Construction method of steel shell elements

Abstract

To provide a construction method with a reduced construction period and cost through labor saving of work.SOLUTION: A construction method includes steps of inserting an adjacent steel shell element 3 to a steel shell element 2 to be inserted previously in a state in which a temporary steel pipe 6 is attached on the inserted steel shell element 2 after the temporary steel pipe 6 is attached thereon to enlarge a section to the adjacent steel shell element 3 side; and pulling the temporary steel pipe 6 after installation of the steel shell element 3. Surplus soil to be reduced after insertion installation of the steel shell element 3 is allowed to be reduced, because the surplus soil remaining between side plates of the previously inserted steel shell element 2 and the post inserted steel shell element 3 is reduced only by the amount equal to an area of an enlarged section through installation of the temporary steel pipe 6.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to a method for constructing steel shell elements for constructing a tunnel with a constant cross-sectional area in the tunnel direction in an outer shell preceding tunnel, which is constructed by repeating the procedure of sequentially inserting steel shell elements with a rectangular hollow cross section while connecting joints with already inserted steel shell elements to construct an outer shell structure with a closed cross section using the steel shell elements in the ground, and then removing the soil and sand inside this outer shell structure. [Background technology]

[0002] A conventional non-cut-and-cover method for constructing tunnels that cross over roads or railways is to install rectangular steel shell elements, each about 1 m long, in the ground, one after the other, with special joints, and then fill the steel shell elements with concrete to form a shell structure. The tunnel is then completed by excavating and removing the soil from inside the shell structure.

[0003] The present applicant also proposed in Patent Document 1 below a new joint structure for steel shell elements equipped with a watertight section for constructing underground structures by sequentially inserting steel shell elements while connecting them to already inserted steel shell elements. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-71904 Summary of the Invention [Problem to be solved by the invention]

[0005] As disclosed in the above Patent Document 1, in the construction of conventional steel shell elements, as shown in FIG. 9, openings 52 are provided on one side of a steel shell element 50 at predetermined intervals along the element axial direction for removing soil and sand remaining between the side plates 51, 51 of adjacent steel shell elements 50, 50 after thrust, and a closing plate 53 is provided for closing the openings 52. As shown in FIG. 10, the following steel shell element 50 is thrust while fitting the convex joint 55 into the concave joint 54 of the preceding thrust element 50, and then, as shown in FIG. 11, the closing plate 53 for closing the opening 52 provided in the side plate 51 is removed and the soil and sand remaining between the side plate 51 of the preceding thrust element 50 and the side plate 51 of the following thrust element 50 is removed through the opening 52.

[0006] As described above, in conventional construction, the residual soil between the side plates of the leading and trailing steel shell elements had to be excavated and removed manually in a narrow tunnel, which was extremely time-consuming and resulted in a longer construction period and increased costs.

[0007] Therefore, a main object of the present invention is to provide a method for constructing a steel shell element that is labor-saving and reduces construction time and costs. [Means for solving the problem]

[0008] In order to solve the above problems, the present invention according to claim 1 provides a method for inserting a rectangular hollow cross-section steel element into the ground while connecting the joints of the inserted steel element and the inserted steel element, and repeating the process to insert the steel element into the ground. rectangular A method for constructing a steel shell element when constructing a shell structure having a closed cross section and then removing soil and sand from the shell structure to construct an outer shell leading tunnel, comprising: The steel shell elements are classified into four types of steel shell elements: start elements that are inserted first; standard elements that are placed in the middle of the upper deck, lower deck, and both side walls of the shell structure; adjustment elements that are placed at the four corners of the shell structure; and closing elements that are inserted last. The starting element is installed by a procedure of inserting a temporary steel pipe, which expands the cross section of the starting element, into the adjacent steel shell element side on both side plates with a bolt; The standard element is installed by a procedure in which a temporary steel pipe, which expands the cross section only on the side of the next element to be connected and inserted to the standard element, is attached with a bolt, and the standard element is inserted while connecting the joint parts with the inserted steel shell element, The adjustment element is installed in a state in which a temporary steel pipe that expands the cross section only on the side of the next element to be connected to the adjustment element and inserted is attached with a bolt, and the adjustment element is inserted while connecting the joint portions with the inserted steel shell element, The closing element is installed without a temporary steel pipe, by penetrating the adjacent steel shell elements that have been previously installed while connecting their joint portions to each other, The next steel shell element is inserted into the inserted steel shell element, and when the installation of the succeeding steel shell element is completed, the temporary steel pipe attached to the previously inserted steel shell element is removed by removing the bolt and pulling out. A method for constructing a steel shell element is provided.

