JP2012211453A - Composite segment and shield tunnel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a composite segment for use in constructing a shield tunnel, which allows the emission of carbon dioxide to be reduced during manufacturing, having sufficient durability.SOLUTION: A composite segment comprises a hollow formwork 10 with an arcuate curvature formed from a plate-shaped object which contains iron, and a geopolymer composition 11 made from a silicon-containing filler and an alkali activator as raw materials. The geopolymer composition 11 is poured into the formwork 10, so that, by vapor curing or the like, the silicon contained in the geopolymer composition 11 and the iron contained in the formwork 10 make a chemical bond for fastening of the formwork 10 to the geopolymer composition 11, resulting in the formation of the composite segment.

Description

  The present invention relates to a segment and a shield tunnel used for lining in a shield method, and more particularly to a synthetic segment using a geopolymer composition and a shield tunnel constructed by connecting the synthetic segments.

  In tunnel construction for subways, roads, sewers, underground waterways, underground rivers, etc., shield construction methods are often used because tunnels can be constructed using members called segments while excavating even in soft ground. ing. A tunnel having a circular cross section excavated by the shield method is called a shield tunnel, and is constructed by a shield machine having a rotating face plate called a cutter head at a cylindrical tip.

  This shield tunnel is constructed by excavating the ground with a shield machine and lining with segments at the rear of the shield machine. The segment is an arc-shaped block assembled as a lining in the shield method, and is generally a member made of steel or reinforced concrete (RC). The lining is performed by assembling these segments and covering the inner wall of the tunnel excavated by the shield machine in an arch shape.

  In addition to the steel and RC segments mentioned above, this segment also uses a synthetic segment that can realize excellent bending rigidity and axial compression rigidity by integrating the steel plate and RC with an appropriate joining member. It has come to be.

  As the synthetic segment in which the steel plate and RC are integrated by a joining member, those exemplified in FIGS. 1 and 2 are known. The composite segment 1 shown in FIG. 1 is provided with a plurality of gibber bars 3 which are reinforcing bars protruding upward from the inner surface of a steel plate 2 constituting the mold, and the mold frame is formed by the plurality of gibber bars 3. The adhesion area between the concrete 4 poured into the inside is increased and the adhesion between the steel plate 2 and the concrete 4 is ensured. The composite segment shown in FIG. 1 is manufactured by pouring concrete 4 into a mold formed by four curved steel plates 2 and two steel plates (not shown). The figure which the surface of the concrete 4 shown with an oblique line exposed is shown.

  The composite segment 5 shown in FIG. 2 is provided with a plurality of shear key hardwares 7, which are plate-like hardware projecting from the inner surface of the steel plate 6 constituting the mold, at regular intervals. The adhesion area between the concrete 8 poured into the concrete is increased and the adhesion between the steel plate 2 and the concrete 8 is ensured. Similarly in FIG. 2, the concrete 8 is poured into a mold formed by the four curved steel plates 6 shown in FIG. 2 and two steel plates (not shown), and is cured to produce a composite segment. The figure which the surface of the concrete 8 shown with an oblique line exposed is shown.

  However, these synthetic segments have a problem that it is necessary to provide a large number of gibber muscles 3 and shear key hardware 7 in order to secure a sufficient bonding area, and cannot be provided at a low cost.

  By the way, due to the problem of global warming, energy conservation has been promoted in order to reduce emissions of greenhouse gases such as carbon dioxide, and materials that have as little carbon dioxide emissions as possible have been selected. Yes. At present, the mass-produced cement is Portland cement, and its main raw material is limestone. Therefore, carbon dioxide is discharged when it is decomposed into calcium oxide during firing. For this reason, the geopolymer method has attracted attention as a technique for producing concrete that does not use Portland cement.

  The geopolymer method is a technique for producing artificial rocks by joining powders together using a condensation polymer of silicic acid as a binder. For example, Patent Document 1 describes that a geopolymer composition is produced by using a filler, an alkali activator, and an aggregate as raw materials, mixing them, and reacting the mixture. In addition, in this Patent Document 1, by adding anhydrous sodium metasilicate and kneading, the amount of alkali can be increased and water can be reduced, whereby a geopolymer which is a high-strength geopolymer composition. It is described that mortar and concrete can be obtained, and that long-term strength can be obtained at the same level as when cured at 80 ° C. for 8 hours.

