JP6733862B2 - Construction method of the underground widening part - Google Patents

Description

The present invention relates to a method for constructing an underground widened portion, an outer shell shield, and a water stop device.

As an underground structure with a large cross section at an underground junction, a technique for constructing the outer shell of a large cross section tunnel by arranging and integrating a plurality of rectangular shield tunnels adjacent to each other, and the NATM method (New Australian Tunneling) A construction technique for constructing a large-section tunnel by a mountain construction method such as Method) is disclosed.

Further, for example, in Patent Document 1, a step of excavating an advanced tunnel, a step of forming a water blocking area at a predetermined interval from within the advanced tunnel around the advanced tunnel, and an inside of the water blocking area In, a step of constructing a plurality of small section tunnels surrounding the advanced tunnel, and a step of constructing an outer shell surrounding the advanced tunnel by utilizing the plurality of small section tunnels inside the water stop region A method of constructing an underground structure is disclosed.

Further, for example, in Patent Document 2, when excavating the underground to construct an underground cavity, a plurality of roof shield tunnels are arranged outside the planned location of the underground cavity at predetermined intervals. By constructing a shield roof pre-construction surrounding the planned construction position, and from the inside of the roof shield tunnel to the joining position between adjacent roof shield tunnels diagonally forward or diagonally backward with respect to the extending direction of the roof shield tunnel. A freezing pipe is driven to form a freezing zone, and adjacent roof shield tunnels are excavated in the freezing zone, and adjacent roof shield tunnels are joined to each other and between the roof shield tunnels. There is disclosed a method for constructing an underground cavity, which comprises first performing a series of permanent lining walls, and then excavating the inside of the permanent lining wall to complete an underground cavity.

In addition, for example, in Patent Document 3, as compared with a segment that is permanently installed in the preceding tunnel, a cutable segment that can be cut by a trailing shield machine is provided in the branch merging portion on the preceding tunnel side instead of the permanent segment. There is disclosed a method of constructing a branching and joining part of a shield tunnel including a preceding tunnel construction step.

JP, 2006-348718, A Japanese Patent No. 4803429 Japanese Patent No. 4934416

When constructing the widened part of the ground such as the branching/merging part of the tunnel, ensure the stability of the ground, realize water stoppage during the construction, minimize the subsidence of the ground, and improve the groundwater environment. Minimizing the impact is required. In addition, due to geographical conditions, especially in urban areas, in many cases it is not possible to open and cut, and it is necessary to be able to construct a branch confluence without cutting.

In view of such problems, it is an object of the present invention to provide a technique relating to a construction method of an underground widening portion that can be constructed without cutting and is excellent in safety.

In order to solve the above problems, the present invention removes a segment of a shield tunnel, constructs a starting base of a shield for constructing an underground widening section around the shielding tunnel, and starts a shield machine from the starting base. Build a plurality of leading shields with cuttable segments arranged in an annular shape at intervals, launch a shield machine from the starting base, and while cutting a part of the leading shield, build a plurality of trailing shields in an annular shape. , It was decided to construct a ring-shaped outer shell shield that forms the outer shell of the underground widening part outside the shield tunnel.

More specifically, the present invention is a method for constructing an underground widening part, in which a segment of a shield tunnel is removed, and a starting base for constructing a starting base of a shield machine for constructing an underground widening part around the shield tunnel is constructed. And a starting shield machine starting from the starting base, and a leading shield building process for building a plurality of leading shields having cutable segments arranged in an annular shape at intervals, and a trailing shield from the starting base. Starting the machine, while cutting a part of the preceding shield, constructing a trailing shield that constructs a plurality of trailing shields in an annular shape, and constructing a water stop area around the leading shield and the trailing shield. A step of constructing an outer shell shield that connects the leading shield and the trailing shield adjacent to the leading shield, and constructs an annular outer shield that forms the outer shell of the underground widened portion outside the shield tunnel. And an excavation step of excavating the inside of the outer shell shield after the outer shell shield is constructed.

According to the method for constructing the underground widening portion according to the present invention, the segment of the shield tunnel is removed, and the starting base of the shield for constructing the underground widening portion around the shield tunnel is constructed, so that the ground is not excavated. The middle widened part can be constructed. Further, by constructing a water blocking area on the outer circumferences of the leading shield and the trailing shield, the ground is stabilized, and water can be prevented from entering the inside of the leading shield and the trailing shield. As a result, the impact on the groundwater environment can be minimized. Further, by excavating the inside of the outer shell shield after constructing the outer shell shield and constructing the widened portion in the ground, the subsidence of the ground surface can be minimized. As a result, it is possible to perform the construction of the underground widened portion while ensuring sufficient safety. The water stop area can be constructed by forming frozen soil around the leading shield and the trailing shield. Further, the water blocking area may be constructed by improving the ground by injecting a chemical solution or the like around the outer circumferences of the leading shield and the trailing shield. The step of constructing the outer shell shield may include a step of constructing an RC ring lining body by assembling a reinforcing bar and placing concrete.

Here, in the water stopping step, water can be stopped in the case part on the opposite side of the starting base. This can prevent water from entering the inside of the leading shield and the trailing shield. The soil on the opposite side of the starting base can be stopped by creating frozen soil. In addition, the stem on the opposite side of the starting base can be stopped by, for example, providing a reaching shaft or improving the ground.

