JPH0468198A - Construction method of tunnel - Google Patents

Abstract

PURPOSE:To reduce a construction cost by placing primary lining concrete a space between a form and a bedrock, placing secondary lining concrete to the internal surface after reinforcing it with lock bolts or shorings after the stripping of the form. CONSTITUTION:Primary lining concrete 8 is placed in a space between a lining form 4 connecting and placing to a gabl frame 3 provided to the rear of a shield machine 1 and a bedrock. In that case, the thickness of the concrete 8 is equivalent to that against approximately the minimum earth pressure of an excavated tunnel. After the stripping of the form 4, when the earth pressure is increased higher than the minimum value, the concrete 8 is penetrated to drive lock bolts 10 into the bedrock and, at the same time, steel shorings 11 are erected to reinforce. After that, secondary lining concrete 12 is placed to the internal surface of a secondary lining. According to the constitution, a construction cost can be reduced.

Description

[Detailed description of the invention] Industrial applications This invention relates to a tunnel construction method.

Conventional Technology In general, construction methods such as (1) shield construction method, (2) NATM construction method, and (3) ECL construction method are often used to construct urban tunnels and mountain tunnels.

In the shield construction method (1), excavation is performed using a shield machine as shown in Fig. 3, and a tail void called a tail seal is formed between the tail seal 21 provided at the rear end of the skin plate 20, the segment 22, and the ground 23. A void 24 is formed, and this void is filled by backfilling with mortar grout or the like.

Next, in the NATM construction method (2), as shown in Figure 4 (A), a tunnel is excavated without using a shield machine, a primary lining is performed by concrete spraying, and this primary lining is made of concrete. The thickness of 30 reduces the ground pressure applied to the lining by allowing the ground 34 to deform, and
The thickness should be such that it has enough strength to not break, and if it cannot withstand the pressure saw by itself, rock bolts 31 or steel ring supports 32 will be used together, and 33 is a secondary lining. shows. For this reason, there is an advantage that the thickness of the primary lining concrete 30 is thinner than in the conventional mountain construction method.

Next, in the ECL method (3), as shown in Figure 5 (A), a shield machine 40 is used to excavate, and a formwork 4 is placed near the rear of the excavation.
1, and a lining concrete 43 is placed in the gap formed between the ground 42 and the formwork 41, and this lining concrete 43 has a strength that can withstand the maximum ground pressure of the excavated tunnel. In order to achieve this, the thickness should be made thicker than that which can withstand the ground pressure, or a reinforcing lining made of reinforced concrete 44 should be added as shown in Figure (B), or fibers should be mixed in as concrete. As a result, as a general rule, secondary lining is often not performed.

Problems to be Solved by the Invention However, in the Sealtoe method of (1) above, there is a problem in that the voids 24 are not completely filled with mortar grout, resulting in unfilled tail voids, which cause ground subsidence. When designing, it is not possible to positively evaluate the ground reaction force as a spring support, so there is also the problem that a thick and expensive product must be used, which is uneconomical.

Next, in the NATM method (2) above, since the primary lining concrete 30 is designed to allow the deformation of the ground as described above, it is necessary to There is a problem that it cannot be applied in cases where the ground does not stand on its own, such as urban tunnels, or in cases where there is a large amount of oil and water. In addition, in addition to having to use auxiliary construction methods that are time-consuming, such as the pressure construction method, in the case of urban tunnels, it is necessary to use
As shown in Figure 1, the construction must be carried out in parts with a smaller backing, which raises the problem of high construction speed and construction costs. Furthermore, there is the problem that rebound loss occurs when concrete is sprayed, and dust countermeasures are required to prevent this from occurring.

Next, the ECL method (3) above has the advantage of not causing unfilled tail voids in concrete like the seal method, but as mentioned above, it is The thickness of the construction concrete 43 is set over the entire length of the tunnel to a constant thickness that is greater than the maximum ground pressure of the tunnel, or is made of reinforced concrete, so the ground pressure is small and this type of construction is possible. In areas where this is not necessary, there is a problem of waste of concrete or reinforcing bars, etc. Furthermore, when lining with reinforced concrete, excavation must be temporarily interrupted, which slows down the construction speed and increases construction costs. There is also the problem of

Therefore, the purpose of the present invention is to solve the problems of the conventional construction methods as described above, to eliminate the occurrence of unfilled tail voids, to eliminate the need for expensive segments, and to be able to operate from 1 to To provide a tunnel construction method capable of suppressing the generation of dust in a tunnel, eliminating waste of materials such as concrete or reinforcing bars, and speeding up construction speed and reducing construction time costs.

