WO2006057545A1

WO2006057545A1 - Tunnelling method using pre-support concept and an adjustable apparatus thereof

Info

Publication number: WO2006057545A1
Application number: PCT/KR2005/004050
Authority: WO
Inventors: Dong-Hyun Seo
Original assignee: Dong-Hyun Seo
Priority date: 2004-11-29
Filing date: 2005-11-29
Publication date: 2006-06-01
Also published as: KR20060059833A; JP2008522058A; JP5103516B2; KR100740200B1; JP4768747B2; JP2011052536A

Abstract

The present invention relates to a tunnelling method using pre-support concept in which comprising the steps determined excavation line of a tunnel and performing grouting excavating the tunnel along the predetermined excavation line and installing drain boards at the excavated surface installing segments to the respective pre-supports at the lower sides of the drain boards in series such that insertion protrusions and insertion recesses formed in the lateral sides of the segments are engaged with each other to form lining and pressing and fixing the segments to the pre-supports by attaching pressing plates to the pre-supports penetrating the segments.

Description

Description TUNNELLING METHOD USING PRE-SUPPORT CONCEPT

AND AN ADJUSTABLE APPARATUS THEREOF Technical Field

[1] The present invention relates to a tunnelling method using pre- support concept in which when constructing an entrance and an exit of a tunnel, a soft ground tunnel with a thin cover constructed in urban area, and a large sectional tunnel after excavating a pilot tunnel and installing pre-support piles to installed pre-supports by drilling per¬ forations, segments as lining forming materials such as precast segments, trusses made of reinforcing bars, and steel ribs are coupled with the pre-supports while the large sectional tunnel, that is, a main tunnel is excavated to an excavation line, and in a case of installing vertical pipe roofs in multiple steps and grouting instead of the pre- supports installed in a very soft ground in the radial direction, the excavation line is reinforced by inner lining supporting material such that the pre-supports do not interfere with the pipe roofs, and relates to an adjustable apparatus thereof. Background Art

[2] Conventionally, there is an auxiliary tunnelling method for previously improving ground by grouting for reinforcement of ground when constructing a shallow overburden tunnel. However, the conventional auxiliary tunnelling method has a weak reinforcing effect in comparison to the effort required to install the reinforcement.

[3] Moreover, there are other tunnelling methods of pre-supporting ground only with a pipe roof and of hydraulically pressing a large shield using a shield tunnel concept and excavating a tunnel. However, in the auxiliary tunnelling method using the pipe roof, the transversal reinforcement is insufficient, and the method using a shield tunnel concept cannot be applied to a large section because of excessive costs for a local tunnel. Disclosure of Invention

Technical Problem

[4] Therefore, the present invention has been made in view of the above problems, and it is an object of the present invention to provide a tunnelling method using pre-support concept, as a tunnelling method for constructing an entrance and an exit of a tunnel such as a soft ground tunnel with a thin cover constructed in an urban area, for reducing land subsidence and excavating a tunnel while forming a tunnel lining.

[5] In accordance with an aspect of the present invention, the above and other objects can be accomplished by the provision of a tunnelling method using pre-support concept including the steps of: drilling and installing a plurality of pre-supports from ground to a predetermined excavation line of a tunnel and performing grouting; excavating the tunnel along the predetermined excavation line and installing drain boards at the excavated surface; installing segments to the respective pre-supports at the lower sides of the drain boards in series such that insertion protrusions and insertion recesses formed in the lateral sides of the segments are engaged with each other to form lining; and pressing and fixing the segments to the pre-supports by a ttaching pressing plates to the pre-supports penetrating the segments. Technical Solution

[6] Hereinafter, preferred embodiments of the present invention will be described in detail.

[7] Figs. Ia to 3 are sectional views illustrating the installation of pre-supports toward a predetermined excavation line of a tunnel in the various forms prior to the excavation of the tunnel according to a tunnelling method of the present invention. Fig. 4 is a sectional view illustrating the installation of a pillar of a tunnel having two arches after excavating three arches with pre-supports. Fig. 5 is a sectional view illustrating that according to a tunnelling method of the present invention, a tunnel is excavated after the installation of pre-supports and every pre-support is connected and fastened to each other along an excavation line of the tunnel by segments. Fig. 6 is a sectional view il¬ lustrating that according to the tunnelling method of the present invention, a tunnel is excavated after installation of pre-supports and the pre-supports are connected and fastened to each other along the excavation line of the tunnel by trusses made of re¬ inforcing rods. Fig. 7 is a sectional view illustrating that according to a tunnelling method of the present invention, pre-supports are installed and reinforced by a plurality of pipe roofs at regular intervals in the transversal direction of a tunnel, and after that, the tunnel is excavated, arch-shaped steel ribs are installed at regular intervals in the longitudinal direction of the tunnel and are connected to the pre-supports by fastening. Fig. 8 is a sectional view illustrating that according to a tunnelling method of the present invention, pre-supports are positioned in the vicinity of the excavation line of a tunnel such that the pre-supports do not interfere with a plurality of pipe roofs. Fig. 9 is a perspective view illustrating that according to a tunnelling method of the present invention, a plurality of pipe roofs is installed at regular intervals in the transversal direction of a tunnel and arch-shaped steel ribs are installed at a predetermined interval in the longitudinal direction of the tunnel such that the arch-shaped steel ribs are connected to the pre-supports by fastening. Fig. 10 is a perspective view illustrating the connection between pre-supports by steel plates according to a tunnelling method of the present invention. Fig. 11 is a sectional view taken along the line A-A in Fig. 9. Fig. 12 is a sectional view illustrating that rock bolts are fastened to the lower side of the excavation line of a tunnel according to a tunnelling method of the present invention. Fig. 13 is a partial sectional view illustrating that in the tunnelling method according to the present invention, pre-supports are piled deeper than the excavation line of a tunnel for the self-reinforcement of a facing of the tunnel. Fig. 14 is a sectional view taken along the line B-B in Fig. 13. Fig. 15 is a sectional view taken along the ling C-C in Fig. 13. Fig. 16 is a perspective view illustrating that, in the tunnelling method according to the present invention, band-type drainage members are installed in the circumference of a tunnel between the excavation face and segments when forming linings using trusses made of reinforcing bars and shotcrete. Fig. 17 is a sectional view illustrating other drainages of a tunnel in the tunnelling method according to the present invention. Fig. 18 is an enlarged sectional view illustrating the drainages in Fig. 17. Fig. 19 is a sectional view illustrating effect of applying pre-stress to pre-supports when shell forming members such as pre-stress type pre-supports, segments, or the like are connected to each other by pressing plates in a tunnelling method according to the present invention. Fig. 20 is a detail sectional view illustrating a leading end supporting pre-stress type pre-support indicated by D in Fig. 19. Fig. 21 a sectional view illustrating pre-supports installed in a shallow overburden tunnel with thin cover in a tunnelling method according to the present invention. Fig. 22 is a perspective view illustrating a reinforced truss used in a tunnelling method according to the present invention. Fig 23 is a sectional view taken along the line X-X in Fig. 22. Fig. 24 is a sectional view taken along the line Y-Y in Fig. 22. Figs. 25 to 29 are views illustrating the sequence of installation of pre-supports in a tunnelling method according to the present invention.

