JP3012894B2 - Simple underground construction method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a simple underground construction method for use in the construction of an underground wall for an excavation pier.

[0002]

2. Description of the Related Art In a method of designing a mountain retaining frame in an excavation work, as shown in FIG. 8, a lateral pressure acting on an excavating wall 1 is supported by a 0-level notch 2 at an upper portion and a ground at an excavating bottom 3 at a lower portion. A one-way analysis method is employed in the vertical direction of the beam.

[0003]

When the soft ground is deep,
Alternatively, when the root cutting depth is shallow, the retaining wall 1 is desirably as small as possible, such as a self-supporting type, but the deformation is large, and becomes considerably large considering the influence on the surrounding ground. .

An object of the present invention is to eliminate the disadvantages of the prior art, and the wall thickness required as a retaining wall is not affected by the badness of the ground such as when the soft layer is thick, and it is possible to cope with the wall having a cross section as small as possible. Another object of the present invention is to provide a simple underground construction method capable of improving the cost and the construction period by making it possible to omit the retaining wall deeper than the bottom of the root.

[0005]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention firstly provides a wall pile which supports the end of the retaining wall at predetermined intervals in the continuous direction of the retaining wall, and the lower end of which is a retaining pile. The length should reach the hard layer that can be a virtual fulcrum that supports the wall, and it is constructed by providing overhangs on the left and right,
A pile retaining wall having a minimum length necessary for root cutting is connected between the wall piles by overlapping with the overhang portion, and secondly, the pile retaining wall is provided with self-hardening muddy water in an excavation hole. Alternatively, cement milk is injected and kneaded, and a section steel having a web oriented horizontally is arranged in an interdigital shape. Third, the section steel is provided with holes in the web at appropriate intervals. In addition, the gist of the present invention is to provide a ground anchor for fixing to the support layer on the wall pile.

As shown in FIG. 8, when the soft layer is deep, a very large bending moment acts on the stress of the retaining wall generated by root cutting, and the rigidity of the retaining wall needs to be large. According to the present invention as set forth in claim 1, the required depth of the retaining wall is reduced to the final root by receiving the retaining wall by a wall pile having a length reaching the hard layer so that the lower end can be a virtual fulcrum for supporting the retaining wall. The bending moment generated by the cutting becomes like a simple beam supported by a virtual fulcrum between the notch and the hard layer, similarly to the calculation in the general notch open cut method.

In this way, the design can be made simply by the distance between the wall piles without being greatly influenced by the depth of the soft layer and the strength of the ground.

According to the second aspect of the present invention, the retaining wall is a so-called soil cement continuous wall in which self-hardening muddy water or cement milk is injected and kneaded into the excavation hole. It can be easily and quickly constructed by using a large chain saw, etc., but by arranging the shaped steel in an interdigitated shape, the strength can be increased and the bending moment as a retaining wall can be sufficiently counteracted.

According to the third aspect of the present invention, in addition to the above-described functions, the shaped steel is excellent in economy and workability by appropriately arranging holes in the web.

According to the fourth aspect of the present invention, in the case where a so-called self-standing mountain retaining wall type is used without erection of a cut, when the excavated ground has a weak strength and a large lateral pressure is applied,
Alternatively, when the soft layer is deep and the strength of the wall pile is insufficient, the ground anchor can prevent the wall pile from falling forward.

[0011]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a plan view showing one embodiment of the simple underground construction method of the present invention, FIG. 2 is a vertical front view of the same, FIG. 3 is a vertical side view of the same, 3 is a root bottom, A is a root cutting side, and B is a root cutting side. On the back side, α is a soft layer and β is a hard layer.

In the figure, reference numeral 4 denotes a retaining wall in the excavation work, and the retaining wall 4 has a minimum length which can be supported so that the excision wall is not collapsed.

Prior to constructing such a retaining wall 4, a wall pile 5 is supported at predetermined intervals in a continuous direction of the retaining wall 4 so as to support the ends of the retaining wall 4, and the lower end thereof supports the retaining wall 4. It is constructed so as to reach the hard layer β which can be a virtual fulcrum 8.

The wall pile 5 has a cross-shaped or T-shaped shape, and the retaining walls 4 are overlapped and connected at the left and right overhangs. The wall pile 5 is constituted by a continuous wall and is constructed on site, but may be made of precast concrete or steel.

After arranging the wall piles 5 at appropriate intervals in this way, the retaining wall 4 is constructed in the meantime. The retaining wall 4 is to be constructed with a continuous soil cement wall. Excavation is carried out using a bentonite solution and aeration together with a large-sized chain saw, and after completion, the mixture is stirred and mixed while injecting a cement paste (cement milk).

As a continuous excavation method for the soil cement wall constituting the retaining wall 4, a construction machine called a soil changer, which is a small-sized triaxial pile driving machine of the SMW method, is used in addition to the above-mentioned trender method. A triaxial method may be adopted.

Before the self-hardening muddy water (bentonite solution) or cement milk injected into the borehole is kneaded and hardened, the H or I section steel having the web 10a in the horizontal direction and the main stress in the horizontal direction is provided therein. Wire shape steel 10
With a hanging member such as 11 or the like, they are arranged side by side in an up-down direction and arranged in an interdigital shape.

