JP2018168597A - Method for constructing outer shell precedent tunnel - Google Patents

Abstract

To construct a tunnel having a variable cross section that a cross-section area is gradually changed in an outer shell precedent tunnel construction method.SOLUTION: Between steel shell elements 2, 3, a joint portion has a structure in which concave joints 24, 26 mounted on the tip end of protrusion members 23, 25 for protruding from one side of the steel shell element 2 to the other side of the steel shell element 3 and convex joints 38, 40 mounted on the tip end of protrusion members 37, 39 for protruding from the other end of the steel shell element 3 to one side of the steel shell element 2 are fitted together. In the joint portion of adjacent steel shell element 2, 3, each protrusion length of the apron members 23, 25 of the concave joints 24, 26 is gradually changed, whereby an outer shell structure 1 whose cross section can be variable to a tunnel direction is constructed.SELECTED DRAWING: Figure 1

Description

  The present invention repeats a procedure of sequentially inserting a steel hollow shell element having a square hollow cross section while connecting a steel shell element and a joint that have already been penetrated, and an outer shell structure having a closed cross section by the steel shell element in the ground. This is a method for constructing a tunnel with a variable cross-section in which the cross-sectional area is gradually changed in the tunnel direction in the method of constructing a tunnel ahead by constructing a tunnel by removing the inner earth and sand of this outer shell structure. .

  In recent years, as shown in FIG. 13, steel shell elements 50, 50... With joints are sequentially excavated and connected to form an outer shell structure in a rectangular shape by an upper plate 52A, a lower plate 52B, and both side wall plates 52C, 52C. 52 is constructed, and the steel shell elements 50, 50... Are filled with concrete 51, and then the non-open cutting method of completing the tunnel by excavating and removing the inner soil of the outer shell structure 52 has been put into practical use. . This tunnel construction method is called the outer shell leading tunnel construction method, and has the advantage of having little influence on the surrounding ground, so it is often applied to underpass construction of roads and railways.

  The present applicant also repeats the above-mentioned steel shell in Patent Document 1 described below in which a main pushing jack is installed on the starting side and the steel shell elements having a square cross section are sequentially connected to the steel shell elements that have already been inserted. In the steel shell element construction method for constructing an underground structure with an element, the thrust transmission member of a predetermined length is attached in tandem on one side of the steel shell element previously penetrated. On the side adjacent to the thrust transmission member attached to the steel shell element, after connecting the drilling device with the thrust transmission member attached to the penetrated steel shell element, the steel shell element of a predetermined length is successively followed. The thrust of a predetermined length is sequentially applied to the thrust transmission member attached to the penetrated steel shell element and attached to the penetrated steel shell element. A thrust transmission member having a predetermined length is sequentially attached to one side of the steel shell element to be inserted and the steel transmission element is inserted, and the thrust transmission members disposed at these two locations are pushed in by the former push jack, A steel shell element construction method was proposed in which the steps of intrusion while indirectly pulling were repeated sequentially.

JP 2009-263883 A

  Conventionally, the outer shell leading tunnel construction methods implemented or proposed have a problem that only a single-section tunnel having the same cross-sectional area in the tunnel direction can be constructed. For this reason, there is a drawback in that it is not possible to cope with the case where it is desired to gradually expand or reduce the cross-sectional area in the tunnel direction due to land problems or restrictions on securing the internal space, or to gradually increase or decrease the tunnel height in the ground depth direction. It was.

  Accordingly, a main object of the present invention is to provide a method for constructing a tunnel having a variable cross section in which the cross-sectional area is gradually changed in the outer shell preceding tunnel construction method.

