JPH0718311B2 - Stabilization method of tunnel mirror - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention is intended to stabilize concrete by spraying concrete on the tunnel peripheral surface of an excavated portion and installing anchor bolts on the portion during tunnel construction. When applying the Natom method of construction while
Alternatively, the present invention relates to a stable construction method for a tunnel mirror section that prevents collapse of the excavated surface (hereinafter referred to as the mirror section) and collapse of the top end during excavation work on sandy ground that is poorly self-sustaining.

(Prior Art) Conventionally, as a stable construction method of the tunnel mirror part, (i) No. 5A,
As shown in FIG. 5B, a method of forming a face-holding portion referred to as (a) on the mirror portion in parallel with excavation to prevent the ground from collapsing, (ii) shown in FIGS. 6A and 6B. To spray concrete (b) onto the mirror, (iii) Figs. 7A and 7B
As shown in the figure, a method of reinforcing the sprayed concrete (b) portion with an anchor bolt (c) in the method (ii), (iv) an epoxy resin, a glass fiber instead of the mirror sprayed concrete. Incorporated inorganic resin,
Method of forming a thin film by spraying a polyurethane-based chemical solution onto the ground, (V) As shown in FIGS. 8A and 8B, a simple ground improvement chemical solution (d) is injected into the target improvement range in the ground. The way to do was done.

(Problems to be solved by the invention) However, in the first method, since the nucleus is close to the mirror portion, the work space is narrowed, and it is difficult to spray concrete or attach anchor bolts around the excavated tunnel. Becomes

Further, the second method cannot be expected to have a stabilizing effect when the mirror portion is entirely changed due to disturbance of the ground due to excavation.

Further, the third method requires time and labor for cutting the anchor bolt during excavation.

Further, the above-mentioned fourth method has many materials that require special handling, and many restrictions are imposed in terms of preventing pollution.

Furthermore, in the fifth method, since it is impossible to inject the ground improvement chemical solution into a predetermined planned position or range, it is not possible to expect a sufficient effect, and it takes a long time to inject the chemical solution. .

The present invention has been proposed in view of the above-mentioned problems of the prior art, and an object of the present invention is to provide a stable tunnel mirror section that is easy to construct and effectively stabilizes the mirror section in the ground. The point is to provide a construction method.

(Means for Solving the Problem) In order to achieve the above-mentioned object, a stable construction method of a tunnel mirror portion according to the present invention has a limit height at which a rock in front of the mirror portion can stand on its own when excavating a tunnel. It is configured to maintain a vertical interval in the interior and to form a thin plate-shaped horizontal consolidation layer having a certain depth in the ground in layers.

At this time, since the thin plate-shaped solidified layer is formed in layers on the mirror portion, a chemical solution injection pipe insertion hole is drilled horizontally in the ground in front of the mirror portion with respect to the excavation direction, and then the pipe is inserted into the hole. Adjusting and inserting so that the center line connecting the two injection ports is positioned horizontally, the injection pipes each having an injection injection port at a position on the diagonal of the pipe cross section at the tip end are inserted, and then while the injection pipe is being pulled out, The ground improvement chemical solution is injected into the ground through each injection port.

Further, when forming the solidified layer, the chemical solution injection pressure and injection rate from the chemical solution injection tube and the withdrawal rate of the chemical solution injection tube are controlled.

(Operation) According to the present invention, as described above, the mirror portion is provided with a vertical interval within the limit height at which the rock mass can stand on its own, and a thin plate-shaped horizontal consolidation layer having a certain depth is provided in the rock mass. By forming the layers, the ground of the entire mirror portion is in a state of sandwiching a plurality of solidified layers.

For this reason, since the grounds sandwiched by the solidified layers are self-supporting, the entire mirror portion is stabilized.

Thus, when forming the solidified layer, in the chemical liquid injection pipe insertion hole that was excavated horizontally from the mirror portion in the front ground to the excavation direction,
Adjust the chemical injection pipe so that the center line connecting the injection injection port, which is provided at the diagonal position of the pipe cross-section at the tip of the injection pipe, is located horizontally, and insert the chemical injection pipe while pulling out the injection pipe. By injecting the ground improvement chemical solution into the ground from the inlet, the chemical solution is injected into that portion while the soil of the ground is thinly scraped off by the injection pressure of the improvement chemical solution, so the solidified layer horizontal to the ground Is reliably and continuously created.

Further, when injecting the ground improvement chemical solution into the ground through the chemical solution injection pipe, by controlling the injection pressure and injection amount of the chemical solution and the withdrawal speed of the injection pipe, a solidified layer is formed evenly in the ground. It is also possible to adjust the injection range of the soil improvement chemical solution.

(Examples) The present invention will be described below with reference to illustrated examples.

The tunnel was excavated by the upper half section method, and the mirror part (1)
In each front ground (2) of the upper half (A) and the lower half (B), the vertical distance h is maintained within the limit height at which the ground (2) can stand by itself, In (2), a plurality of thin plate-shaped horizontal consolidation layers (3) having a constant depth 1 are formed.

