JP2003138584A - Construction method for underground skeleton - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rational underground construction method by improving a conventional caisson construction method. SOLUTION: A water stop wall 4 reaching a non-water permeation layer 3 and serving also as earth retaining is installed by surrounding a position where an underground skeleton 1 is sunk and provided. The underground skeleton is first constructed in a ground surface part on an inner side of the water stop wall. Pumping of underground water is performed from inner side ground 2 of the water stop wall to dig the inner side ground of the water stop wall while reducing a level of underground water down to below a digged bottom face so that the underground skeleton is sunk and installed by guiding it by the water stop wall and reaches a desired depth. When sinking and installing the underground skeleton, a waterproof layer is formed on its outer face. A weight of the skeleton is supported by the required number of temporarily provided real columns, a blade tip ground reaction force, and a friction force of a peripheral face to prevent unexpected sinking of the skeleton. A jack is installed in a skeleton connection part of the temporarily provided real columns to perform expansion and shrinkage control in accordance with inclination of the skeleton and a situation of stress by interlocking relationship. Mud earth or mud water is poured into a cavity part between the skeleton and the water stop wall or the ground to reduce friction resistance, and mud water is solidified after the sinking and installation of the underground skeleton are completed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of constructing an underground skeleton, which is applied when constructing a skeleton of an underground portion of a building or the like, and particularly to constructing an underground skeleton in advance at the surface portion to excavate the ground therebelow. Concerning the construction method to be sunk.

[0002]

2. Description of the Related Art As is well known, this type of construction method is called the caisson method (submarine construction method), and the underground structure is first constructed as a caisson (submersible) at the surface and the ground below it is excavated. The underground skeleton is sequentially sunk in order to reach the desired depth. Especially when the groundwater level is higher than the bottom of the excavation, a pressurized working chamber is provided at the bottom of the caisson to keep the internal pressure above the groundwater pressure to push down the groundwater level inside the caisson and perform excavation in a dry state. The pneumatic caisson method is widely used.

[0003]

With the conventional caisson method in the past, large-scale excavation is performed, which may cause obstacles such as subsidence of the surrounding ground. When excavating, the excavated soil becomes sludge and must be disposed of as industrial waste. In addition, since the pneumatic caisson method requires excavation work under high pressure, it is not preferable as a working environment.
There is also a concern that compressed air will blow out to the surrounding area. Therefore, it is not always preferable to apply the conventional general caisson method particularly to the construction of buildings in urban areas, and effective improvement measures have been demanded. In addition, in caisson excavation and digging work, there are cases where it is difficult to dig during the construction due to changes in the ground condition and the inclination of the skeleton, so it was desired to develop a stable digging work method.

[0004]

In view of the above circumstances, the invention of claim 1 is to install a water blocking wall reaching the impermeable layer so as to surround the position where the underground structure should be laid down, also as a mountain retaining, and By excavating the inside ground of the water stop wall while lowering the groundwater level to the bottom of the excavation bottom by performing underground construction in advance on the surface part inside the water wall and pumping groundwater from the inside ground of the water stop wall, It is characterized in that the underground structure is guided while being guided by the water blocking wall to reach the desired depth.

According to a second aspect of the invention, in the method of constructing an underground skeleton according to the invention of claim 1, when the underground skeleton is sunk,
It is characterized by forming a waterproof layer on the outer surface of the underground structure to enhance the waterproof performance of the underground structure.

According to a third aspect of the present invention, in the method for constructing an underground skeleton according to the first or second aspect of the invention, the weight of the skeleton is supported by a temporary structure true column having a required number of the columns and a blade tip ground reaction force and a peripheral surface friction force. The feature is that it is installed while preventing unexpected subsidence of the skeleton caused by changes in the bearing capacity of the ground and progress of excavation work.

The invention of claim 4 relates to claim 1, 2 or 3
In the method of constructing an underground skeleton of the invention of 1), by installing a jack on the skeleton connecting part of the temporary structure true pillar, and by performing expansion and contraction control according to the inclination and stress condition of the skeleton respectively, stable, safe and highly accurate It is characterized by carrying out simple deposition.