In order to solve the above-mentioned problem, as the present invention according to claim 1, the steel shell element having a square hollow cross section is sequentially inserted while connecting the steel shell element and the joints that have already been inserted into the ground. In the outer shell preceding tunnel construction method of constructing a tunnel by removing the inner earth and sand of the outer shell structure after constructing the outer shell structure of the closed cross section by the steel shell element,
The joint portion includes a concave joint provided at the tip of an overhang member that protrudes from one steel shell element to the other steel shell element between adjacent steel shell elements, and the other steel shell element. It is a structure in which a convex joint provided at the tip of the overhang member protruding toward the steel shell element on one side is fitted,
Constructing an outer shell structure with a variable cross section in the tunnel direction by gradually changing the extension length of one of the concave and convex joints at the joint of adjacent steel shell elements An outer shell advance tunnel construction method is provided.

  In the first aspect of the invention, in the outer shell preceding tunnel construction method, the joint portion projects between the adjacent steel shell elements from the steel shell element on one side toward the steel shell element on the other side. Adjacent to each other, and a concave joint provided at the tip of the overhanging member that protrudes from the other steel shell element toward the one steel shell element. In the joint part of the steel shell element, an outer shell structure with a variable cross section is constructed in the tunnel direction by gradually changing the overhang length of the overhang member on one side of the concave joint and the convex joint. did. In other words, it is possible to construct an outer shell structure with a variable cross section in the tunnel direction by gradually changing the overhang length of the overhang member supporting the joint at the joint between adjacent steel shell elements. It becomes. The portion that is widened or reduced by changing the overhang length of the joint will be described with reference to FIG. 13. The upper plate 52A, the lower plate 52B, and the side plates 52C, 52C of the outer shell structure 52 It is not necessary to be all of them, and may be a part of the upper plate 52A and the lower plate 52B, or a part of the side wall plates 52C and 52C.

  According to a second aspect of the present invention, in the steel shell element, the basic cross-sectional dimension defined by the maximum width dimension and the maximum height dimension of the square hollow section is constant in the tunnel direction. A shell advance tunnel construction method is provided.

  In the second aspect of the present invention, each steel shell element has a basic cross-sectional dimension defined by the maximum width dimension and the maximum height dimension of the square hollow section in the tunnel direction. Since the cross-sectional shape of each steel shell element should basically match the excavation cross-sectional shape of the excavator, it is desirable that the basic cross-sectional dimension of each steel shell element be constant in the tunnel direction.

  The present invention according to claim 3 is a procedure according to any one of claims 1 and 2, which is a procedure of penetrating a concave joint of a steel shell element that has already been penetrated while connecting a convex joint of the next steel shell element. An outer shell leading tunnel construction method is provided.

  The invention according to claim 3 is a procedure for inserting a concave joint of a steel shell element that has already been penetrated while connecting the convex joint of the next steel shell element. In other words, when penetrating, the concave joint part of the steel shell element is penetrated without being connected, and when the next steel shell element is penetrated, the convex joint is connected with the concave joint of the installed steel shell element. It is desirable to install. According to this procedure, the penetration accuracy and efficiency of the steel shell element are improved, and at the same time, it is easy to ensure water blocking.

  As the present invention according to claim 4, in the joint arrangement surface of the square hollow cross section in the steel shell element, a stepped portion is formed by forming a cross-sectional defect portion on both sides or one side portion, and a non-cross-sectional defect portion A projecting member extending from the end of the projecting member toward the adjacent steel shell element, the concave joint is provided at the tip of the projecting member, and the projecting length of the projecting member is gradually changed. The method for constructing an outer shell preceding tunnel according to claim 3, wherein the concave joint is located in the stepped portion.