[0009] In the invention described in claim 1, In particular, for standard elements and adjustment elements, temporary steel pipes that enlarge the cross section only on the side of the next element to be connected and inserted are attached with bolts, and the elements are inserted while connecting the joints with the inserted steel shell elements. After the installation of the succeeding steel shell element is completed, the temporary steel pipe is removed. This reduces the amount of residual soil accumulated between the side plates of the preceding steel shell element and the next steel shell element by the amount of the expanded cross section caused by the placement of the temporary steel pipe, and reduces the amount of residual soil to be excavated and removed after the steel shell element is installed. This reduces the labor required for the work, and enables reductions in construction time and costs.

[0010] As the present invention according to claim 2, there is provided a method for constructing steel shell elements according to claim 1, wherein each of the steel shell elements has a basic cross-sectional dimension defined by the maximum width dimension and maximum height dimension of the combined shape of the rectangular hollow cross section and the temporary steel pipe, which is constant in the tunnel direction.

[0011] In the invention described in claim 2 above, the cross-sectional shape of each steel shell element is basically preferably matched to the excavation cross-sectional shape of the excavator, so the basic cross-sectional dimensions of each steel shell element are constant in the tunnel direction.

[0012] As the present invention according to claim 3, there is provided a method for constructing a steel shell element according to either claim 1 or 2, wherein the temporary steel pipe is arranged so that its cross section expands to a range that almost coincides with the tip of the joint portion protruding toward the adjacent steel shell element.

[0013] In the invention described in claim 3, the temporary steel pipe is arranged so that its cross section expands to a range that almost coincides with the tip of the joint part protruding toward the adjacent steel shell element, so that when the steel shell element is inserted, it is only necessary to excavate a substantially rectangular cross section, which simplifies the excavation equipment and improves versatility.

[0014] Claim 4 As the present invention relating to the above, the procedure of inserting the steel shell element is to connect the convex joint of the next steel shell element to the concave joint of the inserted steel shell element, and insert the steel shell element while connecting the convex joint of the next steel shell element to the concave joint of the inserted steel shell element.3 A method for constructing any of the steel shell elements is provided.

[0015] The above claims 4 In the described invention, when a steel element is inserted, the concave joint portion of the steel element is inserted without being connected, and when the next steel element is inserted, the convex joint is connected to the concave joint of the already installed steel element. This procedure improves the insertion accuracy and efficiency of the steel element, and at the same time makes it easier to ensure watertightness.

[0016] Claim 5 As the present invention relating to the present invention, the excavator used when penetrating the steel shell element has a front excavation part whose shape matches the combined shape of the rectangular hollow cross section of the steel shell element and the temporary steel pipe, and has an auxiliary cutter in the body part for excavating the soil portion corresponding to the joint part, or the excavator performs over-excavation in a range including the joint part. 4 A method for constructing any of the steel shell elements is provided.

