JP6009880B2 - Long steel pipe tip receiving method - Google Patents

Description

  The present invention relates to a long steel pipe tip receiving method. More specifically, prior to excavation of a mountain tunnel which is a construction field, a plurality of steel pipes are radially laid on a defective ground in front of a face, The present invention relates to a long steel pipe tip receiving method in which a solidified material is injected to reinforce a natural ground.

  When excavating a mountain tunnel in a soft, unsatisfactory ground, a pre-construction work to reinforce the ground in front of the face has been constructed prior to tunnel excavation. As an example of the tip receiving method, there is an injection type long steel pipe tip receiving method. This method is driven into the natural ground in front of the face while connecting a plurality of steel pipes with an elevation angle of about 8 to 10 ° radially from the lower part of the support by an excavator called a drill jumbo that is generally used in tunnels. The solidified material is injected into the ground from the inside of the steel pipe to reinforce the defective ground.

  Generally, for example, as shown in FIGS. 9 to 12, about four steel pipes 108, 109, and 110 are connected along the top edge of the face within the range of 120 ° from the upper half of the tunnel center. As an extension of about 12.5 m, it is placed at intervals of 450 mm. Regarding the order of placing the steel pipes 107 at this time, the odd-numbered holes and the even-numbered holes are generally identified and distributed, and after the odd-numbered steel pipes are cast and the solidification material injection is improved, After evaluating the mountain reinforcement effect, it is often the case that even hole placement and injection improvement are repeated alternately. Usually, the steel pipe used is 4.0 inch outer diameter 114.3mm and wall thickness: 6mm, and male and female screws for connection are processed at both ends of the steel pipe cut to about 3.0m per one. Yes.

  In addition, the above-described injection-type long steel pipe tip receiving method does not require widening of the excavation cross section, “non-widening type” shown in FIG. 9 (see, for example, Patent Document 1), and widening shown in FIG. It is roughly classified into “widening type” and “minimum widening type” shown in FIG. One general construction section extension of the receiving construction method is to connect about four steel pipes of the type called the leading pipe 108, the intermediate pipe 109, and the terminal pipe 110 to form a steel pipe 107, with a total of about 12.5m in front of the ground. It is driven into a mountain and solidified material is injected from the inside of the steel pipe to reinforce the surrounding natural ground. The extension of the construction section where tunnel excavation progresses by about 9.0m due to the reinforcement of the front ground is called 1 shift at 9m.

JP 2008-75292 A

  The injection-type long steel pipe tip receiving method is roughly classified into “non-wide type” and “wide type”. The biggest problem with the non-wide type is that the elevation angle of the steel pipe to be placed is 10 ° or more. The distance from the support structure that does not change the cross section is proportionally increased, and the effect of injecting the solidified material is outside the range where it is difficult to exert the effect. May interfere with the safety of construction. On the other hand, in the widened type, the steel pipe has a small elevation angle of about 5 °. However, the steel support built along with the excavation of the tunnel needs to be manufactured large in order to expand in about three stages. That is, it is necessary that the support work at the point where the advance receiving method is started has the largest cross section. This has a side that is difficult to cope with the geological properties of the suddenly changing natural ground. In addition, the widened type has a so-called sawtooth shape in which the tunnel excavation cross-section becomes larger or smaller at a certain distance, and it may not be stable due to the structural characteristics of the tunnel. In some cases, before the secondary lining work, it is filled with shotcrete or the like to stabilize it into a flat shape, which often tends to directly increase the cost of materials and labor. Also, in recent tunnel excavation, the trend of reduction of construction costs including shortening of construction period is remarkable, and there is a demand for the development of inexpensive construction methods that are safer and have better workability than conventional pre-construction methods. Yes.

  Moreover, in the injection type long steel pipe tip receiving construction method of the conventional construction method, a regular pipe of about 3.0 m to 4.0 m is placed in each of the leading pipe, the intermediate pipe and the terminal pipe. As a result, the connection points of each steel pipe are located in the same cross section at the time of tunnel excavation, and the weak points of rigidity as the receiving member are arranged in the same way. It may be raised as a problem that the problem is directly linked to the event of the failure.

