JPH0821183A - Method for starting tunnel excavation - Google Patents

Abstract

PURPOSE:To greatly simplify preparatory works including formation of a portal to a retaining wall body and solidification of ground before starting of excavation, and to ensure safety of the work. CONSTITUTION:The front end of a cylindrical member 2 is stuck and fixed to a position where a portal is formed to the front of a retaining wall body 1, and a space between the outer circumferential face of a shiled type tunnel excavator 4 installed against the ground in a space inside the cylindrical member 2 and the inner face of the cylindrical member 2 is slidably sealed with a plurality of rubber sealing materials 3 provided along the inner circumferential face of the cylindrical member 2. While segment 5 for lining for the tunnel are connected to the rear end of the tunner excavator 4, a bearing structural body 6 for the tunnerl excavator 4 is constructed. Then, a portal is formed to the retaining wall body 1 with the tunnerl excavator 4 started together with segment members 5, and the segment members 5 are connected and fixed to the portal. Then, excavation of tunnerl is started with the excavator 4 that is separated from the segment member 5.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for starting tunnel excavation, and more specifically, it is safe to seal a gap between a well and a tunnel excavator when starting and penetrating the tunnel excavator from the well into the ground. Regarding the method of starting excavation.

[0002]

2. Description of the Related Art Recently, a shield type excavator is often used for excavating a tunnel or the like. When starting construction with such an excavator, first create an earth retaining wall body reinforced with concrete etc. on the front ground surface at the position where the excavator is started and inject the chemical liquid etc. into the ground in the approach direction Form a deep solidified ground layer, then form a wellhead for the excavator to enter this wall, attach an entrance packing device to this, and then destroy and remove all the wall remaining at the wellhole, After fitting the tip of the machine into the wellhead and installing it and sealing the gap between the wellhead and the excavator with the entrance packing device, the sealing performance between the excavator and the entrance packing device is checked by a pressure resistance test to ensure safety. Was checked, and then the excavator was started toward the solidified layer.

[0003] Such a conventional method requires a lot of man-hours and days for forming a wellhead, and also requires labor to remove the wall body remaining on the front surface before fitting the excavator. . In addition, the depth of the solidified ground layer behind the earth retaining wall must be increased to about 10 m in order to prevent the collapse of sediment and water discharge during these operations, which increases the construction cost. was there.

Therefore, the inventor of the present invention has a cylindrical member sealed and fixed to the wellhead in order to prevent a water accident even if the amount of work for forming the wellhead and the depth of the solidified ground layer are reduced by hand. A rubber hollow seal material is provided along the inner peripheral surface of the seal material, and the head and tail portions of the seal material are joined to each other by a rubber filler and expanded by a fluid press-fitted into the hollow portion. Inventing a wellhead sealing device having a structure in which an outer peripheral surface of a cylindrical body penetrating the space inside the cylindrical member toward the ground by a sealing material and the inner surface of the cylindrical member are slidably sealed, Applying (Japanese Patent Application No. 5-1474)
No. 85).

[0005]

However, although the new wellhead sealing device has a significantly improved sealing performance as compared with the conventional device, it does not work on the ground behind the wall when the ground is extremely soft. It was not possible to completely omit the preliminary solidification stabilization treatment. Therefore, the present invention further facilitates the formation of the wellhead to the earth retaining wall body, and further omits the solidification stabilization treatment of the ground before the wellhead formation, greatly simplifies the preparatory work for the installation start of the excavator. The purpose is to provide a new tunnel excavation start method that can be made safe.

[0006]

A tunnel excavation start method capable of achieving the above object is to seal and fix a front end portion of a cylindrical member at a planned wellhead position on a front surface of an earth retaining wall, and then to perform the cylindrical member. Sliding between the outer peripheral surface of the shield-type tunnel excavator installed in the inner space toward the ground and the inner surface of the cylindrical member by a plurality of rubber sealing materials provided along the inner peripheral surface of the cylindrical member. Movably sealing, and further connecting a segment member for tunnel lining to the rear end portion of the tunnel excavator and constructing a support structure for the tunnel excavator, and then starting the tunnel excavator together with the segment member To form a wellhead in the earth retaining wall, and subsequently, the segment member is fixedly coupled to the wellhead, the tunnel excavator is separated from the segment member, and It is characterized in that to start excavation by channel excavator.

The method for starting tunnel excavation according to the present invention will be described with reference to the drawings. Here, the earth retaining wall 1 for providing a tunnel entrance, which is the starting point of a tunnel, is an underground working space which is an intermediate point of tunnel excavation work, for example. It may be a part of the wall surrounding the wall, or may be built at a planned site of a wellhead such as a hillside. Further, the cylindrical member 2 whose front end portion is sealed and fixed to the front surface of the earth retaining wall body 1 has a pressure resistant structure including a front end member 2a, a main member 2b, and a rear end member 2c as shown in FIG. 4, for example. Each of the divided parts, such as two, three, or four, is assembled into a cylindrical shape by connecting them with bolts 2d and nuts 2e.

For the cylindrical member 2 in which the front end member 2a is fixed to the earth retaining wall body 1 by anchor bolts 2f or the like,
A plurality of rubber sealing materials 3 are sequentially provided along the inner peripheral surface. The seal member 3 used here is formed of a long rubber hollow seal member as previously proposed by the present inventor in Japanese Patent Application No. 5-147485. A device in which the head part and the tail part are connected to each other so as not to form a gap around the inner surface is preferably used, but the present invention is not limited to this.

