KR970007349B1 - Method for making tunnels - Google Patents

Abstract

To be able to excavate a tunnel stably and in a short period of time, three processes are implemented. A mine excavating process ; a mine ahead is excavated to a side wall mine, in a width exceeding the side wall part of the tunnel, herein a concrete wall body is installed, an installation process ; a steel rib(10b) having an arching correction means(16) which is supported by the concrete wall body(4) is arranged to be integrally connected with the steel rib which is adjusted to be neared to the inner periphery face of the tunnel by changing the curvature of the steel ribs so the initial transition of the ground is controlled, then a reinforcing process ; plural steel pipes(18) are buried along the outer periphery face to be radially arranged, and treated with grouting to stabilize the inner periphery of the tunnel.

Description

Tunnel excavation method of soft ground in urban area

1 is a front view showing an example of excavation of a tunnel according to the present invention.

FIG. 2 is a partially enlarged cross-sectional view showing an extract of the cross section of the advanced shaft shown in FIG. 1. FIG.

3 is a partially enlarged cross-sectional view for illustrating an excavation example related to the top of the tunnel of FIG.

4 is a view for describing the structure of the steel ribs installed in the tunnel annular portion of FIG.

5 is an enlarged view of portion “Z” of FIG.

6 is a side cross-sectional view taken along the line Y-Y of FIG.

7 is a side cross-sectional view of a tunnel for showing an example of the arrangement of steel pipes buried above the steel ribs.

8 is a schematic view showing an example of a link member for connecting adjacently arranged steel ribs in a traveling direction of a tunnel.

9 is a graph showing the correlation between the support pressure and the tunnel deformation according to the present invention and the conventional method.

* Explanation of symbols for main parts of the drawings

2: advanced construction 4: concrete wall

8: top 10a, 10b: steel lip

12: annular portion 16: arching correction means

18: steel pipe 14: support

22: link member 22

The present invention relates to a tunnel excavation method, and more particularly, to a tunnel excavation method of a soft ground in the urban area that can safely excavate the ground of the soft ground in which a large load such as a building is distributed on the ground surface.

Tunnel excavation works are selected in advance according to the geological conditions obtained through surveying and geological surveys.

The excavation procedure of the tunnel in the soft ground is to dig a part of the tunnel in order to make an advanced mine, and to gradually expand the periphery thereof.

On the other hand, according to the excavation site, the advanced pit is a true chamber pit that digs the central top of the tunnel, a low snow pit that digs the bottom of the center, and two side walls which are formed on both side walls. (側壁 導 坑), central digging ditches, lower digging ditches digging the central bottom deeper than the excavation range, and parallelism digging parallel to the tunnel outside the excavation range of the tunnel Gang (平 行 導 坑) and the like.

During the excavation of the tunnel, the ground around the tunnel is deformed and stabilized due to the arching effect that tries to maintain the original position by shear resistance.

However, in soft ground where the ground shear resistance is small and the toffee in the upper part of the tunnel is too small (where the thickness of the toffee is expressed as the ratio of non-H / D to the tunnel diameter, which is called the soil layer ratio. Diameter) When the upper part of the upper toffee is in the relaxation region, the arching effect cannot be expected, and when the tunnel is excavated under such conditions, special attention should be paid to the problem of soil collapse.

As a well-known method in the related art, one of the methods that can excavate a tunnel in unstable ground such as soft ground is the NATM method.

In this NATM method, shotcrete and rock bolts are installed alone or in parallel to the excavated inner circumferential surface in parallel with the excavation of the tunnel, allowing small deformation of the ground around the tunnel and releasing large stresses. This is how to stabilize the tunnel.

However, the NATM method also has no effect in soft ground or small soil conditions (for example, H / D <1) where large loads such as buildings are widely distributed on the earth's surface.

When the tunnel is excavated in the urban area as the soft ground where large loads are distributed, the thickness of the bottom plate existing on the top surface of the tunnel is extremely thin due to the underground buried portion of the building distributed on the ground surface.

In this case, the thickness of the ground may be limited to at least 3 meters. If the thickness of the ground is thin, the installation of the lock bolt is impossible and the weight itself of the building distributed on the ground acts as a load, causing excessive deformation and only shotcrete. The NATM method is not suitable as a tunnel excavation method for urban soft ground because it cannot cope with the collapse sufficiently.