At the time of construction of the horizontal solidified layer (3), a chemical solution injection pipe insertion hole is drilled horizontally in the forward direction from the mirror portion (1) by a known method, and the chemical solution is injected into the insertion hole. Insert tube (4).

The chemical liquid injection pipe (4) is provided at its tip end with injection injection ports (5) at diagonal positions of the cross section of the pipe, and the center line connecting both injection ports (5) is adjusted to be horizontal. Is inserted into the insertion hole.

Then, while pulling out the injection pipe (4), the ground improvement chemical solution is injected into the ground (2) through the respective injection ports (5).

At this time, the soil of the natural ground (2) is thinly scraped off by the injection pressure of the chemical liquid, and the chemical liquid is injected into the scraped part, so that a horizontal solidified layer (3) is formed in the natural ground.

By controlling the injection pressure and the injection amount of the liquid medicine and the withdrawal speed of the liquid medicine injection pipe (4) from the insertion hole, the thin plate-like horizontal shape can be ensured evenly in the ground (2). The solidified layer (3) is formed and the injection range of the soil improvement chemical solution can be adjusted.

Even if the cross-sectional dimension of the mirror portion (1) is large, the ground improving chemical solution is injected by the injection pipe (4) at regular intervals along a horizontally extending planning line of the mirror portion (1). Then, a continuous horizontal solidified layer (3) is formed in layers.

According to the method shown in the above-mentioned certain example, the ground (2) of the entire mirror portion (1) is in a state of sandwiching the plurality of horizontal consolidation layers (3), and is sandwiched between the respective consolidation layers (3). Since each grounded ground (2) is self-supporting, the entire mirror section (1) is stable.

(Effects of the Invention) According to the present invention, as described above, when excavating a tunnel, the ground in front of the mirror keeps a vertical distance within a limit height at which the rock can stand on its own, and By constructing a thin plate-shaped horizontal solidified layer with a certain depth in layers, the entire mirror section becomes stable and it becomes possible to excavate a tunnel with a large cross section.

Further, according to the present invention, since there is no nucleus on the front surface of the mirror portion as in the conventional construction method, a wide working space can be taken, and the construction is facilitated together with the fact that it is not necessary to install a ground anchor.

Further, even when the mirror portion is displaced to the front, it becomes possible to make the mirror portion stand on its own.

Further, according to the present invention, it is not necessary to pay special attention to the conventional method of spraying an epoxy resin or the like on the ground to form a thin film, and it is not necessary to use a material that causes pollution.

The invention of claim 2 excavates a chemical solution injection pipe insertion hole in the ground ahead of the mirror part in a horizontal direction with respect to the excavation direction, and injects into the hole at a tip of the pipe at a diagonal position of the pipe cross section. The injection pipe with the inlet is adjusted and inserted so that the center line connecting both injection ports is positioned horizontally, and then the ground improvement chemical solution is injected into the ground from each of the injection ports while pulling out the injection pipe. By doing so, the horizontal solidified layer can be surely formed continuously in the ground.

According to a third aspect of the present invention, when the ground improvement liquid is injected into the ground from the chemical injection pipe, the injection pressure and the injection amount of the same and the insertion hole of the injection pipe excavated in the ground of the injection pipe are used. By forming a thin plate-shaped horizontal consolidating layer in the ground while controlling the pulling speed of the, it is possible to reliably form the consolidating layer in the planned position and range in the ground. .

[Brief description of drawings]

FIG. 1 and FIG. 2 are front elevational views showing a state of implementation of an embodiment of a stable construction method of a tunnel mirror section according to the present invention, respectively, and a longitudinal side view, and FIGS. 3 and 4 are tip ends of chemical injection tubes, respectively. FIG. 5A and FIG. 5B, FIG. 6A and FIG.
FIG. 6B, FIG. 7A and FIG. 7B, and FIG. 8A and FIG. 8B are respectively a front view and a vertical side view showing each example of the conventional method. (1) …… Mirror, (2) …… Ground, (3) …… Solidified layer,
(4) …… Medical solution injection pipe, (5) …… Injection injection port

Claims (3)

[Claims] 1. When excavating a tunnel, the ground in front of the mirror keeps a vertical distance within a limit height where the ground can stand on its own,
In addition, a stable method for the tunnel mirror part is characterized by forming a thin plate-shaped horizontal consolidation layer with a certain depth in the same mountain in layers. 2. A chemical liquid injection pipe insertion hole is excavated horizontally from the mirror portion to the front ground in the excavation direction, and then injection injection ports are provided in the same hole at the tip of the pipe at positions diagonally across the pipe cross section. 2. A ground improvement chemical solution is injected into the ground from each of the inlets while the inlet pipes are adjusted and inserted so that the center line connecting both inlets is positioned horizontally, and then the inlet pipes are pulled out. Stabilization method of the tunnel mirror section described. 3. When injecting the ground improvement chemical solution into the ground from the chemical solution injection pipe, while controlling the injection pressure and injection amount of the chemical solution and the withdrawal speed of the chemical solution injection pipe from the injection pipe insertion hole, The stable construction method for a tunnel mirror portion according to claim 1 or 2, wherein a horizontal solidified layer having a thin plate shape is formed in layers in the ground.