[8] Process in the tunnelling method using the pre-support concept and supporting the pre-supports and segments according to the present invention will be described as follows. Firstly, as shown in Figs. 1 to 4, pre-supports 10 such as rock bolts installed in the radial direction toward the ground of the tunnel are installed by boring from pre¬ determined ground of a tunnel toward the excavation line 20 of the tunnel, and grouting 66 is performed. Fig. 1 is a view illustrating the installation of the pre- supports 10 toward the excavation line of the tunnel in the radial direction, Fig. 2 is a view illustrating the installation of the pre-supports 10 toward the excavation line of the tunnel in the vertical direction, Fig. 3 is a view illustrating the installation of the pre-supports 10 toward the excavation line in the vertical and radial directions, and Fig. 4 is a view illustrating the installation of pillars of a tunnel with two arches after excavating three arches. In more detail description of the drawings, the installation of the pre-supports in Fig. 1 is applied when the upper surface of a tunnel is relatively wide or has an arch-shape, the installation of the pre-supports in Fig. 2 is applied when the transversal region of ground of a civil tunnel is restricted, the installation of the pre-supports in Fig. 3 is applied when lateral sides of the excavation line of a tunnel must be additionally stabilized and the pre-supports vertical to the lateral sides of the tunnel approach the lower side of the formation line to serve as soil resisting bodies of the lateral side walls of the tunnel, and in the installation of the pre-supports, and as shown in Fig. 4, vertical steel pipe pre-supports are installed at the position where pillars are installed in a tunnel with two arches after excavating three arches such that the pre-supports serve as the pillars of the tunnel and are integrated with steel plates 13 and angle steels 14 by welding and connecting the steel plates 13 and the angle steels 14 to the pre-supports to construct a pre-support tunnel.

[9] As described above, the tunnel is excavated after the installation of the pre- supports 10. As shown in Figs. 5 to 11, the installation of the pre-supports 10 is carried out by which a plurality of pre-supports 10 is piled toward the excavation line 20 of the tunnel from the upper surface of the predetermined excavation line 20 of the tunnel, that is, the ground in the radial direction, and after that, the tunnel is excavated. As shown in Fig. 5, in the excavation line 20 of the tunnel, segments 30, whose insertion protrusions 31 and insertion recesses 32 are respectively formed in the sides and in the opposite sides thereof, are inserted into and coupled with each other. The respective segments 30 have holes into which the pre-supports 10 are inserted and are coupled with each other by fastening pressing plates 11 to the pre-supports 10. Moreover, between the segments 30 and the excavation line of the tunnel, drain boards 40 are inserted. Backfill grouting for filling a gap between the segments 30 and the excavation line of the tunnel is carried out through the holes of the pressing plates 11 before the installation of drain filters and waterproof paper to the front sides of the segments in the installation of dual layer shells like the conventional tunnelling method.

[10] Fig. 6 shows an example using trusses 33 constructed with reinforcing bars instead of the segments 30 as a supporting plate. As shown in the drawing, the trusses 33 connect the pre-supports 10 to each other and the insides thereof are shotcreted. As shown in Figs. 7 to 11, instead of the segments 30, pipe roofs 34 are installed at regular intervals in the transversal direction of the tunnel along the longitudinal direction of the tunnel, and after that, the tunnel is excavated, drain boards 40 are installed in the excavation surface, arch-shaped steel ribs 35 are installed in the lower sides of the pipe roofs 34 in the longitudinal direction of the tunnel, and between the steel ribs 35, steel plates 36 are installed to connect the steel ribs 35 to each other. Between the pipe roofs 34 and the steel plates 36, the shotcrete 37 is placed. In other words, as shown in Figs. 5 to 11, a member constructing the shell is installed such that one of the precast segments 30, the reinforced trusses 33, and the steel ribs 35 are selectively installed according to conditions. [11] Fig. 7 shows that the pressing plates press the excavation line of the tunnel when fastening the rock bolts to prevent the tunnel from being partially collapsed, and Fig. 8 shows that the pre-supports are positioned in the vicinity of the excavation line of the tunnel in the tunnelling method of the present invention so that the pre-supports do not interfere with the pipe roofs. In other words, the pre-supports are positioned at the upper side of the excavation line of the tunnel such that the pre-supports do not interfere with the pipe roofs 34 in the longitudinal direction of the tunnel.

[12] Fig. 12, as described above, shows that after excavation of the tunnel, the pre- supports 10 connected to each other by the segments 30 are coupled with the pressing plates 11 within the excavation line 20 of the tunnel and are fastened, and in the lateral lower sides of the excavation line 20, that is, in regions where the excavation is relatively easily performed, the rock bolt 50 and the segments 30 are installed in the tunnel.

[13] As shown in Figs. 13 to 15, for the self -reinforcement of the facing, the pre- supports 10 are piled deeper than the excavation line 20, and as such, when the pre- supports 10 are piled deeper than the excavation line 10, the shear of the facing is reinforced.

[14] Fig. 16 is a perspective view illustrating that, in the tunnelling method according to the present invention, band-type drain boards 40 are installed in the circumference of the tunnel between the excavation face and the segments 30 when forming linings using trusses made of reinforcing bars and shotcrete. By continuously installing the drain boards 40 in the circumference of the tunnel, water is smoothly drained.

[15] Figs. 17 and 18 show drainages 70 installed between the precast segments and the excavation surface in the tunnelling method according to the present invention. The drainages 70 include drainage pipes 72, which are installed between the segments 30 and the excavation line 20 of the tunnel and are connected to each other at regular intervals through T-shaped connection pipes 71, weep drainage pipes (See Fig. 203) connected to the T-shaped connection pipes 71 of the drainage pipes 72 in the radial direction with respect to the excavation line 20 and having through-holes 73a formed in the outer circumference, horn-shaped funnels 74, into which the lower outer cir¬ cumferences of the weep drainage pipes 73 without the through-holes 73a are inserted, for preventing grouting liquid 74a from flowing into the through-holes 73a, and caps 75 for covering the upper sides of the weep drainage pipes 73. The drainages 70 can reduce ground erosion and overbreak due to gushing water in the tunnel, and the horn- shaped funnels 74 installed in the lower outer circumferences of the weep drainage pipes 73 for preventing the grouting liquid 74a from blocking the through-holes 73a of the weep drainage pipes 73 serve as a check valve so that draining is smoothly carried out without blocking the drainage pipes 72. The drainages according to a first preferred embodiment of the present invention as shown in Fig. 16 and the drainages according to a second preferred embodiment of the present invention as shown in Fig. 17 are applied together or selectively according to ground conditions and the lining conditions.

