Ground retention material used for ground exploration device

Abstract

To provide a ground exploration device using an ultrasonic sensor capable of accurately inspecting the condition of the inner wall of the ground directly above a shield tunneling machine.SOLUTION: A ground retention material to be filled inside a cylindrical body 15c fitted in a through hole 15h drilled in the top of a skin plate M1 of a slurry shield tunneling machine 1 and installed inside the equipment is composed of a mixture of bentonite, a polymer agent, and water. In the ground retention material, the amount of bentonite is 40 kg / m3 or more and 60 kg / m3 or less, and the amount of the polymer agent is 0.50 L / m3 or more and 2.0 L / m3 or less.SELECTED DRAWING: Figure 12

Description

[Technical Field]

[0001] The present invention relates to a ground retention material used in a ground exploration device, for example, a ground retention material used in a ground exploration device that uses an ultrasonic sensor to explore the condition of the inner wall surface of the ground directly above a shield tunneling machine. [Background technology]

[0002] When excavating the ground with a shield tunneling machine, if there is any significant loosening or cavity on the inner wall of the excavation tunnel directly above the shield tunneling machine, there is a risk of ground subsidence, etc. As a countermeasure, the condition of the inner wall of the ground is constantly measured and monitored using a ground exploration device, so that ground subsidence, etc. can be detected at an early stage and dealt with.

[0003] Such a ground exploration device is described, for example, in Patent Document 1, which discloses a technology for measuring the amount of over-excavation around the shield machine by emitting ultrasonic waves from an ultrasonic sensor located at the rear end of the nozzle in the injection direction into a water column formed by water sprayed toward the ground from the nozzle of a water flow generating device installed inside the shield machine. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2021-134549 Summary of the Invention [Problem to be solved by the invention]

[0005] However, when bentonite-based materials are used as a medium for ultrasonic propagation in a natural ground exploration device that uses an ultrasonic sensor, the mineral materials contained in the bentonite-based material contain a large amount of particles, which results in a high particle concentration in the bentonite-based material, causing the ultrasonic waves to be scattered, resulting in the problem that it is not possible to explore the condition of the inner wall surface of the natural ground directly above the shield tunneling machine.

[0006] The present invention has been made in light of the above-mentioned technical background, and aims to provide a technology that can effectively inspect the condition of the inner wall surface of the ground directly above a shield tunneling machine using a ground inspection device that uses an ultrasonic sensor. [Means for solving the problem]

[0007] In order to solve the above problems, the ground retention material used in the ground exploration device of the present invention as set forth in claim 1 comprises: a through hole provided at the top of a skin plate of a shield machine in a state where it penetrates the inside and outside of the skin plate; a cylindrical body provided with the outer peripheral surface of its upper end connected to the inner peripheral surface of the through hole; an injection hole provided on the outer peripheral surface of the cylindrical body in a state where it penetrates the inside and outside of the cylindrical body; an injection pipe connected to the injection hole; an injection pump that pressure-feeds the ground retention material into the cylindrical body through the injection pipe; pressure detection means that detects the injection pressure inside the injection pipe; a plate-like body attached to the lower end surface of the cylindrical body; and an ultrasonic sensor attached to the underside of the plate-like body. The ground retention material used in the ground exploration device comprises: a through hole provided at the top of the skin plate of a shield machine in a state where it penetrates the inside and outside of the skin plate; 3 The amount of bentonite is 40 kg / m 3 More than 60kg / m 3 and the amount of the polymer agent is 0.50 L / m 3 More than 2.0L / m 3 The present invention is characterized by the following:

[0008] The natural ground retention material used in the natural ground exploration device of the present invention described in claim 2 is the invention described in claim 1, wherein the amount of the polymer agent is 0.65 L / m 3 More than 1.00L / m 3 The present invention is characterized by the following: [Effects of the Invention]

