Soil property measuring device

Abstract

To measure soil properties further accurately using a density meter and a moisture meter.SOLUTION: A property measuring device 20 includes a cylinder tube 21a, a transmission-type density meter 22 for detecting density of excavated soil, and a scattering-type moisture meter 23 for detecting the amount of moisture contained in the excavated soil. The density meter 22 includes a radiation source unit 22a attached to an outer circumferential surface of the cylinder tube 21a, for irradiating the excavated soil guided into the cylinder tube 21a with gamma rays, and a radiation detection unit 22b attached to a position spaced apart from the radiation source unit 22a on the outer circumferential surface of the cylinder tube 21a, for detecting gamma rays emitted from the radiation source unit 22a and passing through the excavated soil guided into the cylinder tube 21a. The moisture meter 23 is attached to the outer circumferential surface of the cylinder tube 21a at a position where the radiation source unit 22a and the radiation detection unit 22b do not overlap when viewed from the axial direction of the cylinder tube 21a.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to an apparatus for measuring soil properties. [Background technology]

[0002] Patent Document 1 discloses that the density of soil excavated using a cutter head is measured by a density meter. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2001-98892 A Summary of the Invention [Problem to be solved by the invention]

[0004] In the invention disclosed in Patent Document 1, for example, it is conceivable to grasp the properties of soil and sand in more detail by measuring the moisture content of the soil and sand. In this case, it is conceivable to install a moisture meter and a density meter on the outer circumferential surface of the pipe at intervals in the axial direction of the pipe.

[0005] In this case, however, the soil and sand measured by the moisture meter and density meter will be different, and there is a possibility that the properties of the soil and sand will not be accurately grasped.

[0006] The present invention aims to more accurately measure the properties of soil and sand using a density meter and a moisture meter. [Means for solving the problem]

[0007] The present invention is a property measuring device for measuring the properties of excavated soil excavated by an excavation pusher, and comprises a pipe having an internal space in which the excavated soil remains or a space through which the excavated soil passes, a transmission type density meter for detecting the density of the excavated soil guided into the pipe, and a scattering type moisture meter for detecting the amount of moisture contained in the excavated soil guided into the pipe, wherein the density meter has a radiation source unit attached to the outer surface of the pipe and irradiates gamma rays toward the excavated soil guided into the pipe, and a radiation detection unit attached to the outer surface of the pipe at a position spaced from the radiation source unit and detects gamma rays irradiated from the radiation source unit and passing through the excavated soil guided into the pipe, and the moisture meter is attached to the outer surface of the pipe at a position where the radiation source unit and the radiation detection unit do not overlap when viewed from the axial direction of the pipe. Effect of the Invention

[0008] According to the present invention, when a density meter and a moisture meter are attached to the outer peripheral surface of a pipe, it is possible to bring the axial positions of these pipes closer together, making it possible to measure the properties of the soil and sand more accurately. [Brief description of the drawings]

[0009] [Figure 1] 1 is a cross-sectional view showing a schematic configuration of a shield machine to which a property measuring device according to an embodiment of the present invention is applied. [Diagram 2] FIG. 2 is a front view of a cutter head of a shield machine according to an embodiment of the present invention. [Diagram 3] FIG. 2 is a cross-sectional view of the axial structure of the property measuring device according to the embodiment of the present invention. [Figure 4] FIG. 2 is a cross-sectional view of the radial structure of the property measuring device according to the embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, a property measuring device 20 according to an embodiment of the present invention will be described with reference to the drawings.

[0011] First, with reference to Fig. 1, a shield machine 1 (excavation propulsion machine) to which the property measuring device 20 is applied will be described. The shield machine 1 excavates the ground (natural ground) to form an excavation hole, and constructs a shield tunnel T (tunnel) by assembling segment rings 9, which will be described later, to cover the inner wall of the excavation hole. In the following description, the face side, which is the direction in which the shield machine 1 advances, will be referred to as the "front", and the tunnel mouth side, which is the opposite direction, will be referred to as the "rear".

