JP2017125340A - Construction method of underground outer shell structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a construction method of an underground outer shell structure which may be applied to long distance construction and also has a response to increment in propulsion force of a steel shell element.SOLUTION: One square steel shell element is defined as a leading element 1. A square steel shell element established between adjacent two leading elements 1, 1 is defined as a closing element 2. The leading element comprises concave joints 14 to 17 on four corners, which respectively have opening directed to the side of the closing element 2 and has a c-shape section. The closing element 2 comprises plate convex joints 24 to 27 on four corners, which are respectively inserted into the concave joints. A leading element boring machine 3 comprises joint part cutters 33 to 36 capable of deleting the concave joint parts on four corners. Joint region is replaced with substitution material 9. The convex joints 24 to 27 of the closing element 2 is made into a jointed state to the concave joints 14 to 17 of the established leading element 1. It is established under the ground with a following closing element boring machine 4.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a method for constructing an underground shell structure having a large cross section underground by non-cutting.

  Conventionally, a method of constructing an underground shell structure having a large cross section in a tunnel shape underground has been proposed. Specifically, a square steel shell element having a special joint is continuously installed in the soil by a propulsion method while joining the joints, and the steel shell element is filled with concrete, and is used as a member. A construction method has been proposed in which a structure main body is constructed, and then the earth and sand inside the structure main body is excavated to construct an outer shell structure in the ground.

  For example, in Patent Document 1 below, when a plurality of tunnels are constructed at adjacent positions by propelling a steel shell element, a male joint portion formed at the end of the steel shell element of one adjacent tunnel and the other tunnel A steel shell element joint structure for propelling while engaging a female joint portion formed at an end of the steel shell element, wherein the male joint portion is a thickness of a stress material portion of the steel shell element. A protrusion that covers the outer surface of the stress material portion of the adjacent steel shell element with a step substantially corresponding to the above, and the female joint portion has the stress material portion end surface at the stress material portion on the male joint portion side. Between the end surfaces of the stress material portions facing each other with a gap between them and having a covering portion that covers the protruding portion of the male joint portion, and after the steel shell element is propelled, Can be connected by welding, and the covering portion is The steel shell element joint structure is used in addition to the steel shell element joint structure that covers the projecting part of the male joint part leaving a construction clearance and allows the water-stopping material to be filled in the construction clearance during propulsion. A method of constructing a tunnel, in which a steel shell element is promoted to construct a preceding tunnel, and a male joint portion or a female joint portion formed in the steel shell element of the preceding tunnel is used for a subsequent tunnel. In the state where the female joint part or male joint part of the steel shell element is fitted, and the construction clearance between the covering part of the female joint part and the projecting part of the male joint part is filled with a water-stopping material. A step of constructing a subsequent tunnel by propelling a steel shell element, and a step of welding and connecting end faces of opposing stress material portions of the preceding and subsequent steel shell elements after completion of the tunnel construction. When Tunnel construction method using the joint structure of the steel shell element, characterized in that it comprises has been proposed.

  In recent years, when constructing joints of underground roads, underground parking lots, etc., after constructing the outer part of the tunnel with multiple small-section shield machines, remove the earth and sand in the frame to create a tunnel (non-open-cut large-section method ( MMST method) has been proposed.

  For example, in Patent Document 2 below, a tunnel connection method for excavating and widening a ground between adjacent tunnels excavated at a predetermined interval and structurally connecting the tunnels, A step of press-fitting a mountain retaining plate from a segment constituting the tunnel into a ground between the tunnels, covering the ground between the tunnels, and performing a mountain retaining; and a plurality of mold steel members attached to a segment piece on the wide side of the segment And opening the segment, and excavating a natural mountain surrounded by the mountain retaining plate from the opening to widen the tunnel, and connecting the segments with a PC steel rod. A characteristic tunnel connection method has been proposed.

