JP3156025B2 - Independent open cut method for large scale and large depth - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a self-supporting open cut for carrying out a so-called open cut in a large-scale and deep underground excavation work by making the retaining wall self-supporting without installing any cutting beam. Concerning the construction method.

[0002]

2. Description of the Related Art Conventionally, a large-scale underground excavation work is mainly carried out mainly by a multi-section beam excavation method, a straight-head pre-striking method, a vertical buttress method, and the like. By the way, as shown in FIGS. 10A and 10B, the multi-section girder excavation method is a method in which the facing members of the bulge 2 installed on the inner periphery of the retaining wall 1 are pressed and supported by the horizontal girder 3. The fire beam 4 and the cutting beam support 5 are adopted as necessary. This multi-section beam excavation method is often used in ordinary underground work.

[0003] In addition, in the straight-column precedent reverse hitting method, as shown in Fig. 11, a straight-column 6 is preliminarily constructed in the ground inside a retaining wall, and the ground is placed on the first basement floor. Each time excavation is performed, a concrete body such as pillars, beams, floors, and outer peripheral walls of the floor is constructed, and when the concrete has developed strength and is in a state of supporting the retaining wall 1 from the inside, the ground is re-formed. This is a construction method in which excavation is further advanced for one underground floor, and the jointing of the underground concrete skeleton is advanced downward (see JP-A-59-21831, JP-B-3-37603, etc.). This straight-column pre-reverse construction method is often used in large-scale underground construction and when the excavation depth is large.

Further, in the vertical buttress method, as shown in FIG. 12, a buttress (buttress wall) 7 is provided integrally on the inner surface of the retaining wall 1 in a plan view and in a radial direction when viewed from the top, so that the earth pressure is reduced. This is a method of resisting groundwater pressure. This vertical buttress method is implemented as a method for performing a large-scale underground construction by a self-standing mountain retaining method. A soil stradding type mountain retaining excavation method in which a beam-shaped soil stradd is provided inside the retaining wall to stiffen the retaining wall (Japanese Patent Publication No. 63-65)
768, JP-A-60-226917) are also implemented.

[0005]

[Problems to be Solved by the Invention] In the above-described multi-stage cutting beam excavation method, the cutting beams 3 are densely erected in proportion to an increase in excavation depth.
It is difficult to secure appropriate safety or workability. In addition, assuming that the resultant forces of earth pressure and groundwater pressure acting on the facing mountain retaining walls 1 and 1 balance each other, the stability and safety of the mountain retaining frame are ensured, so that each excavation is performed at each stage. It is necessary to lay all the cutting beams at that stage in a plane before proceeding to the next root cutting process. Therefore, in large-scale underground construction, excavation of the ground cannot be started during the erection period of the cutting beam, and there is a problem in improvement of workability such as interruption of the process. The tall-column pre-backing method is often used for underground construction where the excavation depth is large, but many large-scale high-rise buildings are directly foundations. The pillars are used only for temporary construction, which is uneconomical.
Also, in this case, unless the concrete has developed strength, the reverse striking frame of each step is constructed in a plane.
The next stage of root cutting cannot be started, and there is still a problem in improving workability. In the vertical buttress method described above, if the root cutting depth is large, it is structurally difficult to resist the external force of earth pressure and groundwater pressure only with the vertical buttress 7, and eventually it is necessary to erection of the cutting beam, The realization of the open cut method cannot be expected. Accordingly, an object of the present invention is to provide a construction method capable of performing an efficient open-cut construction in a short period of time on a large-scale, large-scale underground excavation work based on a self-supporting underground outer wall structure without any cutting beams. Is to provide.

[0006]

As a means for solving the above-mentioned problems of the prior art, a large-scale and large-scale self-supporting open-cut method according to the first aspect of the present invention is applied to an outer periphery of a ground excavation area. Building a continuous underground continuous wall having vertical ribs as a retaining wall in a closed shape;
The slab level position floor, the earth retaining wall inner surface planar shape Ru I <br/> other the entire circumference of the first-stage horizontal rib of the closure ring, drilling bottom
By placing concrete on the ground as a substitute for formwork
Ri, the method comprising: constructing in earth retaining walls integral structure, wherein the first
After the stage horizontal ribs of concrete expressed the strength, and the earth
Promoting root cutting work of the board, slab level position of the first floor underground
The planar shape over the entire inner surface of the retaining wall is a closed ring.
The second stage horizontal rib Jo, and mold substitute Excavation bottom ground
And concrete casting to construct a structure integrated with the retaining wall .
The step of constructing a horizontal rib at a slab level position is repeated by a required number of steps up to a predetermined root cutting depth.

[0007] The invention according to claim 2 is described in claim 1.
Independent open cut method for large scale and large depth
The root excavation work for the ground is to be replaced with the horizontal rib formwork.
The side ground, and the central ground with a low degree of influence on the ground
And excavate the ground in the center in advance.
And features .

