JPH02217589A - Removal of underground obstruction in excavating work - Google Patents

Abstract

PURPOSE:To economically crush and remove obstructions in a wide range in a short time by a method in which hard obstructions in an excavating area are crushed by non-free face explosion of explosives set in the pit of the ground. CONSTITUTION:In a method excavating the ground almost horizontally, when hard obstructions E6, if any, are present in an excavating area S, a pit 2 leading to the obstructions E6 is excavated from the surface E of the ground. A desired amount of explosives are charged for the obstructions E6 into the pit 2 for non-free face explosion to crush the obstructions E6. The obstructions E6 so crushed are settled to the lower part of the area S by water jet, etc., for removal.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a method for removing underground obstacles in tight tunnel type mechanical excavation type propulsion construction and shield construction, and in particular, the present invention relates to a method for removing underground obstacles such as rock that was not predicted during the propulsion process. This article relates to an underground obstacle removal method that is convenient when an obstacle is encountered.

(Conventional technology) When carrying out excavation promotion work such as constructing sewer pipes or tunnels, preliminary polling is performed to understand the geology of the area to be excavated, and a specific excavation method that matches the geology is determined.

However, in actual propulsion construction and shield construction, unforeseen obstacles such as hard rock often appear during the excavation promotion process, regardless of prior geological surveys. If an obstacle that cannot be propelled is encountered, for example, with the mud shield method, the cutter torque will increase abnormally and the mud removal pipe will be blocked, making it impossible to proceed, so countermeasures can be taken to prevent this from interfering with propulsion. Obstacles must be crushed or removed to a certain extent.

Conventional methods for removing underground obstacles, when removing them from places other than underground, involve cutting the obstacles by polling, or crushing them by driving steel pipes into them. When removing it from underground, after stabilizing the ground by using chemical injection methods or pressure-air methods to stabilize the face, it can be removed directly by humans, or it can be removed mechanically by modifying drawing boards and cutters. Was.

Also, the obstacles are relatively wide, like hard rocks! In some cases, the propulsion method itself had to be changed from, for example, the muddy water propulsion method to the cutting edge propulsion method.

(Problem to be solved by the invention) However, with the former method of cutting or crushing obstacles, small obstacles such as rocks and sunken trees can be dealt with quickly, but when the obstacles are relatively large such as bedrock, they can be dealt with quickly. When the number of poles exceeds 1,000,000,000 steel pipes are used, the number of poles and steel pipes must be increased, and the pitch must be kept close to a certain degree, which naturally lengthens the construction period. In addition, if the construction period is extended for such a long time, there is a risk that it will not be possible to restart the project due to the tightening of the ground during the propulsion work.

In addition, with construction methods other than the former, not only will the scale be large, but changing the drawing board and cutter of the shielding machine will be quite dangerous work. Furthermore, changing the surface construction method itself was not economical, and the construction period was extremely long.

The present invention was made in view of this background, and is capable of dealing with obstacles in a relatively wide area in a short period of time compared to conventional construction methods. The purpose is to provide a method for removing intermediate obstacles.

(Means for Solving the Problems) In order to achieve the above object, the underground obstacle removal method in the propulsion work of the present invention is aimed at removing hard obstacles in the propulsion area in the propulsion work in which the base material is roughly horizontally underground. A drilled hole leading to the obstacle is provided on the ground surface of the object, and a required amount of explosives is charged to the obstacle through the drilled hole to perform free-surface blasting, thereby crushing the obstacle. Features.

(Function) In the present invention, for example, if an unexpected obstacle that appears on the face is encountered during the propulsion process using the muddy water shield method, the same Ft Yoimono can be subjected to non-free surface blasting separately from the same method. Since the material is crushed by a method, it can be used over a relatively wide range.

In addition, crushed obstacles can be removed by sinking to the lower part of the propulsion area using means such as water jets, so the original propulsion method can be maintained as is.

In this specification, non-free surface blasting means blasting performed with an amount of explosive that does not destroy the free surface, and the blasting type belongs to wide-bottom blasting.

In addition, hard obstacles are hard objects that pose an obstacle to each excavation propulsion method, and are not limited to rocks, bedrock, and the Mt.
Includes sunken wood, sheet piles, earth retaining materials, etc.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings.

FIG. 1 is a vertical cross-sectional view of the ground schematically showing a configuration for removing underground obstacles according to the present invention, and FIG. 2 is an enlarged vertical cross-sectional view showing the state of charge of explosives.

In the example shown in the figure, an unexpected obstacle lies in the propulsion area S during the process of constructing a sewer pipe using the muddy water propulsion method, and the cutter torque of the shield machine 1 increases significantly due to the obstacle. This is an example in which the present invention is applied to a case where directional control becomes impossible.

The geology of the ground includes sandstone layer El and sandstone layer E2 partially existing from the lower layer to the upper layer, silt ILIE3, and sand layer E4.
, silt F'E5. Propulsion area S is ground surface E
It was confirmed that it was located about 10m below the silt layer NE3 and sand layer E4.

However, as a result of additional investigation, it was found that within the propulsion area S, there are 20 to 70 hard sandstones E6 as obstacles over a distance of approximately 10 m.
It was found that the thickness was distributed as ew+. Sandstone E
6 has a high degree of consolidation, - axial compressive strength of 29 to 310 kg/
It was Cm'.