  Further, Patent Document 3 below discloses a tunnel connection method for excavating and widening a ground between adjacent tunnels excavated at a predetermined interval and connecting the tunnels, and at least one of the tunnels is connected. A step of press-fitting a mountain retaining plate from a segment to the ground between the tunnels, covering the ground between the tunnels, and performing a mountain retaining; and a supporting material from one segment to the other inside the mountain retaining plate A step of excavating a natural mountain surrounded by the mountain retaining plate to widen the tunnel, and a connecting member installed between the support material and the mountain retaining plate to fix the mountain retaining plate And a step of supporting the tunnel. A tunnel connection method characterized by including:

Japanese Patent Laid-Open No. 2006-200294 Japanese Patent No. 2777539 Japanese Patent No. 2698317

  However, the tunnel construction method according to Patent Document 1 is based on a procedure in which the steel shell elements adjacent to the installed steel shell elements are sequentially installed by the propulsion method while fitting the joints together. When closing the last steel shell element (closing element) after making one round in a rectangular shape, the construction errors up to now will be accumulated and concentrated at this location, so it is necessary to make a separate closing element for connection There is. In addition, when the construction error is greatly different between the start part and the arrival part, a case where fitting is impossible is assumed.

  Furthermore, especially when the propulsion distance is long, the construction error must be expected to be about 50 mm to 100 mm. The joint structure according to Patent Document 1 cannot cope with this, and the propulsive force increases as the propulsion distance increases. There was a problem of increasing.

  On the other hand, in the case of the MMST method according to Patent Documents 2 and 3, since adjacent steel shell elements are not connected to each other (the preceding tunnel and the trailing tunnel), the mountain retaining plate is passed over with a dedicated press-fitting machine, After injecting chemicals into the outer ground to improve the ground and stop the water, the steel shell elements were joined together by the procedure of excavating the connection part, so the range of ground improvement became wider and the water stop There is a problem that the certainty is low and a press-fitting device for press-fitting the mountain retaining plate is required. That is, it takes a lot of work and time to connect the steel shell elements.

  Therefore, the main problem of the present invention is that in the method of constructing an underground shell structure having a large cross section in the basement by non-opening, it is easy to absorb construction errors and can be used for long-distance construction, and propulsion of steel shell elements. The purpose is to economically and efficiently construct an underground shell structure that can cope with an increase in force and that is further excellent in water stopping performance and strength performance.

In order to solve the above-mentioned problem, as the present invention according to claim 1, a large number of square steel shell elements connected to each other through joints are installed in the ground by a propulsion method so as to be closed in the circumferential direction in a sectional view. After that, the concrete is filled in the square steel shell element to construct the structure, and then the earth and sand inside the structure is excavated to construct the outer shell structure in the ground. In the method
Among the many square steel shell elements, every other square steel shell element is used as a preceding element, and after installing the preceding element, a square steel shell element installed between two adjacent preceding elements is used as a closing element. And the preceding element is provided with a concave joint having a U-shaped cross section with openings toward the closing element at the four corners, respectively, and the closing element is inserted into the concave joint at the four corners. With fittings,
When installing the preceding element in the ground by the propulsion method; using as the preceding element excavator a digging machine equipped with a joint cutter capable of excavating the concave joints at the four corners; In addition to being installed in the ground while being followed, the area excavated by the joint cutter is replaced with a replacement material,
Next, when the closing element is installed in the ground by a propulsion method; the convex joint of the closing element is fitted in the concave joint of the preceding element that has already been installed, and is followed by the closing element excavator Installed in the ground,
After stopping the water between each element by filling the concave joint of the preceding element with a grout material, the partition between adjacent elements is removed to allow the elements to communicate with each other, and the inside of the element is filled with concrete. Then, after the structure is constructed, a method for constructing the underground shell structure is provided, wherein the shell structure is constructed in the ground by excavating the earth and sand inside the structure.

