JP2016094722A - Method and device for detecting looseness in natural ground on working face side of shield machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and a device for detecting looseness in a natural ground on a working face side of a shield machine for detecting looseness that induces collapse instead of detecting a collapse, thereby calling for attention before a collapse occurs.SOLUTION: A collapsing surface of a natural ground is forecasted by clarifying wet density and moisture density (moisture content) of soil with wet density and moisture density (moisture content) detection means for the soil installed in a front part of a shield machine. The wet density detection means and the moisture density (moisture content) detection means for the soil has a radiation source rod that radiates gamma rays and neutron rays from the front part of the shield machine, and the gamma rays and the neutron rays are scattered repeatedly while advancing in the soil. The wet density and the moisture content are derived from a radiation dose that reaches the detector.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a method and an apparatus for detecting the looseness of a face mountain that causes disturbance in the face stability in a sealed shield method.

  The stability of the face in the sealed shield method is ensured by balancing the earth pressure of the face and the mud pressure filled around the face.

  On the other hand, if the face of the face is loosened due to natural conditions or human factors (particularly due to the effects of close construction in urban areas), the balance of earth pressure and mud pressure when the shield machine passes there As a result, in an extreme case, the balance cannot be maintained, leading to excessive soil uptake and ground eruption, which may cause ground collapse and damage to adjacent structures.

  For this reason, it was necessary to dig up carefully in places where looseness is a concern, but there was a problem of fear of handling due to attention and a decrease in work efficiency, and countermeasures were required.

The following patent document is proposed as a detection device and a detection method capable of detecting a collapse of a natural ground due to excavation of a shield machine, and is provided at the front part of the shield machine, and an ultrasonic transmission means for transmitting an ultrasonic wave. Ultrasonic receiving means for receiving the ultrasonic waves emitted from the ultrasonic transmitting means and reflected by the ground fall surface, and means for recognizing the shape of the ground fall surface based on the output signal of the ultrasonic reception means; Are provided.
JP-A-6-307187

  In Patent Document 1, as shown in FIGS. 7 to 9, ultrasonic sensors 7 a to 7 d are provided on the cutter face 3 of the shield machine 1, and ultrasonic sensors 7 e and 7 f are provided on the skin plate 5. Reference numeral 9 denotes a rotation shaft, and 10 denotes a rotation angle detector that detects a rotation angle.

  Ultrasonic waves are emitted from the ultrasonic sensors 7a to 7f, the ultrasonic waves reflected by the collapsing surface 11 are received by the ultrasonic sensors 7a to 7f, and the received signals are processed, so that the collapsing surfaces are separated from the ultrasonic sensors. A distance up to 11 is calculated.

  Further, the rotation angle of the cutter face 3 is detected. The personal computer recognizes the shape of the collapsing portion 13 using the distance from each ultrasonic sensor to the collapsing surface 11 and the rotation angle.

  The system capable of early detection of the collapse due to loosening using the ultrasonic transmission means of the Patent Document 1 and the ultrasonic reception means that receives the ultrasonic waves that are emitted from the ultrasonic transmission means and reflected by the ground collapse surface. The ultrasonic observation result is computer-processed and reconstructed as a face surface profile, and it is determined whether an abnormal uneven surface due to collapse occurs on the profile.

  Therefore, even if a collapse occurs, it cannot be determined until the magnitude is such that an abnormality is detected by an ultrasonic echo.

  The object of the present invention is to eliminate the disadvantages of the prior art, and not to detect a collapse, but to detect the presence of a slack that induces a collapse, and to alert the operator in the previous stage of the collapse. And providing an apparatus.

  In order to achieve the above-mentioned object, the present invention provides a method for detecting the looseness of the face of the shield machine by providing soil wet density detection means, soil wet density and moisture density (water content) detection means at the front of the shield machine. Predicting the fall of the natural ground by grasping the wet density and moisture density (moisture content) of these soils, and the soil wet density detecting means and the moisture density (moisture content) detecting means are source rods Gamma rays and neutron rays are emitted from the front of the shield machine, and the gamma rays and neutron rays emitted from the source rod repeatedly scatter in the process of traveling through the soil, and the wet density from the amount of radiation that reaches the detector The gist is to determine the water content.

  First of all, as a device for detecting the slack face of the shield machine, it is provided at the front part of the shield machine and transmits a gamma ray and a neutron beam, and a gamma ray and a neutron ray emitted from the source rod. Radiation measuring means for receiving and determining the soil wet density and moisture density (water content) from the radiation dose; and second, the source rod for transmitting gamma rays and neutron rays is the skin plate of the shield machine The gist is to provide a plurality of radiation directions in the inner circumferential direction with different intervals, and to add a device for projecting the source rod outward of the skin plate. .