[0017] The above claims 5 In the described invention, the excavator used to penetrate the steel shell element has a front excavation section whose shape matches the combined shape of the rectangular hollow cross section of the steel shell element and the temporary steel pipe, and is equipped with an auxiliary cutter in the body section for excavating the soil portion corresponding to the joint section, or the excavator is capable of over-excavating an area that includes the joint section, making it easier for the steel shell element to penetrate the excavation section excavated by the excavator. [Effects of the Invention]

[0018] As explained above in detail, the present invention can provide a method for constructing a steel shell element that can reduce the labor required and shorten the construction period and reduce the cost. [Brief explanation of the drawings]

[0019] [Figure 1] 1 is a cross-sectional view of a shell 1 constructed in accordance with the present invention. [Figure 2] FIG. 2 is a perspective view showing a construction procedure (part 1) of the shell structure 1. [Figure 3] FIG. 10 is a perspective view showing the construction procedure (part 2) of the shell structure 1. [Figure 4] FIG. 10 is a perspective view showing the construction procedure (part 3) of the shell structure 1. [Figure 5] FIG. 10 is a perspective view showing the construction procedure (part 4) of the shell structure 1. [Figure 6] FIG. 1 is a cross-sectional view showing the excavation range. [Figure 7] FIG. 2 is a front view of the drilling rig 20. [Figure 8] FIG. 2 is a longitudinal cross-sectional view of the drilling equipment 20. [Figure 9] FIG. 1 is a cross-sectional view showing a conventional steel-shell element 50. [Figure 10] FIG. 1 is a cross-sectional view showing a construction procedure (part 1) of a conventional steel-shell element 50. [Figure 11] FIG. 10 is a cross-sectional view showing a construction procedure (part 2) of a conventional steel-shell element 50. DETAILED DESCRIPTION OF THE INVENTION

[0020] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[0021] 1 and 2 to 5, the present invention is a method for constructing a shell structure 1 in the ground, in which a large number of steel elements are connected together in a rectangular, circular, polygonal, or other shape in cross section, by repeatedly inserting steel elements 3 having a rectangular hollow cross section into the ground while connecting their joints with already inserted steel elements 2, and then removing soil and sand from inside the shell structure 1 to construct an outer shell leading tunnel. In particular, the present invention is a method for constructing a tunnel with a constant cross-sectional area in the tunnel direction.

[0022] The shell-first tunnel construction method has the advantage of having little impact on the surrounding ground, and is therefore widely used as a construction method for constructing underpass tunnels without excavating the ground beneath roads, railways, etc.

[0023] In particular, in the present invention, a temporary steel pipe 6 that expands the cross section of the adjacent steel shell element 3 is attached to the steel shell element 2 that is to be inserted first, and the adjacent steel shell element 3 is inserted with the temporary steel pipe 6 attached to the inserted steel shell element 2, and after the construction of the steel shell element 3 is completed, the temporary steel pipe 6 is pulled out, thereby saving labor in the construction when constructing the outer shell structure 1. This will be described in more detail below.

[0024] The steel shell elements are classified into four types according to differences in cross-sectional shape and penetration method: start element 2, which is inserted first; standard elements 3, 3..., which are placed in the middle of the upper deck 1A, lower deck 1B, and both side wall slabs 1C, 1C of the shell structure 1; adjustment elements 4, 4..., which are placed at the four corners of the shell structure 1; and closing element 5, which is inserted last. In Fig. 1, the circled numbers inside each of the steel shell elements 2 to 5 indicate the insertion order.

[0025] First, as shown in Fig. 2, the start element 2 has a basic form of an element with a rectangular hollow cross section composed of an upper plate 20, a lower plate 21, and side plates 22, 22. On both sides of the upper plate 20 and the lower plate 21, protruding members 23, 23 are provided, extending outward from the side plate 22 and toward the adjacent steel shell element 3, and concave joints 24, 24 are provided at the tips of the protruding members 23 along the longitudinal direction of the member. The protruding length of the protruding members 23 is approximately constant over the entire length.