  In the first aspect of the present invention, among the many square steel shell elements, every other square steel shell element is used as the preceding element, and after the preceding element is installed, it is installed between two adjacent preceding elements. A square steel shell element is used as a closing element, and the preceding element is provided with concave joints having a U-shaped cross section with openings toward the closing element at the four corners, respectively, and the closing elements are provided at the four corners in the concave joints, respectively. A plate-like convex joint to be inserted is provided.

  In other words, as in the conventional method, when the steel shell element adjacent to the installed steel shell element is installed in order by fitting the joints together, the construction error accumulates. As in the case of the invention, after installing every other square steel shell element as a preceding element among a number of square steel shell elements, the procedure is to install a closing element between two adjacent preceding elements. Because construction errors are not dispersed and accumulated, all elements can be installed smoothly even in long-distance construction.

  Further, in the present invention, when the preceding element is installed in the ground by the propulsion method, an excavator equipped with a joint cutter capable of excavating the concave joint portion at the four corners is used as the preceding element excavator, When installing in the ground while following the element excavator, replacing the area excavated by the joint cutter with a replacement material, and then installing the closing element in the ground by a propulsion method; The convex joint of the element is fitted in the concave joint of the preceding element that has been installed, and the element is installed in the ground while following the closed element excavator. Therefore, since the joint portion has been replaced in advance by a replacement material when the preceding element is installed, it becomes possible to cope with an increase in the propulsive force of the steel shell element even in long-distance construction. Thus, it can be installed smoothly by the propulsion method while the convex joint is fitted in the concave joint of the preceding element.

  Furthermore, after installing the preceding element and the closing element, it is possible to reliably stop water between the elements by filling the recess joint of the preceding element with a grout material.

  The construction method of the underground shell structure according to claim 1, wherein the replacement material is made of a material having low strength performance, excavation wall collapse prevention performance, and water stoppage performance. Is provided.

  In the invention according to the second aspect, the performance required as the replacement material is defined. As the replacement material, a material having low strength performance, excavation wall collapse prevention performance, and water stopping performance is preferably used.

  As a third aspect of the present invention, the opening portion of the concave joint of the preceding element includes a water stop portion, and the water stop portion has a leaf spring shape extending from both sides of the opening toward the center of the opening. A packing is provided, and when the concave joint and the convex joint are fitted, the plate-like convex joint is inserted between the packings on both sides while being deformed so as to expand the packing. Item 2. A method for constructing an underground shell structure according to any one of Items 1 and 2 is provided.

  The invention of claim 3 employs a seal structure that can prevent earth and sand from flowing into the concave joint in a state where the convex joint of the closing element is fitted to the concave joint of the preceding element. is there. Further, by adopting such a seal structure, it is possible to prevent the injected grout material from flowing out to the outside when filling the grout material into the concave joint after the installation of the element is completed.

  As a fourth aspect of the present invention, there is provided a method for constructing an underground shell structure according to any one of claims 1 to 3, wherein adjacent elements are connected to each other by a plurality of steel bars arranged at the upper part and the lower part. Is done.

  In the invention according to the fourth aspect, adjacent elements can be connected to each other by a plurality of steel rods arranged at the upper and lower parts, whereby each element can be rigidly connected and sufficient strength characteristics can be secured. It becomes.

  As this invention which concerns on Claim 5, the said excavator for closing elements is equipped with the joint part auxiliary cutter for crushing the earth and sand in the vicinity of the opening part of the concave joint of the said preceding element. A method for constructing the underground shell structure described in 1. is provided.

  In the invention according to the fifth aspect, the excavator for the closing element is equipped with a joint portion auxiliary cutter for removing earth and sand from the front portion of the opening of the concave joint of the preceding element. The area excavated by the joint cutter of the preceding element excavator is replaced by the replacement material, but when the excavator for the closed element is subsequently excavated, the area replaced by the replacement material is roughened, Since there is a possibility that earth and sand may fall off and increase the propulsive force by the convex joint, the joint auxiliary cutter is provided in the closing element excavator, and the earth and sand near the opening of the concave joint is crushed. To do.