[0009] According to the present invention, it is possible to effectively inspect the condition of the inner wall surface of the natural ground directly above a shield machine using a natural ground inspection device that uses an ultrasonic sensor. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a side view of an earth pressure shield tunneling machine according to an embodiment of the present invention. [Figure 2] FIG. 2 is a front view of the cutter head of the earth pressure shield machine of FIG. 1. [Figure 3] This is a rear view of the partition plate of the mud pressure shield machine in Figure 1, looking at the position of line II from the direction of the arrow. [Figure 4] FIG. 2 is a plan view of the natural ground exploration device and its surroundings installed in the front body of the mud pressure shield machine of FIG. 1. [Figure 5] FIG. 5 is a side view of the natural ground exploration device of FIG. 4 and its surroundings. [Figure 6] FIG. 5 is a rear view of the natural ground exploration device and its surroundings in FIG. 4. [Figure 7] FIG. 7 is a partially cutaway enlarged rear view of the natural ground exploration device of FIG. 6. [Figure 8] FIG. 8 is a partially cutaway side view of the natural ground exploration device of FIG. 7. [Figure 9] 8(a) is a plan view of the natural ground exploration device of FIG. 7 as seen from above, and FIG. 8(b) is a plan view of the natural ground exploration device of FIG. 7 as seen from below. [Figure 10] FIG. 8 is a configuration diagram of a main part of a natural ground exploration system including the natural ground exploration device of FIG. 7. [Figure 11] 8 is a diagram summarizing the results of an experiment conducted by the inventors on the composition of materials constituting the natural ground retention material used in the natural ground exploration device of FIG. 7. [Figure 12] 8 is a diagram summarizing the results of an experiment conducted by the inventors on the composition of materials constituting the natural ground retention material used in the natural ground exploration device of FIG. 7. [Figure 13] 8 is a diagram summarizing the results of an experiment conducted by the inventors on the composition of materials constituting the natural ground retention material used in the natural ground exploration device of FIG. 7. [Figure 14] FIG. 8 is an enlarged, partially cutaway rear view of the natural ground exploration device of FIG. 7 during natural ground exploration. [Figure 15] FIG. 2 is a side view of the earth pressure shield machine during excavation. [Figure 16]This is a side view of the mud pressure shield machine during excavation, following Figure 15. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. In the drawings for explaining the embodiment, the same components are generally designated by the same reference numerals, and repeated description thereof will be omitted.

[0012] Figure 1 is a side view of the mud shield machine of this embodiment, Figure 2 is a front view of the cutter head of the mud shield machine of Figure 1, and Figure 3 is a rear view of the partition plate of the mud shield machine of Figure 1, looking from the direction of the arrow at the position of line II. Note that for the purpose of explanation, the interior of the mud shield machine 1 is shown as a see-through view in Figure 1.

[0013] The mud pressure shield tunneling machine 1 of this embodiment shown in Figures 1 to 3 is an excavation machine that fills the chamber 4 between the cutter head 2 and the equipment body 3 with soil excavated by the cutter head 2, and then injects and mixes the soil to turn it into mud with high plastic fluidity (the ability to deform and move freely), and uses the resulting earth pressure to construct an excavation tunnel while stabilizing the face.

[0014] Although not particularly limited, the diameter of the cutter head 2 of the mud shield machine 1 is, for example, about 4070 mm, and the length of the mud shield machine 1 is, for example, about 9170 mm.

[0015] 1 and 2, the cutter head 2 is an excavation machine that excavates the face of the natural ground. The cutter head 2 is formed, for example, in a circular shape when viewed from the front, and is installed in front of the equipment body 3 in a state in which it can rotate freely in both forward and reverse directions along the circumferential direction of the cutter head 2.

[0016] The cutter head 2 is configured, for example, as a spoke-type cutter head. That is, as shown in Fig. 2, the cutter head 2 includes a hub portion 2H in the center of the excavation surface (the surface facing the cutting face), an outer peripheral ring portion 2R provided so as to surround the outer periphery of the hub portion 2H, four spoke portions 2S provided between the hub portion 2H and the outer peripheral ring portion 2R, face plate portions 2F provided between adjacent ones of the four spoke portions 2S, and an opening portion 2A provided between the spoke portion 2S and the face plate portion 2F.

[0017] A bit 5a called a center bit and an additive injection section 7a are installed on the hub section 2H of the cutter head 2. In place of the center bit, other excavation members such as a cone head type roller bit may be installed.

[0018] The additive injector 7a is an injector that injects a soil-making material, such as a bentonite-based additive, toward the face in front of the cutter head 2. Note that the additive injected from the additive injector 7a may be an aerated material instead of a bentonite-based additive, or both a bentonite-based additive and an aerated material may be used.

[0019] A plurality of bits 5b called outer bits are mounted on the front surface (the surface facing the working face) of the outer ring portion 2R of the cutter head 2. In addition, two bits 5c called copy cutters are mounted on the outer peripheral surface (the surface facing the inner peripheral surface of the excavation hole) of the outer ring portion 2R, positioned opposite each other. These bits 5c have functions such as over-excavation when constructing sharp curves and controlling the attitude of the earth pressure shield machine 1.