  The present invention has been made in view of the above situation, and an object thereof is to provide an inexpensive long steel pipe tip receiving method with high safety and good workability.

In order to solve the above problems, the invention according to claim 1 is characterized in that prior to excavation of a tunnel, a solidifying material is injected into a surrounding natural ground from a plurality of steel pipes radiated in front of the face. In the receiving long steel pipe tip receiving method, in the cross section of the receiving section, the steel pipes of double or more are arranged vertically, and the steel pipes placed in front of the face face are a plurality of pipes having different axial lengths. The gist is that the joints of the pipes differ in the axial direction among the plurality of steel pipes .
The invention according to claim 2 is characterized in that, in claim 1, the joint portion of the pipe is different in the axial direction between the plurality of steel pipes placed in front of the same face.
The invention according to claim 3, the gist that construction in claim 1 or 2, an elongate steel pipe destination received at a distance of less than half of the top-bottom height of the crest from Osshako of the tunnel And
Invention of Claim 4 is set to any one of Claims 1 thru | or 3, The steel pipe cast in front of the said face is an intermediate | middle of the space | interval of the adjacent steel pipe among the several steel pipes cast last time. The gist is to drive from the position.
A fifth aspect of the present invention is the steel pipe placed in front of the face according to any one of the first to fourth aspects, wherein the nominal diameter is 2.0 inches, 2.5 inches, 3.0 inches, The gist is that it can be selected from 4.0 inches and 5.0 inches.

  According to the long steel pipe tip receiving construction method of the present invention, since the steel pipes of the double or more are arranged vertically in the cross section of the receiving section, a high quality tip receiving effect is obtained. In addition, the end receiving pipe can be extended at the same placement angle as that of the widening type by extending the end pipe even in the non-widening type, so that the receiving steel pipe and the supporting work are close to each other, and the improvement effect of the solidified material is combined. Acts to prevent flaking from the top edge during excavation. As a result, an inexpensive long steel pipe tip receiving method with high safety and good workability can be provided.

The present invention will be further described in the following detailed description with reference to the drawings referred to, with reference to non-limiting examples of exemplary embodiments according to the present invention. Similar parts are shown throughout the several figures.
It is explanatory drawing for demonstrating the long steel pipe tip receiving construction method which concerns on an Example, (a) shows the cross section substantially orthogonal to the axial direction of a tunnel, (b) shows the longitudinal cross section along the axial direction of a tunnel. Show. It is explanatory drawing for demonstrating the steel pipe used with the said long steel pipe tip receiving construction method, (a) shows the steel pipe of an assembly state, (b) shows the steel pipe of a decomposition | disassembly state. It is explanatory drawing for demonstrating the construction order of the said long steel pipe tip receiving construction method, (a) shows the 1st shift stitch placement, (b) shows the 2nd shift stitch placement. It is explanatory drawing for demonstrating the construction order of the said long steel pipe tip receiving construction method, (a) shows the 3rd shift casting and (b) shows the 4th shift casting. It is explanatory drawing for demonstrating the construction order of the said long steel pipe tip receiving construction method, (a) shows the AA line cross-section enlarged view of FIG. 3, (b) is the BB line cross-sectional expansion of FIG. The figure is shown. It is explanatory drawing for demonstrating the construction order of the said long steel pipe tip receiving construction method, (a) shows the AA line cross-section enlarged view of FIG. 4, (b) is the BB line cross-sectional expansion of FIG. The figure is shown. It is a principal part enlarged view of Fig.3 (a). It is a principal part enlarged view of FIG.3 (b). It is explanatory drawing for demonstrating the conventional long steel pipe tip receiving construction method (non-widening type | mold), (a) shows the cross section substantially orthogonal to the axial direction of a tunnel, (b) follows the axial direction of a tunnel. A longitudinal section is shown. It is explanatory drawing for demonstrating the conventional long steel pipe tip receiving construction method (widening type), (a) shows the cross section substantially orthogonal to the axial direction of a tunnel, (b) is a longitudinal section along the axial direction of a tunnel Show the surface. It is explanatory drawing for demonstrating the conventional long steel pipe tip receiving method (minimum widening type | mold), (a) shows the cross section substantially orthogonal to the axial direction of a tunnel, (b) follows the axial direction of a tunnel. A longitudinal section is shown. It is explanatory drawing for demonstrating the steel pipe used by the conventional long steel pipe tip receiving construction method, (a) shows the steel pipe of an assembly state, (b) Shows the steel pipe of a decomposition | disassembly state.