Further, the method for constructing the underground widened portion according to the present invention may further include a filling step of filling the back shield with the backfill material. As a result, when cutting with a shield machine, it is possible to suppress the difference in resistance between the ground portion and the leading shield portion. As a result, the trailing shield can be cut more stably. The backfill material preferably has the same strength as the surrounding ground. Examples of the backfill material include air mortar and fluidized soil.

In the step of constructing the outer shell shield, a part of the segment forming the trailing shield is removed to build a communicating portion in which the leading shield and the trailing shield adjacent to the leading shield are constructed to form the communicating portion. Connect the end of the leading shield to the outer surface of the end of the trailing shield, and install the sheet so as to straddle the inside of the end of the leading shield and the outer surface of the end of the trailing shield. You may A part of the skin plate which comprises a segment is illustrated by a part of segment.

By arranging the sheet so as to straddle the inside of the end of the leading shield and the outer peripheral surface of the end of the trailing shield, it is possible to further suppress the infiltration of water into the inside of the leading shield and the trailing shield.

Here, the present invention can be specified as an outer shell shield. For example, the present invention is an outer shell shield formed by alternately arranging a leading shield and a trailing shield in an annular shape, and includes a communicating portion in which the leading shield and the trailing shield communicate with each other, and the communicating portion. A waterproof portion covering the connecting portion of the leading shield and the trailing shield is provided, and the end portion of the leading shield forming the communicating portion is connected to the outer peripheral surface of the end portion of the trailing shield forming the communicating portion, The waterproof portion is arranged so as to straddle the inside of the end portion of the leading shield and the outer peripheral surface of the end portion of the trailing shield.

By connecting the end portion of the leading shield to the outer peripheral surface of the segment of the trailing shield having higher strength than the leading shield, the strength of the connecting portion between the leading shield and the trailing shield can be improved. Further, since the waterproof part is arranged so as to straddle the inside of the end of the leading shield and the outer peripheral surface of the end of the trailing shield, it is possible to further suppress the infiltration of water into the inside of the leading shield and the trailing shield. .. The waterproof part suppresses the intrusion of water from the natural ground, and can be formed by a layer, a film, a sheet, or the like made by spray waterproofing.

Further, the present invention can be specified as a water stop device that can be used in the water stop process described above. For example, a water shutoff device for building frozen soil on the outer circumference of an outer shell shield formed by alternately arranging leading and trailing shields in an annular shape, wherein the inside of a segment of the leading shield and the trailing shield A freezing tube through which a cooling medium flows and a covering material that covers the freezing tube.

By providing the freezing pipe, it is possible to construct frozen soil on the outer circumferences of the segments of the leading shield and the trailing shield, in other words, the outer circumference of the outer shell shield. Further, by covering the freezing pipe with the covering material, the cooling performance is improved and the frozen soil can be efficiently constructed.

Further, the water stopping apparatus according to the present invention may be configured to further include a heat insulating material that covers the coating material. Thereby, the cooling performance is further improved, and the frozen soil can be constructed more efficiently.

In addition, in the water stopping apparatus according to the present invention, the segments of the leading shield and the trailing shield may include inner filling concrete. As a result, the cold heat of the cooling medium flowing through the freezing pipe is efficiently transferred to the ground around the outer shell shield. As a result, frozen soil can be efficiently constructed.

ADVANTAGE OF THE INVENTION According to this invention, the technique regarding the construction method of the underground widening part which can be constructed by non-opening and is excellent in safety can be provided.

FIG. 1A shows an outline of an underground widening portion constructed by a method of constructing an underground widening portion according to the first embodiment. FIG. 1B is a sectional view of a starting base side of an underground widening part constructed by the method of constructing an underground widening part according to the first embodiment. FIG. 1C shows a cross-sectional view of the reaching point of the underground widening portion constructed by the method for constructing the underground widening portion according to the first embodiment. FIG. 2 shows a construction flow of the underground widening portion according to the first embodiment. FIG. 3 shows the construction status of the shaft. FIG. 4 shows the construction of the circumferential shield. FIG. 5 shows a completed state of the circumferential shield. FIG. 6 shows the construction of the leading shield. FIG. 7 shows the completed state of the leading shield. FIG. 8 shows a state where the leading shield is filled with air mortar. FIG. 9 shows the construction status of the trailing shield. FIG. 10 shows the construction status of the trailing shield. FIG. 11 shows a completed state of the trailing shield. FIG. 12 shows a state in which frozen soil has been created in the chest. FIG. 13 shows a state in which frozen soil is formed on the outer circumference of the outer shell shield. FIG. 14 shows a state in which frozen soil is formed on the outer circumference of the outer shell shield. FIG. 15 shows the outer appearance of the outer shell shield when the RC ring lining body is built inside. FIG. 16 shows the removal status of segments and air mortar. FIG. 17 shows the installation state of the waterproof sheet at a location where the leading shield and the trailing shield are horizontally arranged. FIG. 18 shows the installation state of the waterproof sheet at the location where the leading shield and the trailing shield are vertically aligned. FIG. 19 shows the state of construction of the RC ring lining body at a location where the leading shield and the trailing shield are horizontally continuous. FIG. 20 shows a construction state of the RC ring lining body in a portion where the leading shield and the trailing shield are vertically continuous. FIG. 21 shows an outer shell shield in which an RC ring lining is constructed. FIG. 22 shows a state where the frozen soil on the outer circumference of the outer shell shield is thawed. FIG. 23 shows a situation of excavation inside the outer shell shield. FIG. 24 shows a construction completed state. FIG. 25: shows the outline of the underground widening part built by the construction method of the underground widening part which concerns on 2nd Embodiment. FIG. 26: shows the construction flow of the underground widening part which concerns on 2nd Embodiment. FIG. 27 shows a construction state of a vertical shaft according to the second embodiment. FIG. 28 shows a construction state of the circumferential shield according to the second embodiment. FIG. 29 shows a completed state of the circumferential shield according to the second embodiment. FIG. 30 shows a construction state of the leading shield according to the second embodiment. FIG. 31 shows a construction situation in the preceding shield according to the second embodiment. FIG. 32 shows a state of construction of a trailing shield according to the second embodiment. FIG. 33 shows a state in which frozen soil is formed on the outer circumference of the outer shell shield according to the second embodiment. FIG. 34 shows the installation state of the waterproof sheet at a location where the leading shield and the trailing shield according to the second embodiment are horizontally arranged. FIG. 35 shows a sectional view of the shield when the shield is frozen. FIG. 36 shows a sectional view taken along line AA of FIG. 35. FIG. 37 shows a case where the freezing tube is coated with a coating material. FIG. 38 shows an example of a freezing tube. FIG. 39 shows another example of the freezing tube.