[0008]

In the case of a mountain retaining wall (underground continuous wall) 1 constructed in a simple rectangular shape as shown in FIG. 1, the earth pressure, groundwater pressure, etc. applied to the mountain retaining wall 1 on the opposite side. External force F
Is transmitted as a compressive force stress f in the cross section of the horizontal ribs 12, so that the resultant force is balanced and the retaining wall is stably supported. Therefore, by securing the strength and the cross-sectional area of the horizontal rib 12 so as to correspond to the magnitude of the external force F, a self-standing underground outer wall structure can be obtained.

As shown in FIG. 2, in a site where it is difficult to obtain a balance of the resultant force with the mountain retaining wall on the opposite side as shown in FIG. intermediate support horizontal ribs 12a, 1 transmitting as f '
By the operation of 2b, the balance of the resultant force is maintained, and the stability of the retaining wall is maintained. The horizontal ribs 12 are installed at the slab level of each floor of the underground structure, and are ultimately used as a part of the main slab of each floor, thereby saving temporary materials.

The construction of the horizontal rib 12 is performed, for example, by using the root bottom 1.
When 2 is used as a substitute for the formwork, the formwork work is largely omitted. In this case, in order to take advantage of the so-called open cut feature, the ground of the form substitute portion of the horizontal rib 12 and the ground of the central portion having a low degree of influence on the ground portion are divided into two parts in plan view. By excavating the ground in advance, the root cutting can be promptly performed in parallel with (or before or after) the construction of the horizontal ribs 12, and the construction period can be shortened.

[0011] Thus, the realization of the self-sustained open cut method allows a high degree of freedom in planar construction.
It is easy to carry out earth and sand during excavation and carry in construction materials for the underground skeleton, so that underground construction can be performed efficiently.

[0012]

BRIEF DESCRIPTION OF THE DRAWINGS FIG.
First, FIG. 1 shows, as a very general embodiment of the present invention, an embodiment of a self-supporting open-cut method that assumes a simple rectangular planar shape and a balance of resultant forces of two facing mountain retaining walls. . In the figure, reference numeral 1 denotes a retaining wall constructed in a closed shape so as to surround the outer periphery of the excavated ground, and reference numeral 12 denotes a horizontal rib constructed in a closed loop shape on the entire periphery of the inner surface of the retaining wall 1.

FIG. 2 shows two horizontal ribs 12 which are asymmetrical in plan view and face each other in order to treat an external force F acting on the retaining wall 1 with stresses f ', f' in two perpendicular directions.
An embodiment of a self-supporting open-cut method using an intermediate portion supporting horizontal rib 12a for connecting the members in the immediate vicinity is shown.
FIG. 3 shows a stage in which the third horizontal rib 12 is integrated with the retaining wall 1 at a slab level position on the second basement floor in accordance with the progress of the ground excavation work. The horizontal ribs 12 can be constructed, for example, by using the ground of the root bottom 11 instead of the formwork, thereby eliminating formwork work, reducing temporary materials, and reducing man-hours. By the way, when constructing the ground of the root excavation bottom 11 as a substitute for a formwork, a method of leveling the root excavation floor horizontally and placing concrete directly on it is also possible. A method of laying an edge-cutting material such as a plastic sheet or a ceiling material (implanted material) on 11 and placing concrete on it, and then proceeding with the next-stage root-cutting work in a form in which the surface separation with concrete is clean. Is also preferred. Or install a shoring on the root bottom,
It is also possible to carry out a conventional method of supporting and constructing a rib formwork. In addition, as a method of integrally constructing the horizontal ribs 12 with the mountain retaining wall 1, conventionally, a method of forming an underground outer wall into a composite wall integral with the mountain retaining wall is known and well-known. A method in which a shear connector is provided and the shear connector is connected to the reinforcing member of the horizontal rib is preferably implemented.

Next, FIG. 4 shows, as a first step of a more specific construction procedure of the self-supporting open cut method according to the present invention,
This shows a stage in which the retaining wall 1 having a vertical rib 13 projecting outward is constructed. Specifically, a continuous wall excavator excavates a series of trenches for an underground continuous wall and a vertical rib in the ground in units of construction sections. When constructing the RC underground continuous wall, as shown in FIG. 8, a reinforcing cage 14 in which the continuous wall portion and the vertical rib portion are integrated is built, and concrete is poured into the body. The position of the vertical rib 13 is basically the position of the center line. In some cases, an inward vertical rib is provided inside the retaining wall 1. However, the retaining wall 1 is SR
When constructed as a C-structured underground continuous wall, vertical ribs are not usually used together as shown in FIG. 9, and a reinforcing cage 14 and a steel frame 15 made of H-section steel or the like are combined in an excavated linear groove. A steel reinforced reinforcement is built and concrete is poured.