  The items shown here are for illustrative purposes and exemplary embodiments of the present invention, and are the most effective and easy-to-understand explanations of the principles and conceptual features of the present invention. It is stated for the purpose of providing what seems to be. In this respect, it is not intended to illustrate the structural details of the present invention beyond what is necessary for a fundamental understanding of the present invention. It will be clear to those skilled in the art how it is actually implemented.

1. Long steel pipe tip receiving construction method Embodiment 1 The long steel pipe tip receiving method is a long steel pipe that is pre-received by injecting solidified material into the surrounding natural ground from within a plurality of steel pipes (7) radiated in front of the face prior to excavation of the tunnel. In the tip receiving construction method, a steel pipe (7) having double or more is arranged in the upper and lower sides in the cross section of the tip receiving section (see, for example, FIG. 1 and the like). The “first receiving section” is intended to extend a construction section for excavating a tunnel. The “cross section” is intended to mean a transverse section that is substantially orthogonal to the axial direction of the tunnel.

  The above-mentioned construction method can set the casting angle of the steel pipe to 5 to 8 ° while corresponding to the non-widening type and the widening type. As a means for solving this problem, the length of one end steel pipe was extended from about 3.0 m to 4.0 m. By extending this steel pipe, the conventional widening height can be limited to about 30 cm to 10 cm from the standard even in the case of the receivers classified as the widening type.

  Embodiment 1 As a long steel pipe tip receiving construction method according to the above, for example, a form in which a long steel pipe tip receiving construction is performed at a distance of 1/2 or less of the top and bottom height (h) from the tunnel lining (6) to the top end ( For example, see FIG. As a result, the ground in front of the tunnel face is a soft ground that is soft over a long distance and has a low degree of consolidation, and when the long steel pipe tip receiving method is continuously constructed, it is possible to extend the appropriate construction section. Can be constructed with a certain shift length.

  Embodiment 1 As a long steel pipe tip receiving method, for example, the steel pipe (7) to be placed in front of the face face is driven from an intermediate position between adjacent steel pipes among a plurality of steel pipes (7 ') previously placed. The form (for example, refer FIG.5, FIG.6 etc.) to provide can be mentioned. In this case, steel pipes are arranged in a staggered manner by setting only the odd-numbered holes for the steel pipe casting of the multi-point receiving method constructed last time and only for the even-numbered holes. In this way, the steel pipes are placed in a staggered arrangement for each shift, and the shift length, which is an extension of the construction section, is set to about 5.0 m, so that the above-described multiple arrangement can be realized more suitably.

  In the above-mentioned form, for example, the steel pipes to be cast for each shift are conventionally formed in a so-called staggered arrangement with an interval of about 45 cm and an odd-numbered hole and an even-numbered hole being alternately arranged in a vertical direction so that the double spacing is 90 cm. By limiting the excavation length to about 5.0 m despite the number of installations being ½, any excavation cross section can achieve a high-quality pre-receiving effect due to the multiple structure of double or more (for example, see FIG. 1 etc.) ). In addition, the end receiving pipe can be extended at the same placement angle as that of the widening type by extending the end pipe even in the non-widening type, so that the receiving steel pipe and the supporting work are close to each other, and the improvement effect of the solidified material is combined. Acts to prevent flaking from the top edge during excavation. This is because the steel pipe diameters of 2.0 inches, 2.5 inches, 3.0 inches, 4.0 inches, and 5.0 inches are selected as will be described later depending on the properties of the natural ground. It works more effectively and economically to support bad grounds.