  In the invention described in claim 4, when the concave joint and the convex joint are formed between the adjacent steel shell elements by projecting sideward from the square hollow section as in the prior art, Due to the gradual change of the overhang length, there arises a problem that the separation width of the square hollow cross section becomes too large. The part of the separation width of this square hollow cross section is a portion that becomes an unexcavated portion, and there is a need to manually remove earth and sand before filling with concrete. Therefore, a stepped part is formed by forming a cross-sectional defect part on both sides or one side part on the joint arrangement surface of the square hollow cross section, and from the end part of the non-cross-sectional defect part to the adjacent steel shell element In addition, a projecting member extending in the direction is provided, and the concave joint is provided at the tip of the projecting member. The overhanging length of the overhanging member is gradually changed, and the concave joint is positioned in the stepped portion. In this way, the separation width of the square hollow cross section between the adjacent steel shell elements is not set by setting the joint portion to a position within the square hollow cross section instead of being positioned laterally away from the square hollow cross section. Therefore, it is possible to save labor in the subsequent earth and sand removal work.

  As the present invention according to claim 5, a convex joint is provided at the tip of the overhanging member protruding from the corner of the steel shell element toward the adjacent steel shell element, and the overhanging length of the overhanging member is constant. An outer shell preceding tunnel construction method according to any one of claims 3 and 4 is provided.

  In the invention according to claim 5, a protruding joint is provided at the tip of the overhanging member protruding from the corner of the steel shell element toward the adjacent steel shell element, and the overhang length of the overhanging member Is assumed to be constant. When a convex joint is provided at the tip of the projecting member protruding from the corner of the steel shell element toward the adjacent steel shell element, it is connected to the concave joint at the stepped portion of the penetrated steel shell element. Is possible. In addition, when the projecting joint of the steel shell element to be penetrated is connected to the concave joint of the steel shell element that has already been penetrated, if the protruding length of the convex joint of the steel shell element to be penetrated is not fixed, Since the recessed joint that has been penetrated is at a fixed position at the wellhead, the position of the steel shell element to penetrate moves in the width direction due to the change in the protruding length of the convex joint, and the steel shell element cannot be penetrated. Therefore, it is preferable to keep the protruding length of the convex joint of the subsequent steel shell element constant.

  As described above in detail, according to the present invention, it is possible to construct a tunnel having a variable cross section in which the cross-sectional area is gradually changed in the outer shell preceding tunnel construction method.

It is a principal part perspective view which shows the outer shell structure 1 of a variable cross-section part. The outer shell structure 1 is shown, (A) is a plan view, (B) is a reaching side section, and (C) is a starting side section. The central steel shell element 2 is shown. (A) is a plan view, (B) is a reaching side section, and (C) is a starting side section. The widened connecting steel shell element 3 is shown, (A) is a plan view, (B) is a reaching side section, and (C) is a starting side section. The equal-width connecting steel shell elements 5 are shown, (A) is a plan view, (B) is a reaching side section, and (C) is a starting side section. It is an expanded sectional view of a joint part. 3 is an enlarged cross-sectional view of a concave joint 6. FIG. FIG. 3 is an enlarged cross-sectional view showing a water stop part 13. FIG. 6 is an enlarged sectional view of a joint portion showing a modification of the convex joint 7. The 1st example of the excavator 45 to be used is shown, (A) is a front view, (B) is a cross-sectional view of a portion where the auxiliary cutter 46 is disposed. The 2nd example of the excavator 45 used is shown, (A) is a front view, (B) is sectional drawing of the arrangement | positioning site | part of the auxiliary cutter 46. FIG. It is a principal part perspective view at the time of making the outer shell structure 1 a variable cross section in the height direction. It is sectional drawing which shows the example of the tunnel 52 constructed | assembled with the outer shell preceding tunnel construction method.

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

As shown in FIG. 1, the present invention repeats the procedure of penetrating the steel shell elements 3 and 4 having a square hollow cross section while sequentially connecting the steel shell elements 2 and the joints that have already been penetrated. After constructing the outer shell structure 1 which is closed to a rectangular shape, a circular shape, a polygonal shape or the like in a cross-sectional view by a number of steel shell elements, the tunnel is formed by removing the inner earth and sand of the outer shell structure 1 In the outer shell leading tunnel construction method of building
The joint portion is between the adjacent steel shell elements 2 and 3 (2, 4) at the tip of the overhanging member 23 protruding from the steel shell element 2 on one side toward the steel shell elements 3 and 4 on the other side. A structure in which a concave joint 24 provided and a convex joint 38 provided at the tip of an overhanging member 37 protruding from the other steel shell elements 3 and 4 toward the one steel shell element 2 are fitted. In the joint portion of the adjacent steel shell elements 2 and 3, by gradually changing the overhang length of the overhang member 23 on one side of the concave joint 24 and the convex joint 38, in the tunnel direction. An outer shell structure having a variable cross section is constructed.