According to a fifth aspect of the present invention, in the method for constructing an underground skeleton of the invention according to claim 1, 2, 3 or 4, the skeleton wall surface is displaced inward by a necessary dimension with respect to the blade edge portion of the skeleton skeleton, and the skeleton thus generated By injecting mud or muddy water into the water-stop wall or the void of the ground, it reduces the extra frictional resistance at the time of deposition, and solidifies the muddy water after the deposition is completed to impermeable wall outside the underground structure. Is formed.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT FIG. 1 shows an embodiment of the present invention. The construction method of the underground skeleton of the present embodiment is based on the open caisson method, and the underground skeleton 1 of the underground portion of the building is pre-constructed as a caisson on the ground surface,
By excavating the ground below it, the underground skeleton 1 is sunk to reach the desired depth, but the water blocking wall 4 reaching the impermeable layer 3 surrounding the position where the underground skeleton 1 should be sunk is piled up. It is also installed, and groundwater is pumped from the inner ground 2 of the water stop wall 4 to lower the groundwater level WL to the bottom of the excavation bottom to excavate the inner ground 2 of the water stop wall 4 in a dry state. In addition, the underground structure 1 is guided by the water blocking wall 4 and is sunk.

As the water blocking wall 4, a soil cement column wall having a steel material such as H-section steel as a core material can be preferably adopted.
In that case, the steel material as the core material can be effectively utilized as a guide for the subsidence of the underground structure 1. It should be noted that the water blocking wall 4 may be one that also serves as a mountain retaining wall and can guide the subsidence of the underground structure 1. Alternatively, the water blocking wall 4 may be provided as a temporary structure and finally removed, or the underground outer wall of the main structure. It may be left as it is as a part of the structure, and for example, a simple structure such as a steel sheet pile or a large-scale structure such as a continuous underground wall can be arbitrarily adopted.

An appropriate construction method can be adopted for pumping groundwater from the inner ground 2 of the water stop wall 4, but a deep well construction method in which a deep well 5 is provided inside the water stop wall 4 and water is pumped from there Is realistic. In any case,
In the present embodiment, since the water blocking wall 4 is provided so as to reach the impermeable layer 3, the inflow of groundwater from the outside is blocked by the water blocking wall 4, and the pumping amount is greatly increased as compared with the case where the water blocking wall 4 is not provided. Can be reduced to

When the underground skeleton 1 is sunk, a waterproof layer 6 such as asphalt or coating film waterproof is formed on the outer surface of the underground skeleton 1 to enhance the waterproof performance of the underground skeleton 1. This waterproof layer 6
Since the formation work of can be performed on the ground before the underground structure 1 is sunk, the waterproofing work for the underground outer wall 7 can be rationalized.

The underground structure 1 is sunk while filling the space between the water blocking wall 4 and the underground structure 1 with cohesive soil in the form of mud or muddy water. As a result, the sliding effect of mud or muddy water is obtained, and the frictional resistance at the time of subsidence is reduced. Further, when muddy water having a specific gravity of about 1.1 is used, the muddy water pressure exceeds the mountain retaining side pressure, and the displacement of the water blocking wall 4 which also serves as mountain retaining can be suppressed. Then, the impermeable wall is formed by finally solidifying the mud or muddy water, which contributes to the improvement of the waterproof performance of the underground structure 1.

A required number of temporary structure true columns 8 are arranged below the underground structure 1, and the underground structure 1 is supported through the jacks 9. As a result, it is possible to prevent unexpected subsidence of the skeleton caused by changes in the bearing capacity of the ground and progress of excavation. In addition, it is possible to perform stable and safe work against frictional resistance and inclination of the skeleton when sunk, and it is possible to sank with high precision.

According to the construction method of the present embodiment, the submerged body 1 is surrounded by the water stop wall 4 around the submerged position, and ground water is pumped from the inner ground 2 to excavate the ground water level WL in a lowered state. Therefore, it is possible to excavate in a dry state even though it is substantially an open caisson method, and it is possible to avoid underwater excavation like the conventional open caisson method, which is excellent in workability and disposes excavated soil as sludge. There is no need. Of course, compared to the conventional pneumatic caisson method, it does not require work under pressure, so the working environment can be improved, and there is no need to provide a pressure work room in the underground structure 1, There can be no problems such as squirting into.

Since the water blocking wall 4 also serves as a mountain retaining wall,
It is possible to eliminate adverse effects such as subsidence of the surrounding ground due to excavation,
Further, since the water blocking wall 4 guides the subsidence of the underground structure 1, the subsidence structure 1 can be easily installed with high precision.

Therefore, according to the present invention, the caisson method can be adopted even in an area where it has been difficult to adopt in the past due to the condition of the ground and the constraints of the surrounding environment, and there is no problem in the construction of buildings especially in urban areas. It is possible to adopt. And according to the present invention, the underground structure 1
It is possible to work in parallel with the preceding construction and excavation work, and it is also possible to achieve a high degree of prefabrication and unitization of the underground structure 1. As a result, it is possible to compare various conventional general underground construction methods, such as the reverse construction method. By doing so, the rationalization of construction can be realized, and the construction period and the construction cost can be greatly reduced.

