JPH11152988A - Construction method of underground structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce a constructing quantity of earth-retaining by constructing a shaft between a pair of earth-retaining walls constructed in the ground and hauling a shield excavator therein to excavate a hole for upper and lower floors and excavating the soil between the upper and lower floor slabs after these floor slabs have been formed. SOLUTION: A pair of right and left earth-retaining walls 10 are constructed in the ground from a road face. A starting shaft 15 and an arrival shaft are formed at the ends of the earth-retaining walls 10. Several small shield excavators are parallelly arranged in the starting shaft 15 to horizontally start in the lower floor part 19 to excavate the ground. In the same way, the upper floor part 24 is also excavated and segments with supports 21 are installed to support the natural ground 22. Reinforcements are arranged in the tunnel after the primary lining to connect them to the earth-retaining walls 10 and then, concrete is placed to construct the lower floor slab 27. After the upper floor slab 28 has been constructed likewise, the soil within the ground 29 is excavated and decorative walls 31 or the like of the side walls are finished and then the shaft 15 is filled back. The upper layer is not opened and hence, earth-retaining walls are not required and also a deep embedment is not required for the earth-retaining wall of the lower layer part and hence, a constructing quantity of the earth-retaining wall can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for constructing an underground structure, and more particularly to a method for constructing a rectangular structure at a large depth.

[0002]

2. Description of the Related Art Conventionally, as a method of constructing a rectangular structure such as a road, a railroad, a tunnel, a common ditch or a basement of a building underground, there are an excavation method and a shield method.

[0003]

However, in the open-cutting method, since the entire construction area is dug from the road, the entire surface becomes a road covering area, and the road covering area is wide. There were drawbacks, such as inconveniences such as vibration, transportation of earth and sand, steel materials, etc., and traffic regulation by opening and closing the lining.

[0004] In addition, the existing underground buried objects need to be cut and suspended, and their maintenance and management are also difficult.

[0005] The larger the overburden portion of the structure (the deeper the structure), the larger the amount of soil and the larger the amount of backfill.

In recent years, as the depth of the underground of a structure to be built becomes deeper, the pressure of groundwater has a more serious effect on the safe construction of construction.

One of these is a phenomenon called "blowing due to pressurized water".

[0008] "Bulling" refers to ground 1 as shown in FIG.
As the soil is dug down, the mass W becomes smaller,
If the groundwater pressure Pw is constant, the overall stability condition W> ΣPw is reversed somewhere and the ground is destroyed.

[0009] As a general measure against these,

[0010] Reduce groundwater pressure. In this case, settlement of the surrounding ground may occur or the well may dry up.

[0011] The soil mass is increased by soil improvement. In this case, the construction cost becomes expensive.

The earth retaining wall 3 is made to penetrate the deeper water-impermeable layer 2 to block the groundwater pressure Pw. In this case, generally, the water-impermeable layer 2 is extremely deep, the construction of the retaining wall becomes expensive, and further, the groundwater flow is interrupted.

[0013] "Underwater excavation" is performed by filling the earth retaining excavation with water in order to balance with the pressure to be applied. After the excavation is completed, a pressure-resistant board is constructed of underwater concrete. However,
Such a large-scale underwater excavation has difficulties and involves many dangers, and has a drawback that the pressure plate becomes considerably thick and the construction becomes expensive.

When a large rectangular section is constructed by a shield method (for example, the MMST method), the excavated section cannot be excavated at a stretch, so the required excavated section is divided into several sections 4a to 4h as shown in FIG. Then, it is necessary to sequentially excavate each of the above sections by the shield excavator 5 (box shield method) and to communicate 6a to 6h between the divided sections 4a to 4h, but this communication is dangerous and expensive. Requires reinforcement work. In FIG. 8, 7 is a primary lining member (segment), 8 is a gap connecting member, and 9 is a main body structure.

[0015] Further problems of the shield method are listed below.

A large horizontal force is applied to the shield lining member,
Since a vertical force acts, a primary lining member (segment) having high rigidity must be used. Further, since the cross section is rectangular, the member thickness of the segment is considerably larger than that of the circular cross section.

[0017] The large space where the shield excavation is performed and the segments are assembled serves only as a temporary retaining wall, and ultimately has no relation to the main body structure and becomes a useless space.

As described above, in the conventional open-cutting method,
There were also problems with the shield method.

The present invention has been made to eliminate the above disadvantages.