[0020] The spokes 2S of the cutter head 2 are made up of four frame members that connect the hub 2H and the outer ring 2R. This arrangement of the spokes 2S allows the aperture ratio of the opening 2A to be increased, allowing gravel to be taken into the chamber 4 without breaking it as much as possible.

[0021] In addition, the aperture ratio of the opening 2A can be adjusted by installing a face plate portion 2F between adjacent spoke portions 2S. This face plate portion 2F is fixed to the outer peripheral ring portion 2FR and is also fixed to the hub portion 2H by a connecting rod portion 2FR.

[0022] At the center of the width direction (circumferential direction of the cutter head 2) on the front surface (surface facing the cutting face) of the spoke portion 2S and the face plate portion 2F, multiple bits 5d called leading bits are installed along the radial direction of the cutter head 2 (direction from the center of the front surface of the cutter head 2 toward the outer periphery).

[0023] In addition, a plurality of scraper teeth 6 are provided along the edges of the front of each spoke portion 2S at both ends in the width direction. In addition to the bit 5d, other excavation members such as roller bits may also be provided on the spoke portion 2S.

[0024] In addition, an additive injection section 7b is provided in the spoke portion 2S. The additive injected from this additive injection section 7b is, for example, the same as that described for the additive injection section 7a above. This additive injection section 7b may be arranged on a different rotational trajectory within the front of the cutter head 2. This allows for more diversified control of the injection of additive, thereby enabling more accurate and efficient plastic fluidization of the excavated soil. Note that the additive injected from the additive injection section 7b may be an aerated material instead of a bentonite-based additive, or both a bentonite-based additive and an aerated material may be used.

[0025] As shown in FIG. 1, the device body 3 includes a front body section 3a, a rear body section 3b provided behind the front body section 3a, and a tail seal section 3c provided at the rear end of the rear body section 3b.

[0026] The forward section 3a and the aft section 3b are equipped with cylindrical skin plates M1, M2 made of, for example, steel. The skin plates M1, M2 are hollow exterior bodies that form the outer shape of the equipment main body 3 and also form a hollow space for installing equipment and the like inside the equipment main body 3. The forward section 3a and the aft section 3b are engaged with each other by inserting the tip of the skin plate M2 into the skin plate M1 while it is in contact with the inner circumferential surface of the skin plate M1.

[0027] A bulkhead plate 8 is provided on the front side of the skin plate M1 of the forward body section 3a, at a position set back from the front surface inward of the equipment main body 3, dividing the hollow space within the equipment main body 3 into a face side and an inboard side. The chamber 4 is provided closer to the face than the bulkhead plate 8 (i.e., in the space between the cutter head 2 and the bulkhead plate 8).

[0028] 1 and 3, fixed blades 9a are provided in a fixed state on the front surface (chamber 4 side) of partition plate 8. Fixed blades 9a are provided in a state of protruding from the front surface of partition plate 8 toward chamber 4.

[0029] 1 and 2, stirring blades 9b are fixed to the back surface of the spokes 2Sa of the cutter head 2. The stirring blades 9b are provided in a state of protruding from the back surface of the cutter head 2 toward the chamber 4, and rotate as the cutter head 2 rotates.

[0030] The fixed blades 9a and the stirring blades 9b are members that mix, stir, and knead the soil, sand, additives, and water inside the chamber 4 when the cutter head 2 rotates. Note that the fixed blades 9a may be configured to inject additives from the tip thereof.

[0031] As shown in Figure 1, the tail seal portion 3c is a water-stopping mechanism that prevents groundwater, backfill material, etc. from flowing into the inside of the equipment main body 3, and is installed along the circumferential direction of the skin plate M2 with the front end side of the tail seal portion 3c joined to the inner surface of the rear end part of the skin plate M2.

[0032] The rear end of the tail seal 3c is in close contact with the outer circumferential surface of the segment SG. In addition, the tail seal 3c itself and the rear end of the tail seal 3c that is in close contact with the segment SG are constantly supplied with a filler (tail grease). This maintains the waterproofing performance.

[0033] Here, an example is shown in which a double sealing member of the tail seal portion 3c is installed along the axial direction (excavation direction) of the equipment main body 3, but the installation configuration of the sealing member is not limited to double, and may be, for example, single, or triple or more.

[0034] On the other hand, as shown in Figures 1 and 3, in the mud pressure shield machine 1, on the inside of the machine rather than the partition plate 8, there are installed an additive injection section 7c, an earth pressure gauge 10 (see Figure 3), a cutter driver 11, a center bending jack 12a, a shield jack 12b, a screw conveyor 13, an erector 14 (see Figure 1), and a ground exploration device 15 (see Figure 1), etc.