  According to the first and third aspects of the present invention, it is found that the collapse of a natural ground can be predicted by measuring the density and water content of the natural ground, and the density and water content of the natural ground are measured. It is possible to predict the collapse of natural ground.

  According to the second aspect of the present invention, it is optimal to use a small amount of RI (radioisotope) as the soil wet density detection means and the moisture density (water content) detection means. Gamma rays and neutron rays repeatedly scatter in the process of traveling through the soil, and the wet density and water content can be determined from the amount of radiation that reaches the detector.

  According to the present invention described in claim 4, wide detection in the outer peripheral direction of the skin plate is possible because the radiation directions of radiation are different.

  According to the fifth aspect of the present invention, it is possible to measure by projecting the radiation source bar outward from the skin plate not by the rotating shield machine during excavation but by the shield machine in a stopped state.

  As described above, the method and apparatus for detecting the slack face of the shield machine according to the present invention can detect the presence of a slack that induces the collapse, not the detection of the collapse, and can call attention at the stage before the collapse. is there.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is an explanatory view showing one embodiment of a method and apparatus for detecting a slack face of a shield machine according to the present invention, FIG. 2 is a cross-sectional view along line A and B in FIG. 1, and FIG. The shield machine 15 used for the hermetic shield method is shown.

  In the main body of the shield machine 15, 16 is a skin plate, 17 is a cutter face, and the cutter face 17 has a cutter bit 18, a special leading bit 19, an outermost peripheral special leading bit 20, an outer peripheral side protection bit 21, Various bits such as a trim bit 22, an injection tube 23, a copy cutter 24, and the like are provided.

  Inside the skin plate 16, there is a cutter turning electric motor 25, a soil discharging mechanism 26 by a screw shaft having a screw turning motor 29, a soil discharging mechanism 26, a shield jack 30, a middle break, and the like. A jack 31, a (segment) erector 32, an injection pipe 33, a tail packing 34, and the like are disposed.

  In the figure, 36 is a segment, and 37 is a shape holding device. In FIG. 2, 38 is a soil pressure gauge, and 39 is a manhole.

  In the present invention, a soil wet density detecting means and a moisture density (moisture content) detecting means are provided in the front part of the shield machine 15 and inside the skin plate 16, and the soil wet density and moisture density (moisture content) are provided by these. ), It was decided to predict the ground collapse surface.

  The soil wet density detecting means and the moisture density (water content) detecting means receive a gamma ray and a neutron beam, and a gamma ray and a neutron ray emitted from a radiation source 40a of the source rod 40. And a radiation detector 41 as radiation measuring means for obtaining the soil wet density and moisture density (water content) from the radiation dose.

  In this way, the soil wet density detecting means and the moisture density (water content) detecting means are provided with the source rod 40 to emit gamma rays and neutron rays from the front of the shield machine 15, and the gamma rays emitted from the source rod 40. The neutron beam is repeatedly scattered in the process of traveling through the soil, and the wet density and water content are obtained from the radiation dose reaching the radiation detector 41.

As for the measurement method, the wet density is a gamma ray backscattering method, the water content is a fast neutron backscattering method, the measurement range is the wet density: 1.20 to 2.50 g / cm ³ , the water content: 0.05 to 0.80 g / cm ³ .

  Gamma ray source: 60Co (cobalt), strength: 2.6MBq or less, density measurement, half-life: 5.27 years, neutron source: 252Cf (californium), strength: 1.1MBq, density measurement The half-life is 2.65 years and the measurement time is 1 minute to 5 minutes.

The radiation detector 41 is an SC counter for gamma rays, a ³ He (helium-3) tube for neutron rays, a gamma ray: 0 to 999999 cpm neutrons: 0 to 999999 cpm, and the calculated value is a wet density.・ Moisture density, dry density, moisture content, compaction, porosity, saturation, average value, maximum value, minimum value, standard deviation, etc. were made possible.

  As shown in FIG. 3, a plurality of source rods 40 for transmitting gamma rays and neutron rays are provided on the inner side of the skin plate 16 of the shield machine 15 at intervals in the circumferential direction. To be different.

  In the example shown in the drawing, a total of nine pieces are arranged, four at a time interval of 30 ° to the left and right with the radiation emitted so as to be directed vertically upward.

  As shown in FIGS. 4 and 5, the source rod 40 is surrounded by a lead shield 42, and hydraulic jacks 43 are arranged on both sides so that the source rod 40 is moved by the transfer plate 44. A device 45 for projecting the radiation source bar 40 to the outside of the skin plate 16 was added.

  At that time, the source rod 40 was provided with a distance meter 46.

  Next, the usage will be described. The soil wet density detection means and the moisture density (water content) detection means by the RI can correct the measurement result by a calibration experiment even if there is a shield between the measurement object and the skin plate 16 of the shield machine 15. Since it penetrates if it is about, it is possible to measure natural ground from inside the shield machine 15.

