JP6282144B2 - Support structure and construction method - Google Patents

Description

  The present invention relates to a support structure constructed at a tunnel wellhead and a method for constructing a support structure at the wellhead.

  A structure called a mine gate is constructed at the mine entrance that is the entrance to the mountain tunnel. In order to reduce a sense of incongruity felt by the runner, a normal tunnel constructed perpendicularly to the tunnel axis direction is generally used as this gate. However, in recent years, for the purpose of omitting the amount of cut, retaining wall, etc., an oblique tunnel constructed obliquely with respect to the tunnel axis direction has been adopted.

  In tunnel construction, when excavating natural ground, a support structure is constructed to support the rock mass so that it does not collapse. Here, the tunnel is composed of a wellhead portion and a general portion from the wellhead toward the tunnel axis direction that is the excavation direction. The general part is a part that forms a ground arch, and the ground arch is formed by a natural mountain itself supporting the tunnel. The wellhead portion is a portion near the wellhead where it is difficult to form the ground arch.

  For the construction of support work at the pit entrance when constructing an oblique mine, the method of adjusting the support work angle (diagonal support form) to adjust the support work angle to match the oblique angle is used as the construction method. (See Non-Patent Document 1).

  This construction method will be briefly described with reference to FIGS. FIG. 1 is a view of the tunnel as seen from above. The tunnel extends from the entrance which is the entrance to the face in the direction indicated by the arrow X, and the oblique tunnel 10 is constructed at the entrance obliquely with respect to the tunnel axial direction indicated by the arrow X. . At the wellhead part continuous with the wellhead, a support 11 that is a steel support member formed in an arch shape is installed in accordance with the oblique angle by adjusting the left and right support intervals. In addition, in FIG. 1, since the tunnel is seen from the upper side, each support work 11 is illustrated so as to extend in a rod shape.

  One support work 11 is installed adjacent to the back surface of the oblique pit 10, and the other support works 11 are installed with different support intervals at the left and right side wall portions 12a and 12b. In FIG. 1, the support interval on the left side wall portion 12a toward the left side is a constant interval b, for example, 500 mm, and the support interval on the right side wall portion 12b is also set to a constant interval, for example, 1000 mm. For this reason, a line perpendicular to the tunnel axis direction is used as a reference, and the inclination angle with respect to the reference line, that is, the inclination angle θ of each support 11 is different.

  The support work 11 is formed by, for example, smoothly bending an H-shaped steel having an H-shaped cross section as shown in FIG. 2 into an arch shape, and each support work 11 has an oblique angle as shown in FIG. It is installed diagonally according to. And the adjacent support work 11 is connected with connection members, such as the volt | bolt which supports the load of the horizontal direction called the inner beam 13. As shown in FIG. In FIG. 2, since the support work 11 is installed obliquely, the inner beam 13 has a special shape.

  The support works 11 are excavated in the natural ground, sprayed with concrete 14 by primary spraying on the excavated surface, installed at each position, and connected by inner beams 13. Thereafter, as shown in FIG. 3, the concrete 15 is sprayed by secondary spraying, and the concrete 15 is filled between the support works 11. Incidentally, in FIG. 3, dark portions with the same reference numerals 14 and 15 indicate sections that have already been constructed, and light portions indicate sections that have been newly constructed. After this construction, a waterproof sheet is attached to the inner side surface (the surface formed on the right side), and lining concrete is placed.

Ayano Hamada and two others, “Application of the slope pit gate at the tunnel entrance of mountainous area”, Summary of the 58th Annual Conference of the Japan Society of Civil Engineers, Japan Society of Civil Engineers, September 2003, Vol. 58, No. 6 , P. 123-124

  In the conventional construction method as described above, since the support interval is changed at the left and right side walls, the amount of steel used in the wellhead is increased, and the shape and length differ for each support construction. There was a problem of becoming complicated. Moreover, since the excavation progress length is shortened, there is a problem that the excavation process becomes long.

  In either of the left and right side wall portions 12a and 12b, the support interval is about 500 mm at a minimum, and there is not enough clearance. Therefore, there is a problem that a portion where it is difficult to spray concrete occurs and the filling property of the concrete is lowered. It was. In addition, as shown in FIG. 3, the surface after the secondary spraying may cause an uneven surface due to the concrete 15 and the flange surface of the support work 11, and the waterproof sheet may be damaged. There was also a problem that the back restraint of the slab could increase and induce cracks.