[0026] A temporary steel pipe 6 is attached to each of the side plates 22, 22 of the start element 2, expanding the cross section toward the adjacent steel shell element 3. The temporary steel pipe 6 is a steel pipe with a substantially rectangular cross section that extends in the tunnel direction, and is fixed to the outer surface of the side plates 22 with a plurality of bolts 7...

[0027] In the start element 2, the temporary steel pipes 6 are provided between the protruding members 23, 23 extending on each side of the upper plate 20 and the lower plate 21 and the concave joints 24, 24 provided at the ends of the protruding members 23, 23. In other words, the height dimension H6 of the temporary steel pipe 6 is smaller than the height dimension H of the rectangular hollow cross section by the thickness of the concave joints 24, 24. The temporary steel pipes 6 are formed with a constant cross-sectional shape in the tunnel direction.

[0028] A plurality of bolts 7 are used to secure the temporary steel pipe 6 to the start element 2. To secure the bolts 7, through holes are provided in the side plates 22 of the start element 2, and through holes are provided in the temporary steel pipe 6 at corresponding positions, with nuts secured to the inside of the holes. The bolts 7 are inserted into the through holes from the inside of the rectangular hollow cross section and screwed onto the nuts. This allows workers to enter the rectangular hollow cross section after the start element 2 has been inserted and installed, and remove the bolts 7.

[0029] The start element 2 has concave joints 24, 24 on both sides, and is the first steel element to be penetrated and installed into the ground. The excavator used to penetrate and install the steel element 2 is an excavator 40 having a cross-sectional shape that matches the basic cross-sectional dimensions defined by the maximum width dimension B and maximum height dimension H of the shape of the combined shape of the rectangular hollow cross section and the temporary steel pipe 6.

[0030] Next, the standard element 3, which is arranged adjacent to one side of the start element 2, has a basic form of an element with a rectangular hollow cross section composed of an upper plate 30, a lower plate 31, and side plates 32, 32, as shown in detail in Figure 3. On one side (the start element 2 side) of the upper plate 30 and lower plate 31, protruding members 33, 33 are provided extending outward from the side plate 32, and a convex joint 34 is provided at the tip of this protruding member 33 along the longitudinal direction of the member. On the side opposite to the convex joint 34, the upper plate 30 and lower plate 31 are provided with a protruding member 35 extending outward from the side plate 32, and a concave joint 36 is provided at the tip of this protruding member 35 along the longitudinal direction of the member. The protruding length of the protruding members 33, 35 is approximately constant over the entire length.

[0031] A temporary steel pipe 6 is attached to the side plate 32 on the side where the concave joint 36 of the standard element 3 is provided, expanding the cross section toward the adjacent steel element (the next steel element to be connected to and inserted into the standard element 3). On the other hand, the temporary steel pipe 6 is not provided on the side plate 32 on the side where the convex joint 34 is provided. The temporary steel pipe 6 has the same structure as that used in the start element 2, so its explanation will be omitted.

[0032] The excavator used when penetrating and installing the standard element 3 may be the same as the excavator 40 used for the start element 2.

[0033] After several of the standard elements 3 are placed adjacent to each other (three in the illustrated example), the adjustment element 4 is placed adjacent to them in the next order. The adjustment element 4, as shown in Figure 1, is basically a rectangular hollow cross-section element consisting of an upper plate, a lower plate, and a side plate. On one side of the upper and lower plates (the side of the previously placed standard element 3), a protruding member is provided that extends outward from the side plate, and a convex joint is provided at the tip of this protruding member along the longitudinal direction of the member. Furthermore, on the lower side of each side plate (the side of the next standard element 3), a protruding member is provided that extends outward from the lower plate, and a concave joint is provided at the tip of this protruding member along the longitudinal direction of the member. The protruding length of the protruding member is approximately constant over the entire length.