[16] Fig. 20 is a sectional view illustrating the pre-stress type pre-supports 60 to which pre-stress can be applied. As shown in Figs. 19 and 20, the pre-stress type pre-supports 60 are structured such that steel rods 61 as tensile members are inserted into polyethylene pipes 67, which are inserted into steel pipes 62 having protrusions 63 formed in the outer circumferences thereof. Between the steel pipes 62 and the steel rods 61, anticorrosion lubricant is coated so that the steel pipes 61 and the steel rods 61 are prevented from corrosion and are freely deformed by tensile force. The pre- supports 10 are pulled such that the tensile members, that is, the steel rods 61 are pulled by a hydraulic jack while pushing the pressing plates 11 and a tensile force is applied by fastening fixing devices 12 or nuts with a predetermined torque. The pre- stress type pre-supports 60 are fixed in the basic soil by frictional force between the steel pipes 62 and the grouting 66.

[17] When the shell forming members such as the pre-supports 10 and the segments 30 of the present invention are connected by the pressing plates 11, a pre-stress is applied to the pre-supports 10 so that land subsidence is reduced and arching effect is improved.

[18] Figs. 25 to 29 show the process of constructing the pre- support tunnel according to the present invention. Firstly, the pre-supports 10 are piled from ground to the pre¬ determined excavation line 20 in the radial direction and in the vertical direction (See Fig. 25), the upper section of the tunnel is excavated along the excavation line 20 (See Fig. 26), the pre-supports 10 on the arching line are respectively connected to the segments 30 by the pressing plates 11 and the fixing devices 12 (See Fig. 27), the rock bolts 50 are installed in the lower half section of the tunnel (See Fig. 28), and the respective rock bolts 50 are connected to the segments 30 by the pressing plates 11 and the fixing devices 12 so that the tunnelling is completed (See Fig. 29).

[19] In a very shallow overburden tunnel with a cover of 5m to 6m, as shown in Fig. 21, pre-stress is generated such that the steel rods 61 are fixed to the segments 30 or concrete slabs 80 installed on the upper ground of the tunnel, one side of the pre-stress type pre-supports 60 is excavated from the inside of the shaft of the tunnel, and the segments 30 are attached to the pre-stress type pre-supports 60 and are fastened. This tunnelling method is applied to the soil ground without sufficient friction generated from surroundings of the pre-supports of the soil tunnel to give a perfect arching effect of the surroundings of the tunnel and to increase shear stress, and to reduce the land subsidence. [20] Fig. 30 is a sectional view illustrating that the pre-supports are inserted into per¬ forations formed in the radial direction in a pilot tunnel within in a large sectional tunnel. Fig. 31 is a sectional view illustrating that in the tunnelling method, a large sectional tunnel is excavated after the installation of the pre-supports and the segments are connected to the respective pre-supports in the excavation line of the tunnel. Fig. 32 is a sectional view illustrating that in the tunnelling method, a large sectional tunnel is excavated after the installation of the pre-supports and the trusses made of re¬ inforcing bars are connected to the respective pre-supports in the excavation line of the tunnel. Fig. 33 is a sectional view illustrating that in the tunnelling method, a large sectional tunnel is excavated after the installation of the pre-supports and the rein¬ forcement using a plurality of pipe roofs at regular intervals in the transversal direction, and arch-shaped steel ribs are connected to the pre-supports after the arch- shaped steel ribs are installed at regular intervals in the longitudinal direction of the tunnel in the excavation line of the tunnel.

[21] As shown in Fig. 31, the tunnelling method using the pre-supports according to the present invention includes the steps of 1) excavating a pilot tunnel 21 in a large sectional tunnel, 2) forming a plurality of perforations 22 in the radial direction in order to install the pre-supports 10 in the pilot tunnel 21, 3) inserting the pre-supports 10 into the perforations 22 formed in the radial direction in the above step, grouting, and curing the grout, 4) excavating the pilot tunnel along the excavation line 20 of the large sectional tunnel and installing drain boards 40 in the excavated surface, 5) installing the segments 30 to the respective pre-supports 10 at the lower sides of the drain boards 40 in series such that the insertion protrusions 31 and the insertion recesses 32 formed in the lateral sides of the segments 30 are engaged with each other, and 6) attaching the pressing plates 11 to the pre-supports 10 inserted into the segments 30 and fastening the fixing devices 12 to press and fix the segments 30 to the pre- supports 10.

[22] As shown in Fig. 32, the tunnelling method using the pre-supports according to the present invention includes the steps of 1) excavating a pilot tunnel 21 in a large sectional tunnel, 2) forming a plurality of perforations 22 in the radial direction in order to install the pre-supports 10 in the pilot tunnel 21, 3) inserting the pre-supports 10 into the perforations 22 formed in the radial direction in the above step, grouting, and curing the grout, 4) excavating the pilot tunnel along the excavation line 20 of the large sectional tunnel and installing drain boards 40 in the excavated surface, 5) installing the trusses 33 made of reinforcing bars to the respective pre-supports 10 at the lower sides of the drain boards 40 in series such that the pressing plates 11 are attached to the pre-supports 10 penetrating the trusses 33 and the fixing devices 12 are fastened to press and fix the trusses 33 to the pre-supports 10, and 6) placing shotcrete 37 into the trusses 33.

[23] As shown in Fig. 33, the tunnelling method using the pre-supports according to the present invention includes the steps of 1) excavating a pilot tunnel 21 in a large sectional tunnel, 2) forming a plurality of perforations 22 in the radial direction in order to install the pre-supports 10 in the pilot tunnel 21, 3) inserting the pre-supports 10 into the perforations 22 formed in the radial direction in the above step, grouting, and curing, 4) installing pipe roofs 34 at regular intervals in the transversal direction of the sectional tunnel along the longitudinal direction of the tunnel, installing drain boards 40 at the lower sides of the pipe roofs 34 while excavating the tunnel after the installation of the pipe roofs 34, installing arch-shaped steel ribs 35 at the lower sides of the pipe roofs 40 in the transversal direction along the longitudinal direction of the tunnel to interpose the drain boards 40 between the pipe roofs 34 and the steel ribs 35, coupling the steel ribs 35 with each other by steel plates 36 installed between the steel ribs 35, and fastening fixing devices 12 to fix pressing plates 11, and 5) placing shotcrete 37 between the pipe roofs 34 and the steel plates 36.

[24] In the above, the pre-supports are divided into a steel rod type pre-support, a steel wire type pre-support, and a precast type pre-support. Fig. 34 is a detail sectional view illustrating a hollow steel rod type pre-support used in the tunnelling method according to the present invention, and Fig. 35 is a sectional view taken along the line E-E in Fig. 34.

[25] A pressure grouting apparatus using the hollow steel rod type pre-supports will be described in detail. The pressure grouting apparatus for inserting pre-supports 10 into perforations 22 formed in the radial direction in a pilot tunnel 21 and for pressure- grouting the perforations 22 in order to excavate and construct a pre-support tunnel, includes a plurality of hollow steel rod type pre-supports 110, which have threads 110a formed in the outer circumferences and a plurality of centerizers 112, having protruded bars 111 protruded outwardly from the outer circumferences thereof to maintain distance between centers of the perforations 22 and coupled with the intermediate outer circumferences of the hollow steel rod type pre-supports 110, and are connected to each other by couplers 113, for performing pressure-grouting by injecting grout liquid 74a into the perforations 22, and a packer 120 engaged with the threads of the hollow steel rod type pre-support 110 positioned at the entrance of the perforation 22 to fill the perforation 22 by injecting the grout liquid 74a into the perforation 22 through the hollow steel rod type pre-supports 110 and after that for packing the entrance of the perforation 22.

[26] The packer 120 includes a donut-shaped first stopper 121 engaged with the threads

110a of the hollow steel rod type pre-support 110, a rubber packer 122 having a rubber horn and engaged with the threads 110a of the hollow steel rod type pre-support 110, that is, a side of the first stopper 121 to be installed to face the entrance of the perforation 22, a short pipe 123 coupled with the outer circumference of the hollow steel rod type pre-support 11, that is, a side of the rubber packer 122 to move on the outer circumference of the hollow steel rod type pre-support 110 to make the rubber horn of the rubber packer 122 closely contact the inner circumference of the perforation 22 and having a wedge-shaped rubber packing 123a coupled with the outer circumference thereof, a second donut-shaped stopper 124 coupled with the outer cir¬ cumference of the short pipe 123, that is, the side of the rubber packing 123a to make the wedge-shaped rubber packing 123a closely contact the inside of the rubber horn of the rubber packer 122 such that a side of the second donut-shaped stopper 124 is locked by the wedge-shaped rubber packing 123a, and an insertion pipe 125 fastened to the threads 110a of the hollow steel rod type pre-support 110 to move the wedge- shaped rubber packing 123a from the side of the short pipe 123 to the rubber horn of the rubber packer 122.

[27] The couplers 113 are installed in the outer circumferences of the threads 110a, that is, parts for connecting the hollow steel rod type pre-supports 110 to each other and locking pins 113a are inserted into the inner circumferences to maintain the connection between the hollow steel rod type pre-supports 110.

[28] Meanwhile, Fig. 36 is a detail sectional view of a steel rod type pre-support used in the tunnelling method according to the present invention, Fig. 37 is a detail sectional view of a steel wire type pre-support used in the tunnelling method according to the present invention, Fig. 38 is a sectional view taken along the line F-F in Fig. 37, and Fig. 39 is a sectional view taken along the line G-G in Fig. 37.

[29] As shown in Fig. 36, since the steel rod type pre-support 114 has no center hole, a grout hose 114a for injecting the grouting liquid 74a into the perforation 22 is coupled along the side of the steel rod pre-support 114.

[30] As shown in Figs. 37 to 39, in a steel wire type pre-support 115, a grout hose 114a passing through a center of the perforation 22 is inserted into center holes of first and second spacers 115a and 115b, and a plurality of steel wires 115c is installed in the outer circumferences of the first and second spacers 115a and 115b.

[31] Fig. 40 is a sectional view illustrating an insertion pipe 125. The insertion pipes

125 fill the perforation 22 by injecting the grout liquid through the center hole of the hollow steel rod type pre-support 110, are engaged with the threads 110a of the hollow steel rod type pre-support 110 such that the short pipe 123 having the rubber packing 123a closely contacts the inside of the rubber horn of the rubber packer 122, and are released from the engagement with the threads 110a after curing the grout liquid, in order for these operations to be smoothly performed, the inner circumferences of the insertion pipe 125 are coated with lubricant 125a to prevent them from corroding, and are connected to each other by release preventing couplers 125b in series. Moreover, at the end of the insertion pipe 125 positioned in the pilot tunnel 21, a releasing lever 125c is coupled to be rotated when the insertion pipes 125 are disassembled.

[32] Fig. 43 is a sectional view illustrating a state of an air packer before being operated to the hollow steel rod type pre-support according to the present invention, and Fig. 44 is a sectional view illustrating a state of the air packer after being operated to the hollow steel rod type pre-support according to the present invention. As shown in Figs. 43 and 44, the packer device 120 includes a hollow pipe 131 engaged with the threads 110a of the hollow steel rod type pre-support 110 as the entrance of the perforation 22, an air packer 132 coupled with the outer circumference of the hollow pipe 131 and filled with air to closely pack the inner circumference of the perforation 22, a third donut-shaped stopper 133 coupled with a side of the air packer 132, and a fourth donut-shaped stopper 135 coupled with the opposite side of the air packer 132 in relation to the entrance of the perforation 22 and having an introducing hole to fill the air packer 132 with air through a packer pressing hose 134.

[33] Fig. 45 is a sectional view illustrating the installation of blast holes in the per¬ forations to the excavation line of the main tunnel in the pilot tunnel of the large sectional tunnel according to the present invention, Fig. 46 is a plan view of Fig. 45, and Fig. 47 is an enlarged sectional view of the portion "I" in Fig. 46.

[34] In the pilot tunnel 21 of the large sectional tunnel, a pre-support protector prevents the pre-support 110 from breaking due to the blasting when the perforation 22 is filled with charge to the excavation line 20 of the main tunnel and a blast hole is blasted. The pre-support protector includes a polyethylene foam pipe 141 installed on the outer cir¬ cumference of the short pipe 123 on the outer circumference of the hollow steel rod type pre-support 110 which is inserted into the perforation 22 formed outside the excavation line 20 of the main tunnel, a tamping envelope 142 positioned at the end of the entrance of the hollow steel rod type pre-support 110 to sequentially accommodate polyethylene foam 142a and sand 142 for reduction of shock wave, and low speed charge 143 and sand tamping are tamped repeatedly at the side of the tamping envelope 142 to blast.

[35] Fig. 48 is a sectional view illustrating a drilling machine for drilling the perforation hole in the pilot tunnel of the large sectional tunnel in the radial direction, Fig. 49 is a sectional view illustrating that a drilling rod coupled with a guide beam of the drilling machine used in the large sectional tunnel according to the present invention is rotated according to change of rotational angles, and Fig. 50 is a plan view illustrating the drilling machine.

[36] In order to excavate the pre-support tunnel, a plurality of the drilling machines is installed in the pilot tunnel to drill the perforations toward the excavation line in the radial direction. The drilling machine includes a main body 151 having a power transmission installed in the longitudinal direction of the pilot tunnel, out hydraulic lifts 152 installed to the lateral front and rear sides of the main body 151 to support the main body 151 and to adjust the height of the main body 151, a central shaft 153 positioned on a longitudinal central line of the pilot tunnel 21 and supported to be rotated at the central portion of the main body 151, a drilling device 154 coupled with the front side of the central shaft 153 to rotate in the transversal direction of the pilot tunnel 21 and to drill a plurality of perforations 22 in the radial direction, and a level 155 coupled with the rear side of the central shaft 153 to check whether the main body 151 is level and to control the out hydraulic lifts 152.

[37] The drilling device 154 includes a guide beam 154b coupled with the front side of the central shaft 153 in the vertical direction through a shaft rotating device 154a, and a drilling rod 154c coupled with the guide beam 154b to drill the perforation 22 and rotated together with the guide beam 154b being rotated by 180 degrees by the shaft rotating device 154a when the guide beam 154b rotates and the rotation angle α of the guide beam 154b with respect to the horizon line is an obtuse angle.

[38] In the pilot tunnel 21, a section of the pilot tunnel 21 is excavated such that the center of curvature of a crown 20a of the excavation line 20 of the main tunnel is identical to the center of curvature of a crown 21a of the pilot tunnel 21.

[39] The drilling machine is a device for mechanically and precisely installing the pre- support in the pilot tunnel 21. For such a mechanical installation, it is advantageous that the section of the tunnel must be designed to have a single curvature, at least the crowns 20a and 21a of 120 degrees must be designed to have a single curvature.

Advantageous Effects

[40] As described above, according to the tunnelling method using pre-support concept and the adjustable apparatus thereof, since a plurality of pre-supports 10 is installed from the ground of the excavation line 20 of the tunnel by drilling, the installation does not interfere with the excavation so that the period needed to construct a tunnel is reduced, land subsidence is reduced compared to when the rock bolts are installed in the conventional tunnel, stand-up time for excavating a tunnel is prolonged, the tunnelling method has an arch-forming effect of the ground surrounding the tunnel, a ground improvement effect, a support-forming effect, an internal pressure effect of the convergence of a tunnel, and a keying effect of rock mass.

[41] Moreover, since the segments 30 and the pre-supports 10 are connected and fastened to each other to press the convergence of the tunnel, a lining effect can be obtained, and since the ground of the crown can be pressed in a short time, the tunnelling method can be applied to a soil tunnel. When installing vertical piles to both of the sidewalls of the tunnel from ground, the vertical piles serve to resist soil from the sidewalls, and the central vertical piles serve as pillars in a tunnel which has two arches after excavating three arches. Since the drain boards are installed at the excavation surface of the tunnel and the segments 30, drainage is smoothly carried out and efflorescence arisen from the shotcrete in the conventional tunnel does not occur. Moreover, since the shallow overburden tunnel with a thin cover resulting at the entrances and the exits of tunnels constructed in urban regions or in mountainous regions can be constructed without excessive excavation of original ground, the tunnel can be constructed without damage of natural environment. In especially, since friction of the pre-supports is insufficient in a tunnel with a very thin cover of 5 m to 6 m, either concrete slab 80 serving as a reaction beam against ground is placed or the pre- supports are pressed by segments so that pre-stress is applied to steel rods 61 as tensile members of the pre-stress type pre-supports 60, so that land subsidence is reduced, and shear stress is increased. Brief Description of the Drawings

[42] The above and other objects, features and other advantages of the present invention will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which:

[43] Figs. 1 to 3 are sectional views illustrating the installation of pre-supports toward a predetermined excavation line of a tunnel in the various forms prior to the excavation of the tunnel according to a tunnelling method of the present invention;

[44] Fig. 4 is a sectional view illustrating the installation of a pillar of a tunnel having two arches after excavating three arches with pre-supports;

[45] Fig. 5 is a sectional view illustrating that according to a tunnelling method of the present invention, a tunnel is excavated after the installation of pre-supports and all the pre-supports are connected and fastened to each other along an excavation line of the tunnel by segments;

[46] Fig. 6 is a sectional view illustrating that according to the tunnelling method of the present invention, a tunnel is excavated after installation of pre-supports and the pre- supports are connected and fastened to each other along the excavation line of the tunnel by a truss made of reinforcing rods;

[47] Fig. 7 is a sectional view illustrating that according to a tunnelling method of the present invention, pre-supports are installed and reinforced by a plurality of pipe roofs at regular intervals in the transversal direction of a tunnel, and after that, the tunnel is excavated, arch-shaped steel ribs are installed at regular intervals in the longitudinal direction of the tunnel and are connected to the pre-supports by fastening;

[48] Fig. 8 is a sectional view illustrating that according to a tunnelling method of the present invention, pre-supports are positioned in the vicinity of the excavation line of a tunnel such that the pre-supports do not interfere with a plurality of pipe roofs;

[49] Fig. 9 is a perspective view illustrating that according to a tunnelling method of the present invention, a plurality of pipe roofs is installed at regular intervals in the transversal direction of a tunnel and arch-shaped steel ribs are installed at a pre¬ determined interval in the longitudinal direction of the tunnel such that the arch-shaped steel ribs are connected to the pre-supports by fastening;

[50] Fig. 10 is a perspective view illustrating the connection between pre-supports by steel plates according to a tunnelling method of the present invention;

[51] Fig. 11 is a sectional view taken along the line A-A in Fig. 9;

[52] Fig. 12 is a sectional view illustrating that rock bolts are fastened to the lower side of the excavation line of a tunnel according to a tunnelling method of the present invention;

[53] Fig. 13 is a partial sectional view illustrating that in the tunnelling method according to the present invention, pre-supports are piled deeper than the excavation line of a tunnel for the self -reinforcement of a facing of the tunnel;