Means for Solving the Problems In order to achieve the above-mentioned objects, the present invention excavates a tunnel with a shield machine, and excavates a tunnel between the highly rigid formwork placed near the rear of the shield machine and the ground. A primary lining concrete is placed in the gap that is formed, and a shield machine, formwork, and poured concrete are used to counter the initial displacement of the ground due to excavation, and the thickness of the concrete placed in this way is shall have a thickness that resists the minimum ground pressure of the excavated tunnel, and if the ground pressure increases beyond the minimum value after the formwork is removed, it shall be reinforced with rock bolts or ring shoring, and then This method is characterized by placing a secondary lining concrete on the inner surface of the lining concrete.

In the embodiment of the present invention shown in FIG. It's good to be there.

The shield skin plate 2 of the shield tail portion of such a shield machine 1 is equipped with a gable frame 3, and this gable frame 3
A desired number of lining formworks 4 are placed in connection with the shield excavation, and simultaneously with shield excavation, the concrete is supplied by the concrete pouring pipe 7 without causing an unfilled tail boil in the gap between the formwork 4 and the ground mass 6. Then, concrete is placed to form the primary lining concrete 8.

In this case, the thickness of the lining concrete 8 shall be the thickness that resists the minimum ground pressure over the entire length of the tunnel, and this ground pressure is determined by various factors such as ground quality, depth, and water pressure, as in the case of conventional tunnel excavation. It is determined by considering the conditions.

The lining concrete 8 cast as described above resists the initial displacement of the ground 6 with the cooperation of the shield machine 1 and the formwork 4 in the initial stage W of casting. After that, in addition to the above-mentioned conditions, in areas X where the ground pressure is large, lining construction A rock bolt 10 is driven into the ground through the concrete 8, and a steel ring support 11 is erected for reinforcement, and only the rock bolt 10 is used in a smaller ground pressure area Y. In the pressure zone Z, reinforcement is not performed using them, and finally, secondary lining concrete 12
concrete on the inner periphery.

Effects of the Invention The present invention is as described above, and is capable of reducing the almost minimum ground of an excavated tunnel formed between a highly rigid formwork placed near the rear of a shield machine that excavated a tunnel and another mountain. Place primary lining concrete in the gap with a thickness that resists the pressure, and if the ground pressure increases beyond the minimum value after the formwork is removed, reinforce it with rock bolts or ring shoring, etc., and then Since the secondary lining concrete is placed on the inner surface of the primary lining concrete, the thickness of the tunnel lining can be adjusted according to the ground pressure without creating unfilled tail voids, and the waste of concrete can be reduced. In addition to being able to prevent use, construction speed can be increased, and L-channels can be easily constructed even in geological formations with different conditions without the need for expensive segments. Moreover, since there is no need to spray concrete, the generation of dust can be suppressed, and in this way, the overall construction cost can be reduced.

[Brief explanation of the drawing]

Fig. 1 is a vertical front view of an embodiment of the method of this invention, and Fig. 2 (
A), (B), (C), and (D) correspond to the lines A-A in Figure 1, respectively.
Cross-sectional views taken along B-B, CC, and D-D, Figure 4 (A) is a schematic explanatory diagram of an example of the conventional NATM construction method, Figure 4 (B) is a schematic explanatory diagram of an equivalent example, and Figure 5 ( A) is a schematic explanatory diagram of an example of the conventional ECL construction method, and (B) is a schematic explanatory diagram of an equivalent example. 1... Shield machine 3... Skin plate 3.
... Gable frame 4 ... Lining formwork 6 ... Ground 8 ... Primary lining concrete 10 ... Rock bolts 11 ... Steel ring shoring 12 ... Secondary lining concrete (A) (C) )Figure (B) (D) Figure 4 (A) (B)

Claims (1)

[Claims] 1. Excavate a tunnel with a shield machine, and place primary lining concrete in the gap formed between the highly rigid formwork placed near the rear of the shield machine and the ground.
The shield machine, formwork, and poured concrete are used to counter the initial displacement of the ground due to excavation, and the thickness of the concrete cast in this way is a thickness that resists almost the minimum ground pressure of the excavated tunnel, If the ground pressure increases above the minimum value after the formwork is removed, reinforce it with rock bolts or ring shoring, and then pour secondary lining concrete on the inner surface of the primary lining concrete. A method of constructing a tunnel characterized by: