JPH02311620A - Underground structure construction method - Google Patents

Abstract

PURPOSE:To shorten a construction term as well as to permit easy construction by collecting water in the inner part of an earth retaining wall and excavating the ground in the water, while constructing a structure as balancing buoyancy in parallel with the progress, and installing it in a specified position. CONSTITUTION:An earth retaining wall 1 is set up in the ground, and the inner ground is excavated, setting up an earth anchor 2 there. Next, an assembling pit 3 of an excavator is excavated on the excavating ground, constructing the lower part of an underground structure 4. Then, a pipe body 5 is set up on a bottom part of the structure 4, and water is poured in an inner part of the earth retaining wall, floating the structure on the water. Successively, a lower ground of the structure 4 is excavated in the water by a sand pump excavator 6 with a cutter, and in parallel with progress of this excavation, each upper part of the structure 4 is built up in a series in order on a lower part of the structure 4. In addition, mud produced by excavation at this time is discharged to the outside by a mud discharge pipe 7 and, after it is excavated as far as specified depth, the excavator 6 is removed and the structure 4 is installed. Finally, water is drained and a consolidation material is charged in and around the structure 4.

Description

Detailed Description of the Invention "Field of Industrial Application" This invention relates to a construction method for constructing an underground structure such as an underground structure or a structure having an above-ground building on top of the underground structure, and in particular, a construction method for constructing an underground structure such as an underground structure or a structure having an above-ground building. This relates to a construction method in which the retaining wall is floated on water stored inside the retaining wall and then submerged.

[Prior art and problems to be solved by the invention] Traditionally, common methods for constructing underground structures include the cut-and-cover method using mountain retaining supports, construction methods using pneumatic caisson, or oven caisson. known to.

However, in the cut-and-cover method using mountain retaining shoring,
Since groundwater pressure and earth pressure outside the mountain retaining wall apply loads to the retaining wall, the retaining wall must be made strong, which poses a problem in that the construction costs associated with the retaining wall increase.

In addition, in the construction method using pneumatic caissons, there are safety issues for workers due to work in pressurized air, instability of construction due to uneven load acting on the structure as it is sunk, impossibility of sinking due to surrounding friction, and advanced excavation. There were various problems when constructing underground structures, such as the requirement for accuracy and over-design of the sub-slab as the work room slab, which was determined by the conditions at the time of construction.

Furthermore, the oven caisson construction method had problems with attitude control and position control during excavation, and with underground construction of the hydraulic bottom slab after excavation was completed.

"Means for Solving the Problems" This invention solves the above-mentioned conventional problems by storing water inside the retaining wall and canceling out part of the groundwater pressure and earth pressure outside the retaining wall. In addition to simplifying the mountain retaining wall, the lower part of the structure to be constructed is floated on water inside the mountain retaining wall, the ground below this structure is excavated underwater with an excavator, and the progress of this excavation is monitored. At the same time, the upper part of the structure is built one after another on top of the lower part of the structure, and the pneumatic caisson construction method is carried out by erecting the upper part of the structure one after another and sinking it into a predetermined position by the weight of this structure or the load of water poured into the structure. This paper proposes a construction method for underground structures that can solve various problems.

``Example j'' An example of the present invention shown in the drawings will be described below.
As shown in Figure 1, a retaining wall 1 is installed by pouring steel sheet piles, steel pipes, or continuous underground walls around the planned construction ground.
The ground inside the ground is excavated to a required depth and an earth anchor 2 is installed, and a bit 3 for assembling an excavator is excavated on the excavated ground.

At this time, if the surrounding environment permits, the above-mentioned excavation can be omitted by making the retaining wall protrude above the ground.

Next, as shown in FIG. 2, the lower part of the underground structure 4 is constructed on the excavated ground, and the structure 4 is constructed as shown in FIG.
A pipe body 5 for assembling and repairing an excavator is installed at the bottom of the pipe body 5 so as to communicate with the lower part of the bottom, and after passing the assembly member of the sand pump excavator 6 with a cutter through the pipe body 5 and assembling it in the bit 4 below, the mountain retaining wall is installed. Water is injected into the interior of the structure 1 and stored higher than the groundwater level outside, and the structure 4 is floated.

This water pressure inside the mountain retaining wall cancels out the groundwater pressure outside the mountain retaining wall 1 and a part of the soil, making it possible to simplify the mountain retaining wall 1.

Next, as shown in FIG. 4, the ground below the structure 4 is excavated underwater using an excavator 6, and as this excavation progresses, the upper part of the structure 4 is successively placed over the lower part of the structure 4. erected in

Note that the mud excavated at this time is discharged to the outside through a mud drain pipe 7.

After excavating to a predetermined depth and dismantling and removing the excavator 6, the structure is sunk in a predetermined position while balancing the buoyancy by the weight of the structure or an additional load such as the water load poured into the structure,
As shown in FIG. 5, if the buoyant force exceeds the buoyant force, the bottom of the structure 4 is tied to the earth anchor 8 to counteract the buoyant force.

Finally, while draining the water in the retaining wall 1, a consolidation material 9 such as underwater concrete is filled around the structure 4 to complete the construction.

It goes without saying that the structure 4 constructed according to the present invention can be similarly constructed in the case of constructing a structure in which an above-ground building is erected continuously to an underground part as shown in FIG.

"Effects of the Invention" As described above, according to the present invention, water is stored inside the retaining wall to cancel out part of the groundwater pressure and earth pressure outside the retaining wall.
In addition to simplifying the mountain retaining wall and reducing its construction cost, the lower part of the structure to be constructed is placed 27 times above water inside the mountain retaining wall, and the ground below this structure is submerged using an excavator. It is possible to shorten the construction period for excavating and erecting the upper part of the structure one after another on the lower part of the structure in parallel with the progress of this excavation. Since the structure is sunk into a predetermined position by the water load, there is no uneven load or surrounding friction acting on the structure as it is sunk, and a high degree of excavation precision is not required (and there is no need to worry about the conditions at the time of construction). It can be constructed relatively easily and safely without over-designing the sub-slab as the workroom slab determined by the above.

[Brief explanation of drawings]

1 to 6 are longitudinal sectional side views sequentially showing the construction steps of the present invention. ■...Mountain retaining wall, 2...Earth anchor, 3...Bit,
4. Structure, 5. Pipe body, 6. Excavator, 7. Sludge removal pipe, 8. Earth anchor, 9. Consolidation agent.

Claims (1)

[Claims] 1) Water is stored inside the mountain retaining wall to cancel out part of the groundwater pressure and earth pressure outside the mountain retaining wall, and the lower part of the structure to be constructed is floated on the water inside the mountain retaining wall. The ground below the object is excavated underwater with an excavator, and as this excavation progresses, the upper parts of the structures are erected one after another on the lower parts of the structures, and the weight of this structure or the load added to it is A construction method for underground structures that is characterized by sinking them into a predetermined position while balancing the buoyancy with the buoyancy.