Under the above geological conditions, the underground obstacle removal method of the present invention was implemented using the following procedure.

As shown in the figure, a hole 2 leading to hard sandstone E6 is formed on the ground surface E using a boring machine, and a PVC vibrator 4 is placed in the hole 2.
The vibrator 4 was erected to hold the hole wall, and the explosive 3 was charged to the lower part of the vibe 4. After completing the preparation work for free surface blasting, the explosives 3 were ignited in sequence to crush the hard sandstone E6.

Here, the holes 2 are drilled at a plurality of locations corresponding to the distribution of the sandstone E6 as shown in FIG. 1 by a boring machine installed on the pier gantry 5 (see FIG. 3!!!?). The diameter of the drilled holes 2 was set to 50 to 70+w, and the hole spacing was set to about 700 nm by back calculation from the approximate value at which sandstone E6 would be crushed, taking into account factors such as the tensile strength and blasting force of sandstone E6.

As the PVC vibrator 4, a bottomed vibrator with an inner diameter of about 30 m was used. The vibrator 4 was charged with an explosive 3 in a cartridge package containing the required amount as shown in FIG. This explosive 3 is generally called dynamite, and a tamping material 7 is placed inside the vibe 4.
Coarse sand was used to maintain the load so that sufficient explosive power was obtained.

The amount of charge was empirically set at 80% of the thickness of sandstone E6. Explosive 3 was detonated using a No. 6 electric detonator, and ignited using a blaster connected to a normal explosive generator, with single blasts sequentially starting from the shield 61 side.

The conditions of the cane during blasting vary depending on the site conditions, but noise and
The impact of the blast was within an acceptable range in all respects.

The above blasting method is performed without opening the front of the shield machine I, and is premised on not damaging the free surface that is the ground surface E, so it is equivalent to non-free surface blasting.

As a result of the blasting, the part of sandstone E6 near the charge was subjected to compressive stress due to the blasting, causing rupture cracks and being fractured, and the part of sandstone E6 away from the charge suffered from radial cracks due to tensile stress. As a whole, as shown in Figure 3, it is believed that the debris was crushed to the extent that it did not cause any trouble to the shield machine I.

Although the extent of the fracture could not be visually observed, it was confirmed from the following process that when the steel pile was driven from the ground surface E into the sandstone E6, there was almost no resistance compared to before blasting.

The crushed sandstone E6 was completely settled and removed to the lower part of the propulsion area S using the vibro hammer 8 in combination with a water jet as shown in FIGS. 3 and 4.

Specifically, two water jet vibrators 9 are fixed to H steel (H-300 than l r
After casting deeply to about rt, a water jet cutter (maximum discharge Nil 60L/M [N) was activated for about 5 minutes. As a result, the crushed sandstone E6 is removed from the lower part of the propulsion area S, making it perfect for removing obstacles to the propulsion work.

Here, almost no resistance due to sandstone E6 was observed during pouring. This shows that the sandstone E6 has been crushed by the blasting described above.

Further, by removing the crushed sandstone E6 outside the propulsion area S before the shield machine 1 restarts in this way, there is no fear that the shield ml will be loaded with crushed materials.

Note that the construction method of the present invention is not limited to this example. For example, if a specific leakage propulsion method is determined based on the assumption that obstacles in the propulsion area will be removed by this method, the construction period can be shortened. This will enable rational construction. Furthermore, free-surface blasting is generally recognized to be more applicable to rocks with a high degree of brittleness than to rocks with a low degree of brittleness, so it can be widely applied to various types of underground obstacles.

(Effects of the Invention) As explained above, in the present invention, for example, an underground obstacle appearing on a face can be crushed by drilling a hole in the ground surface leading to the obstacle and performing free-surface blasting. Therefore, it can be done in a short time and with minimum construction cost. In addition, crushed obstacles can be removed by sinking to the lower part of the propulsion area using simple means such as an autajet, thereby ensuring that the original propulsion method can be maintained as is.

Therefore, the underground obstacle removal method of the present invention is extremely advantageous over conventional removal methods in terms of both construction cost and construction period, and provides high reliability as a removal measure.

[Brief explanation of the drawing]

Fig. 1 is a longitudinal sectional view of the ground schematically showing the state in which explosives are charged according to an embodiment of the present invention, Fig. 2 is an enlarged sectional view of main parts showing the state of charging of explosives, and Fig. 3 is crushing. 4. Vertical cross-sectional view showing an example
This figure is a partial perspective view showing the installed state of the water jet of FIG. 3. 1 ・ e 3 ψ E ・ S ◆ ・Shield machine・Drilling・Explosives・Ground surface・・Hard sandstone (obstacle)・・Propulsion area

Claims (1)

[Claims] (1) In propulsion work that excavates underground approximately horizontally, for hard obstacles in the propulsion area, drill holes leading to the obstacles are drilled on the ground surface, and the required amount of explosives is delivered to the obstacles through the drill holes. A method for removing underground obstacles in propulsion construction, characterized in that the obstacles are crushed by charging with a charge and performing non-free surface blasting.