  The outer shell leading tunnel construction method has advantages such as little impact on the surrounding ground, so it is frequently used as a construction method when constructing an underpass tunnel by non-cutting the ground under the route such as a road route or railway route It is what has been.

  In particular, the present invention provides a method of constructing a tunnel having a variable cross section in which the cross-sectional area of the outer shell structure 1 is gradually changed in the outer shell preceding tunnel construction method. This will be described in more detail below.

  FIG. 1 is a main part perspective view showing a part of an outer shell structure 1 having a variable cross section. For example, as shown in FIG. 13, when the outer shell structure 52 is constructed in a rectangular shape by the upper plate 52A, the lower plate 52B, and the side wall plates 52C, 52C, FIG. The principal part perspective view at the time of making it a variable cross section so that the width dimension of the outer shell structure 1 may be gradually increased from the side to the arrival side is shown.

  The illustrated outer shell structure 1 (upper plate or lower plate) shows an example constituted by three steel shell elements 2 to 4 as shown in FIG. That is, the central steel shell element 2 is arranged in the middle, and the widening connecting steel shell elements 3 and 4 are arranged on both sides thereof. These three steel shell elements 2 to 4 have the same basic cross-sectional dimension in the tunnel direction defined by the maximum width dimension B and the maximum height dimension H of the square hollow section. That is, according to the cross-sectional dimension of the excavating part to be used, each of the steel shell elements 2 to 4 has a maximum width dimension of B and a maximum height dimension of H, and this basic cross-sectional dimension is in the tunnel direction. It is made the same throughout. In the drawing, the square hollow portions of the steel shell elements 2 to 4 are indicated by thick wavy lines.

  First, as shown in detail in FIG. 3, the central steel shell element 2 has a square hollow cross-section element composed of an upper plate 20, a lower plate 21 and side plates 22 and 22 as a basic shape. In the upper plate 20, stepped portions are formed by forming cross-sectional defect portions 20 </ b> B and 20 </ b> B on both side portions, leaving the central portion 20 </ b> A. And the extension members 23 and 23 extended toward the steel shell elements 3 and 4 which adjoin from both ends (protrusion corner) of the said center part 20A are provided, and a member longitudinal direction is provided at the front-end | tip of these extension members 23 and 23 Concave joints 24, 24 are provided along.

  In the lower plate 21, stepped portions are formed by forming cross-sectional defect portions 21B and 21B on both side portions, leaving the central portion 21A. And the extension members 25 and 25 extended toward the steel shell elements 3 and 4 which adjoin from the both ends (protrusion corner) of the said center part 21A are provided, and member longitudinal direction is at the front-end | tip of these extension members 25 and 25. Are provided with concave joints 26 and 26.

As can be seen by comparing FIG. 3 (B) and FIG. 3 (C), the overhang members 23 and 25 gradually increase in length from the start side to the arrival side. That is, the protruding length of the protruding member 23 and 25 at the start side is a L _1, is reached side projecting length of said projecting member 23 and 25 are L _2. The difference between the overhang lengths (L ₂ −L ₁ ) is the amount of widening. Further, the overhang length of the overhang member 23 (25) is adjusted so that the positions in the width direction of the concave joints 24 and 26 are located in the cross-sectional defect portion 20B (21B).