An object of the present invention is to complete the construction in a short time while completely reinforcing measures to prevent excessive displacement of the ground due to the load load of the building applied through the ground surface when excavating the tunnel at a shallow depth in the soft ground on which the building is erected. It is to provide tunnel excavation method of soft ground in the urban area.

In accordance with the above object, the present invention is a mining excavation process of excavating the advanced mining with a side wall, but excavating to an area exceeding the side wall of the tunnel and placing a concrete wall therein; Section and the annular sections on both sides, and then install a steel rib with arching correction means between the concrete walls of the advanced pit, and by using the arching point means described above, A copper bar installation process for adjusting the contact with the inner circumferential surface to suppress an increase in ground displacement; A plurality of steel pipes are embedded along the outer circumference of the semi-circular steel ribs, arranged in a radial direction parallel to the excavation direction of the tunnel, and then grouted to stabilize the inner circumferential surface of the tunnel. do.

In the present invention as described above, the arching correction means for allowing the steel ribs to be in close contact with the inner circumferential surface of the tunnel may use a hydraulic jack, a screw jack, or an electric jack.

And the steel ribs located on the ceiling center side of the tunnel can be supported by the prepared support until the annular portion of the tunnel is excavated.

In this case, the support is easy to use the length adjustable ones.

Steel pipes arranged on the outer circumferential surface of the steel ribs are preferably buried in a predetermined portion of the ground by their own major method, and in the case of embedding, it is best to make the arrangement angle of the steel pipes along the traveling direction of the tunnel horizontal. However, in reality, the horizontal arrangement of the steel pipe is difficult, so the arrangement angle is preferably limited to the range of 1 to 6 degrees to have an effect almost equivalent to the horizontal arrangement.

In addition, it is preferable to use a steel pipe having a plurality of holes drilled in the outer circumferential surface, which is a compact grouting process by embedding the steel pipe in the ground and then spraying the grouting material at low speed through the hole in the outer circumferential surface thereof. Comp∞don Grouting).

In addition, the steel ribs in close contact with the inner circumferential surface of the tunnel may be connected to each other adjacent to each other by a separate link member in order to improve the rigidity of the reinforcement.

As described above, the present invention has a considerably low ratio (discharge ratio) between the diameter of the tunnel to be completed and the thickness of the upper toffee, and when the ground arch effect at the tunnel face cannot be expected.

1) Minimize relaxation area by performing advanced diameter of small diameter on tunnel side wall,

2) Concrete wall is placed on the side wall of advanced pit, constraining tunnel side wall part and utilizing as a support for supporting steel rib,

3) Excavate the cross section to minimize the excavation area of the top end of the tunnel and install the steel ribs.

4) Install Forepole on the outer circumferential surface of the top of the steel rib,

5) By jacking one end of the steel ribs, the steel ribs and the sulfool are brought into close contact with each other so that a sufficient internal pressure can be applied.

1) Minimize the relaxation area of the ground around this tunnel,

2) Stabilize the tunnel by suppressing excessive deformation by applying internal pressure,

3) Even in the worst case, as the topol, steel ribs and sidewall concrete, the top load can be supported without excessive deformation, thereby preventing the collapse of the tunnel and excessive deformation of the superstructure.

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

EXAMPLE

(Pit excavation process)

Referring to FIG. 1, the tunnel excavation of the present invention begins by digging the lower sidewall portions of both tunnels similarly to the sidewall robing form to form two advanced shafts 2.

The advanced mine 2 can be distinguished from the generalized sidewall mine type in that the excavation cross section is set to an area exceeding the outside of the tunnel.

When the advanced pit 2 extends to a certain extent along the traveling direction of the tunnel, the formed space is shotcrete-treated and a concrete wall 4 that is roughly matched to the outside of the tunnel is poured.

If necessary in the process of placing the concrete wall (4), the ground can be stabilized by embedding a plurality of long and short lockblets (6) radially toward the inner periphery of the tunnel.

(Dongbari installation process)

Referring back to FIG. 1, after finishing the concrete wall 4, the top 8 is dug along the periphery of the tunnel to be excavated.

When a predetermined space corresponding to the top 8 is formed, steel ribs 10a are installed on the upper inner circumferential surface of the tunnel as shown in FIG.

This steel rib 10 is temporarily supported by the ordinary support 14 until the annular portions l2 on both sides are excavated. The support 14 may be easily constructed by using a length adjustable one.

After the excavation of the top 8 and the installation of the steel rib 10a are completed, the annular portions 12 on both sides are excavated.

The excavated annular portion 12 is provided with a steel rib 10b depicted in FIG. 4 so as to be integrally connected with the intermediate steel rib 10a.

The steel ribs 10b described above are curved to have almost the same curvature as the steel ribs 10a of the top 8, but are provided with arching correction means 16 on the side supported by the concrete wall 4.

The arching correction means 16 may be supported by the concrete wall 4 to change the curvature of the semicircular foam formed by the connection of the steel ribs 10a and 10b.

The steel ribs 10a and 10b are brought into close contact with the excavation surface (inner circumferential surface) of the tunnel due to the change in curvature provided by the arching correction means 16, and as a result, the initial overdisplacement of the ground is suppressed.

A specific example of the arching correction means 16 is depicted in FIG.

In the depicted example, the arching correction means 16 is a screw 161, which is rotated by the knob 160, is supported by a fixed end 162 on one side and a screw-fit with the movable end 163 on the other side. It shows a screw jack.

The change in the curvature of the steel ribs 10a and 10b by the depicted screw jacking arching correction means 16 is more specifically defined by the operator by rotating the knob 160 to the fixed end 162 and the movable end ( 163 is shown as the distance between the arrows in FIG. 5 increases in the X direction, and the steel ribs 10a and 10b closely adhere to the inner circumferential surface of the tunnel due to the increase in curvature, thereby firmly supporting the ground, thereby improving the initial displacement of the ground. It will be suppressed.

In the present invention, the arcing correction means 16 is not limited to the screw jack method, and for example, an electric jack or a hydraulic jack may be applied.

(Excavation Surface Reinforcement Process)

As the above-described process is repeated, the steel ribs 10a and 10b are arranged innumerably at equal intervals in the depth of the tunnel. However, among these steel ribs 10a and 10b, the heights of the steel ribs 10a disposed at the top 8 of the tunnel are arranged non-horizontally in the traveling direction of the tunnel.

6 is a cross-sectional view showing the height change pattern of the steel rib 12a along the traveling direction of the tunnel by cutting in the Y-Y line direction of FIG.

The plurality of steel ribs 10a are arranged to return gradually to the initial height as the distance goes into the tunnel at a predetermined distance, thereby forming a sawtooth shape.

In an initial stage in which a number of steel ribs 10a and 10b corresponding to one tooth shape are arranged to form a constant slope, steel pipes 18 are embedded along the slope as shown in FIG.

The steel pipe 18 is embedded in the ground innumerable at equal intervals along the curved surface of the steel ribs (10a) (10b), the arrangement angle is best to be horizontal to the direction of the tunnel, but the construction difficulty Because of this, the angle of inclination? Rises slightly upward. This inclination angle [theta] is limited to the range of 1 to 6 degrees having the effect of a substantially horizontal arrangement in the present invention.

The grouting material is compressed and supplied through the embedded steel pipe 18 to reinforce the ground of the main part of the channel.

In the case where a plurality of holes are drilled on the outer circumferential surface of the steel pipe 18, the grouting material supplied with compression is excellent in the ground reinforcing effect by the compact grouting effect that is evenly mixed into the gaps of the ground through the holes.

The steel ribs 10a and 10b arranged in a semicircular shape along the inner circumferential surface of the tunnel may be connected to each other in the advancing direction of the tunnel.

FIG. 8 shows an example of a link member for allowing adjacent steel ribs 10a and 10b to be connected in a traveling direction of a tunnel.

FIG. 8 (a) shows an example in which one end of the link member 22 is welded to the steel ribs 10a and 10b via the rod 20, and FIG. 8 (b) shows the steel ribs 10a. The bracket (24) in the (10b) has been shown how to hook the hook-shaped end of the link member 22 is connected.

As such, the connection method of the steel ribs 10a and 10b by the link member 22 may be appropriately used in the present invention.

In addition, the link member 22 has a joint surface in which the ground monolayer structure extends horizontally, so that the link member 22 may be particularly effective when there is an instability of the ground layer along the excavation direction of the tunnel.

After the excavation surface reinforcement process is completed, the middle back part 26 and the large back part 28 shown in FIG. 1 are excavated to form a rough outline of the tunnel. In the same way, the excavation of the tunnel is terminated by selecting the floor and laying the rail on it, carrying out the plastering of the inner circumferential surface of the tunnel while transporting the sliding form corresponding to the outside of the tunnel over the rail.

As a result of measuring the deformation of the tunnel constructed by the present invention as described above compared with the conventional method, it is shown as a graph of FIG.

In FIG. 9, the intersection line (A) is the present invention, and the intersection line (B) is the case of reinforcement by shotcrete of 2 inches thick, and the intersection line (C) is a lock bolt of 1 inch diameter and 10 peak length. The case of reinforcing and reinforcing mechanically every 5 feet from the center within 10 feet of the excavation surface, and the cross line (D) indicates reinforcing only with steel ribs, and the cross line (E) is 1 inch in diameter and 10 in length. It shows the case where the rock bolt of the pit is mechanically buried and reinforced every 5 feet from the center about 30 feet of the excavation surface. Finally, the intersection line F is a measure when the breaking state of the steel rib is poor.

As can be seen from the graph of Fig. 9, the method of the present invention has a superior effect of the tunnel strain on the supporting material pressure over the conventional method in all parts of the ceiling, sidewall, and bottom.

As described above, the tunnel excavation method of the present invention can excavate advanced prongs to facilitate the entrance and exit of materials and equipment required for excavation of the top of the tunnel, and when the excavation of the top of the tunnel is completed, the steel ribs are immediately installed. Excavate the annular parts on both sides while temporarily supporting it by the support to prevent subsidence of the ground, and then install the steel ribs on the annular parts on both sides and connect them with the steel ribs on the top, and at the same time, By changing the curvature of the ribs so that these steel ribs are in close contact with the inner circumferential surface of the tunnel, the ground is not excessively displaced. Then, after reinforcing the ground by the grouting process, the steel pipe is buried along the curved surface of the steel rib. Excavate the middle and large back of the to form a rough tunnel contour, and then the bottom of the tunnel in the usual way. A pick there is an advantage capable of performing tunnel to very stable, even soft ground, which is a large load, because the water present in the earth's surface for performing plasterwork inner circumferential surface by using a sliding groove is fast.

Claims (7)

A mining excavation process of digging the advanced mining (2) by sidewall mining, digging to an area exceeding the sidewall of the tunnel, and placing the concrete wall (4) thereon; The center-side top 8 of the tunnel is excavated and steel ribs 10a are hypothesized therein, and then the annular portions 12 on both sides are excavated and supported by the concrete wall 4 of the advanced mine 2. A steel rib 10b having an arching correction means 16 is installed to be integrally connected to the steel rib 10a, and the steel ribs 10a and 10b are formed by the arching correction means 16. A copper bar installation step of changing the curvature so as to be in close contact with the inner circumferential surface of the tunnel to suppress initial displacement of the ground; A plurality of steel pipes 18 are embedded along the outer circumference of the semi-circular steel ribs 10a and 10b to be arranged in a radial direction parallel to the excavation direction of the tunnel, and then grouted to stabilize the inner circumferential surface of the tunnel. Tunnel excavation method for soft ground in the city, characterized in that the reinforcing process is performed in order. The method of claim 1, wherein the arcing correction means (16) is a tunnel excavation method for the soft ground of the urban area, characterized in that any one of a hydraulic jack, a screw jack or an electric jack. The soft ground of claim 1, wherein the steel ribs 10a positioned at the center of the inner circumferential surface of the tunnel are supported by a support port 14 prepared in advance until the annular portion 12 of the tunnel is excavated. Tunnel excavation method. The tunnel excavation method of the soft ground of the urban area, characterized in that the length of the support (14) is adjustable. The method of claim 1, wherein the steel pipe (18) arranged in a plurality along the curved surface of the steel rib (10a) (10b) is a tunnel excavation method of the soft ground in the urban area, characterized in that a plurality of holes are drilled in the outer peripheral surface. . The tunnel excavation method of the soft ground of claim 1, wherein the steel pipe 18 is embedded so that the inclination angle θ according to the tunnel traveling direction is inclined upward in a range of 1 to 6 degrees. . The tunnel of claim 1, wherein the steel ribs 10a and 10b are interconnected by separate link members 22, which are adjacent to each other according to the traveling direction of the tunnel. Excavation method.