  When the uneven surface as described above is generated, it is difficult to drive the lock bolt perpendicular to the concrete spraying surface, and there is a problem that the natural ground cannot be stabilized. Further, the shape processing and construction of the inner beam 13 shown in FIG. 2 are complicated, and there is a problem that the coupling force is reduced.

  For this reason, provision of the support structure which can improve these problems, and its construction method was desired.

  In view of the above problems, the present invention is a supporting structure constructed in a tunnel mine on the back side of an oblique tunnel constructed obliquely with respect to the tunnel axis direction, and is adjacent to the rear surface of the oblique mine and allows traffic. An arch-shaped first support member installed so that the opening to be formed is formed obliquely with respect to the tunnel axial direction, and each opening having one end connected to the first support member and allowing passage There is provided a support structure including a plurality of arch-shaped second support members having different lengths installed so that the portions are oriented in the tunnel axis direction and formed at regular intervals.

  Further, it is a method for constructing a supporting structure in the tunnel mine on the back side of the oblique pit constructed obliquely with respect to the tunnel axis direction, and an opening that allows passage is formed obliquely with respect to the tunnel axis direction. A plurality of arch-shaped second support members having different lengths so that each opening is oriented in the direction of the tunnel axis and formed at regular intervals. Connecting each end of the member to the first support member; between the inner wall surface of the tunnel and the first support member and the plurality of second support members; between the first support member and each of the second support members; And a step of filling concrete between the second support members. The method for constructing the support structure is provided.

  According to the present invention, the construction is simple, the excavation process can be shortened, the filling property of sprayed concrete can be improved, and the risk of damage to the waterproof sheet and occurrence of cracks can be reduced.

The figure which illustrated the conventional support structure. The figure which illustrated the place which connected the adjacent support work at the time of constructing the conventional support structure by the inner beam. The figure which illustrated the place which installed the support work at the time of constructing the conventional support structure, and sprayed concrete. The flowchart which illustrated the flow of tunnel construction. The figure which illustrated the support structure of this invention. The figure which illustrated the cross section cut | disconnected by cutting line AA of FIG. The figure which illustrated the cross section cut | disconnected by the cutting line BB of FIG. The figure which illustrated the cross section cut | disconnected by the cutting line CC of FIG. 6 in which the support work 21 and the support work 22 are not connected. The figure which illustrated the cross section cut | disconnected by the cutting line DD of FIG. 6 which the support work 21 and the support work 22 connected. The flowchart which illustrated the flow of the construction which builds the support structure of this invention.

  The support structure of the present invention is a support structure that is constructed at a tunnel entrance when an oblique pit is constructed. An oblique mine is a mine whose wall faces obliquely with respect to the tunnel axis direction, which is a tunnel excavation direction, and also obliquely with respect to a direction perpendicular to the tunnel axis direction.

  Here, the tunnel construction process will be briefly described. In the tunnel construction, as shown in the flowchart of FIG. 4, the process starts from step 400, and in step 410, provisional equipment such as tree cutting, electrical equipment, and water supply equipment is prepared. Temporary equipment includes wastewater treatment equipment, muddy water treatment equipment, sprayed concrete plant equipment, etc. necessary for construction. After these preparations, in step 420, wellheading is performed. A wellhead is located near a felled natural ground, a steel arch-shaped support member is installed, and adjacent support members are connected to each other by an inner beam to support the outside of the natural ground. Is a part of the construction of the mine gate, and is extended until it is adjacent to the natural ground.

  When the wellhead construction is completed, in step 430, excavation machines such as explosives, hydraulic excavators, road headers and the like are used to excavate natural ground. This excavation is performed for a certain excavation length. At this time, the generated shear (crushed rock) is appropriately carried out of the tunnel mine. In step 440, a support work is installed to support the excavated tunnel ceiling and the tunnel wall that is the side wall of the tunnel so as not to collapse, and they are connected by inner beams.