Next, an embodiment of the present invention will be described with reference to the drawings. In the following embodiments, as an example of a method of constructing the underground widening portion 1 according to the present invention, a case of constructing the underground widening portion 1 where the main line shield 2 (tunnel) and the lamp shield 3 (tunnel) branch/merge explain. However, the embodiments described below are examples for carrying out the present invention, and the present invention is not limited to the modes described below.

<First Embodiment>
<Overall structure>
FIG. 1A shows an outline of an underground widening portion constructed by a method of constructing an underground widening portion according to the first embodiment. FIG. 1B is a sectional view of a starting base side of an underground widening part constructed by the method of constructing an underground widening part according to the first embodiment. FIG. 1C shows a cross-sectional view of the reaching point of the underground widening portion constructed by the method for constructing the underground widening portion according to the first embodiment. The underground widening portion 1 according to the first embodiment widens a branching/merging portion where the main line shield 2 and the lamp shield 3 branch/merge, and includes an outer shell shield 4. The outer shell shield 4 has an annular shape in cross section, and a starting base 7 is provided on the independent side of the main line (main line shield 2 in FIG. 1A), and from the starting base 7 a branching/merging side (in FIG. 1A). , Leading shields 5 and trailing shields 6 that extend toward the front side of the drawing) are alternately arranged in an annular shape. Inside the outer shell shield 4, the main line shield 2 is provided on the starting base 7 side, and the main line shield 2 and the lamp shield 3 are provided side by side on the arrival point side opposite to the starting base 7. The end portion of the lamp shield 3 is located inside the outer shell shield 4 and in the vicinity of the reach-side portion. Inside the outer shell shield 4, the road alignment of the lamp shield 3 and the road alignment of the main line shield 2 branch and merge.

<Construction method>
FIG. 2 shows a construction flow of the underground widening portion according to the first embodiment. 3 to 24 are explanatory diagrams corresponding to the construction flow. In steps S01 to S03, the starting base 7 of the shield machine is constructed. Steps S01 to S03 correspond to the starting base construction process of the present invention.

First, in step S01, as shown in FIG. 3, an underground pit 82 is constructed at an arbitrary position on the main line shield 2. More specifically, a freezing pipe (horizontal pipe, vertical pipe) through which brine (corresponding to the cooling medium of the present invention) flows is buried under the main line shield 2, and the frozen soil 81 for the vertical shaft is provided in a wider area than the vertical shaft 82. Created. The existing ground freezing method can be used to create the frozen soil 81 for the vertical shaft. By forming the frozen soil 81 for the vertical shaft, the ground around the vertical shaft 82 is retained, and the infiltration of water into the vertical shaft 82 can be suppressed. When the frozen soil 81 for the vertical shaft is created, a part of the segment forming the main line shield 2 is removed, and the vertical shaft 82 is constructed below the main line shield 2. Instead of creating the frozen soil 81 for the vertical shaft, the ground may be improved by injecting a chemical solution or the like.

In step S02, as shown in FIG. 4, excavation is started by the sealed shield machine that constructs the circumferential shield. More specifically, the sealed shield machine is installed in the guide ring provided on the outer circumference of the main shield 2 in the shaft 82, and the sealed shield machine digs around the main shield 2. In the first embodiment, a first circumferential shield 83a having a diameter larger than that of the main line shield 2 is gradually built around the main line shield 2 with the shaft 82 as a base point. The dotted line in FIG. 4 shows the unconstructed portion of the circumferential shield. When the first circumferential shield 83a is constructed, the second circumferential shield 83b having a diameter larger than that of the first circumferential shield 83a is gradually constructed. The diameter of the second circumferential shield 83b is substantially the same as the diameter of the outer shell shield 7. That is, in the first embodiment, the circumferential shield 83 is constructed by dividing it in the radial direction twice.

In step S03, as shown in FIG. 5, the circumferential shield 83 is completed. The circumferential shield 83 functions as the starting base 7 of the shield machine that constructs the leading shield 5 and the trailing shield 6. Further, the circumferential shield 83 also functions as a wall for the main line (main line shield) of the underground widening portion 1 on the single side.