The section steel 10 has a web 10a with circular or square holes 10b provided at appropriate intervals. Holes like this
By providing 10b, the material cost of the shaped steel 10 can be reduced,
In addition, when the section steel 10 is installed, self-hardening muddy water (bentonite solution) or cement milk passes through the holes 10b, thereby improving workability.

The section steel 10 can be installed at the stage when the drilling hole is formed, and then self-hardening muddy water or cement milk can be injected and stirred.

In the thus-constructed structure of the simple underground construction of the present invention, as shown in FIG. 3, the axial force of the notch 7 and the imaginary fulcrum 8 acting as a reaction force with respect to the stress acting on the wall pile 5. About the reaction force is the same as the calculation by the general open cut method. Moreover, since the wall pile 5 has a large bending rigidity, it has a large resistance to deformation. As a result, even if the interval between the notches 7 is greatly increased, it can be easily countered.

In the case of the so-called self-standing mountain retaining wall type without the ridge 7 being installed, when the strength of the excavated ground is weak and large lateral pressure acts, or the soft layer α is deep and the proof strength of the wall pile 5 is insufficient. In this case, the ground anchor 6 may be cast on the rear side B to prevent the wall pile 5 from falling forward. The installation angle of the ground anchor 6 is best when it is vertical, but it is more effective when it is placed diagonally on the rear side.

Next, a case where the present invention is used for a cutting open cut method will be described. As shown in FIG. 4, a wall pile 5 is constructed at a pillar position, and a mountain retaining wall 4 having a length necessary for root cutting is constructed at a main underground outer wall position.

As shown in FIG. 5, the first root cutting is performed to the first floor slab position or to a depth position that does not cover the first floor slab, thereby constructing the first stage cutting 7a.

As shown in FIG. 6, the root is cut to a depth necessary for the construction of the first basement slab or to a position not to reach the slab, thereby constructing the second-stage cut 7b.

As shown in FIG. 7, the third root cutting is performed to a depth necessary for constructing the foundation beam slab 9, and the foundation beam slab 9 is constructed.

If the rigidity of the wall pile 5 is sufficient, FIG.
It is effective to omit the step shown in (1) and perform root cutting to the final flooring position in FIG.

After the underground construction is completed, the wall pile 5 is used as a permanent pillar,
It is economical and rational to use the retaining wall 4 as a permanent underground outer wall.

[0028]

As described above, according to the simple underground construction method of the present invention, the wall thickness required for the mountain retaining wall is not affected by the badness of the ground (thickness of the soft layer), and the mountain retaining wall has a cross section as much as possible. It can be dealt with in small things and is very reasonable.

In addition, it is possible to improve the cost and the construction period by omitting the retaining wall deeper than the root bottom.
This eliminates the need for highly difficult work such as raising a belly or setting up a blow beam, and also facilitates excavation work with a large heavy machine by reducing the number of cutting steps.

Furthermore, the wall pile can be used as a permanent underground pillar, and the retaining wall can be used as an underground outer wall, so that it is more economical.

[Brief description of the drawings]

FIG. 1 is a cross-sectional plan view of a main part showing one embodiment of a simple underground construction method of the present invention.

FIG. 2 is a vertical sectional front view of an essential part showing one embodiment of the simple underground construction method of the present invention.

FIG. 3 is a vertical sectional side view showing one embodiment of the simple underground construction method of the present invention.

FIG. 4 shows an example of a simple underground construction method according to the present invention,
It is a vertical side view which shows a 1st process.

FIG. 5 is an example of one construction by the simple underground construction method of the present invention,
It is a vertical side view which shows a 2nd process.

FIG. 6 is an example of one construction by the simple underground construction method of the present invention,
It is a vertical side view which shows a 3rd process.

FIG. 7 is an example of a simple underground construction method according to the present invention,
It is a vertical side view which shows a 4th process.

FIG. 8 is an explanatory diagram showing a conventional example.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Mountain retaining wall 2 ... Cut-off 3 ... Root bottom 4 ... Mountain retaining wall 5 ... Wall pile 6 ... Ground anchor 7 ... Cut-out 7a ... 1st-stage cut 7b ... 2nd-stage cut 8 ... Virtual fulcrum 9 ... Foundation Beam slab 10 ... Shaped steel 10a ... Web 10b ... Hole 11 ... Wire

Continuation of the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) E02D 5/02-5/20 E02D 29/00 E02D 29/045-29/055 E02D 17/04

Claims (4)

(57) [Claims] 1. A wall pile that supports an end portion of a retaining wall at predetermined intervals in a continuous direction of the retaining wall, the length of the wall pile reaching a hard layer whose lower end can be a virtual fulcrum that supports the retaining wall, And, it is constructed by providing overhangs on the left and right and constructing by connecting a pile retaining wall having a minimum length required for root cutting between the wall piles by overlapping with the overhang. Simple underground construction method. 2. The simplified retaining structure according to claim 1, wherein the retaining wall is formed by injecting self-hardening muddy water or senmet milk into the excavation hole and kneading the material, and in which the shaped steel whose web is oriented horizontally is arranged in an interdigital shape. Underground construction method. 3. The simple underground construction method according to claim 2, wherein holes are formed in the web at appropriate intervals. 4. The simple underground construction method according to claim 1, wherein a ground anchor for fixing to the support layer is provided on the wall pile.