[0012] FIG. 1 is a cross-sectional view showing the schematic configuration of a shield tunneling machine 1, and FIG. 2 is a view of the shield tunneling machine 1 as seen from the front of FIG.

[0013] The shield machine 1 of this embodiment is used in an air bubble shield method. As shown in Fig. 1, the shield machine 1 is equipped with a cylindrical skin plate 2 capable of supporting an inner wall W1 of the natural ground, a rotary cutter head 3 (cutter) attached to the skin plate 2, and a partition wall 4 provided inside the skin plate 2 and dividing the inside of the skin plate 2 in the front-rear direction. Inside the skin plate 2, segment rings 9 are constructed successively as the shield machine 1 advances. Note that the cross-sectional shape of the skin plate 2 is not limited to a circle, and may be an ellipse or a rectangle.

[0014] The skin plate 2 is provided behind the cutter head 3. A jack 5 is fixed to the inner wall of the skin plate 2 behind the bulkhead 4. The jack 5 receives a reaction force from the segment ring 9 and propels the skin plate 2 forward, pressing the cutter head 3 against the natural ground. When the skin plate 2 is propelled and the segment ring 9 comes out of the skin plate 2, a backfilling material (not shown) is filled between the outer peripheral surface of the segment ring 9 and the inner wall W1 of the natural ground.

[0015] The cutter head 3 is a disk-shaped structure having an outer diameter approximately equal to that of the skin plate 2. As shown in Fig. 2, the cutter head 3 has hollow spoke portions 31 extending radially from the rotation axis C1, an annular ring portion 32 to which the tip sides of the spoke portions 31 are connected, an opening 33 formed between adjacent spoke portions 31, and a plurality of cutter bits 34, 35 arranged at predetermined intervals in the circumferential and radial directions on the surface of the spoke portions 31 facing the excavation face (face).

[0016] 1, the cutter head 3 is connected to a motor 6 via a cutter shaft 6a and a reduction gear mechanism 6b, and is rotated in front of the skin plate 2 by the driving of the motor 6. When the cutter head 3 rotates while being pressed against the natural ground, the natural ground is excavated by the cutter bits 34, 35.

[0017] A chamber 2a is formed between the cutter head 3 and the partition wall 4. Soil generated by excavation by the cutter head 3 (hereinafter referred to as "excavated soil") is guided into the chamber 2a through an opening 33 (see FIG. 2) provided in the cutter head 3. The chamber 2a corresponds to the "space in which the excavated soil accumulates" in the claims.

[0018] A stirring rod (not shown) protruding into the chamber 2a is provided on each spoke portion 31 of the cutter head 3. As the cutter head 3 rotates, the stirring rod stirs the soil and sand remaining in the chamber 2a.

[0019] 1, a property measuring device 20 for measuring the properties of the excavated soil in the chamber 2a is attached to the partition wall 4. In addition, the partition wall 4 is also provided with a resistivity meter (not shown) for detecting the resistivity of the excavated soil in the chamber 2a, an earth pressure meter (not shown), and the like.

[0020] In addition, the partition 4 is provided with a screw conveyor 7 for discharging the soil and sand in the chamber 2a to the rear of the partition 4, and a number of fixed blades (not shown) protruding into the chamber 2a for stirring the soil and sand accumulated in the chamber 2a.

[0021] In the shield tunneling machine 1, by filling the chamber 2a with soil and sand to generate soil pressure (earth pressure) in the chamber 2a, the earth pressure and groundwater pressure at the tunnel face can be suppressed and the tunnel face can be stabilized. The earth pressure in the chamber 2a is adjusted by controlling the amount of soil discharged from the chamber 2a by the screw conveyor 7, or by controlling the excavation speed of the shield tunneling machine 1. The earth pressure in the chamber 2a can also be adjusted by injecting, for example, an aqueous solution (liquid) containing a mud-adding agent into the soil in the chamber 2a.

[0022] As shown in Fig. 1, the shield machine 1 further includes an air bubble injection pipe 10 that injects air bubbles into the tunnel face in order to increase the fluidity of the excavated soil. One end of the air bubble injection pipe 10 is connected to an air bubble supply device (not shown) such as a pump, and the other end opens to the front of the cutter head 3.

