Method of entering the vertical shaft of an open shield machine in the open shield construction method

Abstract

To provide a method for an open shield machine to enter an arrival shaft in an open shield construction method, in which concrete boxes are buried vertically one after the other by appropriately repeating a process of advancing a shield machine and an installation process of suspending a new concrete box from above behind a propulsion jack retracted inside a tail section of the shield machine and joining it to an existing concrete box, which does not require gas cutting work for the arrival shaft and has little impact on the surrounding area when the open shield machine enters the arrival shaft, and the arrival shaft of the open shield machine.SOLUTION: In an open shield construction method, an entrance to an arrival shaft of an open shield machine 1 is formed by H-shaped steel piles 18 installed at both ends and a steel panel wall 19 whose ends can engage with the H-shaped steel piles 18 and be dropped into them, and just before the open shield machine 1 enters, a steel panel wall 19 is pulled out and the open shield machine 1 is allowed to enter the arrival shaft.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to a method for entering a vertical shaft of an open shield machine in an open shield construction method for constructing underground structures such as water supply and sewerage systems, underground tunnels, etc. in urban areas. [Background technology]

[0002] The open shield method is a highly rational method that takes advantage of the advantages of the open cut method and the shield method, and enables safe, economical construction while minimizing the impact on the surrounding environment in construction locations where conventional methods are difficult or expensive, such as soft water-bearing ground, curved construction, or close to houses, when laying pipes for sewers, storm water drains, agricultural irrigation channels, etc.

[0003] First, this open shield method will be explained with reference to Figures 19 to 21. In the figures, 1 is an open shield machine, which has left and right side wall panels 1a as its main components, which are connected between them by a bottom plate and beam members, with openings on the front, rear and top, and a cutting edge 2 at its tip. Also, multiple propulsion jacks 3 are arranged vertically facing rearward in the center or near the rear end of the side wall panels 1a. A movable side wall panel 1b that can slide freely is provided at the tip of the side wall panel 1a.

[0004] In the figure, 7 is a press bar that is appropriately hung from above and installed at the rear end of the propulsion jack 3, and is made of a frame using box steel or shaped steel. Also, in the figure, 8 is a bulkhead that acts as a partition wall to prevent soil and groundwater from flowing into the open shield machine 1 from the face of the tunnel ahead of the open shield machine 1 and to collect the soil and groundwater forward.

[0005] The open shield method is carried out between a starting shaft 9 and a destination shaft (not shown). Although not shown, the open shield machine 1 is assembled inside the starting shaft 9, the ground in front of the starting shaft 9 is excavated with a shovel-type excavator 6 installed on the ground, the driving jack 3 of the open shield machine 1 is extended, and the open shield machine 1 is advanced by using a reaction force against a reaction wall 10 inside the starting shaft 9, and the first concrete box 4 that forms the underground structure is lowered from above and set behind the retracted driving jack 3 inside the tail part of the open shield machine 1.

[0006] Struts are provided between the propulsion jack 3 and the reaction wall 10 to adjust the distance appropriately.

[0007] In addition, the starting shaft 9 is composed of steel sheet piles 11 such as sheet piles, mirror steel sheet piles 11a, and supports 12, and in order to launch the open shield machine 1, part of the mirror steel sheet pile 11a is mirror cut, but if necessary, ground improvement work 13 may be performed on the front part of the starting shaft 9 by injecting chemicals, etc.

[0008] Next, the excavator 6 similarly excavates and removes soil from the front or top of the open shield machine 1, moving the open shield machine 1 forward and suspending the second concrete box 4 into the tail section of the open shield machine 1 in front of the first concrete box 4.

[0009] When the concrete box body 4 is suspended and lowered into the tail section of the open shield machine 1, height adjustment materials such as concrete blocks are placed under the concrete box body 4, and backfill injection material 14 is filled into the gaps on the left, right and bottom of the concrete box body 4 within this tail section.