[0020]

According to the method of constructing an underground structure of the present invention, a pair of left and right earth retaining walls are formed in a ground from a road, and a shield excavator is loaded between the left and right earth retaining walls. A step of constructing a shaft for carrying out, a step of excavating a hole for a lower floor using a shield excavator carried into the shaft, and a step of excavating a hole for an upper floor using a shield excavator carried into the shaft. Excavating, forming the lower floor slab and the upper floor slab by forming holes for the lower floor and the upper floor, and excavating soil between the lower floor slab and the upper floor slab. It is characterized by.

[0021]

Embodiments of the present invention will be described below with reference to the drawings.

In the tunnel construction method of the present invention, a continuous underground wall (continuous wall) constructed from the road is used as a side wall of the structure, and the upper floor and the lower floor slab are constructed by a rectangular shield construction method from a shaft. So, specifically,

As shown in FIG. 1, a pair of left and right earth retaining walls (continuous walls) 10, 10 are constructed underground from the road. As shown in FIG. 2, there is no need to provide a long embankment 11 below the earth retaining wall required by the conventional open-cutting method, as shown in FIG. In addition, there is no need for an extra wall 12 for road surface lining or earth retaining above, and this portion is filled with sand or a solid muddy solidified wall.

A starting and arriving shaft 1 for loading and unloading the shield machine to the ends of the left and right retaining walls 10, 10.
Build 5,16. In the case of the present invention, for example, as shown in FIG. 1, when constructing the retaining walls 10, 10, plan and avoid the existing object 13 on the ground where removal and relocation are difficult.
If the shrub 14 or the like 14 which is relatively easy to remove and relocate is moved, the construction becomes possible.

After the start position shaft 15 is built, on a road or in the shaft 15, as shown in FIG.
A skin plate 17 having a total width of about 6.0 m to 20 m is assembled, and a required number of small rectangular shield excavators 18 are juxtaposed in the horizontal direction in the skin plate 17.

The rectangular seal excavator 18 is started horizontally in the lower floor portion 19 to excavate the lower floor portion 19, and as shown in FIG. 20 and install this segment 20,
A plurality of columns 21 are installed between the bases 20 to support an upper ground 22 (primary lining), and segment reinforcing ribs 23 are provided as necessary.

Next, the upper floor portion 24 shown in FIG. 2 is similarly excavated by the rectangular shield excavator 18, segments 20 are similarly installed on the upper and lower surfaces of the excavated portion, and a plurality of struts are provided between the segments 20. 21 to support the ground 22 at the top.

As shown in FIG. 5, the rebar 25 is assembled in the mine where the primary lining has been completed, and the work of attaching the reinforcing bar 25 to the connecting wall 10 is performed, and the primary lining segment 20 and the column 21 are buried or removed. A concrete body 26 for the lower slab 19 is cast, and a lower slab 27 is constructed as shown in FIG. Similarly, the upper floor slab 28 is constructed. (Secondary lining)

In order to reinforce the lower slab 27 and the upper slab 28 as necessary, the lower slab is formed in the ground 29 formed between the lower slab 27 and the upper slab 28 prior to the excavation of the entire ground 29. A hole 30 communicating with the plate 27 and the upper floor plate 28 is provided, and a center pillar (not shown) is installed in the hole 30.

The soil in the ground 29 is excavated (uncut tunnel excavation), the interior of the ground 29 is maintained, and the side wall decorative wall 31 is provided.
The construction is completed by reclaiming the shafts 15, 16.

The tunnel construction method of the present invention has the following advantages as compared with the open-cutting method.

With respect to the side wall (retaining wall), the upper layer portion is not excavated, so that the retaining wall is not necessary, and the lower layer portion is only embedding as the retaining wall at the time of shield excavation. No long embedding as shown in Fig. 2 as earth retaining for excavation or long embedding for blocking groundwater is required. Therefore, it is possible to reduce the construction quantity of the connecting wall.

Since it is not necessary to use a groundwater level lowering method or the like in combination with groundwater pressure control, the groundwater around the construction is not reduced, and the well does not dry or cause land subsidence.

In particular, since there is no deep embedding of the connecting wall, there is no occurrence of a damping phenomenon of groundwater acting as an underground dam.