[0023] The shield tunneling machine 1 excavates while injecting shaving cream-like bubbles obtained by foaming an air foaming agent in an air foam supplying device into the tunnel face. The air bubbles injected into the tunnel face improve the fluidity and water-stopping properties of the excavated soil and sand, and also suppress adhesion of the soil and sand in the chamber 2a. This allows smooth excavation while maintaining stability of the tunnel face. For example, an anionic surfactant is used as the air foaming agent. Air bubbles may be injected into the chamber 2a.

[0024] The shield machine 1 configured in this way excavates the natural ground by extending the jacks 5 while rotating the cutter head 3 to excavate the natural ground. An excavation hole is excavated in the natural ground, and the segment rings 9 are successively assembled along the inner circumferential surface of the excavation hole to construct the shield tunnel T. By injecting backfill material into the gaps that arise between the inner circumferential surface of the excavation hole and the outer circumferential surfaces of the segment rings 9, the segment rings 9 become firmly bonded to the natural ground via the backfill material.

[0025] Next, the property measuring device 20 will be specifically described with reference to Figures 3 and 4. Figure 3 is a structural cross-sectional view of the property measuring device 20 in the axial direction, and Figure 4 is a structural cross-sectional view of the property measuring device 20 in the radial direction.

[0026] As shown in Figures 3 and 4, the property measuring device 20 includes a cylinder device 21 for sampling the excavated soil, a density meter 22 for detecting the density of the excavated soil, and a moisture meter 23 for detecting the amount of moisture contained in the excavated soil.

[0027] As shown in FIG. 3, the cylinder device 21 has a cylinder tube 21a (pipe) into which excavated soil is guided, a piston 21b that slides within the cylinder tube 21a, and a drive device 21c that is connected to the piston 21b and moves the piston 21b axially within the cylinder tube 21a.

[0028] The cylinder tube 21a is formed of a cylindrical steel pipe or a resin pipe, and is attached to the partition wall 4 so that an opening on one end side of the cylinder tube 21a communicates with the chamber 2a.

[0029] The piston 21b is formed of a cylindrical member having an outer diameter slightly smaller than the inner diameter of the cylinder tube 21a. A seal member (not shown) is provided on the outer circumferential surface of the piston 21b to seal between the outer circumferential surface of the piston 21b and the inner circumferential wall of the cylinder tube 21a.

[0030] The driving device 21c is a fluid pressure cylinder having a rod 21d, and is attached to the other end (rear side) of the cylinder tube 21a.

[0031] A piston 21b is attached to the tip of the rod 21d. The piston 21b moves between a forward position P1 where the piston 21b closes the opening at one end (chamber 2a side) of the cylinder tube 21a and a backward position P2 where the piston 21b guides the excavated soil in the chamber 2a into the cylinder tube 21a in accordance with the extension and retraction of the drive unit 21c.

[0032] The cylinder device 21 takes in the excavated soil from the chamber 2a to detect the properties of the excavated soil. Specifically, the driving device 21c is driven to move the piston 21b from the forward position P1 to the backward position P2. This draws the excavated soil from the chamber 2a into the cylinder tube 21a.

[0033] In this embodiment, the properties of the excavated soil introduced into the cylinder tube 21a in this manner are measured using the density meter 22 and the moisture meter 23. After the properties have been measured, the driving device 21c is driven to move the piston 21b from the retracted position P2 to the advanced position P1. This causes the excavated soil in the cylinder tube 21a to be pushed back into the chamber 2a.

[0034] The density meter 22 detects the density of the excavated soil introduced into the cylinder tube 21a. The density meter 22 in this embodiment is a transmission type density meter. The density meter 22 has a radiation source unit 22a that irradiates gamma rays toward the excavated soil introduced into the cylinder tube 21a, and a radiation detection unit 22b that detects the gamma rays that are irradiated from the radiation source unit 22a and pass through the excavated soil introduced into the cylinder tube 21a.