  The central steel shell element 2 has concave joints 24, 24 (26, 26) on both sides, and is a steel shell element that is first installed in the ground. The excavator used for the penetration installation of the steel shell element 2 has a ratio of the maximum width dimension B to the maximum height dimension H of the square hollow cross section of 2: 1. As shown in the figure, an excavator 45 having a structure in which square-section cutters are arranged side by side is used. The concave joints 24 and 26 protrude slightly outward in the vertical direction from the square hollow cross section, and gradually move outward in the width direction along with the excavation, so that the body portion corresponds to the concave joints 24 and 26. In order to excavate the earth and sand part, it is desirable to provide auxiliary cutters 46 and 46 on the upper and lower surfaces of the excavator 45, respectively. The propulsion method of the excavator 45 may be a main pushing method or a towing method.

  Next, the connecting steel shell element 3 for widening adjacently disposed on one side of the central steel shell element 2 is constituted by an upper plate 30, a lower plate 31, and side plates 32, 32 as shown in detail in FIG. An element having a square hollow cross section is used as a basic shape. In the upper plate 30, a stepped portion is formed by forming a cross-sectional defect portion 30 </ b> B on one side portion while leaving one side 30 </ b> A (central steel shell element 2 side). And while providing the overhang | projection member 33 extended toward the outward side from the edge part (protrusion corner part) of the said one side 30A, the concave joint 34 is provided in the front-end | tip of this overhang member 33 along the member longitudinal direction. Yes. On the opposite side of the concave joint 34, a convex joint 38 is provided at the tip of an overhanging member 37 that protrudes from the corner of the square hollow cross section toward the central steel shell element 2 side.

  Further, the lower plate 31 also forms a stepped portion by forming a cross-sectional defect portion 31B on one side portion while leaving one side 31A (the central steel shell element 2 side). Then, a protruding member 35 extending outward from the end portion (protruding corner) of the one side 31A is provided, and a concave joint 36 is provided at the tip of the protruding member 35 along the longitudinal direction of the member. ing. On the opposite side of the concave joint 36, a convex joint 40 is provided at the tip of a protruding member 39 that protrudes from the corner of the square hollow cross section toward the central steel shell element 2 side.

As can be seen by comparing FIG. 4 (B) and FIG. 4 (C), in the concave joints 34 and 36, the overhang members 33 and 35 gradually increase in length from the starting side to the reaching side. . That is, the protruding length of the protruding member 33 and 35 at the start side is a L _1, is reached side projecting length of the projecting member 33 and 35 are L _2. The difference between the overhang lengths (L ₂ −L ₁ ) is the amount of widening. Further, the overhang lengths of the overhang members 33 and 35 are adjusted so that the positions of the concave joints 34 and 36 in the width direction are located in the cross-sectional defect portions 30B and 31B. On the other hand, the convex joint side, overhanging length L ₃ of the overhang member 37, 39 for supporting the convex joint 38, 40 is constant over the tunnel direction.

  As an excavator used for the penetration installation of the steel shell element 3, the ratio of the maximum width dimension B and the maximum height dimension H of the square hollow section is 2: 1. As shown in FIG. 11, an excavator 47 having a structure in which square-section cutters are continuously arranged side by side is used. However, projecting members 37 and 39 and convex joints 38 and 40 that protrude greatly to the side are formed on the body. In order to excavate the earth and sand part corresponding to the above, on one side (convex joint side) of the excavator 47 is provided with auxiliary cutters 48, 48 projecting in the horizontal direction from the square hollow part on the upper and lower surfaces, respectively. On the other side (concave joint side) of the excavator 47, it is desirable to provide auxiliary cutters 46 for excavating the concave joints 34 and 36 on the upper and lower surfaces, respectively.

  If the next steel shell element to be connected and penetrated with respect to the widening steel shell element 3 is to be further widened, the same widening steel shell as the widening steel shell element 3 described above is used. The element 3 is used for connection penetration. In the steel shell element 3 for widening, since the overhang members 33 and 35 are gradually overhanging in the width direction, further widening can be achieved by the increase in the overhang length.