  In step 450, concrete is sprayed, the support work is brought into close contact with the inner wall surface of the tunnel, and the space between the support works is filled with concrete. This shotcrete provides a function to resist deformation of the natural ground caused by excavation, compression by external force, shearing and the like. In step 460, a hole is drilled from the inner wall surface of the tunnel toward the inside of the natural ground, and a lock bolt, which is a steel rod-like member, is inserted to integrate these supporting work and sprayed concrete with the natural ground.

  In step 470, a secondary lining is performed. In the secondary lining, a waterproof sheet is attached to the inner surface of the tunnel formed by shotcrete and support, and after installing insulation as necessary, an arch-shaped formwork called a centle is used. Covering concrete is laid between the inner surface. Before the secondary lining, an invert work for forming the bottom surface of the tunnel in an inverted arch shape can be performed. Steps 430 to 470 are repeated to penetrate the tunnel. After passing through the tunnel, in step 480, the remaining tunnel construction such as placing concrete and finishing is performed, and in step 490, the construction is finished.

  The support structure of the present invention is a structure for supporting a natural ground so as to maintain the cross section of the tunnel, which is finally present in the tunnel mine, and is the rear surface of the oblique mine constructed obliquely with respect to the tunnel axis direction. It is built in the side tunnel mine. As illustrated in FIG. 5, this support structure has an arch shape that is adjacent to the rear surface of the oblique pit 20, that is, the surface on the natural ground side, so that the opening is formed obliquely with respect to the tunnel axis direction. And a plurality of arch-shaped supports having different lengths installed such that one end of each is connected to the support work 21 and each opening is formed in the tunnel axis direction and at regular intervals. And the construction 22. Each opening is a space portion through which a person, a vehicle, or the like formed when the support work 21 and the plurality of support works 22 are respectively installed.

  In FIG. 5, the tunnel axis direction is the direction indicated by the arrow line Y, and an oblique pit 20 is constructed obliquely with respect to the tunnel axis direction at the tunnel entrance that is the entrance of the tunnel. The inclination angle of the oblique pit 20 with respect to the tunnel axis direction can literally be expressed as an angle with respect to the tunnel axis direction of 0 °, but the direction perpendicular to the tunnel axis direction is set to 0 °. It can also be expressed as an inclination angle (bevel angle) with respect to. The oblique angle is arbitrary depending on the specifications of the oblique gate. For example, in FIG. 5, the oblique angle θ of the oblique gate 20 is about 30 °.

  The support work 21 constituting the support structure is arranged so as to be inclined according to the oblique angle θ. The plurality of supporters 22 are arranged at regular intervals in order from the shortest length so that the openings are formed in the tunnel axis direction and at regular intervals, and one end of each is connected to the supporter 21. . In FIG. 5, the six supporters 22 displayed as “No. 1” to “No. 6” are arranged at regular intervals in order from “No. 6” to “No. 1” whose length is short, Each end is connected to the support work 21.

  Since the plurality of supporters 22 are installed so as to be arranged at regular intervals in the tunnel axis direction, the arrangement is the same as that in the case of a normal tunnel. Incidentally, the normal gate is a gate that is constructed perpendicularly to the tunnel axis direction and whose wall faces in the tunnel axis direction. For this reason, the support work in the normal gate is installed in parallel to the normal gate so that the opening is formed in the tunnel axis direction at the same support interval on the left and right.

  The support structure can further include a plurality of arch-shaped support works 23 installed at regular intervals in the tunnel axis direction. In FIG. 5, the support intervals a of the plurality of support works 22 and support works 23 are the same on the left and right, for example, about 1000 mm.

  The support works 21, 22, and 23 are arch-shaped ones that are formed by smoothly bending an H-shaped steel made of steel extending in one direction and having an H-shaped cross section so as to have a predetermined curvature. Here, H-shaped steel is used, but if it has sufficient bending rigidity and can properly support the ceiling and wall of the excavated tunnel, I-shaped steel, T-shaped steel, U-shaped steel, Z It may be a shape steel or a steel pipe. The H-shaped steel is composed of two flanges arranged in parallel and a web connecting the centers of the two flanges, and a space formed by the two flanges and the web is a flange portion described later.

  When the oblique angle θ of the oblique pit 20 is a large angle, for example, about 30 °, the first support work 21 installed adjacent to the oblique mine 20 is formed in two or more arch shapes having different curvatures. It is possible to adopt a multi-structure support work formed by stacking the support works. Between the support works, concrete can be filled and connected, whereby a multi-structure support work can be produced. By adopting this multi-structure support work, the rigidity and proof stress of the whole support work can be improved.