[0010] Similar excavation and setting processes of the concrete box bodies 4 are repeated, so that the concrete box bodies 4 are buried vertically in the ground one after another, the concrete box bodies 4 are fastened to each other, and backfill injection material 14 is injected into the sides of the concrete box bodies 4 using grout holes previously installed in the concrete box bodies 4.

[0011] Backfill soil 5 is applied onto the rear concrete box 4 using a bulldozer or shovel, etc., and then compacted with a vibrating roller or the like. Although not shown in the figure, once the open shield machine 1 reaches the arrival shaft, it is disassembled and removed to complete the work.

[0012] Conventionally, the departure shaft 9 and the arrival shaft have been retaining structures of the cut beam support type, which are composed of steel sheet piles 11 such as sheet piles, mirror steel sheet piles 11a, and supports 12, and some mirror cutting is required to start or enter the open shield machine 1.

[0013] As shown in Figures 11 to 14, the arrival shaft is composed of steel sheet piles 11 such as sheet piles and supports 12 similar to those of the departure shaft 9, and in order to allow the open shield machine 1 to reach the arrival shaft, a part of the steel sheet pile 11 at the entrance of the open shield machine 1 is cut. Note that ground improvement work 13 is carried out on the ground in front of the cutting area.

[0014] The following patent document has been proposed and patented as a construction method for the open shield construction method, which eliminates the need for mirror cutting work on the arrival shaft when the open shield machine arrives, and reduces the number of processes by eliminating the need to dig toward the open shield machine or remove the upper part of the open shield machine before entering the tunnel. [Patent Document 1] JP 2016-118018 A

[0015] As shown in Figures 15 to 18, the arrival shaft 15 is U-shaped in plan view with steel sheet piles 11 driven into it, and is open in the direction of the open shield machine 1's arrival. Ground improvement work 13 is applied inside this opening, and the ends of the shield machine 1 and the concrete box 4 are inserted into the arrival shaft 15 by penetrating the ground improvement work 13.

[0016] After a tunnel entrance retaining wall (not shown) is installed at the end of the ground improvement section 13, the upper section of the arrival shaft 15 is excavated, and the upper section components of the open shield machine 1, which have been excavated so that there is no soil on the outside, are removed.

[0017] Next, shoring 12 is erected inside the upper section of the arrival shaft 15, the middle section of the arrival shaft 15 is excavated, the middle section of the open shield machine 1 is removed, and a retaining wall is installed at the entrance up to the middle section. After installing shoring 12 to support the soil between the open shield machine 1 and the steel sheet piles 11, the shield machine 1 is removed while excavating in sequence.

[0018] With this method, no covering plate is needed to be dug facing the open shield machine when it arrives, no mirror cutting work is required, and there is no need to remove the upper part of the open shield machine before entering the tunnel, thereby reducing the number of processes. DISCLOSURE OF THEINVENTION [Problem to be solved by the invention]

[0019] Conventionally, in the open shield construction method, when the open shield machine 1 enters the arrival shaft 15, mirror cutting is performed on the entry side of the arrival shaft 15 before the open shield machine 1 enters, in order to cut the steel sheet pile 11 at the portion where the open shield machine 1 will enter.

[0020] Therefore, work is required to cut the steel sheet piles 11, which results in cutting costs, total loss costs for the steel sheet piles 11 at the cut sections, and scrap costs.

[0021] Furthermore, in areas with particularly high levels of groundwater and soft ground, ground improvement work is carried out at the cut-through point. However, if the ground improvement work has not been carried out sufficiently, there is a concern that groundwater and soil may flow into the arrival shaft 15 during cut-through, loosening the ground around the arrival shaft 15 and affecting the surrounding area.

[0022] In addition, in Patent Document 1, there is no need to cut the mirror on the entry side of the shield machine 1 at the arrival shaft 15, and since the support 12 for the arrival shaft 15 is installed after the open shield machine 1 enters the position of the arrival shaft 15, there is no need to remove the upper part of the open shield machine 1 before the open shield machine 1 enters.

[0023] However, it is necessary to install long steel sheet piles 11 in the extension direction on both sides of the entrance side of the arrival shaft 15.