  According to a sixth aspect of the present invention, a waterproof sheet is stretched on the inner surface side of the fitting portion between the concave joint of the preceding element and the convex joint of the closing element to form a double water-stop structure. A construction method of the underground shell structure according to any one of 1 to 5 is provided.

  In the invention according to claim 6, a waterproof sheet is stretched on the inner surface side of the fitting portion between the concave joint of the preceding element and the convex joint of the closing element to form a double water-stop structure. is there. It becomes possible to ensure a certain water stop by setting it as a double water stop structure.

  As described above in detail, according to the present invention, in the method of constructing a large-section underground outer shell structure underground by non-open cutting, it is possible to easily absorb construction errors and support long-distance construction, and a steel shell element. Therefore, it is possible to economically and efficiently construct an underground shell structure that can cope with an increase in the propulsive force of the ground and that is further excellent in water stopping performance and strength performance.

It is an element allocation figure of a square steel shell element. It is a principal part enlarged view which shows the structure of a coupling part. 2 is a cross-sectional view of a preceding element 1. FIG. 3 is an enlarged view of a concave joint portion of a preceding element 1. FIG. 3 is a cross-sectional view of the closing element 2. FIG. The excavator 3 for leading elements is shown, (A) is a longitudinal sectional view, and (B) is a front view. The closing element excavator 4 is shown, (A) is a longitudinal sectional view, and (B) is a front view. It is a transverse cross section showing joint part auxiliary cutter 43 with which excavator 4 for closure elements was equipped. It is element sectional drawing when the left and right elements are displaced maximum in the vertical direction. It is a joint part enlarged view which shows the grout filling state in a concave type joint. It is the earth and sand removal point work diagram between each element. It is a joint part enlarged view which shows the state which connected each element with the steel rod. It is sectional drawing of the structure 60 constructed | assembled in the ground.

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

  A method for constructing an underground shell structure according to the present invention includes a large number of interconnected via joints along a circular shape, for example, as shown in FIG. Are installed in the ground by the propulsion method, and then the steel shell elements 1 ... 2, ... are filled with concrete to construct a structure, and then the earth and sand inside the structure The outer shell structure is built in the ground.

  The propulsion method has a starter (starter shaft, etc.) and a reacher (reacher shaft, etc.), pushes the excavator into the ground from the starter equipped with propulsion equipment with a hydraulic push jack, and is installed after the excavator It is a construction method in which pipes are added in sequence, the row of pipes is pushed to reach the reaching part, and continuous pipes are installed in the ground, for lifelines such as sewerage, water, gas, power, communication, etc. It is used to install the steel shell elements that make up the underground shell structure in the ground when installing pipe pipes in the ground or constructing a tunnel-like underground shell structure with a large cross section. It is a construction method.

  Hereinafter, the construction method of the underground shell structure of the present invention will be specifically described in detail.

[Structure of square steel shell elements 1 and 2]
In the present invention, as shown in FIG. 1, in assigning the square steel shell elements 1, 2,... (Hereinafter simply referred to as elements), one of the many square steel shell elements 1,. Are assigned as the preceding elements 1, 1... (Colored elements), preferably after all the preceding elements 1, 1... Are installed, installed between two adjacent preceding elements 1, 1. Are assigned as closed elements 2, 2,... (Elements shown in white). That is, it is not according to the procedure of pushing and installing the steel shell elements adjacent to the installed steel shell elements in order while fitting the joints, as shown in FIG. After installing the alternate square steel shell elements as the preceding elements 1, 1,..., The closed element 2 is installed between the two adjacent preceding elements 1, 1. Therefore, since construction errors are not dispersed and accumulated, all elements can be installed smoothly even in long-distance construction.