As a countermeasure against board swelling due to groundwater pressure, the open-cutting method requires auxiliary methods such as “deepening of impermeable walls”, “ground improvement”, and “lowering of groundwater”, which is disadvantageous in terms of construction period and construction cost. In the case of the construction method of the present invention, the auxiliary construction as described above is not required by adopting the closed shield construction method.

Since the soil above the upper slab is not excavated,
Low annoyance to local residents. In addition, there is little hindrance to existing buried objects, and no extra work such as relocation and restoration is required.

Since the amount of excavated soil is reduced and the backfill is performed only at the shaft, the amount of backfill can be reduced.

When excavating the lower floor portion and the upper floor portion, the vertical force is balanced at the upper ground pile via the pillar, and the horizontal force can be covered by the continuous wall. That is, the reaction force can always be balanced on the surrounding ground. Even if the place where the structure is built becomes deeper and the groundwater pressure increases, countermeasures against groundwater pressure will not be a major problem.

The following advantages are obtained as compared with the shield excavation method.

As shown in FIG. 4, the horizontal force (H) and the vertical force (V) can be considered as the external force at the time of the primary lining. In the case of the method of the present invention, the horizontal force is reduced by the rigid wall 10.
And has no effect on segments. However, vertical forces act on the segments. That is, in the method of the present invention, a horizontal force does not act on a segment, but only a vertical force acts. Therefore, if the columns are appropriately arranged, a segment having a high rigidity like the segment of the conventional shield method is unnecessary.
(The structure is simple and the girder height can be reduced)

Since the lower floor slab or the upper floor slab can be excavated at a stretch, a connection step with each part of the shield is unnecessary, and the process is greatly shortened.

In the method of the present invention, since the floor slab of the main structure is built by the cast-in-place concrete method in the space itself formed by excavating the shield, a temporary wasteful space is extremely small.

Several small shield excavators can be used side by side in the horizontal direction, and it is possible to divert and divert various shield excavators with some modifications.

[0044]

[Effect of the Invention] As described above, according to the method of the present invention, there is no need to perform large-scale excavation work, to create a large-scale temporary space, and to reduce the pressure of groundwater as much as the water stoppage of the shield method. No need to interrupt the groundwater flow or lower the water level to change nature. At present, when a large rectangular construction is constructed by a shield method, there is a great advantage that many difficulties caused by a combination of a plurality of small rectangular shields can be solved.

[Brief description of the drawings]

FIG. 1 is a plan view for explaining a construction method of an underground structure according to the present invention.

FIG. 2 is a vertical sectional side view for illustrating a construction method of an underground structure according to the present invention.

FIG. 3 is a side view showing an assembled state of a large ground shield excavator used in the method of constructing an underground structure according to the present invention.

FIG. 4 is an explanatory side view of a primary lining method for constructing an underground structure according to the present invention.

FIG. 5 is a side view for explaining a primary lining method for constructing an underground structure according to the present invention.

FIG. 6 is a side view for explaining a secondary lining in the method of constructing an underground structure according to the present invention.

FIG. 7 is an explanatory side view of a conventional digging method.

FIG. 8 is a vertical sectional side view for explaining a conventional shield method.

[Explanation of symbols]

 Reference Signs List 1 ground 2 impermeable layer 3 retaining wall 4a section 4b section 4c section 4d section 4e section 4f section 4g section 4h section 5 Shield excavator 6a 6b 6c 6d 6d 6e 6f 6g 6h 7 Primary lining Member 8 Gap communication 9 Main body structure 10 Earth retaining wall (continuous wall) 11 Long embedding 12 Extra wall 13 Obstacle difficult to remove 14 Obstacle that can be removed 15 Starting shaft for carrying in 16 To carry out Shaft 17 skin plate 18 small shield excavator 19 lower floor part 20 segment 21 support 22 ground ground 23 segment reinforcement rib 24 upper floor part 25 steel bar 26 concrete body 27 lower floor slab 28 upper floor slab 29 ground 30 hole 31 side wall decoration wall

Claims (1)

[Claims] 1. A step of forming a pair of left and right earth retaining walls from the road in the ground, a step of constructing a shaft for loading and unloading a shield excavator between the left and right earth retaining walls, and loading the shaft into the shaft. Using a shield excavator to excavate a hole for the lower floor, and using a shield excavator carried into the shaft to excavate a hole for the upper floor, and forming the hole for the lower floor and the upper floor A method of constructing an underground structure, comprising: constructing a lower slab and an upper slab, respectively, and excavating soil between the lower slab and the upper slab.