  The oblique angle θ for making a multiple structure can be set according to the result of structural design, testing, and the like. The multiple structure may be a double structure formed by arranging two support works in the vertical direction, or a triple or more structure in which three or more support works are stacked.

  Although not shown in FIG. 5, the keystone plate is attached to the outer peripheral surface of the support work 22 via a metal fitting so as to cover the outer peripheral surface of the support work 22 and the gaps between the plurality of support works 22. This is because the support structure of the present invention will eventually exist in the tunnel mine, but at least the oblique mine part (support work shown by “No. 1” to “No. 6” in FIG. 5). In the part where 22 is installed), the assembly stage is due to placing under light. That is, in the assembly stage, a semi-cylindrical arch shell that finally becomes the foundation of the inner wall surface of the tunnel is constructed using the support 22 and the sprayed concrete with no ground on the back surface. A keystone plate as a back formwork is required.

  6 is a cross-sectional view of the support structure shown in FIG. 5 cut along a cutting line AA. In FIG. 6, only the support work 21 installed adjacent to the oblique pit 20 is shown. The support work 21 may be composed of only one support work. However, as shown in FIG. 6, two arch-shaped support works 21a and 21b having different curvatures are arranged side by side vertically, You can also use what you did. In the case of a double structure, the filled concrete 24 can be filled into the space portion and the flange portion between the two support works.

  Both ends of the support works 21a and 21b are laid with a concrete foundation 25 to fix the support works 21a and 21b. In addition, when it cannot support stably only by support work 21a, 21b, the bracket for a reinforcement can be provided in the leg part of the support work 21 called the wing rib 26. FIG. By attaching this wing rib 26 which is a leg reinforcing member, the support area is increased, and the support force and member rigidity by the support 21 can be improved.

  The wing rib 26 includes, for example, a first plate-shaped member having a predetermined thickness formed into a substantially triangular shape like a main frame using H-shaped steel, a steel rod-shaped member, and concrete, and one side of the plate-shaped member. And a second plate member having a support surface perpendicular to a substantially triangular surface. In this case, the first plate-like member projects from the outer peripheral portion of the leg portion of the support work 21a toward the root-solidifying concrete 25, and the support surface of the second plate-like member is adjacent to the root-solidifying concrete 25 so that the supporting area is increased. The supporting force and the member rigidity can be improved.

  The first plate-like member can be attached by welding or the like to the outer peripheral portion of the leg portion, and the second plate-like member can be fixed to the rooting concrete 25 using a bolt or the like. The leg reinforcing members are not limited to the wing ribs 26 attached to the outer peripheral side of the support work 21 but may be inner ribs attached to the inner peripheral side thereof.

  FIG. 7 is a cross-sectional view of the support structure shown in FIG. 5 cut along a cutting line BB. FIG. 7 shows one of the plurality of support works 22. The support 22 is an arch-shaped support having a predetermined curvature, and a joint plate 30 is provided at one end for connection to the support 21 shown in FIG. The joint plate 30 has a surface oriented obliquely in accordance with the oblique angle of the oblique pit 20, for example, a hole through which a bolt as a fixing means is passed. The joint plate 30 may be connected to the support 21 with bolts and nuts, but may also be connected by welding or the like.

  The other end of the support 22 is embedded and fixed by the root-solidifying concrete 25, like the support 21 shown in FIG. The support work 22 shown in FIG. 7 is an example of the support work 22 indicated by “No. 2” shown in FIG. Since this support work 22 is cut in the middle to be connected to the support work 21 and the joint plate 30 is attached, it is called a defect support work. Other support works 22 such as “No. 1” and “No. 3” are defect support works having the same curvature as the support work 22 indicated by “No. 2”, but having different lengths.