As shown in FIG. 3, the preceding element 1 is an element having a trapezoidal cross section composed of a top plate 10, a bottom plate 11, and side walls 12 and 13, and at the four corners, that is, the top surface of the top plate 10. Concave joints 14 to 17 having a U-shaped cross section with openings toward the closing element 2 are provided at both ends and the bottom surface of the bottom plate 11 and both ends thereof. As shown in FIG. 4 (typically, the concave joint 15 is shown), the concave joints 14 to 17 include a water stop portion S at the opening of the concave joint 15. This water stop portion S includes leaf spring-like packings 5A and 5B extending from both sides of the opening toward the center of the opening, respectively, and when the concave joint 15 and the convex joint 24 are fitted together, The convex joint 24 is inserted between the packings 5A and 5B on both sides while being deformed so as to expand the packings 5A and 5B.
The packings 5A and 5B are configured by opposing two bent plate-like bodies having a plate thickness of about 0.3 to 1.0 mm extending from both sides toward the center of the opening, and the outer end portion is a concave joint. The center edge side is fixed as a free end and acts as a leaf spring. The free ends of the packings 5A and 5B are provided so as to face each other. When the plate-like convex joint 25 of the closing element 2 is fitted, the packings 5A and 5B expand toward the inside of the groove.
Further, as shown in the figure, leaf spring-shaped auxiliary packings 6A and 6B extending from both sides of the opening toward the center of the opening can be provided outside the packings 5A and 5B. By constructing the water stop portion S with double packing, reliable water stop can be achieved. In addition, more reliable water stop can be achieved by injecting a sealing material between these double packings.
The packings 5A and 5B and the auxiliary packings 6A and 6B are attached by bolts 8A (8B) via presser fittings 7A (7B) disposed on the outside.

  On the other hand, as shown in FIG. 5, the closing element 2 is an element having a trapezoidal cross section constituted by a top plate 20, a bottom plate 21, and side walls 22 and 23, and is formed at four corners, that is, at both ends of the top plate 20. Further, plate-like (steel) convex joints 24 to 27 to be inserted into the concave joints 14 to 17 of the preceding element 1 are provided at both ends of the bottom plate 21, respectively.

  As described above, in the present invention, the concave joints 14 to 17 of the preceding element 1 are joints having a U-shaped cross section, and the convex joints 24 to 27 of the closing element of the previous term are plate-shaped joints, and the concave shape is the U-shaped cross section. Since a joint structure that is inserted into the joint is employed, construction errors due to long-distance propulsion can be sufficiently absorbed.

[Structure of propulsion excavators 3 and 4]
An excavator 3 (hereinafter referred to as a “preceding element excavator”) equipped at the head when the preceding element 1 is propelled is excavated in the cross-sectional shape of the preceding element 1 as shown in FIG. Therefore, a cutter unit including a rotary excavation head 30, planetary cutters 31, 31, and a sub-cutter 32 is provided. Moreover, the joint part cutters 33-36 for excavating the area | region containing the said concave joints 14-17 in the four corners of an excavation surface are equipped in the front part. Specifically, joint cutters 33 to 36 composed of spoke-shaped excavating arms extending in three directions are provided at the four corners of the leading element excavator 4, respectively.

  On the other hand, an excavator 4 (hereinafter referred to as a closing element excavator) installed at the head during the propulsion installation of the closing element 2 has a cross-sectional shape of the closing element 2 as shown in FIG. In order to excavate, a rotary excavation head 40, planetary cutters 41, 41..., And sub-cutters 42, 42. Further, on the rear side of the closing element excavator 4, joint portion auxiliary cutters 43, 43. As shown in FIG. 8, the joint auxiliary cutter 43 is a horizontal plate-like rotary cutter driven by an electric motor, and excavates the vicinity of the openings of the concave joints 14 to 17 of the preceding element 1. The area excavated by the joint portion cutters 33 to 36 of the preceding element excavator 3 is replaced by the replacement material 9, but when the closed element excavator 4 is subsequently excavated, the area is replaced by the replacement material 9. Since the area formed is roughened, there is a possibility that earth and sand may fall into this area and increase the propulsive force by the convex joints 24 to 27. Therefore, the joint element auxiliary cutter 43, 43 are provided, and the earth and sand near the openings of the concave joints 14 to 17 are crushed.