In steps S04 to S14, the outer shell shield 4 is constructed. First, in step S04, as shown in FIG. 6, the leading shield 5 is constructed. Step S04 corresponds to the process of constructing the leading shield of the present invention. More specifically, a shield machine (SM) (leading shield machine) is installed at the starting base 7, and a plurality of leading shields 5 are sequentially constructed. When the shield machine (SM) that digs from the starting base 7 digs to the reaching point of the underground widening part, it is returned to the starting base 7 leaving the cutter and the skin plate in the pit and starts digging the next preceding shield 5. To do. A trailing shield 6 is constructed between the leading shield 5 and the leading shield 5. The leading shields 5 are arranged at a predetermined interval so as to finally form a ring, and a plurality of leading shields 5 are sequentially constructed. The leading shield 5 is composed of a machinable segment 52 and a steel segment 51. The leading shield 5 and the trailing shield 6 are constructed such that they partially overlap each other in a cross section orthogonal to the axial direction of these shields. Therefore, the cuttable segment 52 is mainly used in a region overlapping with the trailing shield 6. For the cuttable segment 52, lightweight aggregate concrete, carbon fiber reinforcing bar, carbon fiber reinforcing bar, or the like can be used.

In step S05, the leading shield 5 is completed as shown in FIG. The plurality of completed leading shields 5 are constructed in an annular shape as a whole with the leading shields 5 adjacent to each other having a predetermined gap. Although not shown in FIG. 7, the lamp shield 3 is provided side by side with the leading shield 2 on the arrival point side.

In step S06, as shown in FIG. 8, the leading shield 5 is filled with air mortar (AM). Step S06 corresponds to the air mortar (AM) filling step of the present invention. By being filled with the air mortar (AM), the stability when the trailing shield 6 is cut by the shield machine (SM) is improved. Fluidized soil may be filled instead of air mortar (AM).

In step S07, the trailing shield 6 is constructed as shown in FIG. Step S07 corresponds to the step of constructing the trailing shield of the present invention. More specifically, a shield machine (SM) (rearward shield machine) is installed at the starting base 7, and a plurality of rear shields 6 are sequentially constructed while cutting a part of the front shield 5. When the shield machine (SM) digging from the starting base 7 digs up to the reaching point of the underground widening part, it is returned to the starting base 7 leaving the cutter and the skin plate in the pit and the digging of the next trailing shield 6 Start.

Here, FIG. 10 shows the construction status of the trailing shield. As shown in FIG. 10, the leading shields 5 and the trailing shields 6 are alternately arranged, and partially overlap each other in a cross section orthogonal to the axial direction of the shields. A region of the leading shield 5 that overlaps with the trailing shield 6 is composed of a machinable segment 52, and the other region is composed of a steel segment 51. The leading shield 5 is filled with air mortar (AM). On the other hand, the trailing shield 6 is composed entirely of steel segments 61.

In step S08, the trailing shield 6 is completed as shown in FIG. As a result, the leading shields 5 and the trailing shields 6 filled with air mortar (AM) are alternately arranged to form the annular outer shell shield 4.

In step S09, as shown in FIG. 12, the frozen soil 41 of the chest is formed in the chest opposite to the starting base 7. Step S09 corresponds to a part of the water stopping step of the present invention. More specifically, a freezing pipe (horizontal pipe, vertical pipe) through which brine flows is buried in the case on the side opposite to the starting base 7, and the main line shield 2 and the main line shield 2 of the inner side of the outer shell shield 4 are joined together. Frozen soil 41 of the burial part is formed in a region excluding the lamp shield 3 (not shown in FIG. 12). For example, the frozen soil 41 in the chest may have a thickness of 3 m. As a result, it is possible to prevent water from entering the outer shell shield 4 from the case portion. The thickness of the frozen soil 41 in the burial portion is not limited to the above, but is based on the earth pressure, water pressure, depth, soil quality around the underground widening portion 1, the diameter of the leading shield 6 and the trailing shield 6, and the like. Can be determined as appropriate. It should be noted that a reaching shaft may be provided in place of the frozen soil 41 of the chest to stop the water.

In step S10, as shown in FIG. 13, the outer circumference frozen soil 42 is formed on the outer circumference of the outer shell shield 4. Step S10 corresponds to a part of the water stopping step of the present invention. Here, FIG. 14 shows a state in which frozen soil is formed on the outer circumference of the outer shell shield. FIG. 14 is a partially enlarged view of the outer shell shield 4, and other leading segment 5 and trailing segment 6 are omitted. Freezing pipes 85 (horizontal pipes) that extend in the axial direction of these shields are installed above the leading shield 5 and the trailing shield 6, and outside the leading shield 5 and the trailing shield 6, in other words, on the outer circumference of the outer shell shield. For example, a frozen soil 42 having a thickness of 0.8 m is formed on the outer circumference. As a result, it is possible to prevent water from entering the outer shell shield 4. The thickness of the frozen soil 42 on the outer periphery is not limited to the above, and is based on the earth pressure, water pressure, depth, soil quality around the underground widened portion 1, the diameter of the leading shield 6 and the trailing shield 6, and the like. It can be determined as appropriate. In addition, you may create the frozen soil 42 of the outer periphery using the freezing pipe (vertical pipe) buried in the natural ground.