  Specifically, as shown in FIG. 5, the source rod 40 and the radiation detector 41 are in close contact with the inner surface of the skin plate 16 during shield excavation.

  Gamma rays and neutron rays emitted from the source rod 40 are repeatedly scattered in the course of traveling in the soil, and the wet density and water content can be determined from the amount of radiation reaching the radiation detector 41. It can be detected.

  FIG. 6 shows the flow of looseness evaluation according to the present invention. A calibration experiment was performed on the skin plate 16 of the soil wet density detecting means and the moisture density (water content) detecting means by the RI, and measurement during shield excavation ( Perform in-flight measurement).

  In this way, it is determined in real time whether the density / moisture amount is suspected of being loose.

  When looseness is detected, the shield excavation is stopped as a countermeasure and the process proceeds to a stage where the looseness is further examined.

  As shown in FIG. 6, when it is determined that it is loose, the shield excavation is stopped → scrutiny is performed (external measurement) and the penetration test is performed → the looseness is grasped and countermeasures are taken.

  Since the rotation of the shield is stopped at the scrutiny stage, as shown in FIG. 4, the projecting device 45 projects the source rod 40 outward from the skin plate 16 and inserts it into the ground, so that more accurate measurement is possible. Yes.

  Further, the penetration resistance of the source rod 40 into the natural ground is also useful as an index for evaluating looseness. The push-in mechanism of the source rod 40 by the hydraulic jack 43 of the protruding device 45 may be provided with a pressure sensor (not shown) capable of measuring the reaction force, and the penetration resistance may be measured.

It is explanatory drawing which shows one Example of the face slope looseness detection method and apparatus of the shield machine of this invention. FIG. 2 is a cross-sectional view taken along line A and B in FIG. 1. FIG. 2 is a sectional view taken along line C in FIG. 1. It is a side view which shows the rotation stop state of the shield of the face slope looseness detection apparatus of the shield machine of this invention. It is a side view which shows the state in the middle of shield excavation of the face slope loosening detection apparatus of the shield machine of this invention. It is explanatory drawing which shows the flow of the looseness evaluation by this invention. It is a perspective view of the front part of a shield machine, showing a conventional example. It shows a conventional example and is a front view of a cutter face. It is a sectional side view which shows a prior art example and shows the state of a shield machine and a natural ground.

DESCRIPTION OF SYMBOLS 1 ... Shield machine 3 ... Cutter face 5 ... Skin plate 7a-7f ... Ultrasonic sensor 9, 10 ... Rotation angle detector 11 ... Collapse surface 13 ... Collapse part 15 ... Shield machine 16 ... Skin plate 17 ... Cutter face 18 ... Cutter Bit 19: Special leading bit 20 ... Outermost peripheral leading bit 21 ... Outer peripheral side protection bit 22 ... Trim bit 23 ... Injection pipe 24 ... Copy cutter 25 ... Cutter turning electric motor 26 ... Soil discharging mechanism 27 ... Injection pipe 28 ... Gate opening / closing Jack 29 ... Screw turning motor 30 ... Shield jack 31 ... Folded jack 32 ... Elector 33 ... Injection pipe 34 ... Tail packing 36 ... Segment 37 ... Shape holding device 38 ... Earth pressure gauge 39 ... Manhole 40 ... Radiation rod 40a ... Radiation source 41 ... Radiation detector 42 ... Lead shield 43 ... Hydraulic jack 44 ... Transfer plate 45 ... Projection Location 46 ... Distance Meter

Claims (5)

  Establishing soil wet density detection means and moisture density (moisture content) detection means in the front part of the shield machine, and predicting the rock fall surface by grasping the wet density and moisture density (water content) of these soils A method for detecting slack in the face of a shield machine, characterized by   The soil wet density detecting means and the moisture density (water content) detecting means are provided with a source rod to emit gamma rays and neutron rays from the front of the shield machine, and the gamma rays and neutron rays emitted from the source rod are The method of detecting loosening of a face of a shield machine according to claim 1, wherein the wet density and water content are obtained from the amount of radiation reaching the detector by repeating scattering in the course of traveling inside.   A radiation source rod that transmits gamma rays and neutron rays, and receives gamma rays and neutron rays emitted from the radiation source rod, and receives the gamma rays and neutron rays. And a detector as a radiation measurement means for obtaining a slack face in a shield machine.   4. The face of the shield machine according to claim 3, wherein a plurality of source rods for transmitting gamma rays and neutron rays are provided in the skin plate of the shield machine at intervals in the circumferential direction, and the radiation directions of radiation are different from each other. Looseness detection device.   5. A device for detecting a slack face in a shield machine according to claim 3 or 4, wherein a device for projecting the radiation source bar to the outside of the skin plate is added.

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