  Embodiment 1 As the long steel pipe tip receiving method according to the above, for example, the steel pipe (7) to be placed in front of the face has a plurality of pipes (9) having different axial lengths, and the pipes are arranged between the plurality of steel pipes. There can be mentioned forms in which the joining portions (9a, 9a ′) are different in the axial direction (see, for example, FIGS. 7 and 8). As a result, by changing the length of the intermediate pipe of the steel pipe to be matched to the natural ground properties, it is possible to disperse the weak points of the steel pipe rigidity and to make a more reliable preparatory work that can counter external forces Can be provided.

  About the above-mentioned form, the earth load called a prior | preceding loose load acts on a pre-receiving steel pipe with excavation of a tunnel in the soft bad ground with a low consolidation degree. In steel pipes used in conventional long steel pipe tip receiving methods, the lengths of the leading pipe, the intermediate pipe, and the terminal pipe are each fixed, and the joining portions are easily aligned on the same cross section. By making the connection position, which is the weakest point in strength, not matched, the steel pipe proof strength as a pre-receiver is made uniform and stably acts on the loose load of the natural ground and counters it. Moreover, in the above-mentioned form, for example, the joint portion (9a) of the pipe (9) is made different in the axial direction between the plurality of steel pipes (7) driven in front of the same face, or the steel pipe ( 7 ') and the steel pipe (7) cast this time, the joints (9a', 9a) of the pipes (9 ', 9) can be varied in the axial direction.

  Embodiment 1 As the long steel pipe tip receiving method according to the above, for example, the steel pipe to be placed in front of the face has a nominal diameter of 2.0 inches (50 A, outer diameter 60.5 mm), 2.5 inches (65 A, outer diameter 76). .3 mm), 3.0 inches (80 A, outer diameter 89.1 mm), 4.0 inches (100 A, outer diameter 114.3 mm), and 5.0 inches (125 A, outer diameter 139.8 mm). The form can be mentioned. As a result, a steel pipe having an appropriate outer diameter can be selected according to the geology in which the tunnel is to be constructed, and an optimum and low-priced receiving method that matches the natural ground properties can be realized.

  Hereinafter, the present invention will be specifically described with reference to the drawings.

  If a soft, bad ground that lacks bearing capacity appears during excavation in a mountain tunnel, it will be difficult or impossible to continue excavation. In general, the injection-type long steel pipe tip receiving method is often used, although it depends on the degree of failure of the natural ground.

  In the long steel pipe tip receiving method according to the present embodiment, as shown in FIGS. 1 (a) and 1 (b), the steel pipe is radially radiated at an elevation angle of about 6 ° from the inner peripheral portion of the supporting work 1 on the front end side of the face to the front of the face. 7 is cast. In FIG. 1, reference numeral 2 indicates a wire mesh, reference numeral 3 indicates sprayed concrete, reference numeral 4 indicates lining concrete, reference numeral 5 indicates mirror sprayed concrete, and reference numeral 6 indicates a ceiling (also called “invert”). It is called.)

  The steel pipe 7 is divided into a leading pipe 8, an intermediate pipe 9, and a terminal pipe 10, as shown in FIGS. In the present embodiment, the leading pipe 8 is set to 3.8 m to 4.0 m, and the intermediate pipe 9 is selectively used for odd holes and even holes based on 3.5 m and 2.5 m. The terminal tube 10 is set to 4.0 m.

  The odd-numbered steel pipe allocation is 13.8m in total for the top pipe 8: 3.8m, the intermediate pipe 9: 3.5m × 1 + 2.5m × 1 and the terminal pipe 10: 4.0m. Then, the total length of the top pipe 8: 3.8 m, the intermediate pipe 9: 2.5 m × 1 and the terminal pipe 10: 4.0 m is 10.3 m. Here, the shift length is 5.0 m and the non-widening type receiver is taken as an example. This shift length (5.0 m) is a distance of 1/2 or less of the top / bottom height h from the tunnel lining 6 to the top end (see FIG. 1A).