In step S11, the RC ring lining body 9 is built inside the outer shell shield 4. FIG. 15 shows the outer appearance of the outer shell shield when the RC ring lining body is built inside. Step S11 corresponds to a part of the process of constructing the outer shell shield of the present invention. Here, FIG. 16 shows a removal situation of the segment and the air mortar. FIG. 16 is a partially enlarged view of the outer shell shield 4, and other leading segment 5 and trailing segment 6 are omitted. As shown in FIG. 16, since the trailing shield 6 and the leading shield 5 are communicated with each other to form a communicating portion, the segment on the side of the trailing shield 6, more specifically, the skin plate of the segment is removed. Further, the air mortar (AM) filled in the leading shield 5 is removed. Heavy equipment such as a backhoe is used to remove the air mortar (AM). In addition, the removed segment or air mortar (AM) can be discharged using a unloading vehicle.

FIG. 17 shows the installation state of the waterproof sheet at the location where the leading shield 5 and the trailing shield 6 are continuous in the horizontal direction. In addition, FIG. 18 shows the installation state of the waterproof sheet at a location where the leading shield 5 and the trailing shield 6 are vertically connected. 17 and 18 are partially enlarged views of the outer shell shield 4, and other leading segment 5 and trailing segment 6 are omitted. As shown in FIGS. 17 and 18, the end portion of the leading shield 5 is connected to the outer peripheral surface of the end portion of the trailing shield 6 that constitutes the communication portion. An end portion of the trailing shield 6 that constitutes the communication portion is formed of a steel segment 61 having a higher water blocking property than the cuttable segment 52. The end portion of the leading shield 5 that constitutes the communication portion is formed by a partially cuttable segment 52 that is continuous with the end portion of the steel segment 51. The waterproof sheet 86 is installed so as to straddle the inside of the end of the leading shield 5 made of the cuttable segment 52 and the outer peripheral surface of the end of the trailing shield 6 made of the steel segment 61. The waterproof sheet 86 is fixed by a fixing member 87 (nut 87a, plate 87d, neoprene rubber 87e, butyl rubber washer 87c, washer 87b).

FIG. 19 shows the state of construction of the RC ring lining body at a location where the leading shield and the trailing shield are horizontally continuous. Further, FIG. 20 shows a construction state of the RC ring lining body in a portion where the leading shield and the trailing shield are vertically continuous. 19 and 20 are partially enlarged views of the outer shell shield 4, and the other leading segment 5 and trailing segment 6 are omitted. As shown in FIG. 19 and FIG. 20, the reinforcing bars constituting the RC ring lining body are assembled inside the outer shell shield 4. When the assembly of the reinforcing bars is completed, concrete is poured and the RC ring lining body 9 is completed, as shown in FIG. The form may be assembled around the reinforcing bar.

In step S12, as shown in FIG. 22, the frozen soil around the outer shell shield 4 is thawed.

In step S13, as shown in FIG. 23, the inside of the outer shell shield 4 is excavated. Step S13 corresponds to the excavation process of the present invention. The excavation inside the outer shell shield 4 is divided into a plurality of steps from the upper part so as to be stepwise. At that time, the upper segment of the main line shield 2 is removed. Excavation inside the outer shell shield 4 can be performed by the existing bench cut method. In addition, concrete is placed in parallel with the excavation in the pit on the side opposite to the starting base 7. In other words, concrete is poured in order from the top in a plurality of times, and the wall is constructed. The casing wall opposite to the starting base 7 can be constructed by the existing reverse winding method.

In step S14, the frozen soil 41 in the chest is thawed. Further, the road is constructed such that the road alignment of the ramp shield 3 and the road alignment of the main line shield 2 branch and merge, and the construction of the underground widening portion is completed (see FIG. 24).

<Effect>
According to the construction flow of the underground widening part 1 explained above, by removing the segment of the main line shield 2 and constructing the starting base 7 of the shield for constructing the underground widening part 1 around the main line shield 2, The underground widened portion 1 can be constructed without cutting. In addition, by forming the frozen soil 42 on the outer periphery of the leading shield 5 and the trailing shield 6, the ground is stabilized, and the infiltration of water into the inside of the leading shield 5 and the trailing shield 6 is suppressed. it can. As a result, the impact on the groundwater environment can be minimized. Further, by forming the frozen soil 41 in the chest on the opposite side of the starting base 7, it is possible to more effectively suppress the infiltration of water into the inside of the leading shield 5 and the trailing shield 6. Further, by filling the leading shield 5 with air mortar (AM), the cutting with the trailing shield 6 can be performed more stably.

Further, by removing a part (skin plate) of the steel segment 61 constituting the trailing shield 6 to construct a communicating portion where the leading shield 5 and the trailing shield 6 adjacent to the leading shield 5 communicate with each other, the communicating portion is formed. The waterproof sheet 86 is installed so as to connect the end portion of the leading shield 5 to the outer peripheral surface of the end portion of the row shield 6 and to straddle the inside of the end portion of the leading shield 5 and the outer peripheral surface of the end portion of the trailing shield 6. By doing so, it is possible to further suppress the intrusion of water into the inside of the leading shield 5 and the trailing shield 6.

Also, by assembling the rebar, placing concrete, completing the RC ring lining body 9 to construct the outer shell shield 4, and then excavating the inside of the outer shell shield 4, the subsidence of the ground surface is minimized. You can keep it to the limit. As a result, it is possible to perform the construction of the underground widened portion 1 while sufficiently ensuring safety.

<Second Embodiment>
Next, the construction method of the underground widening portion according to the second embodiment and the underground widening portion constructed by the construction method of the underground widening portion will be described. The same configurations and steps as those in the first embodiment are designated by the same reference numerals, and the description thereof will be omitted.

<Overall structure>
FIG. 25: shows the outline of the underground widening part built by the construction method of the underground widening part which concerns on 2nd Embodiment. The configuration of the underground widening portion 1 according to the second embodiment is basically the same as the underground widening portion 1 according to the second embodiment, and includes a branching and joining portion where the main line shield 2 and the lamp shield 3 branch and join. The width is widened, and the outer shell shield 4 is provided. However, in the underground widening portion 1 according to the second embodiment, unlike the first embodiment, the starting base 7 is provided in the lamp shield 3. Therefore, in FIG. 25, the single side of the main line (main line shield 2) is the front side of the paper surface, and the branch/merging portion side where the main line shield 2 and the lamp shield 3 branch/merge is the back side of the paper surface.

<Construction method>
FIG. 26: shows the construction flow of the underground widening part which concerns on 2nd Embodiment. The differences from the first embodiment will be mainly described below.

First, in step S01, as shown in FIG. 27, an underground shaft 82 is constructed at an arbitrary position on the lamp shield 3. More specifically, a freezing pipe (horizontal pipe, vertical pipe) in which brine (corresponding to the cooling medium of the present invention) flows on the side of the lamp shield 3 opposite to the side adjacent to the main line shield 2. Is buried, and the frozen soil 81 for the vertical shaft is formed in an area wider than the vertical shaft 82. The existing ground freezing method can be used to create the frozen soil 81 for the vertical shaft. By forming the frozen soil 81 for the vertical shaft, the ground around the vertical shaft 82 is retained, and the infiltration of water into the vertical shaft 82 can be suppressed. When the frozen soil 81 for the vertical shaft is created, a part of the segment forming the lamp shield 3 is removed, and the vertical shaft 82 is built on the side portion of the lamp shield 3. Instead of creating the frozen soil 81 for the vertical shaft, the ground may be improved by injecting a chemical solution or the like.

In step S02, as shown in FIG. 28, excavation is started by the sealed shield machine that constructs the circumferential shield. More specifically, the sealed shield machine is installed in the guide ring provided on the outer periphery of the main line shield 2 and the lamp shield 3 in the shaft 82, and the sealed shield machine digs around the main line shield 2 and the lamp shield 3. .. The dotted line in FIG. 28 shows the unconstructed portion of the circumferential shield.

In step S03, as shown in FIG. 29, the donut-shaped circumferential shield 83 is completed. The circumferential shield 83 functions as a starting base 7 of the shield machine for constructing the leading shield 5 and the trailing shield 6 and a berth wall on the branching/merging portion side of the underground widening portion 1.

In steps S04 to S14, the outer shell shield 4 is constructed. First, in step S04, as shown in FIG. 30, the leading shield 5 is constructed. Unlike the first embodiment, the leading shield 5 is constructed from the branch/merge portion side toward the single side of the main line shield 2.

In step S05, the leading shield 5 is completed (see FIG. 7). In step S06-1, the leading shield 5 is filled with air mortar (AM), and in the second embodiment, the freezing pipe 85 and the RC ring lining body 9 are built in the leading shield 5. FIG. 31 shows a construction situation in the preceding shield according to the second embodiment. The air mortar (AM) is filled in a portion (hereinafter, also referred to as a cutting portion) that overlaps with the trailing shield 6 constructed later. Since the air mortar (AM) allows a construction error, it is filled in a range slightly larger than the cut portion. In other words, a mold for air mortar (AM) is assembled at a position outside the outermost peripheral surface of the trailing shield 6 and filled with air mortar (AM). An RC ring lining body 9 is constructed between the air mortar (AM) and the air mortar (AM). Further, in the example shown in FIG. 31, freezing tubes 85 extending in the axial direction of the leading shield 5 are installed at two upper portions of the leading shield 5. The freezing pipe 85 is fixed to the upper portion (the inner surface of the steel segment) of the leading shield 5 by a so-called U band, for example. Further, a mortar 88 (may be concrete) is cast so as to cover the freezing pipe 85, and a heat insulating material (for example, urethane foam) is sprayed so as to further cover the mortar 88.

In step S07, the trailing shield 6 is constructed (see FIG. 9). Here, FIG. 32 shows a construction state of the trailing shield according to the second embodiment. As shown in FIG. 32, the leading shields 5 and the trailing shields 6 are alternately arranged and partially overlap each other in a cross section orthogonal to the axial direction of the shields. A region of the leading shield 5 that overlaps with the trailing shield 6 is composed of a machinable segment 52, and the other region is composed of a steel segment 51. The trailing shield 6 is composed entirely of steel segments 61. Further, the leading shield 5 is filled with air mortar (AM) in a cutting portion and a region larger than the cutting portion, but by constructing the trailing shield 6, the air mortar (AM) in the cutting portion is removed. Then, the air mortar (AM) outside the cutting portion filled in to allow a construction error remains.

In step S08, the trailing shield 6 is completed (see FIG. 11). As a result, the air mortar (AM) outside the cutting portion filled in to allow a construction error is left, the RC ring lining body 9 is constructed, and the freezing pipe 85 is installed behind the leading shield 5 and the trailing shield 5. The shields 6 are alternately arranged to form the annular outer shell shield 4.

In step S09, the frozen soil 41 of the chest is formed in the chest on the side opposite to the starting base 7 (see FIG. 12). In step S10, the frozen soil 42 on the outer periphery is formed on the outer periphery of the outer shell shield 4 (see FIG. 13). Here, FIG. 33 shows a state in which frozen soil is formed on the outer periphery of the outer shell shield according to the second embodiment. FIG. 33 is a partially enlarged view of the outer shell shield 4, and other leading segment 5 and trailing segment 6 are omitted. A freezing pipe 85 (horizontal pipe) is installed above the trailing shield 6 as well as the leading shield 5, a mortar 88 is placed to cover the freezing pipe 85, and a heat insulating material is sprayed to cover the mortar 88. To be As a result, frozen soil 42 having a thickness of 0.8 m is formed outside the leading shield 5 and the trailing shield 6, in other words, on the outer circumference of the outer shell shield.

In step S11, the RC ring lining body 9 is built inside the outer shell shield 4 (see FIG. 15). Specifically, first, since the trailing shield 6 and the leading shield 5 are communicated with each other to form a communicating portion, the segment on the side of the trailing shield 6, more specifically, the skin plate of the segment is removed. At that time, the air mortar (AM) on the outer side of the cutting portion filled in to allow a construction error is removed. Further, as shown in FIG. 34, a hard urethane layer 86a, for example, is provided as a spray waterproof at a location where the leading shield 5 and the trailing shield 6 are continuous in the horizontal direction. Then, in the second embodiment, since the RC ring lining body 9 is built in advance in the leading shield 5, the RC ring lining body 9 is built in the trailing shield 6 and the inside of the leading shield 5 is formed. The RC ring lining body 9 and the RC ring lining body 9 in the trailing shield 6 are connected by a reinforcing bar joint or the like.

In step S12, the frozen soil on the outer periphery of the outer shell shield 4 is thawed (see FIG. 22). Next, in step S13, the inside of the outer shell shield 4 is excavated (see FIG. 23). Further, refractory mortar or the like is sprayed inside the outer shell shield 4. In step S14, the frozen soil 41 in the chest is thawed. Further, the road is constructed such that the road alignment of the ramp shield 3 and the road alignment of the main line shield 2 branch and merge, and the construction of the underground widening portion is completed (see FIG. 25).

<Effect>
According to the construction flow of the underground widening portion 1 according to the second embodiment described above, the segment of the main line shield 2 is removed and the underground widening portion 1 is built around the main line shield 2 as in the first embodiment. By constructing the starting base 7 of the shield, the underground widening portion 1 can be constructed without cutting. In addition, by forming the frozen soil 42 on the outer periphery of the leading shield 5 and the trailing shield 6, the ground is stabilized, and the infiltration of water into the inside of the leading shield 5 and the trailing shield 6 is suppressed. it can. As a result, the impact on the groundwater environment can be minimized. Further, by forming the frozen soil 41 in the chest on the opposite side of the starting base 7, it is possible to more effectively suppress the infiltration of water into the inside of the leading shield 5 and the trailing shield 6. Further, by filling the leading shield 5 with air mortar (AM), the cutting with the trailing shield 6 can be performed more stably.

Further, the cooling performance is improved by covering the freezing pipe 85 with the mortar 88 and the heat insulating material 89. Therefore, the frozen soil 42 can be created more efficiently, and the ground is stabilized.

<Water stop device>
An example of the water stop device used in the freezing method will be described. The water stop device described below can be used, for example, to create the frozen soil 42 around the leading shield 5 and the trailing shield 6 in step S06, step S06-1, step S07, and the like.

FIG. 35 shows a sectional view of the shield when the shield is frozen. FIG. 35 shows the leading shield 5 as an example of the shield. FIG. 36 shows a sectional view taken along line AA of FIG. 35. As shown in FIGS. 35 and 36, the water shutoff device includes a freezing pipe 85, a covering material 88, and a heat insulating material 89. A freezing pipe 85 is installed inside the steel segment 51 that constitutes the leading shield 5. The steel segment 51 is a steel segment in which concrete is filled. The freezing tube 85 is fixed to the steel segment 51 by a so-called U band (not shown). The freezing pipe 85 is covered with a covering material 88 (concrete, mortar, or the like). The covering material 88 is covered with a heat insulating material 89 (for example, urethane foam).

Here, FIG. 37 shows a case where the freezing tube is covered with a covering material. In the example shown in FIG. 37, a low-friction material (for example, silicone, grease, etc.) for allowing the expansion and contraction of the freezing tube 85 inside the coating material 88 is applied to the surface of the freezing tube 85, and the freezing tube 85 and the coating are covered. A low-friction material is interposed between the material and the material. As a result, the brine flows inside the freezing tube 85, and even if the freezing tube 85 contracts due to the temperature decrease, the freezing tube 85 can be contracted.

FIG. 38 shows an example of a freezing tube. In the example shown in FIG. 38, two freezing pipes 85 are connected by a joint 851 (for example, a so-called flexible pipe) that allows the freezing pipe 85 to expand and contract in the axial direction. The joint 851 is a tubular member having an inner diameter slightly larger than the outer diameter of the freezing pipe 85, and annular water blocking members 852 are provided inside both ends. Even if the brine flows inside the freezing pipe 85 and the freezing pipe 85 contracts due to the temperature decrease (see the arrow in FIG. 37 ), the joint 851 covers the connection portion of the freezing pipe 85 to suppress the leakage of the brine. You can The outer diameter of the joint 851 may be smaller than the inner diameter of the freezing pipe 85, and the joint 851 may be installed inside the freezing pipe 85. In this case, water stop members 852 are provided outside both ends of the joint 851 made of a tubular member. Further, the joint 851 may be made of resin and may have a bellows shape to allow expansion and contraction.