[0024] In addition, after the open shield machine 1 reaches the reach position of the reach shaft 15, the support 12 must be installed and the soil in the narrow gap between the shield machine 1 and the steel sheet pile 11 must be excavated and removed by the excavator 6, so the excavation work efficiency is significantly inferior to the conventional case. Furthermore, during excavation work by the excavator 6, workers must enter the narrow gap to instruct the excavation work to the operator of the excavator 6 or scrape off the soil adhering to the steel sheet pile 11, which is called "soil spatula dropping," and this is dangerous.

[0025] The object of the present invention is to provide a method for an open shield machine to enter an arrival shaft in an open shield construction method which improves the inconveniences of the above-mentioned conventional examples, does not require the labor and expense of cutting and removing the steel sheet piles at the mirror cutting section, has minimal impact on the surrounding area, and furthermore, allows the arrival shaft to be constructed in advance without the need to install supports after the open shield machine reaches the arrival shaft, thereby improving the efficiency of excavation work within the arrival shaft. [Means for solving the problem]

[0026] In order to achieve the above object, the present invention provides an open shield construction method in which concrete boxes are buried vertically in sequence by appropriately repeating the steps of: disposing a propulsion jack inside the left and right side wall panels and excavating and discharging soil in front of the front or top opening of an open shield machine with the front, rear and top open; extending the propulsion jack to move the open shield machine forward using the concrete box as a reaction force; and hanging a new concrete box from above behind the propulsion jack contracted inside the tail of the open shield machine and joining it to the existing concrete box. The tunnel entrance is formed by H-shaped steel piles installed at both ends and a steel panel wall whose ends can be engaged with the H-shaped steel piles and dropped into, the steel panel wall is made of shaped steel material as a crosspiece and has a face plate made of steel plate attached, and is arranged in two tiers, one above the other, with the ends fitting into grooves between the flanges of the H-shaped steel piles as rails, and can be lowered and lifted up by a crane or the like, and the steel panel wall is pulled out just before the open shield machine enters, and the open shield machine is allowed to enter the arrival shaft, and after ground improvement is made behind the steel panel wall, the steel panel wall is pulled out and the open shield machine is D The gist of the present invention is to have the machine enter the access shaft.

[0027] According to the present invention described in claim 1, the shape of the arrival shaft is a flat U-shape with steel sheet piles driven in, and on the side of the arrival shaft where the open shield machine reaches, a drop-in steel panel wall is supported at both ends of the retaining wall with H-shaped steel piles, and after ground improvement work is carried out behind this steel panel wall, the steel panel wall is pulled out just before the open shield machine enters the arrival shaft where primary excavation and installation of supports, secondary excavation, flooring, and foundation construction have been completed, and the open shield machine is then allowed to enter the arrival shaft.

[0028] Therefore, since there is no need to cut the steel sheet pile at the cut edge as in the conventional technology, cutting work of the steel sheet pile, cutting costs of the steel sheet pile, and costs of total loss of the steel sheet pile are not incurred, which is economical. Also, since it does not require a long time like cut edge work, there is almost no concern about groundwater or soil flowing into the arrival shaft due to poor ground improvement work in soft ground with high groundwater, and the impact on the surrounding ground.

[0029] Furthermore, there is no need to extend the steel sheet pile in the extension direction of the arrival shaft as in Patent Document 1 mentioned above, and after the open shield machine enters the arrival shaft, excavation does not take place in a narrow space between the open shield machine and the steel sheet pile, and workers do not enter that narrow space, so excavation work efficiency is not significantly impaired and it is safe.

[0030] According to the present invention as set forth in claim 2, after constructing ground improvement work behind the steel panel wall, the steel panel wall can be pulled out, thereby preventing ground collapse and increasing stability. Effect of the Invention

[0031] As described above, the method of entering the arrival shaft with the open shield machine in the open shield construction method of the present invention does not require the labor and expense of cutting and removing the steel sheet piles in the mirror cutting section, and has little impact on the surrounding area. Furthermore, since the arrival shaft can be constructed in advance without the need to install supports after the open shield machine reaches the arrival shaft, the excavation work inside the arrival shaft is more efficient, and it is more economical and safer than conventional technologies, and the number of construction days can be reduced. [Brief description of the drawings]

[0032] [Figure 1] 1 is a plan view showing a first step of an embodiment of a method for entering an arrival shaft of an open shield machine in the open shield construction method of the present invention. FIG. [Diagram 2] 1 is a vertical cross-sectional side view showing a first step of an embodiment of a method for entering an arrival shaft of an open shield machine in the open shield construction method of the present invention. FIG. [Diagram 3] 1 is a plan view showing a second step of an embodiment of a method for entering an arrival shaft of an open shield machine in the open shield construction method of the present invention. FIG. [Figure 4] 1 is a vertical cross-sectional side view showing a second step of an embodiment of a method for entering an arrival shaft of an open shield machine in the open shield construction method of the present invention. FIG. [Diagram 5] 10 is a plan view showing a third step of an embodiment of a method for entering an arrival shaft of an open shield machine in the open shield construction method of the present invention. FIG. [Figure 6] 1 is a vertical cross-sectional side view showing a third step of an embodiment of a method for entering an arrival shaft of an open shield machine in the open shield construction method of the present invention. FIG. [Figure 7] 10 is a plan view showing a fourth step of an embodiment of a method for entering an arrival shaft of an open shield machine in the open shield construction method of the present invention. FIG. [Figure 8] 10 is a vertical cross-sectional side view showing a fourth step of an embodiment of a method for entering an arrival shaft of an open shield machine in the open shield construction method of the present invention. FIG. [Figure 9] FIG. 2 is a perspective view of the arrival shaft of an open shield machine in the open shield construction method of the present invention. [Figure 10] FIG. 2 is a perspective view of the arrival shaft of the open shield machine in the open shield construction method of the present invention, seen from another direction. [Figure 11] FIG. 11 is a plan view showing a first step in a conventional example. [Figure 12] FIG. 11 is a vertical sectional side view showing a first step of a conventional example. [Figure 13] FIG. 11 is a plan view showing a second step in the conventional example. [Figure 14] FIG. 11 is a vertical sectional side view showing a second step of the conventional example. [Figure 15] FIG. 11 is a plan view showing a first step of another conventional example. [Figure 16] FIG. 11 is a vertical sectional side view showing a first step of another conventional example. [Figure 17] FIG. 11 is a plan view showing a second step of another conventional example. [Figure 18] FIG. 11 is a vertical sectional side view showing a second step of another conventional example. [Figure 19] FIG. 2 is a vertical cross-sectional side view showing the excavation process of the open shield method. [Figure 20] FIG. 2 is a vertical cross-sectional side view showing the concrete placement process of the open shield method. [Figure 21] FIG. 1 is a perspective view showing an overview of an open shield method. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0033] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. Figures 1 and 2 are a plan view and a longitudinal sectional side view, respectively, showing a first step of a method for entering a shield machine into a reach shaft in an open shield construction method, and in the drawings, 15 indicates the reach shaft.

[0034] The series of operations from excavation by the open shield machine 1 until it reaches just before the arrival shaft 15, to installation of the box, filling with backfill injection material 14, and backfilling the upper part of the box, are as described in Figures 19 to 21 above, and therefore will not be described here.

[0035] The arrival shaft 15 of the present invention is formed by steel sheet piles 11 driven into a flat U-shape and supports 12, while the entrance to the arrival shaft 15, which serves as the entrance for the open shield machine 1 to enter the shaft, is formed by H-shaped steel piles 18 installed on both ends and steel panel walls 19 whose ends can engage with the H-shaped steel piles 18 and be dropped into them.

[0036] Figure 9 shows this steel panel wall 19, which is made by attaching steel panel faces to sectional steel members arranged in two tiers, one above the other, and the ends fit into the grooves between the flanges of H-shaped steel piles 18, which act as rails.

[0037] In this way, the steel panel wall 19 can be lowered onto the H-shaped steel piles 18 serving as supports by a crane or the like, and can also be lifted up.