[0035] The additive injecting section 7c is an injecting section that injects an additive into the outer periphery of the device body 3. The additive injected from this additive injecting section 7c is, for example, the same as that described above for the additive injecting sections 7a and 7b.

[0036] The earth pressure gauge 10 is a sensor that detects the pressure caused by the mud inside the chamber 4, and is installed with its detection surface facing the inside of the chamber 4. This earth pressure gauge 10 measures the mud pressure inside the chamber 4, and by controlling the measured value so that it falls within a predetermined range, it is possible to proceed with the excavation process while ensuring the stability of the face.

[0037] The cutter drivers 11 are drive sources for rotating the cutter head 2, and a plurality of them are arranged in a line along the circumferential direction of the cutter head 2 between the center and the outer periphery of the front surface of the cutter head 2. Note that an intermediate support drive system is exemplified here as the cutter drive system.

[0038] The articulating jacks 12a are devices that correct the advancing direction of the earth shield machine 1 by bending the machine, and multiple jacks are installed in a line along the circumferential direction of the earth shield machine 1 inside the main body 3. By supplying pressure oil to these articulating jacks 12a and advancing the earth shield machine 1 with the front body 3a and rear body 3b bent in a predetermined direction and angle, it is possible to control the advancing direction of the earth shield machine 1.

[0039] The shield jack 12b is a device that generates a propulsion force to advance the mud pressure shield machine 1 by receiving a reaction force from the segment SG installed at the rear of the equipment main body 3, and multiple shield jacks are arranged in a row along the circumferential direction of the mud pressure shield machine 1 within the equipment main body 3.

[0040] The screw conveyor 13 is a device for discharging the soil and sand taken into the chamber 4 to the outside of the machine, and is provided so as to penetrate the partition plate 8 from the chamber 4 and extend continuously diagonally upward toward the rear of the machine body 3. Here, for example, a ribbon-type screw conveyor 13 is used. That is, a spiral blade 13B without a rotation axis is installed in the pipe of the screw conveyor 13 in a freely rotatable state.

[0041] The erector 14 is an assembly device that grasps the segment SG, rotates it in the inner circumferential direction of the borehole, and transports and installs it to an assembly position in the inner circumferential direction of the borehole.It is installed in the hollow of the skin plate M2 of the rear body section 3b in a state that allows it to rotate in the circumferential direction of the borehole by a hydraulic motor (not shown) for driving the erector, etc.

[0042] The natural ground exploration device 15 is a device that uses an ultrasonic sensor to continuously and non-contactly explore the condition of the inner wall surface of the natural ground directly above the top of the skin plate M1 of the mud shield machine 1 while the mud shield machine 1 is excavating. Here, an example of the configuration of the natural ground exploration device 15 of this embodiment will be described with reference to Figs. 4 to 10.

[0043] Figure 4 is a plan view of the natural ground exploration device and its surroundings installed in the front barrel of the earth pressure shield machine of Figure 1, Figure 5 is a side view of the natural ground exploration device of Figure 4 and its surroundings, and Figure 6 is a rear view of the natural ground exploration device of Figure 4 and its surroundings. For the purpose of explanation, the inside of the front barrel of the earth pressure shield machine 1 is shown as a see-through view in Figures 4 to 6.

[0044] As shown in Figures 4 and 5, the ground exploration device 15 is installed between the front end of the skin plate M1 and the ground collapse exploration device 16, and as shown in Figures 4 and 6, it is installed in the widthwise center of the front body 3a (between the two additive material injection sections 7c, 7c).

[0045] As shown in Figure 5, although not particularly limited, the distance L1 from the front end of the skin plate M1 to the center of the natural ground exploration device 15 is, for example, approximately 1050 mm, and the distance L2 from the front end of the skin plate M1 to the center of the natural ground collapse exploration device 16 is, for example, approximately 1700 mm.

[0046] Figure 7 is a partially cutaway enlarged rear view of the natural ground exploration device of Figure 6, Figure 8 is a partially cutaway side view of the natural ground exploration device of Figure 7, Figure 9(a) is a plan view of the natural ground exploration device of Figure 7 seen from above, Figure 9(b) is a plan view of the natural ground exploration device of Figure 7 seen from below, and Figure 10 is a diagram of the main components of a natural ground exploration system equipped with the natural ground exploration device of Figure 7.

[0047] 7 and 8, the natural ground exploration device 15 is installed at a position slightly set back inward from the top of the skin plate M1 of the earth pressure shield machine 1. A through hole 15h is drilled at the top of this skin plate M1, penetrating between the outer and inner peripheral surfaces of the skin plate M1. The through hole 15h is formed, for example, in a circular shape in plan view.

