the laboratory experiment.

[0101] Here, the "decay fluctuation error" on the vertical axis in Figures 8 and 9 will be explained as follows. That is, in measurements using the RI method, there is an inherent error caused by fluctuations in the number of radiations emitted from the radiation source (fluctuations in the number of atomic nuclei that decay). By performing repeated measurements under constant conditions, the number of detected radiations obtained by a radiation detector is not a constant value, but shows a statistical distribution with a standard deviation. Since the measured value calculated by substituting the number of detected radiations into the calibration formula also shows fluctuations according to the fluctuations in the number of detected radiations, this is called "decay fluctuation error," and the measurement accuracy of an RI density counter can generally be indicated by the standard deviation of the measured value caused by decay fluctuations.

[0102] As shown in Figures 8 and 9, the measurement error was small and good measurement results were obtained for all sizes of simulated casings, demonstrating that, assuming that the minimum necessary strength is ensured, the thickness of the cylindrical body at the location where the RI density meter, etc. is to be installed is preferably about 10 mm to 20 mm.

[0103] It was also determined that the measurement error was smaller when using simulated casings of φ600mm and φ800mm compared to simulated casings of φ1000mm and φ1200mm, which indicates that the measurement error is smaller when the distance between the radiation source and the radiation detector is smaller.

[0104] In addition, when comparing the results of two types of φ800mm simulated casings with wall thicknesses of 12mm and 19mm, it is found that the measurement error of the 12mm-thick simulated casing is significantly smaller, and that the measurement error of the 19mm-thick simulated casing is larger than that of the 12mm-thick, relatively large-diameter (φ1000mm, 1200mm) simulated casings. This demonstrates that the effect of wall thickness on measurement error is extremely large, and that the measurement accuracy increases as the wall thickness becomes thinner.

[0105] Furthermore, the measurement error in Figure 8 is smaller than that in Figure 9, demonstrating that the measurement error can be reduced by placing a lead shield between the radiation source and the radiation detector.

[0106] Also, Figures 10 and 11 demonstrate that the correlation between the measured wet density and the calibration formula is good, regardless of the presence or absence of lead shielding. Furthermore, Figure 12 demonstrates that the correlation between the measured moisture content and the calibration formula is good.

[0107] In addition, the present invention is not limited to the configuration shown here, and may be implemented in other embodiments in which other components are combined with the configurations and the like of the above-mentioned embodiment. In this regard, the present invention may be modified within the scope of the gist of the present invention, and may be appropriately determined according to the application form. [Explanation of symbols]

[0108] 10: Shield body 11: Bulkhead 12:Fixed wing 13: Chamber 14: Hydraulic motor for driving cutter head 16: Shield Jack 17: Erector device 18: Center-folding jack 20: Cutter head 21: Fishtail 22: Cutter spoke 23: Cutter Bit 23A: Copy cutter 24: Boss part 30: Screw conveyor 31: Cylinder 31a: Outer circumference 31b:Inner wall 31c, 31d: recess 32: Screw 33: Rotation axis 34: Spiral wing (wing) 35: Lead shield 36, 37, 38: Reinforcing members 40:RI density measuring device 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: Ray source (neutron source) 60: Measurement Calibration Device 100: Shield tunneling machine L: Axial direction of the rotation shaft

Claims

1. A shield tunneling machine, comprising: a screw having a rotating shaft and a spiral blade attached around the rotating shaft; and a cylindrical body rotatably housing the screw; a screw conveyor connected to a chamber that takes in excavated soil and generates excavated soil; A shield tunneling machine, characterized in that an RI density meter that measures the density of the discharged soil using a radioisotope is provided in a recess where the thickness of the outer periphery of the cylindrical body is reduced.

2. 2. The shield machine according to claim 1, further comprising an RI moisture meter for measuring the moisture content of the discharged soil using a radioisotope, which is provided on the outer periphery of the cylindrical body.

3. The RI density meter and the RI moisture meter each include a radiation source and a radiation detector; The shield tunneling machine described in claim 2, characterized in that on the outer periphery of the cylindrical body, the radiation source and the radiation detector constituting the RI density meter are provided in their own unique recesses at two points other than the two points on a straight line passing through the rotation axis of the screw.

4. 4. The shield machine according to claim 3, wherein the recess is provided above an upper half of the cylindrical body.

5. 2. The shield tunneling machine according to claim 1, wherein the periphery of the recess is reinforced.

6. 4. The shield machine according to claim 3, wherein a lead shield is provided on the outer periphery of the cylindrical body between the radiation source and the radiation detector that constitute the RI density measuring device.

7. The shield tunneling machine further includes a measurement calibration device, The measurement value calibration device includes: A storage unit that stores a calibration formula for calibrating the measurement values ​​obtained by the RI density measuring device and / or the RI moisture measuring device; 3. The shield machine according to claim 2, further comprising a calibration unit which applies the measured value to the calibration formula during actual construction to obtain a calibration value relating to the density and / or moisture content of the discharged soil.

8. A method for calibrating a measurement value in the shield tunneling machine according to claim 7, comprising the steps of: A measurement value calibration method for a shield tunneling machine, characterized in that the RI density meter and / or 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 test measurement values ​​measured by the RI density meter and / or the RI moisture meter when test soil is discharged, and actual measurement values ​​regarding the density and / or moisture content of the discharged soil during the test.

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