Further, when it is not necessary to perform further widening, the equal-width steel shell element 5 shown in FIG. 5 may be used and installed so as to penetrate into the adjacent position of the widening steel shell element 3. The equal-width steel shell element 5, the overhanging length L ₁ only in that it is a constant over the tunnel direction the wider steel shell element 3 of the overhang member 33, 35 of凹継hand 34 The other configuration is the same steel shell element.

  On the other hand, the connecting steel shell element 4 located on the opposite side of the central steel shell element 2 is connected to the widening connecting steel shell element 3 and the equal-width steel shell element 5 with respect to the center line of the central steel shell element 2. The description is omitted because it is a straddling line structure.

  Next, a joint structure connecting the steel shell elements 2 and 3 (2, 4) will be described later. As shown in FIG. 6, this joint structure is a joint structure for sequentially connecting the steel shell elements 3 to the penetrated steel shell elements 2, and is provided in one of the adjacent steel shell elements 2 to 4. The concave joint 6 (24, 26, 34...) And the convex joint 7 (38) provided on the other steel shell elements 3 and 4 are connected.

  As shown in FIG. 7, the concave joint 6 includes a groove portion 8 that opens along the axial direction of the steel shell element and opens toward the adjacent steel shell element, and a water stop portion 9 that closes the opening of the groove portion 8. And the latching | locking parts 10 and 10 which protrude from both sides in the said groove part 8 are provided.

  As shown in FIG. 8, the water stop portion 9 has leaf spring-like packings 11, 11 extending from at least both sides of the opening of the groove portion 8 toward the center of the opening. The packing 11 extends from both sides toward the center of the opening and faces two bent plate-like bodies having a thickness of about 0.3 mm that are bent toward the inside of the groove 8 at an intermediate position. The outer end portion is fixed to the concave joint 6 side, and the central end side serves as a free end, thereby acting as a leaf spring. The free ends of the packings 11 and 11 are provided so as to face each other. Since the packings 11 and 11 are bent toward the inside of the groove 8, when the concave joint 6 and the convex joint 7 are fitted, the packings 11 and 11 expand toward the inside of the groove. .

  As shown in FIG. 8, on the outside of the packings 11, 11, leaf spring-shaped auxiliary packings 12, 12 ′ extending from both sides of the opening toward the center of the opening are provided, whereby the water stop portion 9 is preferably constituted by a double packing 13.

  As shown in FIG. 8, the packing 11 and the auxiliary packings 12 and 12 ′ are attached to the groove portion 8 outside the spacers 16 and the auxiliary packings 12 and 12 ′ disposed between the packings. It is fixed by a bolt 15 through the presser fitting 17. The inner side of the spacer 16 is provided so as to protrude inward from the inner side of the side wall of the groove portion 8, and preferably extends to a bending position of the packing 11 that is bent in the middle.

  The auxiliary packings 12 and 12 'are configured by opposing two plate-like bodies having a thickness of about 0.3 mm extending substantially linearly from both sides toward the center of the opening, and the outer end portions are recessed. It is fixed to the joint 6 side, and acts as a leaf spring by making the opening center end side a free end. The auxiliary packings 12 and 12 'are provided so as to have an overlap margin at the center of the opening. Of the auxiliary packings 12 and 12 ', one auxiliary packing 12 arranged outside in the overlap margin is formed longer outside the other auxiliary packing 12' arranged inside in the overlap margin, The free end of the auxiliary packing 12 is supported by the spacer 16 fixed to the opposite side wall, and the pressure resistance from the outside is improved.

  On the other hand, the other auxiliary packing 12 ′ arranged on the inner side in the overlap margin is formed shorter than the one auxiliary packing 12, preferably slightly beyond the center of the opening. When it is inserted, it is prevented from interfering with the outer auxiliary packing 12 and becoming unexpandable.