  Patent Document 2 discloses a geopolymer high-strength curing that cures by mixing, molding, and curing at high temperature a filler containing a calcined kaolin heat treated at 850 ° C. to 950 ° C. as an active filler. The body is described, and further, by adding a functional filler, it is described that a deodorizing function, a humidity control function, a VOC adsorption function, a photocatalytic function, and a heat insulating function can be imparted.

JP 2008-239446 A JP 2008-254939 A

  Since the above-described geopolymer composition exhibits high compressive strength, the above-described segment can be made of the above-described geopolymer composition instead of steel or RC. Thereby, the discharge | emission amount of the carbon dioxide at the time of the manufacture can be reduced.

  However, the geopolymer composition is adhered to the mold at a temperature equal to or higher than a certain condition (60 ° C.) and cannot be removed from the mold. That is, the geopolymer composition is a material having excellent adhesion to the mold. Further, since the geopolymer composition has a tensile strength comparable to that of conventional hardened cement bodies, durability may be insufficient when used as a segment in a shield tunnel.

  Therefore, it has been desired to provide a segment that can reduce the amount of carbon dioxide emitted during production and has sufficient durability.

  As a result of intensive studies, the inventor of the present invention, when held in a state where a material containing iron, a geopolymer composition using a silicon-containing filler and an alkali activator as raw materials are brought into contact with each other, The silicon contained in the metal and the iron contained in the material are chemically bonded, and the material adheres to the geopolymer composition, so that the durability of the entire geopolymer structure can be improved. It has been found that even if the mold is used as it is as a part of the segment without removing the mold using the contained material, it has sufficient durability as a segment in the shield tunnel. This invention is made | formed by discovering this, The said subject can be solved by providing the synthetic segment of this invention.

  Specifically, this synthetic segment is a geopolymer composition that uses, as raw materials, an arc-shaped hollow mold formed from a plate containing iron, a silicon-containing filler, and an alkali activator. The geopolymer composition is poured into the mold, and the silicon contained in the geopolymer composition and the iron contained in the mold are chemically bonded by steam curing, and the mold is fixed to the geopolymer composition. It will be.

  The formwork is configured by connecting a plurality of curved steel plates, and can include a steel material having an L-shaped cross section that is joined to at least one curved steel plate. Moreover, what has an unevenness | corrugation in the surfaces, such as a striped steel plate, is preferable for a steel plate. Thus, by increasing the area of the portion where the mold and the geopolymer composition are in contact, the adhesion of the geopolymer composition to the mold can be increased and higher durability can be imparted.

  Moreover, a formwork is not restricted to a steel plate, It is also possible to comprise with the board manufactured from the alloy containing iron, such as an iron aluminum alloy.

  In the present invention, in addition to the above-described synthetic segment, a shield tunnel constructed by connecting the synthetic segments can also be provided.

  By providing the synthetic segment of the present invention, it is possible to reduce the amount of carbon dioxide emitted during production, and to provide a shield tunnel having sufficient durability. In addition, by using a mold formed by joining steel materials having an L-shaped cross section and a steel plate having irregularities such as a striped steel plate, the contact area with the geopolymer composition is increased and higher durability is imparted. Since it is not necessary to install a new steel material for joining such as a gibber, it can be provided at a lower cost than the conventional synthetic segment described above.

The figure which illustrated the synthetic | combination segment which joined the formwork comprised from the steel plate and RC with the conventional gibel reinforcement. The figure which illustrated the synthetic segment which joined the formwork comprised from the steel plate with conventional shear key metal fittings, and RC. FIG. 3 shows one embodiment of a synthetic segment of the present invention. The figure which showed another embodiment of the synthetic segment of this invention. The figure which showed another embodiment of the synthetic | combination segment of this invention.

  FIG. 3 is a diagram illustrating one embodiment of the synthetic segment of the present invention. The synthetic segment is composed of an arc-shaped hollow mold 10 formed from a plate containing iron, and a geopolymer composition 11 made from a silicon-containing filler and an alkali activator. The In the synthetic segment, the geopolymer composition 11 is poured into the mold 10, the silicon contained in the geopolymer composition 11 and the iron contained in the mold 10 are chemically bonded, and the mold 10 is attached to the geopolymer composition 11. Manufactured by fixing.

  The mold 10 is formed of a steel plate or a plate manufactured from an alloy containing iron as a material containing iron. The mold 10 is composed of a plurality of curved steel plates along the inner wall of the excavated tunnel mine, and the inside is formed as a hollow one by connecting them. For example, a bottom plate that is curved in an arc shape, an outer peripheral plate that curves along the outer periphery of the bottom plate, an inner peripheral plate that curves along the inner periphery of the bottom plate, and a male fitting for connecting the segments are provided. The first connecting plate and the second connecting plate provided with the female fitting are connected to each other by a fixing member such as a bolt and a nut to form a box-like object whose upper part is opened, and the box-like object is opened. The upper part can be covered with an upper plate having the same shape as the bottom plate to form a hollow mold 10.

  In FIG. 3, the first connecting plate and the second connecting plate are not shown, and the surface of the geopolymer composition 11 indicated by hatching is exposed. The geopolymer composition 11 is poured into the box-shaped material, covered with an upper plate having the same shape as the bottom plate, and fixed and integrated by fixing members such as bolts and nuts. The upper plate is not necessarily required, but it is preferable to provide the upper plate in order to keep the thickness of the geopolymer composition 11 constant and increase the strength.

  The steel plate constituting the mold 10 can be a flat plate such as carbon steel or stainless steel. The above-mentioned bottom plate and top plate can be produced by cutting the flat plate into an appropriate shape. In addition, the outer peripheral plate and the inner peripheral plate can be produced by cutting the bottom plate or the upper plate into rectangles having the outer peripheral length and the inner peripheral length, and bending them into an arc shape. As the thickness of these descending plates, for example, an appropriate thickness of about 1 cm to about 3 cm can be used.

  The first connecting plate includes, for example, a shaft portion extending vertically from the surface thereof, such as a bolt, and a tip portion having a cross-sectional area expanded compared to the cross-sectional area of the shaft portion provided at the tip of the shaft portion. Male fittings are provided. The second connecting plate includes, for example, an opening into which the front end of the male metal fitting can be inserted, the opening continuing to the opening, and the insertion portion through which the shaft of the male metal fitting can be inserted, the opening, and the insertion portion. A female fitting is provided that includes a storage portion for storing the expanded tip portion. The first connecting plate and the second connecting plate are connected to the bottom plate, the outer peripheral plate, and the inner peripheral plate so as to close both end portions of the mold 10, and constitute a box-shaped object together with these plates.

  Although the male metal fitting and the female metal fitting are exemplified above, the present invention is not limited to the above-exemplified configuration, and any configuration known so far may be used.

  The mold 10 may be an alloy containing iron. Examples of the alloy include ferroaluminum (FeAl), ferroboron (FeB), ferrocerium (FeCe), ferrochrome (FeCr), and ferromagnesium (FeMg). , Ferromanganese (FeMn), ferromolybdenum (FeMo), ferroniobium (FeNb), ferronickel (FeNi), ferrosilicon (FeSi), ferrosilicomanganese (FeSiMn), ferrotitanium (FeTi), ferrovanadium (FeV), ferro Examples include tungsten (FeW). For example, as FeAl, a commercially available product having a content ratio of iron and aluminum of 1: 1 (mass ratio) can be used.

  The geopolymer composition 11 can be formed using a silicon-containing filler, an alkali activator, an aggregate, an admixture, and the like using a method similar to a conventional geopolymer method, specifically, Mixing raw materials such as filler, alkali activator, aggregate, admixture, etc., and treating for a predetermined time at a predetermined temperature (60 ° C. or higher), for example, steam curing, the filler is activated by the alkali activator and contained in the filler It can be obtained by polymerizing and curing the silicon component and metal component. Here, steam curing is accelerated curing performed in steam. The steam used for steam curing may be saturated steam or superheated steam, that is, steam having a temperature exceeding 100 ° C. under atmospheric pressure.

As the filler, fly ash, blast furnace slag, sewage incineration sludge and the like can be used. Fly ash is generated at the time of combustion of coal in a thermal power plant, and is collected by an electric dust collector, and mainly contains SiO ₂ and Al ₂ O ₃ . Blast furnace slag is obtained by reducing and melting iron ore with coal and taking it out in a molten state together with pig iron from a blast furnace that produces pig iron, separated by specific gravity difference, and mainly contains CaO, SiO ₂ , Al ₂ O ₃ . As a component, it has a chemical component similar to cement. Since the components of sewage sludge are similar to clays, sewage incineration sludge incinerated with lime, silica, etc. can be used as a cement raw material.

  As the alkali activator, an aqueous solution of potassium hydroxide, sodium hydroxide, sodium silicate, or potassium silicate can be used. When a sodium-based aqueous solution such as sodium hydroxide or sodium silicate is used, the setting time is shortened and the handling becomes difficult. Therefore, it is desirable to use a potassium-based aqueous solution such as potassium hydroxide or potassium silicate.