Thus, after the construction of the retaining wall 1 is completed and the strength of the concrete is developed, excavation of the ground is started, and the horizontal ribs 12 are gradually constructed as shown in FIGS. 3, 5, and 6. . FIG. 5 is a specific example of the embodiment shown in FIG. 1 and shows a stage where the horizontal ribs 12 have been constructed up to the first basement floor and excavation of the ground has proceeded a little. FIG. 6 shows a stage in which the horizontal ribs 12 have been further constructed up to the second basement level and excavation of the ground has proceeded a little. Therefore, in the case of the present embodiment, external forces such as earth pressure and groundwater pressure acting on the retaining wall 1 are transmitted to the retaining wall in the orthogonal direction by the vertical ribs 13 and the horizontal ribs 12, and finally the orthogonal retaining wall. (See the flow of stress f in FIG. 1).

FIG. 7 is a specific example of the embodiment shown in FIG. 2, and shows a structure in which not only the horizontal ribs 12 but also the intermediate portion supporting horizontal ribs 12 are integrally formed. The intermediate portion supporting horizontal rib 12a is also constructed, for example, by using the root bottom 11 as a mold substitute. The intermediate support horizontal ribs 12a transmit the external force acting on the retaining wall 1 to the facing retaining wall for processing (see the flow of the stress f 'in FIG. 2).

[0017]

[Effects of the present invention] The self-supporting open cut method according to the present invention has the following effects. An independent open cut method for large-scale and deep underground excavation can be realized, and efficient underground construction can be achieved. Horizontal rib 1 only on the inner peripheral part of the retaining wall when viewed in plan
When the concrete strength of the horizontal rib is developed, the next excavation work can be started immediately. In particular, by dividing the ground in a plane, the excavation of the ground can be advanced at an early stage, and the construction period can be shortened. For example, in the conventional method, if the excavation is completed and all the supports (cut beams or back-floor slabs) are not completed, the safety as a frame cannot be established and the excavation work cannot be started during that time. With the open cut method, the safety of each part is ensured by completing each part, so the time until the frame is stable (the support work is completed) can be shortened, and the danger during construction Is reduced. Since the central part is open, it is easy to carry out earth and sand during excavation and carry in materials for construction of underground structures. In a direct foundation building, the number of temporary pillars can be reduced compared to the reverse construction method.

[Brief description of the drawings]

FIG. 1 is a plan view showing an embodiment of a self-supporting open cut method using horizontal ribs.

FIG. 2 is a plan view of an embodiment in which a horizontal rib and an intermediate portion supporting horizontal rib are used in combination.

FIG. 3 is a cross-sectional view showing a construction state of a horizontal rib.

FIG. 4 is a perspective view showing a construction state of a mountain retaining wall having a vertical rib.

FIG. 5 is a perspective view showing a stage in which horizontal ribs are installed up to the second stage.

FIG. 6 is a perspective view showing a stage where horizontal ribs have been installed up to the third stage.

FIG. 7 is a perspective view showing a stage in which a horizontal rib using an intermediate portion supporting horizontal rib is used up to the first stage.

FIG. 8 is a plan view of an RC mountain retaining wall having vertical ribs.

FIG. 9 is a plan view of the SRC mountain retaining wall.

FIGS. 10A and 10B are a vertical sectional view and a plan view showing a construction example of a multi-section beam excavation method.

FIG. 11 is a vertical cross-sectional view showing a construction example of a straight-column precedent reverse construction method.

FIG. 12 is a perspective view showing a construction example of a vertical buttress method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Mountain retaining wall 11 Root bottom 12 Horizontal rib 12a Intermediate part supporting horizontal rib

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-60-226918 (JP, A) JP-A-3-275816 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) E02D 29/045-29/055

Claims (2)

(57) [Claims] (1) A vertical retaining wall is provided on an outer periphery of an excavation area of the ground.
A method of constructing an underground continuous wall with a straight rib on the closed configuration, the first floor slab level position primary drilling, planar shape that cotton all around the inner surface of the earth retaining wall first stage horizontal rib of the closure ring Concrete in place of excavated ground
By the steps of constructing in earth retaining walls and integral structure, wherein after the first stage horizontal rib concrete expressed strength, promote Excavation work of the ground, the basement slab level
At the center position, the planar shape over the entire inner surface of the retaining wall is
Closed ring-shaped second level horizontal ribs , root cut bottom ground formwork
The steps of constructing an integrated structure with the retaining wall by casting concrete for use as well as excavating the ground and constructing horizontal ribs at the slab level position on each floor in the same manner are repeated until the required root depth is reached. An independent open cut method for large scale and large depths, characterized by repeating. 2. The root excavation work of the ground is performed by using horizontal ribs instead of formwork.
The surrounding ground to be considered, and the influence on the ground is low.
The ground in the center is separated from the ground, and the ground in the center is dug ahead.
The large-scale device according to claim 1 , wherein
Independent open cut method for large depth.