[54] Fig. 14 is a sectional view taken along the line B-B in Fig. 13;

[55] Fig. 15 is a sectional view taken along the ling C-C in Fig. 13;

[56] Fig. 16 is a perspective view illustrating that, in the tunnelling method according to the present invention, band-type drain boards are continuously installed in the cir¬ cumference of a tunnel between the excavation face and segments when forming linings using trusses made of reinforcing bars and shotcrete;

[57] Fig. 17 is a sectional view illustrating other drainages of a tunnel in the tunnelling method according to the present invention;

[58] Fig. 18 is an enlarged sectional view illustrating the drainage in Fig. 17;

[59] Fig. 19 is a sectional view illustrating effect of applying pre-stress to pre-supports when shell forming members such as pre-stress type pre-supports, segments, or the like are connected to each other by pressing plates in a tunnelling method according to the present invention;

[60] Fig. 20 is a detail sectional view illustrating a leading end supporting pre-stress type pre-support indicated by D in Fig. 19;

[61] Fig. 21 a sectional view illustrating pre-supports installed in a shallow overburden tunnel with thin cover in a tunnelling method according to the present invention;

[62] Fig. 22 is a perspective view illustrating a reinforced truss used in a tunnelling method according to the present invention;

[63] Fig 23 is a sectional view taken along the line X-X in Fig. 22;

[64] Fig. 24 is a sectional view taken along the line Y-Y in Fig. 22;

[65] Figs. 25 to 29 are views illustrating the sequence of installation of pre-supports in a tunnelling method according to the present invention;

[66] Fig. 30 is a sectional view illustrating that the pre-supports are inserted into per¬ forations formed in the radial direction in a pilot tunnel within in a large sectional tunnel;

[67] Fig. 31 is a sectional view illustrating that in the tunnelling method, a large sectional tunnel is excavated after the installation of the pre-supports and the segments are connected to the respective pre-supports in the excavation line of the tunnel;

[68] Fig. 32 is a sectional view illustrating that in the tunnelling method, a large sectional tunnel is excavated after the installation of the pre-supports and the trusses made of reinforcing bars are connected to the respective pre-supports in the excavation line of the tunnel;

[69] Fig. 33 is a sectional view illustrating that in the tunnelling method, a large sectional tunnel is excavated after the installation of the pre-supports and the rein¬ forcement using a plurality of pipe roofs at regular intervals in the transversal direction, and arch-shaped steel ribs are connected to the pre-supports after the arch- shaped steel ribs are installed at regular intervals in the longitudinal direction of the tunnel in the excavation line of the tunnel;

[70] Fig. 34 is a detail sectional view illustrating a hollow steel rod type pre-support used in the tunnelling method according to the present invention;

[71] Fig. 35 is a sectional view taken along the line E-E in Fig. 34;

[72] Fig. 36 is a detail sectional view of a steel rod type pre-support used in the tunnelling method according to the present invention;

[73] Fig. 37 is a detail sectional view of a steel wire type pre-support used in the tunnelling method according to the present invention;

[74] Fig. 38 is a sectional view taken along the line F-F in Fig. 37;

[75] Fig. 39 is a sectional view taken along the line G-G in Fig. 37;

[76] Fig. 40 is a sectional view illustrating a pre-support insertion pipe according to the present invention;

[77] Fig. 41 is a detail sectional view illustrating the portion H in Fig. 34 before inserting and fastening the pre-support insertion pipe according to the present invention;

[78] Fig. 42 is a detail sectional view illustrating the portion H in Fig. 34 after inserting and fastening the pre-support insertion pipe according to the present invention;

[79] Fig. 43 is a sectional view illustrating a state of an air packer before being operated to the hollow steel rod type pre-support according to the present invention;

[80] Fig. 44 is a sectional view illustrating a state of the air packer after being operated to the hollow steel rod type pre-support according to the present invention;

[81] Fig. 45 is a sectional view illustrating the installation of charging holes in the per- forations to the excavation line of the main tunnel in the pilot tunnel of the large sectional tunnel according to the present invention;

[82] Fig. 46 is a plan view of Fig. 45;

[83] Fig. 47 is an enlarged sectional view of the portion I in Fig. 46;

[84] Fig. 48 is a sectional view illustrating a drilling machine for drilling a perforation hole in the pilot tunnel of the large sectional tunnel in the radial direction;

[85] Fig. 49 is a sectional view illustrating that a drilling rod coupled with a guide beam of the drilling machine used in the large sectional tunnel according to the present invention is rotated according to change of rotational angles; and

[86] Fig. 50 is a plan view illustrating the drilling machine. [87]

[88] 10: pre-support 11: pressing plate

[89] 12: fixing device 20: excavation line

[90] 21 : pilot tunnel 22: perforation

[91] 30: segment 31: insertion protrusion

[92] 32: insertion recess 33: truss

[93] 34: pipe roof 35: steel rib

[94] 36: steel plate 37: shotcrete

[95] 40: drain board 50: rock bolt

[96] 60: precast type pre-support 61: steel rod

[97] 62: steel pipe 63: protrusion

[98] 65: anticorrosion lubricant 66: grouting

[99] 67: polyethylene pipe 70: drainage

[100] 71: T-shaped connection pipe 72: drainage pipe

[101] 73: weep drainage pipe 73a: through-hole

[102] 74: horn-shaped funnel 74a: grouting liquid

[103] 110: hollow steel rod type pre-support

[ 104] 110a: thread 111: protruded bar

[105] 112: centerizer 113: coupler

[106] 113a: locking pin 120: packer

[107] 121, 124: first and second stoppers

[108] 113, 122: rubber packers 123: short pipe

[109] 123a: rubber packing 125: insertion pipe

[110] 131: hollow pipe 132: air packer

[111] 133, 135: third and fourth stoppers

[112] 134: packer pressing hose 141: polyethylene foam pipe

[113] 142: tamping envelope 142a: polyethylene foam

[114] 142b: sand 143: charge [115] 144: sand tamping 151: main body

[116] 152: out hydraulic lift 153: central shaft

[117] 154: drilling device 154a: shaft rotating device

[118] 154b: guide beam 154c: drilling rod

[119] 155: level

[120]

[121]

Claims

[1] A tunnelling method using pre-support concept comprising the steps of: drilling and installing a plurality of pre- supports from ground to a predetermined excavation line of a tunnel and performing grouting; excavating the tunnel along the predetermined excavation line and installing drain boards at the excavated surface; installing segments to the respective pre-supports at the lower sides of the drain boards in series such that insertion protrusions and insertion recesses formed in the lateral sides of the segments are engaged with each other to form lining; and pressing and fixing the segments to the pre-supports by attaching pressing plates to the pre-supports penetrating the segments.