As the aggregate, aggregates such as gravel and sand generally used for manufacturing cement can be used. Admixtures include SiO ₂ , Al ₂ O ₃ , CaO, ultrafine powder that hydrates under alkalinity, water-soluble polymer that improves water retention, styrene butadiene rubber, latex, ethylene vinyl acetate, etc. Polymer, and expansion material for preventing cracking due to curing shrinkage.

  The blending of each material to form the geopolymer composition uses fly ash as a filler, sodium silicate aqueous solution as an alkali activator, and standard sand as an aggregate. Fly ash: sodium silicate: standard Sand can be 1: 0.6-0.8: 4-4.5 by mass ratio. When two types of fly ash and blast furnace slag are used as fillers, the mass ratio of fly ash: blast furnace slag: sodium silicate: standard sand is 1: 0.5 to 0.7: 0.9 to 1. It can be set to 1: 5.8-6.2. Standard sand is sand used for tests specified by JIS (Japanese Industrial Standards) of cement and mixed water.

An additive can be added to the geopolymer composition, and as this additive, a metal ion other than the metal ion eluted from the filler, for example, a solution containing Al ³⁺ or Si ⁴⁺ , a solid such as a metal salt or a complex, Fillers having different metal ion contents can be added at any mixing ratio. This additive can be added at any timing between the start of curing of the geopolymer composition and during curing, thereby controlling the strength of the geopolymer composition. Also, metal salts with different solubilities, complexes and fillers with different metal ion contents can be used to control the elution amount of metal ions and to control the curing time of the geopolymer composition.

  When the geopolymer composition 11 is poured into an arc-shaped hollow mold 10 formed from a plate-like material containing iron and steam curing is performed, the geopolymer in contact with the mold 10 The silicon component contained in the composition 11 is chemically bonded to the iron component contained in the mold 10, and the mold 10 and the geopolymer composition 11 are firmly fixed. Since the geopolymer composition 11 is in contact with the entire surface on one side of the bottom plate, the outer peripheral plate, the inner peripheral plate, the first connecting plate, and the second connecting plate of the mold 10, a plurality of gibber lines or Even if no shear key hardware is provided, it is firmly fixed to the entire surface on one side thereof.

  Here, the tensile strength of the synthetic segment formed by attaching the geopolymer composition 11 to the steel mold 10 is approximately the same as the tensile strength of the conventional synthetic segment provided with a plurality of gibber streaks and shear key hardware. there were. From this, it was found that even when used as a shield tunnel segment, it has sufficient durability.

  When the bending moment of the segment ring formed by connecting these synthetic segments in the circumferential direction of the tunnel is excellent and the thickness of the steel plate constituting the mold 10 has to be increased, the temperature in steam curing is There is a possibility that a certain condition (60 ° C. or higher) is difficult to be obtained, and adhesion force is insufficient. In such a case, the adhesive force can be ensured by increasing the area in contact with them.

  Although a method of increasing the contact area by providing a plurality of gibber bars and shear key hardware is also conceivable, it takes time and labor to join them, which is expensive. For this reason, for example, a configuration as shown in FIGS. 4 and 5 can be employed. FIG. 4 shows that a steel plate (angle) 21 having an L-shaped cross section that is curved along the outer periphery of the bottom plate 20 is joined to the bottom plate 20 constituting the mold 10. One surface of the L-shaped angle 21 is welded to the bottom plate 20, thereby forming a portion extending perpendicular to the surface. Both sides of this vertically extending portion come into contact with the geopolymer composition 11 and increase the adhesion area. Although only one angle 21 is shown here, it may be two or more.

  At least one of the bottom plate, the outer peripheral plate, the inner peripheral plate, the upper plate, the first connecting plate, and the second connecting plate constituting the mold 10 or all of them can be formed of a plate having irregularities such as a striped steel plate. FIG. 5 illustrates a part of the plate. 5A shows a cross-sectional view, and FIG. 5B shows a plan view of a part of the striped steel plate 30. FIG. The striped steel plate 30 is a steel plate provided with a non-slip projection 31 continuous on the surface by rolling, and is also called a checker plate. The anti-slip protrusions 31 are formed so as to form a regularly raised pattern. This steel plate is generally plated to prevent corrosion and the like, but in order to directly contact the geopolymer composition 11 and the steel plate, a steel plate not plated is desirable. Although the striped steel plate 30 has only the protrusions 31, a steel plate having both protrusions and grooves is preferable.