[0034] A temporary steel pipe 6 is attached to the lower plate on the side where the concave joint of the adjustment element 4 is provided, expanding the cross section toward the adjacent steel element (the next steel element 3 that is connected to and inserted into the adjustment element 4). On the other hand, the temporary steel pipe 6 is not provided on the side plate on the side where the convex joint is provided. The temporary steel pipe 6 has the same structure as that used in the start element 2.

[0035] The closing element 5 to be inserted last is basically an element with a rectangular hollow cross section composed of an upper plate, a lower plate, and a side plate, and has a protruding member on each side of the upper and lower plates that extends outward from the side plate and toward the adjacent steel shell element 3, and a convex joint is provided at the tip of this protruding member along the longitudinal direction of the member. The protruding length of the protruding member is almost constant over the entire length.

[0036] This steel shell element 5 is not provided with the temporary steel pipe 6. That is, the adjacent steel shell elements 3, 3 that have been inserted first are each provided with a temporary steel pipe 6 that enlarges the cross section on the side of the closing element 5 that is to be inserted last, so there is no need to provide the temporary steel pipe 6 on the closing element 5.

[0037] The temporary steel pipes 6 attached to each of the above-mentioned steel shell elements 2 to 4 are steel pipes extending in the axial direction of the shell structure 1 having a substantially rectangular cross section, and are fixed by a plurality of bolts 7... to a plate member facing the next steel shell element to be inserted among the steel shell elements. After the steel shell element 2 equipped with this temporary steel pipe 6 is inserted and installed, the next steel shell element 3 is inserted while connecting the joints of the inserted steel shell element 2, and once the installation of the succeeding steel shell element 3 is completed, the temporary steel pipes 6 attached to the previously inserted steel shell element are removed and then pulled out.

[0038] In this way, the temporary steel pipe 6 that expands the cross section on the adjacent steel shell element 3 side is attached to the steel shell element 2 that is inserted first, and therefore the amount of residual soil that accumulates between the side plates of the steel shell element 2 that has penetrated first and the next steel shell element 3 is reduced by the amount of the expanded cross section due to the placement of the temporary steel pipe 6, and the amount of residual soil that must be excavated and removed after the penetration and installation of the steel shell element 3 is reduced. This allows for labor savings in the work, and makes it possible to reduce the construction period and costs.

[0039] Furthermore, after the subsequent steel shell element 3 is inserted and installed, the temporary steel pipe 6 attached to the previously inserted steel shell element 2 is pulled out and removed, so that the temporary steel pipe 6 does not adversely affect the filling of concrete into the steel shell element.

[0040] The arrangement range of the temporary steel pipes 6 is between the concave joints 24, 24 or 36, 36 arranged on the inner and outer circumferential sides, respectively, when the shell structure 1 is constructed, and is a substantially rectangular range from the outer surface of the plate member facing the next steel shell element (side plate 22 in the case of the starting element 2 shown in Figure 2) to the tip of the concave joint 24 provided at the tip of the protruding member 23 protruding toward the adjacent standard element 3. Therefore, excluding the portion of the convex joint 34 that is inserted and connected to the concave joint 24 that has been inserted previously, the cross-sectional shape of the steel shell element including the temporary steel pipes 6 is substantially rectangular (see Figure 6).

[0041] Next, the method for inserting the steel shell elements 2 to 5 will be described in detail while following the procedure for constructing the shell structure 1.

[0042] The insertion procedure of the steel shell elements 2 to 5 is the order of numbers No. 1 to No. 15 attached to the cross-sectional view of the shell structure 1 shown in FIG. That is, of the rectangular cross section formed by closing a large number of steel shell elements 2 to 5 into a rectangular shape, the steel shell element 2 (No. 1: starting element) in the center of the upper deck 1A is first inserted, and using this steel shell element 2 as a base point, steel shell elements 3, 3... (standard elements) are inserted horizontally on both sides to form the part that will become the upper deck 1A. Then, steel shell elements 4 (No. 5: adjusting element) for the corner portions are inserted at both ends, and steel shell elements 3, 3... (standard elements) are inserted horizontally one after the other toward the lower side to form the side walls 1C, 1C. Next, steel shell elements 3, 3... (standard elements) are inserted horizontally from the steel shell element 4 (No. 11: adjusting element) at the lower corner, and finally, a closing element 5 is inserted to form the part that will become the lower deck 1B. In this manner, an outer shell structure 1 is constructed that is closed into a rectangular shape in cross section by a large number of steel shell elements 2 to 5.