[0048] Although not particularly limited, the diameter Φ1 (see FIG. 8) of the through hole 15h is, for example, about 165.2 mm, and the thickness T1 (see FIG. 8) of the skin plate M1 is, for example, about 36 mm.

[0049] In the skin plate M1, a cylindrical body 15c is joined to the location where the above-mentioned through hole 15h is formed, with the outer peripheral surface of the upper end of the cylindrical body 15c in contact with the inner peripheral surface of the through hole 15h. As shown in Figures 7 to 9(a), the cylindrical body 15c is made of, for example, a cylindrical steel material, and its upper surface is open.

[0050] The diameter of the cylindrical body 15c is the same as the diameter Φ1 of the through-hole 15h. Although not particularly limited, the height H1 (see FIG. 8) of the cylindrical body 15c is, for example, about 230 mm. The cross section of the cylindrical body 15c is not limited to a circular shape, and may be rectangular or the like.

[0051] The cylindrical body 15c is disposed at the center of the upper surface of the plate-like body 15p. As shown in Fig. 9(a), the plate-like body 15p is formed, for example, in a circular shape in a plan view, but is formed with a larger diameter than the cylindrical body 15c.

[0052] Although not particularly limited, the diameter Φ2 (see Figure 8) of the plate-shaped body 15p is, for example, about 2485 mm, and the height H2 (see Figure 8) from the top of the skin plate M1 to the underside of the plate-shaped body 15p is, for example, about 258 mm.

[0053] The plate-like body 15p is made of a material that transmits ultrasonic waves. If the plate-like body 15p were made of steel, it would not transmit ultrasonic waves, so in this embodiment, the plate-like body 15p is made of a resin such as monomer cast nylon (polyamide 6).

[0054] However, even if the plate-like body 15p is made of resin, if the plate-like body 15p is too thick, the ultrasonic waves will be greatly attenuated and the sensor sensitivity will be significantly reduced, while if the plate-like body 15p is too thin, it will not be able to withstand the earth pressure.

[0055] Therefore, in this embodiment, the thickness T2 of the plate-like body 15p (see Figure 8) is set to, for example, about 30 mm, which is a thickness that does not significantly attenuate ultrasonic waves, has strength equal to or greater than that of the skin plate M1, and can withstand earth pressure.

[0056] 7 and 8, a frame 15f, which is, for example, a circular frame in a plan view, is installed on the upper surface of the plate-like body 15p. The frame 15f and the plate-like body 15p are formed to have the same diameter, and are fastened together in a detachable manner with their outer peripheries aligned in a plan view by a plurality of bolts 15b and nuts 15n arranged near their outer peripheries. The lower end of the cylindrical body 15c is fitted into the frame 15f, and the plate-like body 15p is thereby attached to the lower end surface of the cylindrical body 15c.

[0057] Furthermore, an injection hole 15ih is drilled in the side surface of the cylindrical body 15c, penetrating between the outer and inner surfaces of the cylindrical body 15c, and an injection pipe 15ip is mechanically connected to the injection hole 15ih.

[0058] Then, the inside of the cylindrical body 15c is filled with ground retention material through this injection pipe 15ip. This ground retention material is made of a material that easily propagates ultrasonic waves (a medium for ultrasonic wave propagation). This allows ultrasonic waves to be propagated well through the ground retention material inside the cylindrical body 15c. An example of the configuration of this ground retention material will be described later.

[0059] Although not particularly limited, height H3 (see FIG. 8) from the top of skin plate M1 to the center of injection hole 15ih is, for example, about 130 mm.

[0060] 7 and 10, a pressure sensor 15ps is mechanically connected to the injection pipe 15ip in the extending direction via an on-off valve 15v1. This pressure sensor 15ps is a pressure detection means that detects the pressure inside the injection pipe 15ip, converts it into an electrical signal, and outputs it, and as shown in Fig. 10, is electrically connected to a pressure measuring instrument PM via a cable C1.

[0061] The pressure measuring device PM is a device that measures the pressure inside the injection pipe 15ip based on the electrical signal sent from the pressure sensor 15ps, and is electrically connected to the control unit MC via a cable C2. The pressure measuring device PM and control unit MC are installed on a trailing carriage (not shown) behind the mud pressure shield machine 1.

[0062] 7 and 10, a pressure relief valve 15v2 is mechanically connected between pressure sensor 15ps and cylindrical body 15c midway along the extension direction of injection pipe 15ip. This pressure relief valve 15v2 automatically releases air from inside injection pipe 15ip. This pressure relief valve 15v2 ensures stability of the pressure inside cylindrical body 15c.