[2] A tunnelling method using pre-support concept comprising the steps of: drilling and installing a plurality of pre-supports from ground to a predetermined excavation line of a tunnel and performing grouting; excavating the tunnel along the predetermined excavation line and installing drain boards at the excavated surface; installing trusses made of reinforcing rods to the respective pre-supports at the lower sides of the drain boards in series such that pressing plates are attached to the pre-supports penetrating the trusses and the reinforced trusses are pressed and fixed by fastening fixing devices; and placing shotcrete in the trusses.

[3] A tunnelling method using pre-support concept comprising the steps of: drilling and installing a plurality of pre-supports from ground to a predetermined excavation line of a tunnel and performing grouting; installing pipe roofs at regular intervals in the transversal direction of the tunnel along the direction of the tunnel advance, installing drain boards in the lower sides of the pipe roofs while excavating the tunnel, installing arch-shaped steel ribs in the lower sides of the pipe roofs in the transversal direction of the tunnel along the direction of the tunnel advance, and installing steel plates between the steel ribs to connect the steel ribs to each other and to press and fix the steel plates by fastening pressing plates and fixing devices; and placing shotcrete between the pipe roofs and the steel plates.

[4] The tunnelling method using pre-support concept as set forth in claim 3, wherein the pre-supports are positioned in the vicinity of the excavation line of the tunnel so that the pre-supports do not interfere with the pipe roofs.

[5] The tunnelling method using pre-support concept as set forth in claims 1 ,2 or 3, further comprising the step of coupling and fastening the pre-supports with and to the pressing plates within the excavation line of the tunnel, and installing rock bolts in the lateral lower sides of the excavation line, that is, in regions where the excavation is relatively easily performed.

[6] The tunnelling method using pre-support concept as set forth in claims 1 ,2 or 3, further comprising the step of piling the pre-supports downward deeper than the excavation line of the tunnel for the self -reinforcement of a facing of the tunnel.

[7] The tunnelling method using pre-support concept as set forth in claims 1 ,2 or 3, further comprising the step of installing the pre-supports at the sidewall of the tunnel in the vertical direction such that the pre-supports approach the bottom of the tunnel to reinforce the sidewall of the tunnel.

[8] The tunnelling method using pre-support concept as set forth in claims 1 ,2 or 3, wherein the pre-supports comprise pre-stress type pre-supports in which pre- stress is generated when the pre-supports are pressed by the pressing plates with reactive force.

[9] The tunnelling method using pre-support concept as set forth in claim 8, wherein the installation of the pre-stress type pre-supports is performed by the steps of: drilling from ground to a predetermined excavation line of the tunnel; inserting the pre-supports in which ends of steel rods as tensile members inserted into polyethylene pipes are fixed to the inner circumferences of steel pipes having a plurality of protrusions formed in the outer circumferences thereof, and anticorrosion lubricant is coated on the outer circumferences of the steel rods and the inner circumferences of the steel pipes such that the steel rods are freely deformed in the steel pipes, into perforations drilled in the above step; and grouting between the outer circumferences of the pre-stress type pre-supports inserted in the above step and the perforations.

10. The tunnelling method using pre-support concept as set forth in claim 9, wherein when the pre-stress type pre-supports are installed in a tunnel with a thin cover, ends of the pre-stress type pre-supports are fixed to a concrete slab installed on ground.

11. The tunnelling method using pre-support concept as set forth in claims 1 ,2 or 3, wherein when the pre-supports are installed in a tunnel having two arches after excavating three arches, the pre-supports are installed deeper than the formation line of the tunnel such that the pre-supports, installed at the center of the tunnel having two arches after excavating three arches in the vertical direction, form pillars of the tunnel before the excavation of the tunnel having two arches after excavating three arches.

12. The tunnelling method using pre-support concept as set forth in claim 2, wherein the trusses are welded to each other in the form of a truss in the transversal direction and in the longitudinal direction of the tunnel, and re¬ inforcing bars connect the trusses to each other duplicately in series.

13. A drainage of a tunnel in which a plurality of pre-supports are installed from ground to a predetermined excavating line of the tunnel and segments are installed to the pre-supports at the predetermined excavation line, the drainage comprising: drainage pipes (72) installed between the excavation line (20) of the tunnel and the segments (30) and connected to each other at regular intervals through T- shaped connection pipes (71); weep drainage pipes (73) connected to the T-shaped connection pipes (71) of the drainage pipes (72) with respect to the excavation line (20) in the radial direction and having through-holes (73 a) formed in the outer circumference thereof; horn-shaped funnels (74) inserted into the lower outer circumferences of the weep drainage pipes (73) without the through-holes (73 a) to prevent grouting liquid (74a) from flowing into the through-holes (73a); and caps (75) for covering the upper sides of the weep drainage pipes (73).

14. A tunnelling method using pre-support concept comprising the steps of: excavating a pilot tunnel in a large sectional tunnel; forming a plurality of perforations in the radial direction in order to install the pre-supports in the pilot tunnel; inserting the pre-supports into the perforations formed in the radial direction in the above step, grouting, and curing the grout; excavating the pilot tunnel along the excavation line of the large sectional tunnel and installing drain boards in the excavated surface; installing segments to the respective pre-supports at the lower sides of the drain boards in series such that insertion protrusions and insertion recesses formed in the lateral sides of the segments are engaged with each other; and attaching pressing plates to the pre-supports inserted into the segments and fastening fixing devices to press and fix the segments to the pre-supports.

15. A tunnelling method using pre-support concept comprising the steps of: excavating a pilot tunnel in a large sectional tunnel; forming a plurality of perforations in the radial direction in order to install the pre-supports in the pilot tunnel; inserting the pre-supports into the perforations formed in the radial direction in the above step, grouting, and curing the grout; excavating the pilot tunnel along an excavation line of the large sectional tunnel and installing drain boards in the excavated surface; installing trusses made of reinforcing bars to the respective pre-supports at the lower sides of the drain boards in series such that pressing plates are attached to the pre-supports penetrating the trusses and fixing devices are fastened to press and fix the trusses to the pre-supports; and placing shotcrete into the trusses.