[0035] The radiation source unit 22a irradiates gamma rays using cesium, cobalt, barium, or the like. The radiation source unit 22a and the radiation detection unit 22b are attached to the outer circumferential surface of the cylinder tube 21a at positions facing each other. Note that the opposing positions mentioned here do not only mean positions shifted by 180°, but also include positions shifted slightly (for example, about 180°±10°). Note that, although FIG. 4 shows a case in which the radiation source unit 22a and the radiation detection unit 22b are provided at positions facing each other on the outer circumferential surface of the cylinder tube 21a, they do not necessarily have to face each other.

[0036] The density meter 22 detects the amount of attenuation of gamma rays emitted from the radiation source unit 22a toward the excavated soil guided into the cylinder tube 21a, and calculates the wet density of the excavated soil based on the amount of attenuation.

[0037] The density data of the excavated soil measured by the density meter 22 is transmitted to a controller 40 (see FIG. 3).

[0038] The moisture meter 23 detects the amount of moisture contained in the excavated soil guided into the cylinder tube 21a. The moisture meter 23 is attached to the outer circumferential surface of the cylinder tube 21a. The moisture meter 23 of this embodiment is a scattering type moisture meter.

[0039] The moisture meter 23 has a radiation source unit 23a that emits fast neutrons from a neutron source toward the excavated soil guided into the cylinder tube 21a, and a thermal neutron detector unit 23b that detects thermal neutrons that are scattered inside the excavated soil in the cylinder tube 21a and escape from the soil. Fast neutrons tend to change into thermal neutrons as the soil has a higher moisture content. The number of thermal neutrons is approximately proportional to the number of hydrogen atoms in the object to be measured. Therefore, the moisture content of the soil (moisture content) is calculated by detecting the thermal neutrons that are changed from the fast neutrons emitted from the radiation source unit 23a by the moisture in the excavated soil with the thermal neutron detector unit 23b.

[0040] The moisture content data of the excavated soil measured by the moisture meter 23 is transmitted to the controller 40.

[0041] As shown in FIG. 4, in this embodiment, the moisture meter 23 (radiation source portion 23a and thermal neutron beam detection portion 23b) is attached to the outer peripheral surface of the cylinder tube 21a at a position that does not overlap with the radiation source portion 22a and radiation detection portion 22b of the density meter 22 when viewed from the axial direction of the cylinder tube 21a.

[0042] If the density meter 22 and the moisture meter 23 are provided with a gap in the axial direction of the cylinder tube 21a (the left-right direction in FIG. 3), different soil and sand are measured by the density meter 22 and the moisture meter 23. If the soil and sand measured are different in this way, there is a possibility that the properties of the excavated soil and sand cannot be accurately grasped.

[0043] Therefore, as described above, the moisture meter 23 and the radiation source unit 22a and radiation detection unit 22b of the density meter 22 are attached at positions where they do not overlap when viewed from the axial direction of the cylinder tube 21a, so that the density meter 22 and the moisture meter 23 can be arranged close to each other. As a result, the excavated soil measured by the density meter 22 and the moisture meter 23 is almost the same, so that the properties of the excavated soil can be measured more accurately. Furthermore, by arranging the density meter 22 and the moisture meter 23 close to each other, the length of the cylinder tube 21a in the axial direction can be shortened. This allows the cylinder device 21 (property measuring device 20) to be made smaller. In addition, since the chamber 2a and the measurement position can be arranged close to each other, the properties of the sampled soil can be prevented from changing from the properties in the chamber 2a during the process of being drawn into the cylinder tube 21a.

[0044] It is preferable that the distance between the density meter 22 and the moisture meter 23 in the axial direction of the cylinder tube 21a is as short as possible, but the distance may be equal to or less than half the length of the inner diameter of the cylinder tube 21a.