[0063] 7 and 10, the injection pipe 15ip is mechanically connected to a supply pipe SP1 (see FIG. 10) via a swing valve 15v3 and a ball valve 15v4, in that order from the side closest to the cylindrical body 15c. This supply pipe SP1 is mechanically connected to a ground-holding material supply section RS via an injection pump 15pp.

[0064] As shown in Figure 10, injection pump 15pp is a device that pumps the ground retention material supplied from ground retention material supply unit RS into the inside of cylindrical body 15c, and the drive motor 15ppm of injection pump 15pp is electrically connected to control unit MC via cable C3. Note that injection pump 15pp and ground retention material supply unit RS are installed on a trailing bogie behind the mud pressure shield machine 1.

[0065] In this embodiment, the control unit MC automatically controls the drive motor 15ppm of the injection pump 15pp based on the measurement data of the pressure value sent from the pressure measuring instrument PM so that the pressure inside the cylindrical body 15c is always at a predetermined pressure.

[0066] Here, the predetermined pressure is set to, for example, a pressure equal to or greater than the earth pressure at the face. This earth pressure at the face refers to the earth pressure in front of the cutter head 2 and the earth pressure inside the chamber 4. In the case of a mud shield, this earth pressure at the face corresponds to the face water pressure. This makes it possible to constantly maintain the pressure inside the cylindrical body 15c at or above the earth pressure at the face, thereby maintaining the stability of the ground above the mud shield machine 1. This therefore improves the safety of ground excavation work using the mud shield machine 1.

[0067] As shown in Figures 7 to 9(b), an ultrasonic sensor 15ss is attached to the underside of the plate-like body 15p. The ultrasonic sensor 15ss is an ultrasonic detection means that emits ultrasonic waves from a sensor head and receives the ultrasonic waves reflected from the inner wall surface of the natural ground G facing the natural ground exploration device 15 again with the sensor head.

[0068] As shown in Figure 10, the ultrasonic sensor 15ss is electrically connected to a distance measuring device LM via a cable C4. The distance measuring device LM is an instrument that measures the distance from the top of the skin plate M1 to the inner wall surface of the opposing ground G by measuring the time between the transmission and reception of ultrasonic waves, and is electrically connected to the control unit MC via a cable C5. The distance measuring device LM is installed on the trailing bogie behind the mud pressure shield machine 1.

[0069] The control unit MC is electrically connected to the monitor MD via a cable C6, and creates a visible image of the ground based on the distance measurement data sent from the distance measuring device PM, and displays this image on the monitor MD. This allows the operator to grasp the condition of the inner wall surface of the ground above the mud pressure shield machine 1 in real time.

[0070] The ultrasonic sensor 15ss uses a frequency band of, for example, 400 kHz, which allows detection within a range of several meters. This ultrasonic sensor 15ss cannot receive reflected waves for a certain period of time due to the influence of reverberation vibrations after generating sound waves, and there is an unmeasurable range (for example, a close range of about 0 to 30 cm) where measurement is not possible. Note that the frequency band of the ultrasonic sensor 15ss is not limited to 400 kHz, and other frequency bands can be used.

[0071] In this embodiment, the measurement range of the natural ground exploration is within a range of several meters from the top of the skin plate M1, so the position of the ultrasonic sensor 15ss is set back to allow for a margin into the non-measurable range. In other words, the height of the ultrasonic sensor 15ss is set back below the top of the skin plate M1.

[0072] This allows the ultrasonic sensor 15ss to constantly measure and monitor the condition of the inner wall surface of the ground G directly above the top of the skin plate M1 of the earth pressure shield machine 1, making it possible to detect and deal with problems such as ground subsidence early.This prevents the ground from collapsing and subsidence due to the sudden intake of excavated soil by the earth pressure shield machine 1, improving the safety of ground excavation work.

[0073] Furthermore, by installing the ultrasonic sensor 15ss directly below the cylindrical body 15c, the natural ground exploration device 15 can be made smaller than when the ultrasonic sensor 15ss is installed offset laterally from the cylindrical body 15c.

[0074] Next, examples of the configuration of the above-mentioned ground holding material will be described with reference to Figures 11 to 13. Figures 11 to 13 are diagrams summarizing the results of experiments conducted by the inventors on the blending of materials constituting the ground holding material used in the ground exploration device of Figure 7.