  As shown in FIG. 8, it is desirable to fill a waterstop material 14 between the double packing 13 including the packings 11 and 11 and the auxiliary packings 12 and 12 ′. As the water-stopping material 14, it is preferable to use an oil-based water-stopping material that has high durability against high water pressure, and in particular, to prevent intrusion of groundwater or backing material between the wire brushes of the shield machine. The tail sealer (registered trademark, manufactured by Matsumura Petroleum Chemical Co., Ltd.) to be used is suitable. The waterstop lubricant 14 functions as a lubricant when the flat joint 18 of the convex joint 7 is inserted when the concave joint 6 and the convex joint 7 are fitted, and functions as a waterstop after completion of the fitting. To do.

  The concave joint 6 includes a structure portion 6A having the locking portions 10 and 10 and a side wall portion 6B made of a flat bar having a predetermined thickness fixed to both sides of the opening side end of the structure portion 6A. It is preferable to have a divided structure composed of 6B. The side wall portion 6B is fixed to the structure portion 6A side by a plurality of bolts 15, 15... That are attached to the water stop portion 9 at intervals along the longitudinal direction of the member. The water stop portion 9 is provided at the opening side end portions of the side wall portions 6B and 6B. By making the concave joint 6 into a split structure, the structure portion 6A can take on a force such as a tensile force acting on the joint structure. In addition to the structure portion 6A, the side wall portion 6B is fixed by the bolts 15 for fixing the packings 11 and 11 and the auxiliary packings 12 and 12 'of the water stop portion 9, so that the water stop portion 9 can be attached. Will be improved.

  The structure portion 6A is preferably made of cast metal or hot stamped steel. By constituting the casting or hot stamped steel, the proof strength of the concave joint 6 is improved, and a divided structure consisting of the structural part 6A and the side wall parts 6B and 6B is used, and the casting part or hot stamping is expensive. By using only the structural part 6A as the mold steel part and using a standard flat bar or the like for the side wall part 6B, the manufacturing cost can be reduced and the manufacturability can be improved.

  On the other hand, as shown in FIG. 6, the convex joint 7 includes a flat plate member 18 that is inserted into the groove portion 8 from the opening of the groove portion 8, and is formed in the groove portion 8 at the tip of the flat plate member 18. Protrusions 16, 16 projecting on both sides so as to be engaged with the engaged locking part 10 are provided, and the overall shape forms a horizontal T-shape. As shown in FIG. 9, the convex joint 7 does not have the protrusions 16 protruding on both sides, and the overall shape may be a horizontal I-shape.

  As shown in FIG. 6, when the concave joint 6 and the convex joint 7 are fitted, the flat plate member 18 of the convex joint 7 is deformed so as to expand the packings 11 and 11 and the auxiliary packings 12 and 12 ′, respectively. However, it is inserted between the packings 13 on both sides. In the state in which the flat plate member 18 is inserted, as shown in FIG. 6, the packings 11 and 11 and the auxiliary packings 12 and 12 ′ on both sides are in contact with the flat plate member 18 by a spring action while expanding. . In this way, unlike the conventional structure in which water is stopped when the tips of the water-stopping rubbers projecting on both side walls contact, the expanded leaf spring-shaped packings 11 and 11 and the auxiliary packings 12 and 12 'are pressed against each other. Since the water is stopped by doing so, the absorption of the construction error of the flat plate member 18 (convex joint 7) is increased, and water stoppage can be secured more reliably.

  After fitting the concave joint 6 and the convex joint 7, a grout material is filled in the groove 8 of the concave joint 6, and the concave joint 6 and the convex joint 7 are integrated. It becomes. As the grout material, concrete, mortar, or the like is used, and a material having good fluidity and no shrinkage is preferable. This enables force transmission between adjacent steel shell elements.