  In addition, since a cost can be reduced when using a certain amount by mass production, the formwork 10 can be comprised using this striped steel plate 30. FIG. Using a steel plate having irregularities such as the striped steel plate 30 and the like, the contact area with the geopolymer composition 11 is increased by using the angle 21 having the L-shaped cross section, and the contact force is further increased. Can be granted.

  Since the geopolymer composition 11 can ensure adhesion to the mold 10 by mixing filler, alkali activator, aggregate, admixture as necessary, and curing with steam, In addition, cement raw materials such as limestone, clay, silicic acid raw materials, and iron oxide raw materials need not be fired at a high temperature of 1500 ° C. in a firing kiln such as a rotary kiln, and then rapidly cooled to produce an ingot called a clinker. There is no generation of carbon dioxide due to combustion of fuel and decomposition of limestone during firing. Therefore, carbon dioxide emissions during production can be reduced.

  In the present invention, a shield machine having a rotating face plate called a cutter head at a cylindrical tip is used to excavate natural ground or underground, and then the above-mentioned composite segment is connected in the circumferential direction of the excavated tunnel to form a segment ring. By constructing and connecting the segment rings in the tunnel axis direction, it is possible to construct a shield tunnel by covering the inner wall of the tunnel.

  The synthetic segment is connected in the circumferential direction of the tunnel by inserting the end of the male fitting protruding from the first connecting plate into the female fitting housing of the adjacent synthetic segment and fitting it into the segment ring. The shield tunnel is constructed by connecting the segment rings in the direction of the tunnel axis and extending them. For this reason, it can be set as the structure provided with the above male fittings and female fittings for mutually connecting also to the surface which turned to the tunnel axial direction of the synthetic | combination segment. Similarly, any member known so far can be used as long as they can be connected to each other.

  So far, the synthetic segment and shield tunnel of the present invention have been described in detail with reference to the embodiments shown in the drawings, but the present invention is not limited to the above-described embodiments, and other embodiments, Additions, changes, deletions, and the like can be made within the scope that can be conceived by those skilled in the art, and any embodiment is included in the scope of the present invention as long as the effects and advantages of the present invention are exhibited.

DESCRIPTION OF SYMBOLS 1, 5 ... Synthetic segment, 2, 6 ... Steel plate, 3 ... Giber, 4, 8 ... Concrete, 7 ... Shear key metal, 10 ... Formwork, 11 ... Geopolymer composition, 20 ... Bottom plate, 21 ... Angle, 30 ... Striped steel plate, 31 ... Projection

Claims (8)

A composite segment used to build a shield tunnel,
A hollow formwork curved in an arc shape formed from a plate-like material containing iron;
Including a silicon-containing filler and an alkali activator geopolymer composition as raw materials,
The geopolymer composition is poured into the formwork, and the silicon contained in the geopolymer composition and the iron contained in the formwork are chemically bonded by steam curing, and the formwork is placed in the geopolymer composition. Synthetic segment that is fixed to   2. The synthetic segment according to claim 1, wherein the mold frame is configured by connecting a plurality of curved steel plates, and includes a steel material having an L-shaped cross section joined to at least one curved steel plate.   The synthetic segment according to claim 1, wherein the formwork is constituted by a plate manufactured from an alloy containing a plurality of curved irons.   The synthetic segment according to claim 2 or 3, wherein the steel sheet has irregularities on the surface of the steel sheet. A shield tunnel constructed by connecting a composite segment in the circumferential direction of the tunnel and the tunnel axis direction, wherein the composite segment includes:
A hollow formwork curved in an arc shape formed from a plate-like material containing iron;
Including a silicon-containing filler and an alkali activator geopolymer composition as raw materials,
The geopolymer composition is poured into the formwork, and the silicon contained in the geopolymer composition and the iron contained in the formwork are chemically bonded by steam curing, and the formwork is placed in the geopolymer composition. Shield tunnel that is fixed to   6. The shield tunnel according to claim 5, wherein the mold frame is configured by connecting a plurality of curved steel plates, and includes a steel material having an L-shaped cross section that is joined to at least one curved steel plate.   The shield tunnel according to claim 5, wherein the mold is constituted by a plate manufactured from an alloy containing a plurality of curved irons.   The shield tunnel according to claim 6 or 7, wherein the steel sheet has irregularities on a surface of the steel sheet.