[0075] The ground retention material filled inside the cylindrical body 15c is the additive (such as the bentonite mentioned above) used in the mud pressure shield machine 1. This additive generally contains mineral-based materials, which contain a large amount of particles. If the particle concentration in the additive becomes too high, ultrasonic waves are scattered and exploration becomes impossible.

[0076] Therefore, the inventors prepared a ground retention material using a mixture of, for example, bentonite, a polymer agent, and water, and determined whether the composition of the constituent materials was good or bad by observing the state of ultrasonic wave propagation and the state of viscosity of the ground retention material when the composition of the constituent materials was changed.

[0077] As a result, as shown in Figures 11 and 12, when the amount of bentonite was 80 kg / m 3 It was found that when the amount of bentonite is 30 kg / m, the concentration of bentonite becomes too high to allow the ultrasonic waves to pass through, making it impossible to measure the ultrasonic waves. 3 It was found that when the amount of bentonite is too low, it cannot react with the polymer agent and the viscosity is insufficient. 3 was found to be suitable.

[0078] On the other hand, as shown in Figure 12, when the amount of polymer agent was 0.4 L / m 3 At 0.5L / m, it was found that there was not enough polymer and the viscosity of the ground retention material was insufficient. 3 When the amount of polymer was 9.0 L / m, it was found that the viscosity of the ground retention material was insufficient. 3 When the amount of polymer was 2.0 L / m, it was found that the amount of polymer was too high and the viscosity was too high to pump. 3 It was found that the amount of polymer agent was 0.65 to 1.0 L / m 3 was found to be suitable.

[0079] Therefore, as shown in FIG. 12, in this embodiment, the amount of bentonite with a large particle content is set to 40 kg / m as the blending ratio of the ground retention material. 3 More than 60kg / m 3 The amount of polymer agent is 0.50 L / m or less. 3 More than 2.0L / m 3 Less than or equal to 0.65 L / m 3 More than 1.00L / m 3 As a result, the condition of the inner wall surface of the ground can be properly detected by the ultrasonic sensor 15ss while supporting the ground directly above the top of the skin plate M1 of the mud pressure shield machine 1.

[0080] The ground retention material used here was produced by mixing bentonite containing, for example, SiO2, Al2O3, FeO3, CaO, MgO, KO and NaO, a polymer agent containing, for example, acrylic resin, paraffin oil and surfactant, and water.

[0081] In addition, the ground retention material was produced by mixing water with an auxiliary material made of a mixture of bentonite and a polymer material such as CMC (carboxymethyl cellulose).

[0082] Next, an example of a natural ground exploration method using the mud pressure shield machine 1 in this embodiment will be described with reference to Figures 14 to 16. Figure 14 is an enlarged, partially cutaway rear view of the natural ground exploration device of Figure 7 during natural ground exploration. For the purpose of explanation, Figure 14 shows the inside of the cylindrical body 15c of the natural ground exploration device 15 in a see-through manner.

[0083] First, as shown in Figure 14, during natural ground exploration, the natural ground retention material R is continuously pumped and filled into the inside of the cylindrical body 15c through the injection pipe 15ip of the natural ground exploration device 15. During this process, the pressure inside the cylindrical body 15c is maintained at a predetermined pressure (e.g., earth pressure at the face) or higher based on the pressure measurement value from the pressure sensor 15ps as described above. This makes it possible to constantly maintain the stability of the natural ground G above the mud shield machine 1. This prevents the collapse of the natural ground and subsidence caused by the sudden intake of excavated soil by the mud shield machine 1, thereby improving the safety of natural ground excavation work using the mud shield machine 1.

[0084] Next, ultrasonic waves US are emitted from the sensor head of ultrasonic sensor 15ss toward the inner wall surface of the ground G facing the natural ground exploration device 15, and the ultrasonic waves reflected from the ground G are received again by the sensor head of ultrasonic sensor 15ss, and the distance from the top of skin plate M1 of the mud pressure shield machine 1 to the inner wall surface of the ground G facing that top is measured based on the time between transmission and reception of the ultrasonic waves. In this way, the condition of the inner wall surface of the ground G facing the natural ground exploration device 15 is explored without contact.

[0085] Next, Figures 15 and 16 are side views of the earth pressure shield machine during excavation. Note that Figures 15 and 16 show positions X1 to X3 of the earth pressure shield machine 1. Furthermore, symbol USs indicates ultrasonic waves emitted from ultrasonic sensor 15ss, and USr indicates ultrasonic waves reflected from the natural ground G.

[0086] First, as shown in Figure 15, an excavation hole is formed in the ground G by the excavation operation of the earth pressure shield machine 1. At this time, the ground exploration device 15 of the earth pressure shield machine 1 is operated as described in Figure 14 to continuously measure the distance from the top of the skin plate M1 of the earth pressure shield machine 1 to the inner wall surface of the ground G facing that top.