[0045] 4, in this embodiment, the radiation source unit 22a and the radiation detection unit 22b are attached to the outer circumferential surface of the cylinder tube 21a at positions facing each other, and the angle θ1 formed by the radiation detection unit 22b and the moisture meter 23 with respect to the central axis of the cylinder tube 21a when viewed from the axial direction of the cylinder tube 21a is larger than the angle θ2 formed by the radiation source unit 22a and the moisture meter 23 with respect to the central axis of the cylinder tube 21a. However, this is not limited thereto, and the radiation detection unit 22b may be provided in an area on the opposite side of the central axis of the cylinder tube 21a to the radiation source unit 22a and the moisture meter 23 when viewed from the axial direction of the cylinder tube 21a. In other words, the angle θ1 and the angle θ3 formed by the radiation source unit 22a and the radiation detection unit 22b with respect to the central axis of the cylinder tube 21a may both be larger than 90°. The angle θ1 is preferably 105° or more, 120° or more, or 150° or more. It is preferable that the angle θ3 is larger than the angle θ1. Note that the angles θ1, θ2, and θ3 are all minor angles among the conjugate angles.

[0046] By attaching radiation detection unit 22b of density meter 22 at a position separated from moisture meter 23 (setting angle θ1 to be greater than 90°), it is possible to prevent gamma rays emitted from radiation source unit 23a of moisture meter 23 from being detected by radiation detection unit 22b of density meter 22. This makes it possible to reduce errors occurring in density meter 22.

[0047] Furthermore, by attaching the radiation source unit 22a of the density meter 22 at a position separated from the radiation detection unit 22b (making the angle θ3 larger than 90°, more preferably 120° or more, 135° or more, 165° or more), gamma rays are emitted toward a wider range of the excavated soil and sand guided into the cylinder tube 21a, thereby improving the detection accuracy of the density meter 22. Note that the angle θ2 formed by the radiation source unit 22a and the moisture meter 23 with respect to the central axis preferably has a lower limit of 15° or more, or even 30° or more, and an upper limit of 90° or less, or even 60° or less, or 45° or less.

[0048] Furthermore, as shown in FIG. 4, it is preferable to provide a shielding member 24 made of lead or the like between radiation source portion 23a of moisture meter 23 and radiation detection portion 22b of density meter 22 on the outer circumferential surface of cylinder tube 21a.

[0049] In addition to neutron rays, gamma rays are emitted from radiation source 23a of moisture meter 23. If these gamma rays are transmitted along the outer periphery of cylinder tube 21a, there is a risk of measurement errors occurring when they are detected by radiation detection unit 22b of density meter 22. Therefore, by providing shielding member 24 as described above, it is possible to block gamma rays transmitted from radiation source 23a of moisture meter 23 along the outer periphery of cylinder tube 21a. This makes it possible to prevent gamma rays irradiated from radiation source 23a of moisture meter 23 from being detected by radiation detection unit 22b of density meter 22, thereby suppressing the occurrence of measurement errors. Shielding member 24 may be made of any material as long as it can block at least gamma rays.

[0050] In the above embodiment, when the property measuring device 20 is attached to the partition wall 4, specifically, the excavated soil in the chamber 2a is taken into the cylinder tube 21a and the properties of the taken-in excavated soil are measured by the density meter 22 and the moisture meter 23. However, the present invention is not limited to this, and for example, the cylinder tube 21a may be attached to the case 7a of the screw conveyor 7. In this case, the space inside the case 7a of the screw conveyor 7 corresponds to the "space through which the excavated soil passes" in the claims.

[0051] In addition, in the above embodiment, an example is illustrated in which only one property measuring device 20 is installed, but the property measuring device 20 may be installed in multiple locations as necessary, and the installation location is not limited to above the partition wall 4 and may be any location.

[0052] The property measuring device 20 of the above embodiment provides the following advantages.

[0053] In the property measuring device 20, the moisture meter 23 is attached to the outer circumferential surface of the cylinder tube 21a at a position where the radiation source unit 22a and the radiation detection unit 22b of the density meter 22 do not overlap when viewed from the axial direction of the cylinder tube 21a. By attaching the density meter 22 and the moisture meter 23 in such a positional relationship, the density meter 22 and the moisture meter 23 can be arranged close to each other. As a result, the excavated soil measured by the density meter 22 and the moisture meter 23 are almost the same, so that the properties of the excavated soil can be measured accurately. Furthermore, in the property measuring device 20, by arranging the density meter 22 and the moisture meter 23 close to each other, the axial length of the cylinder tube 21a can be shortened, so that the cylinder device 21 (property measuring device 20) can be made compact.

