JP2781845B2 - Underground obstacle removal method in propulsion work - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION << Industrial application field >> The present invention relates to an underground obstacle removing method in a closed-type mechanical digging type propulsion construction work or a shield construction work, and in particular, an obstacle such as a rock mass which was not predicted in a propulsion process. Convenient underground obstacle removal method when encountering.

<< Conventional Technology >> In excavation promotion work such as construction of sewer pipes and tunnels, drilling is performed in advance to grasp the geology of the propulsion area, and a specific excavation method suitable for the geology is determined.

However, in actual propulsion works and shield works, unpredicted obstacles such as hard rock often appear in the excavation propulsion process, regardless of the prior geological survey. When an obstacle that cannot be propelled is encountered, for example, in the case of the muddy water shield method, an abnormal increase in the cutter torque and blockage of the mud pipe will be caused, and the propulsion will not be possible. Obstacles must be crushed or removed to an extent.

As a conventional underground obstacle removal method, when removing from outside the mine, the obstacle was cut by drilling or the like, or the steel pipe was driven to break the obstacle. In the case of removal from the mine, after stabilizing the face by performing ground stabilization processing by chemical solution injection method or pneumatic method, other than direct removal by humans, modification of face plate and cutter and mechanical excavation method Was.

Further, when an obstacle covers a relatively wide area such as hard rock, the propulsion method itself may have to be changed from, for example, a muddy water propulsion method to a cutting edge propulsion method.

《Problems to be solved by the invention》 However, the former method of cutting or crushing obstacles can quickly cope with small obstacles such as rocks and deciduous trees, but the obstacles are relatively wide In such a case, the number of drillings and the number of steel pipes to be driven increases, and furthermore, the pitch must be increased to some extent. In addition, when the construction period is long as described above, there is a risk that the propulsion work cannot be restarted due to tightening of the ground or the like.

In addition, the methods other than the former are not only large-scale, but changing the face plate and cutter of the shield machine is a very dangerous operation. Further, when the excavation method itself is changed, there are problems such as lack of economy and an extremely long construction period.

The present invention has been made in view of such a background,
It is an object of the present invention to provide an underground obstacle removal method for propulsion construction that can cope with a relatively wide range of obstacles in a short period of time as compared with the conventional construction method and is excellent in economic efficiency.

<< 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 a method for excavating the ground substantially horizontally using a shield machine or the like. For hard obstacles in the propulsion area that is excavated almost horizontally, a drill hole is provided on the surface of the ground that leads to the obstacle, and the obstacle is charged with the required amount of explosive from the drill hole to perform free surface blasting. In this way, the obstacle is crushed, and the crushed object is settled out of the propulsion area to the extent that the shield machine or the like can be re-propelled by an automatic jet.

<< Operation >> In the present invention, for example, in the course of propulsion by the mud shield method, when an unexpected obstacle that appears on the face is encountered, the obstacle is subjected to a free blasting separately from the same method. Since it is crushed, it can be dealt with in a relatively short time.

Further, the crushed obstacle can be settled and removed at the lower part of the propulsion area by means of a water jet or the like, so that the original propulsion method can be maintained.

In this specification, the term "free surface blasting" means blasting that is performed with an explosive amount that does not damage the free surface, and belongs to extended blasting as a blasting form.

Further, the hard obstacle is a hard obstacle that is an obstacle to each excavation propulsion method, and is not limited to rocks, bedrocks and rock layers, but also includes sinking trees, sheet piles, earth retaining materials and the like.

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

FIG. 1 is a vertical sectional view of the ground schematically showing a configuration for removing an underground obstacle according to the present invention, and FIG. 2 is an enlarged vertical sectional view showing a charged state of an explosive.

In the embodiment shown in the figure, in the process of constructing a sewer sewer by the muddy water propulsion method, an unexpected obstacle lies in the propulsion area S, and the shield machine 1
This is an example in which the present invention is applied to a case where the direction torque cannot be controlled due to a large increase in the cutter torque.

The geology of the ground is such that the sandstone layer E1 and the gravel layer E2 partially exist from the lower layer to the upper layer, and the silt layer E3, sand layer E4, and silt layer.
E5. It has been confirmed that the propulsion area S is located about 10 m below the ground surface E and passes through the silt layer E3 and the sand layer E4.

However, as a result of additional investigation, it was found that hard sandstone E6 as an obstacle was distributed in the propulsion area S with a thickness of 20 to 70 cm over about 10 m. Sandstone E6 had a high degree of consolidation and a uniaxial compressive strength of 29 to 310 kg / Cm ² .

Under the above geological conditions, the underground obstacle removing method of the present invention was constructed in the following procedure.

As shown in the figure, a drilling hole 2 leading to the hard sandstone E6 is formed on the ground surface E by a boring machine, and a PVC pipe 4 is drilled.
The explosive 3 was charged in the lower part of the pipe 4 while holding the hole wall. After completing the free surface blast preparation work, explosive 3 was sequentially ignited to crush hard sandstone E6.