  FIG. 8 is a cross-sectional view of the support 21 shown in FIG. 6 cut along a cutting line CC. Filled concrete 24 is filled in the space between the two support works 21a and 21b arranged in the vertical direction and the flange part of each support work 21a and 21b. Between the support work 21a and the support work 21b, not only the filled concrete 24 but also a welded wire mesh 31 is provided. One end of the welded wire mesh 31 is attached to the support 21a and the other end is attached to the support 21b by welding. The welded wire mesh 31 is a reinforcing wire mesh used to reinforce the filled concrete 24. Although the welded wire mesh 31 is used here as the reinforcing member, other members such as reinforcing bars can be used as long as the concrete can be reinforced. In FIG. 8, the keystone plate 35 described above is attached as a back form of the sprayed concrete 36 adjacent to the support work 21.

  FIG. 9 is a cross-sectional view of the support 21 shown in FIG. 6 cut along a cutting line DD. As in FIG. 8, the space between the upper and lower support works 21 a and 21 b and the flange part of each support work 21 a and 21 b are filled with the filled concrete 24, and the welded wire mesh 31 is connected so as to connect them. Is provided. FIG. 9 shows that a support 22 as shown in FIG. 7 is connected. A welded iron plate 32 is attached to the support 21b by welding, and the joint plate 30 provided on the support 22 shown in FIG. 7 is face-to-face and connected by a bolt 33 and a nut 34. Yes.

  The support 22 can use H-shaped steel of the same size as the support 21, but is smaller than the support 21 installed adjacent to the oblique pit 20 in consideration of the connection with the support 21. Can be size. In FIG. 9, the support work 21 has a width and a height of, for example, 250 mm, and the support work 22 has a width and a height of, for example, 200 mm. The support 23 can be the same size as the support 22. Here, the sizes of 250 mm and 200 mm are given as an example, but the size is not limited to these sizes.

  The load due to earth pressure received by the plurality of support works 22 is transmitted to the support work 21 constructed relatively stronger than the support works 22. Also in FIG. 9, a keystone plate 35, which is a thin plate material, is attached to the outer peripheral side of the arch of the support 22 as a back form. The keystone plate 35 becomes a back formwork of the sprayed concrete 36 on the inner wall surface of the tunnel, which will be constructed later from the inner peripheral side of the arch of the support work 22, and the support work even in the state exposed under the light where there is no ground on the back 22 and sprayed concrete 36 are integrated so that an arch shell can be constructed. The keystone plate 35 is attached so as to cover the entire surface including the outer peripheral surface of the support 22 through a metal fitting 37 attached to the outer peripheral surface of the support 22.

  Referring to FIG. 5 again, adjacent support works 22, adjacent support works 22 and support works 23, and adjacent support works 23 are strengthened by, for example, a tie rod that functions as a tension member that connects two members. Can be tight. This is because, for example, all the webs of the supporters 22 and 23 made of H-section steel are installed in the tunnel axis direction, which is the same direction, so that it is a loose connection like the conventional support structure shown in FIG. It is because it does not become. Moreover, since there is sufficient clearance, it can be tightened firmly to the end. By this connection, the support works 22 and 23 are not separated, and the support intervals can be maintained at a constant interval, for example, a = about 1000 mm, and the tunnel ceiling and the pit wall can be stably supported. .

  A method for constructing the support structure will be described with reference to the flowchart shown in FIG. Although this method is not limited to this, it starts from Step 1000, and in Step 1010, the space where the oblique pit 20 and the supporting work 21 and the supporting work 22 adjacent thereto are arranged, and the surrounding and upper natural ground. Are excavated only in a range sufficient for the support works 21 and 22 to be assembled in the light, that is, the slanted pits are all in the lighted condition.

  In step 1020, the support work 21 is placed under the light so that each end of the plurality of arch-shaped support works 22 having different lengths is formed at regular intervals with each opening directed in the tunnel axis direction. It connects with support work 21. The joint plate 30 shown in FIG. 7 and the welded iron plate 32 shown in FIG. At this time, the tie rods can be used to firmly bond between the adjacent support works 22. Moreover, the wing ribs 26 as shown in FIG.

  In step 1030, between the inner wall surface of the tunnel, the support work 21, and the plurality of support works 22, each of the support works 21 and each support work constructed in step 1020. The concrete is sprayed on the space between the support 22 and the flanges of the plurality of supporters 22 and filled with the filled concrete 24 shown in FIGS. 6, 8, and 9. Complete in the light. The filling of the filling concrete 24 may be performed before or during the assembly of step 1020.