  As shown in FIGS. 3 (a) and 5 (a), in the first shift for starting the steel pipe tip receiving work, odd holes and even holes are simultaneously constructed from the same cross section. At this time, the steel pipe 7 is crossed out of the excavation cross section at the 4th support base after the excavation is started by controlling the casting angle to about 6.0 °. In addition, after the construction of the first shift, as shown in FIG. 7, the joining portion 9 a of the intermediate pipe 9 is different in the axial direction between the plurality of steel pipes 7 that have been cast this time. Moreover, in FIGS. 3-6, the steel pipe cast this time is shown with the code | symbol 7, and the steel pipe put last time is shown with the code | symbol 7 '. Moreover, the steel pipes 7 and 7 'cast in odd holes are indicated by broken lines, and the steel pipes 7 and 7' driven in even holes are indicated by solid lines.

  The said non-widening type | mold opposes natural ground external force as a receiving member by carrying out excavation progressing, destroying the terminal pipe | tube 10 about 1.0 m which is the part for which the support construction 1 is built. If it is predicted that bad grounds that are difficult to stand on will continue while tunnel excavation continues, the second shift will be implemented when the excavation has progressed 5.0 m.

  In the second shift, as shown in FIGS. 3 (b) and 5 (b), the placement position where the even-numbered holes of the first shift are reproduced on the mirror part of the face and after marking, the leading pipe 8: A total of 13.8 m of 3.8 m, intermediate pipe 9: 3.5 m × 1 + 2.5 m × 1 and terminal pipe 10: 4.0 m is constructed for even holes. In addition, after the construction of the second shift, as shown in FIG. 8, the joining portion 9a of the intermediate pipe 9 differs in the axial direction between the plurality of steel pipes 7 that have been cast this time, and the steel pipe 7 ′ that has been cast last time. The joint 9a ′ of the intermediate pipe 9 ′ and the joint 9a of the intermediate pipe 9 of the steel pipe 7 that has been placed this time are different in the axial direction.

  If the bad ground still continues, as shown in FIG. 4 (a) and FIG. 6 (a), as a third shift, the so-called staggered placement is performed by placing the steel pipes at the odd hole positions similar to the even holes. Install. Further, as shown in FIGS. 4 (b) and 6 (b), if necessary, as a fourth shift, the steel pipes are arranged at the even-numbered hole positions in the same manner as the odd-numbered holes, and construction is performed in a staggered arrangement. In addition, after the construction of the third and fourth shifts, the joint portion 9a of the intermediate pipe 9 differs in the axial direction between the plurality of steel pipes 7 placed this time in substantially the same manner as after the construction of the second shift. The joint 9a ′ of the intermediate pipe 9 ′ of the steel pipe 7 ′ previously placed differs from the joint 9a of the intermediate pipe 9 of the steel pipe 7 placed this time in the axial direction.

  In this example, a 4.0 inch steel pipe was presented, but depending on various conditions such as the degree of failure of the natural ground and the cross-sectional area of the tunnel, it is also necessary to examine the length of the assigned steel pipe. It can also be applied to inch steel pipes, etc., and can provide a more effective and economical long steel pipe tip receiving method.

  In addition, as an aside, if the ground is improved, the auxiliary construction method such as the receiving work is not necessary, and tunnel excavation can be carried out stably with ordinary support work, the length is generally about 14 m. Is it possible to grasp the ground condition such as the stabilization tendency of the front ground by the response of the chisel descending and the rotation hydraulic pressure of the rock drill when placing the steel pipe, and realize the next shift that is the next process? It becomes one of the means to evaluate.

  Here, in the mountain tunnel field, if tunnel excavation becomes difficult or impossible unless conventional measures are taken and it is difficult for the face to stand on its own, auxiliary construction methods such as receiving are generally adopted as countermeasures. There are many things. Among them, depending on the degree of failure of the natural ground, an auxiliary construction method that is widely adopted is an injection-type long steel pipe tip receiving construction method.

  The general specification of the conventional long steel pipe tip receiving method is that four steel pipes of about 4.0 inches (100A, outer diameter: 114.3mm) are connected, and 12.5m at a 45cm pitch to the outer periphery of the tunnel at 120 °. It is categorized as an auxiliary construction method by casting and injecting solidification material from the inside of the steel pipe into the ground to reinforce the ground. The excavation is resumed by receiving a 12.5 m steel pipe in the form of a tunnel arch, and the excavation length is 9.0 m, so-called 9 m shift is common.

  In the long steel pipe tip receiving method of the present embodiment, depending on the extent of the target bad ground, 2.0 inches (outer diameter 60.5 mm), 2.5 inches (outer diameter 76.3 mm), 3.0 Inches (outer diameter 89.1 mm), 4.0 inches (outer diameter 114.3 mm), and 5.0 inches (outer diameter 139.8 mm) can be selected. Conventionally, the shift length is set to about 5 m. A double or more multiple structure is ensured at any arbitrary position in the pre-installation construction section with about half the number of steel pipe front-receiving methods. In addition, by changing the length of the intermediate pipe 9, it is difficult for the connection directly connected to the decrease in strength of the steel pipe 7 to be in the same position, and a more reliable receiving method is realized. Taking the 4.0 inch steel pipe used as an example, in this embodiment method, the process can be shortened to about 9/10.

  It should be noted that the present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the present invention depending on the purpose and application. In the said Example, although the non-widening type long steel pipe tip receiving construction method was illustrated, it is not limited to this, It is good also as a wide steel type or the minimum widening type long steel pipe tip receiving construction method.

  Furthermore, in the said Example, although the form which implements a long steel pipe tip receiving construction method in the continuous several receiving section was illustrated, it is not limited to this, For example, a long steel pipe tip receiving is carried out in a single receiving section A construction method may be carried out.

  Moreover, in the said Example, although the joining order of the some intermediate | middle pipe | tube 9 from which axial direction length differs was comprised and the steel pipe 7 was comprised and the joining location 9a was varied in the axial direction, it is not limited to this. For example, a head tube 8 or a terminal tube 10 having different axial lengths is prepared, and the steel tube 7 is configured by selectively adopting the head tube 8 or the terminal tube 10 so that the joint portion 9a varies in the axial direction. You may do it.

  Furthermore, in the said Example, although the joining location 9a was made to differ in the axial direction between all the adjacent pair of steel pipes 7 among the some steel pipes 7 cast in front of the same face, it is limited to this. For example, the joint 9a is different between the pair of adjacent steel pipes 7 among the plurality of steel pipes 7 placed in front of the same face, and the joint 9a coincides with the axial direction. May be mixed.

  It is widely used as a technology for long steel pipe tip receiving construction method that reinforces natural ground prior to tunnel excavation.

  DESCRIPTION OF SYMBOLS 1; Supporting work, 2; Wire mesh, 3; Shotcrete, 4; Covering concrete, 5; Mirror-spread concrete, 6; Suspension, 7, 7 '; Steel pipe, 8: Lead pipe, 9; Terminal tube, h;

Claims (5)

Prior to tunnel excavation, in the long steel pipe tip receiving method that injects the solidified material into the surrounding natural ground from a plurality of steel pipes radiated in front of the face,
In the cross section of the receiving section, the steel pipe more than double is arranged up and down ,
The steel pipe to be placed in front of the face has a plurality of pipes having different axial lengths, and the joint portion of the pipe is different in the axial direction among the plurality of steel pipes. Construction method. The long steel pipe tip receiving method according to claim 1, wherein the joint portions of the pipes differ in the axial direction between the plurality of steel pipes placed in front of the same face. The long steel pipe tip receiving method according to claim 1 or 2, wherein the long steel pipe tip receiving method is constructed at a distance of ½ or less of the top and bottom heights from the tunnel roof to the top. The steel pipe for pouring the working face forward, according to any one of claims 1 to 3, characterized in that pouring from the intermediate position of the spacing of the steel pipe adjacent of the plurality of steel tubes the previously hitting set Long steel pipe tip receiving method.   The steel pipe placed in front of the face can be selected from a nominal diameter of 2.0 inches, 2.5 inches, 3.0 inches, 4.0 inches, and 5.0 inches. 5. The long steel pipe tip receiving method according to any one of 4 above.

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