Here, the boreholes 2 are provided at a plurality of locations according to the distribution of the sandstone E6 as shown in FIG. 1 by a boring machine installed on the truss bridge gantry 5 (see FIG. 3). The diameter of drill hole 2 is
The distance between the holes was set to 50 to 70 mm, and the hole interval was set to about 700 mm by calculating backward from the approximate value of the crushing of the sandstone E6 due to the tensile strength and the blasting force of the sandstone E6.

As the PVC pipe 4, a bottomed pipe having an inner diameter of about 30 mm was used. As shown in FIG. 2, the pipe 4 was charged with an explosion 3 having a required medicine amount as a cartridge. This explosive 3 was generally called dynamite, and was loaded and held in a pipe 4 using coarse sand as a tamping material 7 so that a sufficient blasting force could be obtained.

The charge amount was empirically set at 80% of the sandstone E6 thickness. The explosive 3 was detonated by an electric detonator No. 6 and ignited by a single explosion from the shield machine 1 side sequentially using a blaster connected to a normal explosive electromotive device. The conditions at the time of blasting differed depending on the site conditions, but there was not much noise and vibration, and the blasting effect was within an allowable range in all aspects.

The blasting method described above is performed under the condition that the front of the shield machine 1 is not opened and does not damage the free surface of the ground surface E, and thus corresponds to blasting without a free surface.

As a result of the blasting, the vicinity of the charge of the sandstone E6 is subjected to compressive stress due to the blast and generates shear cracks and is crushed, and the part away from the charge of the sandstone E6 is radially cracked by the tensile stress, and as a whole, It is considered that the crusher was crushed to such an extent that the shield machine 1 was not hindered as shown in FIG.

This is not visible for the degree of crushing,
It was confirmed that there was almost no resistance when the steel pile was driven into the sandstone E6 from before, and the following process.

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

More specifically, two water jet pipes 9 are fixed to H steel (H-300 × 300) 10 with fasteners, and a vibratory hammer 8 supported by hanging wires 12 of a crawler crane 11.
After drilling between the drill holes 2 deeper than the propulsion area S by about 1m, the water jet cutter (maximum discharge rate 160L / M
IN) for about 5 minutes. As a result, the crushed sandstone E6
Is removed at the lower part of the propulsion area S, which is perfect for removing obstacles to the propulsion work.

Here, almost no resistance due to the sandstone E6 was found at the time of casting. This indicates that the sandstone E6 has been crushed by the aforementioned blasting.

Also, before the restart of the shield machine 1,
By removing the crushed sandstone E6 to the outside of the propulsion area S, there is no fear that a load due to crushed material is applied to the shield machine 1.

Incidentally, the present invention method is not limited to this embodiment, for example, if a specific excavation propulsion method is determined on the assumption that obstacles in the propulsion area are removed by the present method,
The construction period can be shortened and rational construction can be performed. In addition, free surface blasting is generally recognized to be more suitable for rocks having a higher degree of brittleness than rocks having a lower degree of brittleness, and thus can be widely applied to various underground obstacles.

<< Effects of the Invention >> As described above, in the present invention, for example, an underground obstacle appearing on a face is crushed by performing a free surface blast by providing a drilling hole leading to the obstacle on the ground surface. Therefore, it is possible to deal with it in a short period of time and with minimum construction cost. Further, the crushed obstacle can be settled and removed at the lower part of the propulsion area by a simple means such as a water jet, so that the original propulsion method can be reliably maintained.

Therefore, the underground obstruction removal method of the present invention is extremely advantageous in terms of both the cost and the construction period as compared with the conventional removal method, and high reliability is obtained as a removal measure.

[Brief description of the drawings]

FIG. 1 is a vertical sectional view of the ground schematically showing a state in which explosives are charged according to one embodiment of the present invention, FIG. 2 is an enlarged sectional view of a main part showing a state of explosive charges, and FIG. FIG. 4 is a vertical cross-sectional view showing an example in which a settled obstacle is settled below a propulsion area.
The figure is a partial perspective view showing the state of attachment of the water jet of FIG. 1. Shielding machine 2. Drilling 3. Explosive E. Surface E6. Hard sandstone (obstacle) S. Propulsion area

Continuation of front page (56) References JP-A-53-133919 (JP, A) JP-B-52-45121 (JP, B2) (58) Fields investigated (Int. Cl. ⁶ , DB name) E21D 9 / 06 301

Claims (1)

(57) [Claims] In a propulsion work for excavating the ground substantially horizontally using a shield machine or the like, a drilling hole communicating with the obstacle is provided on the ground surface for a hard obstacle in the propulsion area excavated substantially horizontally. By crushing the obstacle by charging a predetermined amount of explosive to the obstacle from the borehole and performing free surface blasting, the crushed material can be re-propelled by a water jet with a shield machine or the like. An underground obstacle removal method in propulsion work characterized by eliminating settling out of the propulsion area to a degree.