[0054] Furthermore, in the property measuring device 20, a shielding member 24 is provided between the radiation detection unit 22b and the moisture meter 23 on the outer circumferential surface of the cylinder tube 21a, for suppressing detection of radiation irradiated from the moisture meter 23 by the radiation detection unit 22b. With this configuration, it is possible to suppress detection of gamma rays irradiated from the radiation source unit 23a of the moisture meter 23 by the radiation detection unit 22b. As a result, it is possible to suppress the occurrence of measurement errors.

[0055] Although the embodiments of the present invention have been described above, the above-mentioned embodiments merely show some of the application examples of the present invention, and it is not intended that the technical scope of the present invention be limited to the specific configurations of the above-mentioned embodiments.

[0056] In the above embodiment, the shield machine 1 is used in the air bubble shield construction method, but the property measuring device 20 can also be used in other construction methods.

[0057] In the above embodiment, the excavated soil is drawn into the cylinder tube 21a by driving the piston 21b, but the present invention is not limited to this. For example, the opening at the rear end of the pipe attached to the partition wall 4 may be opened and closed. In this case, when detecting the properties, the opening at the rear end of the pipe is opened, and the excavated soil present in the pipe can be pushed out of the pipe by the excavated soil in the chamber 2a. This allows the excavated soil in the chamber 2a to be newly introduced into the pipe. [Explanation of symbols]

[0058] 1. Shield tunneling machine (excavation propulsion machine) 2a Chamber 4...Bulkhead 7. Screw conveyor 7a···Case 20...Property measuring device 21...Cylinder device 21a···Cylinder tube (pipe) 21b Piston 21c...Drive unit 22...density meter 22a...Radiation source section 22b Radiation detection unit 23...Moisture meter 23a...Radiation source section 23b Thermal neutron radiation detector 24... Shielding member 40...Controller

Claims

1. A property measuring device for measuring properties of excavated soil excavated by an excavation propulsion machine, A pipe having an internal space in which excavated soil is retained or through which the excavated soil passes; a transmission type density meter for detecting the density of the excavated soil introduced into the pipe; a scattering type moisture meter for detecting the amount of moisture contained in the excavated soil introduced into the pipe; The density meter comprises: a radiation source unit attached to an outer circumferential surface of the pipe and configured to irradiate gamma rays toward the excavated soil guided into the pipe; a radiation detection unit that is attached to an outer circumferential surface of the pipe at a position spaced from the radiation source unit and detects gamma rays that are irradiated from the radiation source unit and pass through the excavated soil and sand that is guided into the pipe; The moisture meter is attached to the outer peripheral surface of the pipe at a position that does not overlap with the radiation source unit and the radiation detection unit when viewed from the axial direction of the pipe.

2. The property measuring device according to claim 1, A property measuring device in which, when viewed from the axial direction of the tube, the angle that the radiation detection unit and the moisture meter make with respect to the central axis of the tube is larger than the angle that the radiation source unit and the moisture meter make with respect to the central axis of the tube.

3. The property measuring device according to claim 1 or 2, The radiation detection unit is provided in an area opposite the radiation source unit and the moisture meter across the central axis of the tube when viewed in the axial direction of the tube.

4. The property measuring device according to claim 1 or 2, The property measuring device further comprises a shielding member provided between the radiation detection unit and the moisture meter on the outer peripheral surface of the tube, the shielding member preventing the radiation irradiated from the moisture meter from being detected by the radiation detection unit.

5. The excavated soil property measuring device according to claim 1 or 2, A property measuring device, wherein the distance between the density meter and the moisture meter in the axial direction of the tube is equal to or less than half the length of the inner diameter of the tube.

6. The property measuring device according to claim 1 or 2, The tube is a cylinder tube for sampling excavated soil, which is attached to a partition wall that defines a chamber in which the excavated soil is retained.

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