[0087] Next, as shown in Figure 16, the excavation operation of the mud shield machine 1 continues to excavate the excavation hole. At this time, in this embodiment, the excavation operation of the mud shield machine 1 is continued without stopping, and the natural ground exploration device 15 also continues to operate, thereby continuously measuring the distance from the top of the skin plate M1 of the mud shield machine 1 to the inner wall surface of the natural ground G facing that top.

[0088] This makes it possible to visually check (understand) in real time through the monitor MD of the mud shield machine 1 whether there are cavities above the mud shield machine 1, allowing problems such as ground subsidence to be discovered early and dealt with promptly. This therefore improves the safety of excavation work using the mud shield machine 1.

[0089] In this embodiment, as shown in Figure 16, hollow portion CA in the natural ground G can also be filled with natural ground retention material R discharged from the cylindrical body 15c of the natural ground exploration device 15. This makes it possible to explore the natural ground above the earth pressure shield machine 1 while suppressing or preventing problems such as subsidence of the natural ground, thereby further improving the safety of excavation work by the earth pressure shield machine 1.

[0090] The invention made by the inventor has been specifically described above based on the embodiments, but the embodiments disclosed in this specification are illustrative in all respects and are not limited to the disclosed technology. In other words, the technical scope of the present invention should not be interpreted restrictively based on the description of the above embodiments, but should be interpreted solely in accordance with the claims, and includes technologies equivalent to the technologies described in the claims and all modifications that do not deviate from the gist of the claims.

[0091] In the above embodiment, an example is given of the use of an earth pressure shield machine with a ribbon-type screw conveyor, but this is not limited to this, and for example, an earth pressure shield machine with an axle-type screw conveyor in which the shaft is at the center of the conveyor and blades are provided around the shaft may also be used. [Industrial Applicability]

[0092] In the above explanation, the present invention is applied to an earth pressure shield machine, but the present invention can also be applied to a mud water pressure shield machine. [Explanation of symbols]

[0093] 1 Mud pressure shield tunneling machine 2 cutter heads 2H hub section 2R outer ring 2S spoke part 2F face plate section 2FR connecting rod section 2A opening 3. Device body 3a Front trunk 3b Back torso 3c Tail seal part 4 chambers Bits 5a to 5d 6. Scraper Touse 7a~7c Additive injection part 8 Bulkhead plate 9a fixed wing 9b Stirring blade 10 Earth pressure gauge 11 Cutter driver 12a folding jack 12b Shield Jack 13 Screw conveyor 13B Blade 14 Erector 15. Ground exploration equipment 15h through hole 15c Cylindrical body 15p plate 15f frame 15b bolt 15n nut 15ih injection hole 15ip injection piping 15pp infusion pump 15ppm drive motor 15v1 Opening and Closing Valve 15v2 Pressure Relief Valve 15v3 swing valve 15v4 ball valve 15ps pressure sensor 15ss ultrasonic sensor 16. Ground collapse detection device M1, M2 skin plate SG Segment G. Ground C1~C6 cables PM pressure measuring instrument LM distance measuring device MC control section MD monitor R Ground retention material RS Ground Retention Material Supply Department SP1 supply piping US,USs,USr Ultrasound CA cavity

Claims

1. A through hole provided at the top of the skin plate of the shield machine, penetrating the inside and outside of the skin plate; a cylindrical body provided with an outer peripheral surface of an upper end portion connected to an inner peripheral surface of the through hole; an injection hole provided on the outer peripheral surface of the cylindrical body so as to penetrate the cylindrical body from the inside to the outside; an injection pipe connected to the injection hole; an injection pump that pumps the ground holding material into the cylindrical body through the injection piping; a pressure detection means for detecting an injection pressure inside the injection pipe; a plate-like body attached to the lower end surface of the cylindrical body; an ultrasonic sensor attached to the underside of the plate-like body; The ground retention material used in the ground exploration device is made of a mixed material containing bentonite, a polymer agent, and water, and the ground retention material 1m ３ In contrast, the amount of bentonite is 40 kg / m ３ Above, 60kg / m ３ and the amount of the polymer agent is 0.50 L / m ３ Above, 2.0L / m ３ A ground retention material for use in a ground exploration device, characterized by:

2. The amount of the polymer agent was 0.65 L / m ３ Above, 1.00L / m ３ 2. The ground retention material for use in a ground exploration device according to claim 1, wherein:

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