JP3712316B2 - Mirror cutting method for shaft start / reach - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a mirror cutting method for a shaft wall when starting a shield or reaching a shield, and particularly to a mirror cutting method suitable for a narrow space such as a shaft.
[0002]
[Prior art]
The shield method is a method that can excavate and construct a tunnel without using an auxiliary method even in ground with a high groundwater level. Therefore, it has become the main construction method in urban tunnels that are often constructed with high water pressure and unconsolidated ground.
[0003]
In this shield method, the shaft where the shield machine starts and reaches generally has a reinforced concrete structure, and it is difficult to directly cut and open with the shield machine. Therefore, it is necessary to disassemble and separate the mirror.
[0004]
[Problems to be solved by the invention]
However, because the work space is limited, large heavy machinery cannot be used, and manual work is mainly performed by breakers, picks, or core boring machines, which is extremely inefficient and can be difficult in heavy environments. I must.
[0005]
Therefore, there is a technical problem to be solved in order to facilitate the mirror cutting operation of the shield start / arrival part in a narrow space called a vertical shaft, and the present invention aims to solve the problem. To do.
[0006]
[Means for Solving the Problems]
This invention is proposed in order to solve the said subject, and a cathode plate is previously installed in the natural ground side wall surface of the area | region which corresponds to the shield start part or reach | attainment part of a shaft wall. In addition, the current-carrying cables are pulled out from the cathode plate and the reinforcing bars arranged in the region, and the terminals are exposed from the inner wall surface. Prior to starting or reaching the shield, a DC power source is connected to the terminals of these energizing cables, and a negative voltage is applied to the cathode plate and a positive voltage is applied to the reinforcing bar. At the same time, a cathode plate is also installed on the inner wall surface of the area, and a negative voltage is applied. After that, the pit wall housing in the region is disassembled and the shield starting part or the reaching part is mirror cut.
[0007]
In addition, when the pit wall is thick or the like, in addition to the cathode plate on the side wall surface of the natural ground, one cathode plate is embedded in the pit wall of the region in advance , or a plurality of cathode plates and the cathode plate Alternatively, one or a plurality of anode plates, which are smaller by one, are embedded in parallel. Normally, the rebar of the mine wall is doubled near the front and back wall surfaces of the mine wall and moved inward from the wall by the amount of concrete cover, so these electrode plates (cathode plate and anode plate) should be double It will be arranged inside the reinforced bar. Further, similarly to the above, the current-carrying cables are pulled out from these electrode plates, respectively, and their terminals are exposed from the inner wall surface. In addition to applying a DC voltage to the cathode plate and the reinforcing bar on the ground wall and inner wall, a negative voltage is applied to the cathode plate and a positive voltage is applied to the anode plate. To do.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the present invention will be described in detail with reference to FIGS. In FIG. 1, V _A is a start shaft, and when the well wall W of the start shaft V _A is constructed, the cathode plate is previously placed on the surface of the natural ground G facing the region _RA corresponding to the start portion of the shield machine 11. 12a is installed. Then, the reinforcing bars 13 of the pit wall W are doubled. The reinforcing bars 13 are arranged from the front / rear wall surface position of the pit wall W toward the front / rear inner side by the amount of concrete cover to be placed later.
[0009]
In addition, two cathode plates 12b and 12c are respectively disposed on the inner side of the double reinforcing bar 13 in the region R _A (on the ground mountain side, left in the figure) near the reinforcing bar 13 or in front (the mine). Inside (right) in the figure, the reinforcing bars 13 are located at a predetermined distance from the reinforcing bars 13 and the center between the two cathode plates 12b and 12c (that is, the thickness of the well wall W). One anode plate 14a is sandwiched at the center in the vertical direction. In addition, when the thickness of the pit wall W is small or depending on the strength of the concrete, instead of these two cathode plates 12b, 12c and one anode plate 14a, one cathode plate is replaced with the center in the thickness direction of the pit wall W. You may just provide in. If the thickness of the well wall W is even smaller, it is not necessary to install such a cathode plate or anode plate in the well wall W just by installing the cathode plate 12a. On the other hand, when the thickness of the pit wall W is large or the concrete strength is large, the number of cathode plates and anode plates installed in the pit wall W is increased.
[0010]
That is, the number of electrode plates (cathode plates and anode plates) installed in parallel inside the pit wall W is increased or decreased according to the thickness of the pit wall W. Further, the interval between the electrode plates is increased or decreased according to the concrete strength, and as a result, the number of electrode plates increases or decreases. (The standard interval is about 10 cm.) Furthermore, the cathode plates and the anode plates are alternately arranged, and the electrode plates are arranged at positions closest to the front and rear reinforcing bars 13 (electrodes arranged alternately on the yin and yang sides). The outermost electrode plate) must be a cathode plate. Accordingly, one cathode plate, or a plurality of cathode plates and one or a plurality of anode plates, which are one less than the number of the cathode plates, are alternately installed inside the well wall W. .
[0011]
Here, these electrode plates (cathode plates 12a, 12b, 12c and anode plate 14a (cathode plate 12d described later and cathode plates 12e, 12f, 12g, 12h and anode plate 14b of FIG. 2 are also used)) use a wire mesh. Shall. (However, the present invention is not limited to this.) Since the anode plate may be dissolved by electrolysis, a thick wire mesh is used. Moreover, in order to prevent a short circuit of an electric current, it is necessary to fix these electrode plates with nonconductors, such as resin, so that it may not contact directly with the reinforcing bar 13 or a separator (not shown). Furthermore, for the cathode plates (12a and 12d, 12e, 12h, which will be described later) installed on the front and back surfaces of the pit wall, absorbent cotton impregnated with a magnesium chloride solution or the like to reduce the interfacial resistance of the concrete surface (specific illustration is shown (Omitted).
[0012]
Then, the energization cable 15 is connected to each of the cathode plates 12a, 12b, 12c and the anode plate 14a, and the terminal 15a is pulled out to the front. In addition, the energizing cable 15 is connected to the double reinforcing bar 13 for each of the front and rear reinforcing bars 13, and the terminal 15a is pulled out to the front. Incidentally, the energization cables 15 connected to the cathode plates 12b and 12c are merged on the way and are combined into one terminal 15a.
[0013]
Thereafter, concrete is cast to construct the pit wall W of the start pit _VA . As a result, the cathode plate 12a is sandwiched and buried between the well wall W and the natural ground G behind it. The cathode plates 12b and 12c and the anode plate 14a are embedded in the concrete frame of the pit wall W. Then, the terminals 15a of all the energizing cables 15 are exposed from the inner wall surface of the pit wall W to the inside of the start shaft _VA .
[0014]
The shield machine 11 is carried into the starting shaft V _A and the region _RA is used as a mirror to start. Prior to that, the cathode plate 12d is installed on the inner wall surface of the region _RA . The cathode plate 12d is connected to the negative terminal of the upper DC power supply 16a in the drawing. In addition, the terminal 15a of the energizing cable 15 drawn out from the front (right in the figure) reinforcing bar 13 is connected to the positive terminal of the DC power supply 16a and the energizing cable 15 drawn out from the cathode plates 12b and 12c. The terminal 15a is connected to the minus terminal of the DC power supply 16b at the middle stage in the figure, and the terminal 15a of the energizing cable 15 drawn from the anode plate 14a is connected to the plus terminal of the DC power supply 16b. Furthermore, the terminal 15a of the energizing cable 15 drawn out from the reinforcing bar 13 at the back (left in the figure) is connected to the plus terminal of the DC power supply 16c in the lower stage in the figure, and the electricity drawn out from the cathode plate 12a. The terminal 15a of the cable 15 is connected to the negative terminal of the DC power supply 16c.
[0015]
Then, by turning on these DC power supplies 16a, 16b and 16c, a negative voltage is applied to the cathode plates 12a, 12b, 12c and 12d, and a positive voltage is applied to the anode plate 14a and the reinforcing bar 13. As a result, in the region _RA of the pit wall W, a direct current flows from the back reinforcing bar 13 toward the front and rear cathode plates 12a and 12b, and from the anode plate 14a to the front and rear cathode plates 12b and 12c. A direct current flows toward the front, and further, a direct current flows from the front reinforcing bar 13 toward the front and rear cathode plates 12c and 12d.
[0016]
The magnitude of the current is 1 to 5 A / m ² and the voltage between the electrodes is about 50V. Therefore, the DC power supplies 16a, 16b, and 16c are extremely small, and a household power supply is sufficient. In addition, there is no danger of electrical leakage during energization and maintenance is not required. It is desirable that the energization period be at least about one week, and be as long as possible in the process. During this energization period, it is only necessary to perform shield start preparation work such as carrying in / assembling the shield machine 11 and improving the surrounding ground, so even if energization is performed for a long time, the influence on the process is small.
[0017]
With such energization, the calcium ions in the concrete move in the direction of the cathode plates 12a, 12b, 12c, 12d. In addition, the concrete peels from the reinforcing bars 13 due to electrolytic corrosion of the reinforcing bars 13, and cracks occur in the concrete. Since the electrodes (that is, the cathode plates 12a, 12b, 12c, 12d, the anode plate 14a, and the reinforcing bars 13) are installed at short intervals, the movement and cracking of calcium ions reach from the concrete cover to the inner middle layer of the frame. Extends to the entire concrete in the region _RA .
[0018]
Thus, the concrete skeleton in the region _{RA of the} pit wall W is deteriorated as a whole. As a result, the dismantling operation of the area _RA by the breaker, pick, etc. becomes extremely easy, and environmental obstruction factors such as noise, vibration, and dust are reduced. Moreover, since the adhesive force between the reinforcing bar 13 and the concrete is reduced, the separation of the dismantled glass becomes easy. In this way, the region _RA is dismantled and the mirror is cut for starting the shield.
[0019]
Then, the shield machine 11 is started from the start shaft V _A and the shield tunnel 17 shown in FIG. 2 is constructed.
As shown in the figure, the when the shield tunnel 17 reaches close to the arrival pit V _B is to dismantled the region R _B arrival of at shield machine 11 falls to Anakabe W of該到our shafts V _B Mirror cut. The procedure is the same as that in the region R _A of the starting pit V _A.
[0020]
That is, the arrival pit V _B when building a Anakabe W, previously we established a region R cathode plate 12e on the surface of the natural ground G facing the _B, region R in the front and rear double rebar 13 in the _B Two cathode plates 12f, 12g and one anode plate 14b are arranged in parallel at predetermined intervals on the inner side and are alternately arranged in the yin and yang. In addition, a current-carrying cable 15 is connected to each of these electrode plates (cathode plates 12e, 12f, 12g and anode plate 14b) and the reinforcing bar 13, and the terminal 15a is drawn out to the front. Then, by placing concrete and constructing the pit wall W of the reaching vertical shaft V _B , the cathode plate 12e is embedded in the ground wall side surface of the pit wall W, and the cathode plates 12f, 12g and the anode plate 14b are connected to the pit wall. W of embedded in concrete skeleton body, and is exposed to downhole of arrival pit V _B terminals 15a of all the conductive cable 15 from the downhole side wall of Anakabe W.
[0021]
After construction of Anakabe W, by installing a cathode plate 12h downhole side wall region R _B, connected at the figure said cathode electrode plate 12h to the negative terminal of the upper DC power supply 16d. In addition, the terminal 15a of the energizing cable 15 drawn out from the front reinforcing bar 13 (left side in the figure) is connected to the positive terminal of the DC power supply 16d and energized from the cathode plates 12f and 12g. The terminal 15a of the cable 15 is connected to the minus terminal of the DC power supply 16e at the middle stage in the figure, and the terminal 15a of the energizing cable 15 drawn from the anode plate 14b is connected to the plus terminal of the DC power supply 16e. Further, the terminal 15a of the energizing cable 15 drawn from the reinforcing bar 13 at the back (the ground side, right in the figure) is connected to the plus terminal of the lower DC power supply 16f in the figure and drawn out from the cathode plate 12e. The terminal 15a of the energized cable 15 is connected to the minus terminal of the DC power supply 16f.