  In step 1040, the leg portions of the support work 21 and the support work 22 are fixed by placing the root-solidifying concrete 25 shown in FIG. At this time, the wing ribs 26 are also fixed by the reinforced concrete 25 using bolts or the like.

  In step 1050, the excavation progress length equal to one excavation progress length in the normal tunnel is excavated and the support construction 23 is built, and the support structure is extended in the tunnel axis direction by repeating this. In this way, when the tunnel has penetrated and the building of the support work 23 has been completed up to the point of penetration, the process proceeds to step 1060, and this construction is finished. In the case of constructing the oblique pit 20 at the penetration destination, the piercing oblique pit 20 is constructed first in the same manner as in Steps 1010 to 1040, and is penetrated through in Step 1050. In addition, the arch shell in the oblique mine portion exposed under the light is appropriately covered with backfill soil until the tunnel is completed, and the final form of the pit portion is completed.

  Compared with the conventional support structure shown in FIG. 1, this support structure can increase the support interval between the support works 22 and 23, and can secure one excavation progress length similar to that in the case of a normal tunnel. it can. Thereby, construction becomes easy and the construction period can be shortened. Moreover, the filling property of sprayed concrete can be improved by extending a support space | interval.

  Since the plurality of supporters 22 are not installed obliquely, there is no unevenness in the sprayed surface when the concrete is sprayed, and the risk of cracking due to damage to the waterproof sheet attached thereafter or the back restraint of the lining concrete can be reduced. it can. For this reason, compared with the conventional support structure shown in FIG. 1, it can be evaluated that the support structure is superior in quality.

  Moreover, since connection members, such as a lock bolt and a tie rod, can be constructed similarly to the case of a normal mine, the workability and quality of the support structure are improved compared to the conventional support structure shown in FIG. be able to.

  So far, the supporting structure and the construction method thereof according to 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 and Additions, changes, deletions, and the like can be made within the scope that can be conceived by those skilled in the art, and any aspect 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 10 ... Diagonal shaft, 11 ... Supporting work, 12a, 12b ... Side wall part, 13 ... Inner beam, 14, 15 ... Concrete, 20 ... Diagonal tunnel, 21, 21a, 21b, 22, 23 ... Supporting work, 24 ... Filled concrete, 25 ... Rooted concrete, 26 ... Winglib, 30 ... Joint plate, 31 ... Welded wire mesh, 32 ... Welded iron plate, 33 ... Bolt, 34 ... Nut, 35 ... Keystone plate, 36 ... Sprayed concrete, 37 ... Metal fittings

Claims (5)

A support structure constructed in the tunnel mine on the back side of the oblique pit constructed obliquely with respect to the tunnel axis direction,
An arch-shaped first supporting member that is installed adjacent to the back surface of the oblique pit and is formed so that an opening that allows passage is formed obliquely with respect to the tunnel axis direction;
One end of each is connected to the first support member, and a plurality of arch-like shapes having different lengths are installed so that each opening is formed so as to be oriented in the tunnel axis direction and at regular intervals. and a second支保member seen including,
Concrete is filled between the inner wall surface of the tunnel and the first support member and the plurality of second support members, between the first support member and each of the second support members, and between the plurality of second support members. The support structure is in close contact with the inner wall surface of the tunnel .   The first support member is a multi-structure support member formed by vertically arranging two or more arch-shaped support members having a predetermined curvature according to the inclination angle of the oblique shaft with respect to the tunnel axis direction. The supporting structure according to claim 1. Wherein mounted on the legs of the first支保member, it increases the support area includes a leg reinforcing member to improve the supporting force,支保structure according to claim 1 or 2. The support structure according to any one of claims 1 to 3 , further comprising a connecting member that connects the two adjacent second support members while maintaining the predetermined interval. A method of constructing a support structure in a tunnel mine on the back side of an oblique pit constructed obliquely with respect to the tunnel axis direction,
The arch-shaped first support member is disposed so that the opening that allows passage is formed obliquely with respect to the tunnel axis direction, and each opening that allows passage faces in the tunnel axis direction and is constant. Connecting each one end of a plurality of arch-shaped second support members having different lengths so as to be formed at intervals, to the first support member;
Concrete is filled between the inner wall surface of the tunnel and the first support member and the plurality of second support members, between the first support member and each of the second support members, and between the plurality of second support members. A method for constructing a support structure including stages.