[Other examples]
(1) In the above embodiment, the variable cross section in the width direction is shown. However, as shown in FIG. 12, the variable cross section can be formed in the height direction. That is, in the variable section tunnel according to the present invention, only the width direction or height direction of the tunnel may be changed, or both the width direction and height direction of the tunnel may be changed.

(2) In the above embodiment, the example of the outer shell structure 1 in which the cross-sectional dimension is gradually increased from the starting side to the reaching side is shown, but conversely, the cross-sectional dimension is gradually reduced from the reaching side to the starting side. It is also possible to make the outer shell structure 1 to be made to be.

(3) In the above embodiment, in the joint portions of the adjacent steel shell elements 2 and 3, the projecting lengths of the projecting members 23 and 25 of the concave joints 24 and 26 are gradually changed to be variable in the tunnel direction. An outer shell structure having a cross section is constructed. However, if the relationship between the concave joint 24 and the convex joint 38 is reversed, the protruding length of the convex joint 38 of the steel shell element that has already been penetrated is gradually changed. The protruding length of the concave joint 24 of the steel shell element 3 to be penetrated may be made constant. As shown in the present embodiment, the relationship between the convex joint and the concave joint is such that the succeeding steel shell element 3 is connected to the concave joint 24 of the steel shell element 2 that has been penetrated while the convex joint 38 is connected. It is desirable to make it penetrate.

  DESCRIPTION OF SYMBOLS 1 ... Outer shell structure, 2 ... Center part steel shell element, 3.4 ... Connection steel shell element for widening, 5 ... Connection steel shell element for equal width, 6 (24, 26, 34) ... Concave joint, 7 ( 38) ... Convex joint, 23, 25, 33, 37 ... Overhang member, 45 ... Excavator, 46 ... Auxiliary cutter

Claims (6)

After constructing an outer shell structure with a closed cross section by the steel shell element in the ground by repeating the procedure of inserting the steel shell element with a square hollow cross section in sequence while connecting the steel shell element and the joints. In the outer shell preceding tunnel construction method of constructing a tunnel by removing the inner earth and sand of this outer shell structure,
The joint portion includes a concave joint provided at the tip of an overhang member that protrudes from one steel shell element to the other steel shell element between adjacent steel shell elements, and the other steel shell element. It is a structure in which a convex joint provided at the tip of the overhang member protruding toward the steel shell element on one side is fitted,
Constructing an outer shell structure with a variable cross section in the tunnel direction by gradually changing the extension length of one of the concave and convex joints at the joint of adjacent steel shell elements A method for constructing an outer shell preceding tunnel, characterized by:   2. The outer shell preceding tunnel construction method according to claim 1, wherein each of the steel shell elements has a basic cross-sectional dimension defined by a maximum width dimension and a maximum height dimension of a square hollow section in a tunnel direction.   The outer shell preceding tunnel construction method according to any one of claims 1 and 2, comprising a procedure in which a concave joint of a steel shell element that has already been penetrated is connected while a convex joint of the next steel shell element is connected.   A steel shell element that forms a stepped portion by forming a cross-sectional defect portion on both sides or one side portion on the joint arrangement surface of the square hollow cross section in the steel shell element, and is adjacent from the end of the non-cross-sectional defect portion A projecting member extending toward the projecting member, the concave joint is provided at the tip of the projecting member, and the projecting length of the projecting member is gradually changed. The outer shell preceding tunnel construction method according to claim 3, which is located at   5. A projecting joint is provided at the tip of a projecting member projecting from a corner of the steel shell element toward an adjacent steel shell element, and the projecting length of the projecting member is constant. The outer shell preceding tunnel construction method according to any one of the above.   The excavator used for penetrating the steel shell element excavates the earth and sand portion corresponding to the joint portion in the body portion, and the shape of the front excavation portion matches the square hollow cross-sectional shape of the steel shell element. The outer shell preceding tunnel construction method according to any one of claims 1 to 5, further comprising an auxiliary cutter.

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