[0038] In the construction of the arrival shaft 15, after the first excavation in the arrival shaft and the installation of the supports 12, the steel sheet piles 11 are installed in sequence while the second excavation is carried out. After that, the foundation is constructed by laying the foundation, laying crushed stone, leveling and compacting it, and pouring leveling concrete.

[0039] As shown in Figures 3 and 4, after the tip of the open shield machine 1 reaches the steel panel wall 19, the steel panel wall 19 is gradually pulled up and removed from the steps.

[0040] After the steel panel wall 19 is installed, the ground improvement 13 is constructed in front of the steel panel wall 19, and the steel panel wall 19 is pulled out along the ground improvement 13. D Machine 1 enters the arrival shaft during ground improvement work 13.

[0041] In this way, since the head section that the open shield machine 1 reaches is not retained by the steel sheet piles 11, there is no need to cut the head section, and the open shield machine can immediately be prepared to enter the arrival shaft 15.

[0042] As shown in Figures 5 and 6, if the upper part of the open shield machine 1 is higher than the installation height of the support structure 12 and causes a hindrance, the components of the upper part are removed so that the upper part of the open shield machine 1 is lower than the installation height of the support structure 12.

[0043] Thereafter, the open shield machine 1 extends the driving jacks 3 and advances while receiving a driving reaction force from the already installed box body 4 behind. When the tip of the front part of the open shield machine 1 enters the arrival shaft 15, a steel tunnel entrance material 20 is installed to prevent the inflow of soil and groundwater.

[0044] Once the open shield machine 1 has been advanced one box length, the advancement jack 3 is retracted and the box 4 is installed in the tail section 17 using a lifting machine such as a rough terrain crane positioned behind the open shield machine 1 (not shown).

[0045] The above operations are repeated while the open shield machine 1 is advanced to a predetermined position within the arrival shaft 15.

[0046] After the open shield machine 1 is advanced to a predetermined position, it is dismantled and removed / carried away.

[0047] Figures 7 and 8 show the situation when the box construction was completed after the open shield machine 1 was removed. [Explanation of symbols]

[0048] 1. Open shield machine 1a...Side wall plate 1b...Movable side wall plate 2...Blade tip 3...Propulsion jack (shield jack) 4...Concrete box 5...Backfill soil 6...Excavator 7...Press bar 8...Bulkhead 9...Departure shaft 10…Reaction wall 11…Steel sheet pile 11a...Mirror steel sheet pile 12...Shoring 13…Soil improvement 14…Backfill injection material 15... Arrival shaft 16... Front section (open shield machine) 17...Tail section (open shield machine) 18...H-shaped steel pile 19...Steel panel wall 20…Wellhead steel material

Claims

1. In an open shield construction method in which concrete boxes are buried vertically in sequence by appropriately repeating the steps of: disposing a propulsion jack inside the left and right side wall panels, and excavating and discharging soil in front of the front or top opening of an open shield machine with the front, rear and top open; extending the propulsion jack to move the open shield machine forward using the concrete box as a reaction force; and hanging a new concrete box from above behind the propulsion jack contracted inside the tail of the open shield machine and joining it to the existing concrete box. a steel panel wall having H-shaped steel piles installed at both ends and a steel panel wall whose ends can engage with the H-shaped steel piles and be dropped into the wall, the steel panel wall being arranged in two tiers, one above the other, with steel beams used as crosspieces and steel face panels attached to the crosspieces, the ends fitting into grooves between the flanges of the H-shaped steel piles acting as rails, and the wall being capable of being lowered and lowered by a crane or the like and also being lifted up, the steel panel wall being pulled out just before the open shield machine enters the wall, and the open shield machine being allowed to enter the wall into the arrival shaft in an open shield construction method,

2. 2. A method for entering an arrival shaft of an open shield machine in an open shield construction method as described in claim 1, wherein after ground improvement work is performed behind a steel panel wall, the steel panel wall is pulled out and the open shield machine is advanced into the arrival shaft.

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