Next, a shield type tunnel excavator 4 is installed inside such a cylindrical member 2. The sealing material 3 provided on the inner peripheral surface of the cylindrical member 2 has, for example, pressure air in its hollow portion. Etc. are introduced to expand the whole, and discharged to shrink the whole, so that the space between the outer peripheral surface of the tunnel excavator 4 installed inside the cylindrical member 2 and the inner peripheral surface of the cylindrical member 2 is reduced. It can be freely sealed or opened.

Further, a segment member 5 for tunnel lining is connected to the rear end portion of the tunnel excavator 4 so that it can be moved together with the tunnel excavator 4 to the wellhead position. In the rear of the installed tunnel excavator 4, a bearing structure 6 such as a strong wall is built in order to support a reaction force when propelling the tunnel excavator 4.

After the preparatory work is completed in this way, the operation of the tunnel excavator 4 is started, but the ground behind the earth retaining wall 1 needs to be subjected to a pretreatment for stabilization such as solidification. There is no. Then, the tunnel excavator 4 is used to cut the earth retaining wall body 1 in front of the excavator to form a wellhead, and then the tunnel excavator 4 is started. At this time, the segment member 5 is also advanced together with the tunnel excavator 4. While the front seal members 3a and 3b seal the gap between the cylindrical member 2 and the tunnel excavator 4, the rear seal member 3c seals the gap between the cylindrical member 2 and the segment member 5. Work like. Further, after the tunnel excavator 4 has entered the ground, the gap between the cylindrical member 2 and the segment member 5 is sealed by the sealing material 3a, so that the earth retaining wall is maintained while the sealing is maintained. The body 1 and the segment member 5 are joined with concrete or the like to form a wellhead structure.

After the complete wellhead structure is completed in this way, the tunnel excavator 4 and the segment member 5 are disconnected from each other and only the tunnel excavator 4 is moved forward, in the same manner as a normal tunnel excavation work. It is possible to proceed with excavation, but it is also possible to proceed with excavation while carrying out ground stabilization treatment or the like on the front surface of the excavated portion if necessary.

[0013]

In the tunnel excavation starting method of the present invention, the tunnel excavator 4 is installed at an accurate position in the cylindrical member 2 before forming the wellhead in the earth retaining wall body 1, and then the segment member for forming the wellhead is formed. By assembling and preparing 5 in advance, the tunnel excavator 4 can be started very easily. Further, the front end portion of the cylindrical member 2 is sealed and fixed to the earth retaining wall body 1, and the gap between the cylindrical member 2 and the tunnel excavator 4 is multiply sealed by the sealing material 3. , The tunnel excavator 4 even if the ground behind the earth retaining wall 1 contains high-pressure groundwater at the start of the tunnel excavation.
Water leaks from outside the area are completely prevented. Since the wellhead structure can be safely formed, tunnel excavation can be safely carried out by performing the solidification method of the ground and the like to stop the water even if groundwater subsequently comes out.

[0014]

INDUSTRIAL APPLICABILITY The tunnel excavation starting method of the present invention not only completes the excavation preparation work including the installation of the tunnel excavator before the formation of the wellhead in a safe and open environment, but also keeps the soil. Since we have completed measures to prevent the collapse of sediment and the occurrence of flood accidents when excavating the pit on the wall,
The work can be carried out very safely and easily when starting the tunnel excavator and forming the wellhead. Then, the subsequent tunnel excavation can be safely performed according to the conventional work process. Therefore, the conventional chiseling work to form a wellhead in the earth retaining wall and the preliminary solidification and stabilization treatment of the ground behind the earth retaining wall to prevent the outflow of sediment and water are omitted. Therefore, not only is work safety secured, but also the number of work steps and the work period can be shortened, which is extremely economical.

[Brief description of drawings]

FIG. 1 is an explanatory view showing a start preparation state of a tunnel excavator in a tunnel excavation starting method of the present invention.

FIG. 2 is an explanatory diagram showing a state immediately after starting of the tunnel excavator in the tunnel excavation starting method of the present invention.

FIG. 3 is an explanatory diagram showing a state immediately before formation of a wellhead structure in the tunnel excavation starting method of the present invention.

FIG. 4 is an external perspective view showing the configuration of a cylindrical member used in the tunnel excavation starting method of the present invention.

[Explanation of symbols]

 1 Earth retaining wall 2 Cylindrical member 2 2a Front end member 2b Main member 2c Rear end member 2d Bolt 2e Nut 2f Anchor bolt 3 Sealing material 4 Tunnel excavator 5 Segment member 6 Support structure

Claims (1)

[Claims] 1. An outer peripheral surface of a shield type tunnel excavator in which a front end portion of a cylindrical member is sealed and fixed at a planned wellhead position on the front surface of an earth retaining wall and then installed in the space inside the cylindrical member toward the ground. A plurality of rubber sealing materials are provided along the inner peripheral surface of the cylindrical member so as to be slidably sealed between the inner surface of the cylindrical member and a tunnel at the rear end of the tunnel excavator. A lining segment member is connected and a supporting structure for the tunnel excavator is constructed, and then the tunnel excavator is started together with the segment member to form a wellhead in the earth retaining wall body, and subsequently to the wellhead. A method for starting tunnel excavation, characterized in that the segment members are coupled and fixed, the tunnel excavator is separated from the segment members, and excavation by the tunnel excavator is started.