[0022]
When these DC power supplies 16d, 16e, and 16f are turned on, a negative voltage is applied to the cathode plates 12e, 12f, 12g, and 12h, and a positive voltage is applied to the anode plate 14b and the reinforcing bar 13. Thus, the in the area R _B of Anakabe W DC current flows from the back of the reinforcing bar 13 to the front and rear of the cathode plate 12f and the cathode plate 12e, before and after the anode plate 14b cathode plate 12g and the cathode plate 12f A direct current flows toward the front, and further, a direct current flows from the front reinforcing bar 13 toward the cathode plate 12h and the cathode plate 12g before and after that.
[0023]
By such energization, will be in the concrete skeleton in the region R _B of Anakabe W is deteriorated, it is possible to dismantled very easily region R _B moiety, performs a mirror cut for shielding reach . Thus, the shield machine 11 has reached the arrival pit V _B, the shield tunnel 17 through the starting pit V _A to reach pit V _B.
[0024]
It should be noted that the present invention can be variously modified without departing from the spirit of the present invention, and the present invention naturally extends to the modified ones.
[0025]
【The invention's effect】
As described above, the present invention energizes the region corresponding to the shield start or reach of the shaft wall and deteriorates the concrete frame in the region. By embedding each of the electrodes (cathode plate, anode plate and reinforcing bar) at short intervals, it is possible to exert such deterioration phenomenon evenly not only on the surface of the well wall but also over the entire region. it can. Thus, the dismantling and removal of the area portion is extremely easy, and environmental impediment factors such as noise, vibration, and dust can be reduced.
[0026]
Further, since the current to be energized is weak, a simple and inexpensive facility is sufficient, the electrode installation work does not require labor, and the construction cost is low.
[Brief description of the drawings]
FIG. 1 is an explanatory longitudinal sectional view of the vicinity of a shield starting portion, showing an embodiment of the present invention.
FIG. 2 is an explanatory longitudinal sectional view of the vicinity of a shield reaching portion, showing an embodiment of the present invention. .
[Explanation of symbols]
G natural ground R _A shield start portion corresponding to region R _B shield reaches unit region corresponding V _A starting pit V _B arrival pit 12a, 12b, 12c, 12d cathode plate 12e, 12f, 12g, 12h cathode plate 13 reinforcing bar 14a, 14b anode plate 15 Current-carrying cable 15a Current-carrying cable terminals 16a, 16b, 16c DC power supply 16d, 16e, 16f DC power supply

Claims (2)

A cathode plate is set in advance on the ground wall surface of the area corresponding to the shield starting part or reaching part of the shaft wall, and the current-carrying cable is drawn out from the cathode plate and the reinforcing bar arranged in the area, and the terminal is connected to the tunnel. can it are exposed from the inner wall surface, prior to the start or the arrival of the shield, by installing a cathode plate downhole side wall surface of the region, with a negative voltage is applied to the cathode plate of the cathode plate and the ground mountain side wall, After applying a positive voltage to the reinforcing bars, dismantling the well wall in the region and performing mirror cutting of the shield starting part or reaching part. A cathode plate is installed in advance on the ground wall surface of the region corresponding to the shield starting part or reaching part of the shaft wall, and one cathode plate is embedded in the pit wall of the region , or a plurality of cathode plates and One or a plurality of anode plates, which are one less than the cathode plate, are arranged in parallel and alternately embedded, and the reinforcing bar conduction cables arranged in the region are drawn out from these electrode plates and the reinforcing bars arranged in the region. , aft to expose the terminal from the downhole side walls, prior to the start or the arrival of the shield, by installing a cathode plate downhole side wall surface of the region, the cathode plate and the ground mountain walls and Anakabe body of the cathode A vertical shaft in which a negative voltage is applied to the plate and a positive voltage is applied to the reinforcing bar and the anode plate, and then the well wall in the region is disassembled and the shield starting portion or the reaching portion is mirror cut. Shield start Mirror cutting method of reaching parts.

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