FIG. 39 shows another example of the freezing tube. In the freezing pipe 85 shown in FIG. 39, the connection port 85a of the freezing pipe on the upstream side in the flow direction of the brine can be included in the connection port 85b of the freezing pipe on the downstream side rather than the connection port 85b of the downstream freezing pipe. It is thinly formed. The diameter of the connection port 85b of the downstream freezing pipe is the same as the diameter of the other portion (main body). More specifically, the connection port 85a of the freezing pipe on the upstream side is formed to have a diameter smaller than that of the main body portion via the tapered portion 85a1, protrudes outward at the end, and is connected to the connection port 85b of the freezing pipe on the downstream side. When enclosed, an annular protrusion 85a2 is formed that contacts the inner surface of the connection port 85b of the downstream freezing pipe. On the other hand, the connection port 85b of the freezing pipe on the downstream side has a restriction portion 85b1 for restricting the movement of the protrusion 85a2 at the end thereof. The regulation portion 85b1 has an inclined surface 85b2. When the connection port 85a of the upstream freeze pipe is inserted into the connection port 85b of the downstream freeze pipe, the protruding portion 85a2 contacts the inclined surface 85b2 of the restriction portion 85b1. When the protruding portion 85a2 gets over the inclined surface 85b2 of the restricting portion 85b1, the axial movement of the protruding portion 85a1 is restricted. Instead of the above configuration, spiral grooves that are screwed with each other are formed in the connection port 85a of the upstream side freezing tube and the connection port 85b of the downstream side freezing tube so that both can be connected by a screw structure. Good. Moreover, you may form the water stop part which suppresses leakage of brine, such as packing. According to the freezing pipe 85 shown in FIG. 39, since there is no protrusion on the outside, the adhesion with the steel pipe segment 51 is improved. As a result, the cold heat from the freezing pipe 85 can be more efficiently transferred to the natural ground side. Moreover, according to the freezing pipe 85 shown in FIG. 39, a joint as a separate member becomes unnecessary. Therefore, the number of parts can be reduced.

By using the water stop device described above in the freezing method, the steel segment 51 can be frozen, and the energy (cold heat) can be efficiently transmitted to the ground contacting the steel segment 51. Further, the work efficiency in constructing the frozen soil 42 is improved, and the frozen soil 42 can be created more efficiently.

Although the preferred embodiments of the present invention have been described above, the present invention can be implemented by combining the embodiments as much as possible.

1... Underground widening part 2... Main line shield 3... Lamp shield 4... Outer shell shield 5... Leading shield 6... Trailing shield 7... Starting bases 51, 61. ..Steel segment 52...Machinable segment 82...Vertical shaft

Claims (5)

It is a construction method of the underground widening part,
Removing the shield tunnel segment, the starting base of the shield machine for constructing the underground widening part, the starting base construction process of constructing in a circle around the shield tunnel,
Starting the leading shield machine from the starting base, a step of constructing a leading shield in which a plurality of leading shields in which cuttable segments are arranged are spaced apart and are annularly constructed,
Starting the trailing shield machine from the starting base, while cutting a part of the leading shield, a trailing shield building step of building a plurality of trailing shields in an annular shape,
After constructing the leading shield and the trailing shield, a water blocking step of building a water blocking region on the outer circumference of an annular outer shell shield formed by alternately arranging the leading shield and the trailing shield. When,
After constructing the water blocking area, an RC ring lining body having the leading shield and the trailing shield adjacent to the leading shield in communication with each other and having reinforcing bars and concrete inside the leading shield and the trailing shield is provided. Constructing, an outer shell shield construction step of constructing an outer shell shield forming an outer shell of the underground widening portion outside the shield tunnel,
A drilling step of drilling the inside of the outer shell shield after the outer shell shield is constructed,
In the water blocking step, a water blocking device including a freezing pipe through which a cooling medium flows and a covering material that covers the freezing pipe is installed inside the segments of the leading shield and the trailing shield. Construction method. The underground widening according to claim 1, wherein the water stop device installed in the water stopping step has a low friction material between the freezing pipe and the covering material, which allows expansion and contraction of the freezing pipe inside the covering material. Method of construction. A water stop device for use in the method for constructing an underground widening part according to claim 1,
A freezing tube through which a cooling medium flows, which is installed inside the segments of the preceding shield and the following shield in the water stopping step,
A covering material for covering the freezing tube,
The freezing tube extends in the axial direction of the leading shield and the trailing shield,
Water stop device. The water stop device according to claim 3, further comprising a joint that allows expansion and contraction in the axial direction of the freezing pipe, the joint including a tubular member having an inner diameter larger than an outer diameter of the freezing pipe. The freezing tube has a connection port for connecting another freezing tube,
The connection port of the freezing pipe on the upstream side in the flow direction of the brine flowing through the freezing pipe is formed thinner than the connection port of the freezing pipe on the downstream side so as to be included in the connection port of the freezing pipe on the downstream side, Item 3. The water shutoff device according to item 3 .

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