[Procedure for constructing underground shell structure 60]
First, the preceding elements 1, 1... Described above are first installed in the ground by a propulsion method. The leading element excavator 3 is started from the starting part, and the leading element 1 having a predetermined length is successively added to the rear part of the excavating machine 3 while being sequentially added, and the leading element 1 is installed in the starting part by the main pushing jack. Apply thrust from the rear.

  When the preceding element 1 is propelled and installed, as shown in FIG. 6 (A), when the preceding element 1 is installed in the ground with the preceding element excavator 3 being followed, the joint cutter 33 Immediately after excavating the region including the concave joints 14 to 17 by ˜36, the replacement material 9 is injected into the digging region from the inside of the excavator and replaced by the replacement material 9.

As the replacement material 9, a material having low strength performance, excavation wall collapse prevention performance, and water stopping performance is preferably used. For example, by blending bentonite, clay, slag fine powder or cement, polymer, fluidizing agent, etc. at a predetermined ratio, it is possible to provide the above-mentioned performance, and at the same time, inseparability in water, incompressibility, high fluidity. Use the provided materials. The target strength of this material is preferably about 1.0 to 2.0 (N / m ² ). In addition, it is desirable to add self-hardening by blending an appropriate amount of fine slag powder or cement and gradually increase the strength after completion of construction.

  When the installation work of all the preceding elements 1, 1... Is completed, the closing element 2 is then installed between two adjacent preceding elements 1, 1 by a propulsion method. Similar to the installation of the preceding element 1, the excavator 4 for the closing element is started from the starting part, and the closing element 2 having a predetermined length is successively added to the rear part of the excavating machine 4 and installed in the starting part. A thrust is applied from the rear part of the closing element 2 by the pressed push jack. At this time, the convex joints 24 to 27 of the closing element 2 are propelled in a state of being fitted into the concave joints 14 to 17 of the installed preceding elements 1 and 1.

  By the way, in this embodiment, the concave joints 14 to 17 of the preceding element 1 are provided on the top surface of the top plate 10 at both ends thereof, and on the bottom surface of the bottom plate 11 and both ends thereof, Since the convex joints 24 to 27 of the closing element 2 are provided at both ends of the top plate 20 and both ends of the bottom plate 21, there is a maximum error between the preceding element 1 and the closing element 2. Even if it occurs, the effective height H of the element is secured at the joint portion. For example, as shown in FIG. 9, the effective height H is assumed even when the left side element is maximum displaced upward and the right element is maximum displaced downward between three adjacent elements. The joint portion does not exist inside, and there is no cross-sectional defect in the joint portion, so that the effective height H of the element is ensured.

  FIG. 10 shows a cross section of the joint part in a state where the preceding elements 1, 1... And the closing elements 2, 2.

  As shown in the figure, the plate-like convex joint 27 of the closing element 2 is inserted into the concave joint 16 of the preceding element 1, and on the outside (the ground), There is a region replaced by the replacement material 9. At this stage, in order to ensure water-stopping at the joint portion, the concave joint 16 of the preceding element 1 is filled with a grout material 50, and water-stopping between the elements 1 and 2 is performed.

  Next, as shown in FIG. 11, the side walls 12 and 13 of the preceding element 1 and the side walls 22 and 23 of the closing element 2 are removed (the main girder is left and only the skin plate is removed), and between these side walls The existing earth and sand are removed manually, and the elements 1 and 2 are communicated in the circumferential direction.