[0018]

According to the invention of claim 1, a water blocking wall reaching the impermeable layer is installed, and groundwater is pumped from the ground inside the groundwater to lower the groundwater level to below the bottom of the drilling ground. By doing so, the underground skeleton that was constructed in advance on the ground surface is sunk to reach the desired depth, so it is possible to excavate in a dry state. It is possible to eliminate adverse effects such as subsidence of the ground,
Further, since the water blocking wall guides the subsidence of the substructure, the submerged work can be easily performed with high accuracy.

According to the second aspect of the present invention, since the underground skeleton is sunk while the waterproof layer is formed on the outer surface of the underground skeleton, the waterproof performance of the underground outer wall can be enhanced. Moreover, since the waterproofing work can be performed on the ground, the work can be streamlined.

According to the third aspect of the present invention, the required number of temporary structure true columns are placed in the ground below the underground structure, and the weight of the structure is supported by the temporary structure true columns, the ground reaction force of the cutting edge, and the peripheral surface frictional force. Therefore, it is possible to prevent the unpredictable sinking of the skeleton caused by the change in the bearing capacity of the ground and the progress of excavation work. Further, since the influence of the ground supporting force is reduced during excavation, excavation work becomes easy.

According to the fourth aspect of the present invention, the jack is installed at the connecting portion of the temporary structure true column and the skeleton, and the skeleton is sunk by the expansion and contraction control of the jack which is linked to the inclination and the stress state.
Stable, safe and highly accurate depositing is possible without causing unexpected displacement.

According to a fifth aspect of the invention, the wall surface of the skeleton is displaced from the blade edge portion of the underground skeleton by a required dimension inward, and mud or muddy water is poured into the skeleton of the skeleton and the water-stop wall or the ground resulting from the displacement. It can reduce the excessive frictional resistance at the time. After the completion of the construction, the impermeable wall is formed outside the underground structure by solidifying the muddy water, which contributes to the prevention of water leakage to the basement after the completion of the construction.

[Brief description of drawings]

FIG. 1 is a schematic explanatory diagram of a construction method according to an embodiment of the present invention.

[Explanation of symbols]

1 Underground structure (caisson) 2 inside ground 3 impermeable layer 4 water stop wall 5 Deepwell 6 waterproof layer 7 underground wall 8 Temporary structure true pillar 9 jacks

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Takashi Kazumi             Shimizu Construction 1-3-2 Shibaura, Minato-ku, Tokyo             Within the corporation (72) Inventor Satoshi Taki             Shimizu Construction 1-3-2 Shibaura, Minato-ku, Tokyo             Within the corporation (72) Inventor Akihiko Kumada             Shimizu Construction 1-3-2 Shibaura, Minato-ku, Tokyo             Within the corporation F-term (reference) 2D047 AB06 AB08

Claims (5)

[Claims] 1. A water blocking wall reaching the impermeable layer is also installed so as to surround the position where the underground structure should be laid down, also as a mountain retaining, and the underground structure is installed in advance on the ground surface portion inside the water blocking wall. By pumping groundwater from the inside ground of the water wall and lowering the groundwater level to the bottom of the excavation bottom, by excavating the inside ground of the water stop wall, it is desirable that the underground skeleton be sunk while being guided by the water stop wall. A method of constructing an underground skeleton that is characterized by reaching the depth. 2. The method for constructing an underground skeleton according to claim 1, wherein when the underground skeleton is sunk, a waterproof layer is formed on an outer surface of the underground skeleton to enhance waterproof performance of the underground skeleton. Construction method. 3. The method for constructing an underground skeleton according to claim 1 or 2, wherein a required number of temporary structure true columns and a blade edge ground reaction force and a peripheral frictional force support the weight of the skeleton to support the ground. A method for constructing an underground skeleton, which is characterized in that the construction is performed while preventing an unexpected settlement of the skeleton caused by changes and progress of excavation work. 4. The method for constructing an underground skeleton according to claim 1, 2 or 3, wherein a jack is installed at a skeleton connecting portion of the temporary structure true column, and expansion / contraction control is interlocked depending on the inclination and stress condition of the skeleton. The method of constructing an underground structure is characterized by stable, safe, and highly accurate depositing. 5. The method for constructing an underground skeleton according to claim 1, 2, 3 or 4, wherein the skeleton wall surface is displaced inward by a required dimension from the blade edge portion of the skeleton skeleton, and the resulting skeleton and water stop wall or ground are formed. By pouring mud or muddy water into the voids, it reduces the excessive frictional resistance at the time of sinking,
Further, a method for constructing an underground skeleton, which comprises forming an impermeable wall outside the underground skeleton by solidifying muddy water after completion of the deposition.