[0043] A more detailed penetration procedure will be described with reference to Figures 2 to 5, taking the case of penetrating a start element 2 and an adjacent standard element 3 as an example. First, as shown in Figure 2, the start element 2 is penetrated and installed, with a temporary steel pipe 6 attached to each of its side plates 22, 22. An excavator 40 is used to penetrate and install this start element 2. The excavator pulls the start element, or a push jack pushes the excavator and start element 2 while pushing them. The excavator 40 can be, for example, the excavation equipment shown in Figures 7 and 8. The illustrated excavator 40 is a sealed excavation equipment that allows the construction of the shell structure 1 without ground improvement work, even below the groundwater level. It has a cross-sectional shape approximately equal to the combined shape of the steel shell elements 2 to 5 and the temporary steel pipe 6, and is equipped with a main cutter 42 attached to the tip of an auger screw 41 and a predetermined number of planetary cutters 43, 43, to excavate a rectangular cross section. The soil removal method is a screw conveyor method. Auxiliary cutters 44 are detachably attached to each of the four corners to excavate the soil corresponding to the concave joints 24. When the start element 2 penetrates, the auxiliary cutters 44 are provided at the corner positions of the four corners where the concave joints 24 are provided, and when the standard element 3 penetrates, the auxiliary cutters 44 are provided at the upper and lower corner positions where the concave joints 36 are provided on the non-connected side. Note that even if the auxiliary cutters 44 are not provided, the excavator 40 may be configured to perform over-excavation in an area that includes the concave joints 36.

[0044] By providing the steel shell elements 2 to 4 with the temporary steel pipes 6, the collapse of the wall surface excavated by the excavator 40 can be prevented until the adjacent steel shell elements are penetrated.

[0045] Once the insertion of the start element 2 has been completed, the next adjacent standard element 3 (No. 2) is inserted while the convex joint 34 is connected to the concave joint 24 of the inserted start element 2, with the temporary steel pipe 6 attached to the start element 2 left as is, as shown in Figure 3. When the insertion of this standard element 3 is complete, as shown in Figure 4, some soil and sand may remain in the gap between the temporary steel pipe 6 between the elements 2 and 3 and the side plate of the subsequently inserted steel shell element 3.

[0046] Thereafter, as shown in Figure 5, the temporary steel pipe 6 attached to the start element 2 that was inserted earlier is pulled out. Before pulling out the temporary steel pipe 6, all of the bolts 7, 7 ... used to secure the start element 2 are removed.

[0047] After the temporary steel pipe 6 is extracted, if necessary, any residual soil accumulated between the temporary steel pipe 6 and the subsequently inserted standard element 3 is removed. To remove this residual soil, an opening (not shown) is provided in the side plate to which the temporary steel pipe 6 is attached, a cover closing the opening is removed, and the residual soil is manually excavated through the opening. In conventional steel-shell elements, the amount of residual soil between elements is large, so it is necessary to enlarge the opening size or narrow the opening pitch to facilitate the removal of the residual soil from the opening, which may result in a decrease in the strength of the steel-shell element. However, in the steel-shell element according to the present invention, the provision of the temporary steel pipe 6 significantly reduces the amount of residual soil between elements, so the amount of residual soil to be removed from the opening is small, and the opening size can be narrowed or the opening pitch can be increased, thereby ensuring the strength of the steel-shell element. Note that if the opening for removing residual soil is blocked by the temporary steel pipe 6, a separate cover for closing the opening is not required.