  Then, as shown in FIG. 12, adjacent elements 1 and 2 are connected to each other by a plurality of steel bars 51, 51. Tighten. It should be noted that the steel bars 51, 51... Are arranged at a predetermined interval along the width direction of the elements. As shown in the figure, a waterproof sheet 52 is stretched on the inner surface side of the fitting portion between the concave joints 14 to 17 of the preceding element 1 and the convex joints 24 to 27 of the closing element 2. It is good also as a double water stop structure.

  When the above steps are completed, as shown in FIG. 13, after the structure 60 is constructed by filling the inside of the element with concrete, the earth and sand inside the structure 60 is excavated to the ground. Build a shell structure.

[Other examples]
(1) In the above embodiment, after all the preceding elements 1, 1... Are installed, the closing element 2 is installed between the preceding elements 1, 1. If installation of 1 is completed, it is possible to install them between them, so that they may be installed at any time before the installation of all the preceding elements 1, 1.

  DESCRIPTION OF SYMBOLS 1 ... Preceding element, 2 ... Closing element, 3 ... Excavator for preceding element, 4 Excavating machine for closing element ... 5 ... Packing, 6 ... Auxiliary packing, 9 ... Replacement material, 10.20 ... Top plate, 11.21 ... bottom plate, 12, 13, 22, 23 ... side wall, 14-17 ... concave joint, 24-27 ... convex joint, 33-36 ... joint cutter, 43 ... joint auxiliary cutter, 50 ... grout material, 51 ... Steel bar, 52 ... tarpaulin, 60 ... structure

Claims (6)

A large number of square steel shell elements connected to each other through joints are installed in the ground by a propulsion method so that they are closed in the circumferential direction in cross-sectional view, and then the square steel shell elements are filled with concrete. In the construction method of the underground shell structure that constructs the body, then excavates the sediment inside the structure, and builds the shell structure in the ground,
Among the many square steel shell elements, every other square steel shell element is used as a preceding element, and after installing the preceding element, a square steel shell element installed between two adjacent preceding elements is used as a closing element. And the preceding element is provided with a concave joint having a U-shaped cross section with openings toward the closing element at the four corners, respectively, and the closing element is inserted into the concave joint at the four corners. With fittings,
When installing the preceding element in the ground by the propulsion method; using as the preceding element excavator a digging machine equipped with a joint cutter capable of excavating the concave joints at the four corners; In addition to being installed in the ground while being followed, the area excavated by the joint cutter is replaced with a replacement material,
Next, when the closing element is installed in the ground by a propulsion method; the convex joint of the closing element is fitted in the concave joint of the preceding element that has already been installed, and is followed by the closing element excavator Installed in the ground,
After stopping the water between each element by filling the concave joint of the preceding element with a grout material, the partition between adjacent elements is removed to allow the elements to communicate with each other, and the inside of the element is filled with concrete. A method for constructing an underground shell structure, comprising constructing a shell structure in the ground by excavating the soil inside the structure after the construction of the structure.   The method for constructing an underground shell structure according to claim 1, wherein the replacement material is made of a material having low strength performance, excavation wall collapse prevention performance, and water stopping performance.   The opening portion of the concave joint of the preceding element has a water stop portion, and the water stop portion has a leaf spring-like packing extending from both sides of the opening toward the center of the opening, The fitting according to any one of claims 1 and 2, wherein when the convex joint is fitted, the plate-like convex joint is inserted between the packings on both sides while being deformed so as to expand the packing. Construction method of underground shell structure.   The construction method of an underground shell structure according to any one of claims 1 to 3, wherein adjacent elements are connected to each other by a plurality of steel rods arranged at an upper part and a lower part.   The excavator for a closing element is equipped with a joint auxiliary cutter for crushing earth and sand in the vicinity of the opening of the concave joint of the preceding element. Construction method.   The ground according to any one of claims 1 to 5, wherein a waterproof sheet is stretched on an inner surface side of a fitting portion between the concave joint of the preceding element and the convex joint of the closing element to form a double water-stop structure. Method for constructing middle and outer shell structures.

Images