16. A tunnelling method using pre-support concept comprising the steps of: excavating a pilot tunnel in a large sectional tunnel; forming a plurality of perforations in the radial direction in order to install the pre-supports in the pilot tunnel; inserting the pre-supports into the perforations formed in the radial direction in the above step, grouting, and curing the grout; installing pipe roofs at regular intervals in the transversal direction of the sectional tunnel along the longitudinal direction of the tunnel, installing drain boards at the lower sides of the pipe roofs while excavating the tunnel after the installation of the pipe roofs, installing arch-shaped steel ribs at the lower sides of the pipe roofs in the transversal direction along the longitudinal direction of the tunnel to interpose the drain boards between the pipe roofs and the steel ribs, coupling the steel ribs with each other by steel plates installed between the steel ribs, and fastening fixing devices to fix pressing plates; and placing shotcrete between the pipe roofs and the steel plates.

17. A tunnelling method using pre-support concept comprising the steps of: excavating a pilot tunnel in a large sectional tunnel; forming a plurality of perforations in the radial direction in order to install the pre-supports in the pilot tunnel; inserting the pre-supports into the perforations formed in the radial direction in the above step, grouting, and curing the grout; excavating the tunnel along the excavation line and installing drain boards to the excavation surface thereof; and placing shotcrete at the lower sides of the drainage boards.

18. A pressure grouting apparatus for inserting pre-supports into perforations formed in the radial direction in a pilot tunnel and for pressure-grouting the per¬ forations in order to excavate and construct a pre-support tunnel, comprising: a plurality of hollow steel rod type pre-supports (110), which have threads (HOa) formed in the outer circumferences and a plurality of centerizers (112), having protruded bars (111) protruded outwardly from the outer circumferences thereof to maintain distance between centers of the perforations (22) and coupled with the intermediate outer circumferences of the hollow steel rod type pre-supports (110), and are connected to each other by couplers (113), for performing pressure-grouting by injecting grout liquid (74a) into the perforations (22); and a packer (120) engaged with the threads of the hollow steel rod type pre-support (110) positioned at the entrances of the perforation (22) to fill the perforations (22) by injecting the grout liquid (74a) into the perforations (22) through the hollow steel rod type pre-supports (110) and after that for packing the entrances of the perforations (22).

19. The pressure grouting apparatus as set forth in claim 18, wherein the packer

(120) comprises: a donut-shaped first stopper (121) engaged with threads (110a) of the hollow steel rod type pre-support (110); a rubber packer (122) having a rubber horn and engaged with the threads (HOa) of the hollow steel rod type pre-support (110), that is, a side of a first stopper

(121) to be installed to face the entrance of the perforation (22); a short pipe (123) coupled with the outer circumference of the hollow steel rod type pre-support (11), that is, a side of the rubber packer (122) to move on the outer circumference of the hollow steel rod type pre-support (110) to make the rubber horn of the rubber packer (122) closely contact the inner circumference of the perforation (22) and having a wedge-shaped rubber packing (123a) coupled with the outer circumference thereof; a second donut-shaped stopper (124) coupled with the outer circumference of the short pipe (123), that is, the side of the rubber packing (123a) to make the wedge-shaped rubber packing (123a) closely contact the inside of the rubber horn of the rubber packer (122) such that a side of the second donut-shaped stopper (124) is locked by the wedge-shaped rubber packing (123a); and an insertion pipe (125) fastened to the threads (110a) of the hollow steel rod type pre-support (110) to move the wedge-shaped rubber packing (123a) from the side of the short pipe (123) to the rubber horn of the rubber packer (122).

20. The pressure grouting apparatus as set forth in claim 18, wherein the couplers (113) are installed in the outer circumferences of the threads (110a), that is, parts for connecting the hollow steel rod type pre-supports (110) to each other and locking pins (113a) are inserted into the inner circumferences to maintain the connection between the hollow steel rod type pre-supports (110).

21. The pressure grouting apparatus as set forth in claim 18, wherein the packer device (120) comprises: a hollow pipe (131) engaged with the threads (HOa) of the hollow steel rod type pre-support (110) as the entrance of the perforation (22); an air packer (132) coupled with the outer circumference of the hollow pipe (131) and filled with air to closely pack the inner circumference of the perforation (22); a third donut-shaped stopper (133) coupled with a side of the air packer (132); and a fourth donut-shaped stopper (135) coupled with the opposite side of the air packer (132) as the entrance of the perforation (22) and having an introducing hole to fill the air packer (132) with air through a packer pressing hose (134).

22. A pre-support protector for preventing a hollow steel rod type pre-support (110) from breaking due to blasting when a perforation (22) is filled with charge to an excavation line (20) of a main tunnel having a pilot tunnel (21) of a large sectional tunnel and a blast hole is blasted, the pre-support protector comprising: a polyethylene foam pipe (141) installed on the outer circumference of a short pipe (123) on the outer circumference of the hollow steel rod type pre-support (110) which is inserted into the perforation (22) formed outside the excavation line (20) of the main tunnel; and a tamping envelope (142) positioned at the end of the entrance of the hollow steel rod type pre-support (110) to sequentially accommodate polyethylene foam (142a) and sand (142) for reduction of shock wave, and low speed charge (143) and sand tamping are tamped repeatedly at the side of the tamping envelope (142) to blast.

23. A drilling machine installed in the pilot tunnel to drill perforations toward the excavation line in the radial direction for the excavation and construction of a pre-support tunnel, comprising: a main body (151) having a power transmission installed in the longitudinal direction of the pilot tunnel (21); out hydraulic lifts (152) installed at the lateral front and rear sides of the main body (151) to support the main body (151) and to adjust the height of the main body (151); a central shaft (153) positioned on a longitudinal central line of the pilot tunnel

(21) and supported to be rotated at the central portion of the main body (151); a drilling device (154) coupled with the front side of the central shaft (153) to rotate in the transversal direction of the pilot tunnel (21) and to drill a plurality of perforations (22) in the radial direction; and a level (155) coupled with the rear side of the central shaft (153) to check whether the main body (151) is level and to control the out hydraulic lifts (152).

24. The drilling machine as set forth in claim 23, wherein the drilling device (154) comprises: a guide beam (154b) coupled with the front side of the central shaft (153) in the vertical direction through a shaft rotating device (154a); and a drilling rod (154c) coupled with the guide beam (154b) to drill the perforations (22) and rotated together with the guide beam (154b) being rotated by 180 degrees by the shaft rotating device (154a) when the guide beam (154b) rotates and the rotation angle α of the guide beam (154b) with respect to the horizon line is an obtuse angle.

25. The tunnelling method using pre-support concept as set forth in claims 14 to 16, wherein in the pilot tunnel (21), a section of the pilot tunnel (21) is excavated such that the center of curvature of a crown (20a) of the excavation line (20) of the main tunnel is identical to the center of curvature of a crown (21a) of the pilot tunnel (21).