[0048] [Other examples] (1) In the above example, the center of the upper deck was used as the starting point and construction was carried out in sequence on both sides up to the center of the lower deck on the opposite side, but any position may be used as the starting point and construction may be carried out in sequence on both sides up to the opposite side.

[0049] (2) In the above embodiment, the following steel element 3 is inserted while the convex joint 34 is connected to the concave joint 24 of the inserted steel element 2, but the relationship between the concave joint and the convex joint may be reversed, that is, the following steel element 3 may be inserted while the concave joint is connected to the convex joint of the inserted steel element 2. Note that the relationship between the convex joint and the concave joint is preferably such that the following steel element 3 is inserted while the convex joint 34 is connected to the concave joint 2 of the inserted steel element 2, as shown in this embodiment. [Explanation of symbols]

[0050] 1... Outer shell structure, 2... Steel shell element (starting element), 3... Steel shell element (standard element), 4... Steel shell element (adjusting element), 5... Steel shell element (closing element), 6... Temporary steel pipe, 7... Bolt, 24·36... Concave joint, 34... Convex joint, 40... Excavator

Claims

1. A method for constructing a steel shell element when constructing an outer shell preceding tunnel by repeating a procedure of sequentially inserting steel shell elements having a rectangular hollow cross section while connecting joints with already inserted steel shell elements to construct an outer shell structure having a rectangular closed cross section in the ground using the steel shell elements, and then removing soil and sand from inside the outer shell structure, comprising: The steel shell elements are classified into four types of steel shell elements: start elements to be inserted first; standard elements to be placed in the middle of the upper deck, lower deck and both side walls of the shell structure; adjustment elements to be placed in the four corners of the shell structure; and closing elements to be inserted last; The starting element is installed by a procedure of inserting a temporary steel pipe, which expands the cross section of the starting element, into the adjacent steel shell element side on both side plates with a bolt; The standard element is installed by a procedure in which a temporary steel pipe, which expands the cross section only on the side of the next element to be connected and inserted to the standard element, is attached with a bolt, and the standard element is inserted while connecting the joint parts with the inserted steel shell element, The adjustment element is installed in a state in which a temporary steel pipe that expands the cross section only on the side of the next element to be connected to the adjustment element and inserted is attached with a bolt, and the adjustment element is inserted while connecting the joint portions with the inserted steel shell element, The closing element is installed without a temporary steel pipe, by penetrating the adjacent steel shell elements that have been previously installed while connecting their joint portions to each other, This method for constructing steel shell elements is characterized in that a subsequent steel shell element is inserted into an already inserted steel shell element, and when the installation of the subsequent steel shell element is completed, the temporary steel pipe attached to the previously inserted steel shell element is removed by removing the bolts and pulling out.

2. 2. A method for constructing steel shell elements according to claim 1, wherein each of the steel shell elements has a basic cross-sectional dimension defined by the maximum width and maximum height dimensions of the combined shape of the rectangular hollow cross section and the temporary steel pipe, the basic cross-sectional dimension being constant in the tunnel direction.

3. 3. A method for constructing a steel shell element according to claim 1, wherein the temporary steel pipe is arranged so that its cross section expands to a range that substantially coincides with the tip of the joint portion protruding toward the adjacent steel shell element.

4. 4. The method for constructing a steel shell element according to claim 1, wherein the steel shell element is inserted while the convex joint of the next steel shell element is connected to the concave joint of the inserted steel shell element.

5. The method for constructing a steel-shell element according to any one of claims 1 to 4, wherein the shape of the front excavation section of the excavator used when penetrating the steel-shell element matches the combined shape of the rectangular hollow cross section of the steel-shell element and the temporary steel pipe, and the body section is equipped with an auxiliary cutter for excavating the soil portion corresponding to the joint section, or the excavator performs over-excavation in an area that includes the joint section.

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