JPS62242024A - Method for protective pre-set structure - Google Patents

Abstract

PURPOSE:To prevent a structure from being influenced by earth pressure, by forming excavated slots or grooves filled up with stabilizing liquid, on the periphery of the structure, when a work expanding a ground volume like pile driving, deep-seated mixture processing construction, or the like near the pre-set structure is executed. CONSTITUTION:Before a new structure 14 is constructed right over a pre- constructed underground tunnel 12 in poor subsoil 10, then underground-tunnel- protecting columnar wall units 16 are constructed on both the sides of the tunnel 12 at specified intervals. In front of the constructed units 16, excavated slots 20 are formed at a proper internal on the periphery of the tunnel 12 and are filled up with stabilizing liquid 18 made of bentonite liquid mud. After that, the excavated slots 20 are formed with circular cross sections or in groove shapes with small widths, and are arranged roughly on center lines between the external sides of the tunnel 12 and the internal sides of the wall units 16 organized with deep-seated mixture, and to a depth closer to the organized depth of the deep-seated mixture than to the depth of the deepest section of the tunnel 12. As a result, the ground expanding phenomenon of the tunnel 12 can be suppressed.

Description

[Detailed Description of the Invention] (Industrial Application Field) This invention is applicable to deep Kr. This relates to methods for protecting existing structures when construction work such as the mixed treatment method is implemented.

(Prior art and its problems) As is well known, when constructing a new structure near an existing structure, or when carrying out excavation or embankment work near an existing structure,... ! Measures are taken to protect the membrane structure.

In this case, for example, if the existing structure is built on soft ground, the area around the existing structure is often improved and protected using a deep mixing method as a protection method.

However, such a protection method has the following problems.

? In other words, in the deep mixing method, the assimilated material is injected while rotating the O-RAD of the stirring stage that has penetrated into the soil, and the excavated soil and solidification material are mixed and stirred to form a compact in the soil. This is a method of construction.

Therefore, when creating a compact, the volume is f! because the solidifying material is mixed with the excavated soil. Along with swelling, the pressure force of the solidified material is applied to the upper back of the tonosho due to rod penetration and stirring by the rotary blade, and to the grain, so the tonosho in the excavation hole becomes considerably large during the mixing process.

Some of the earth pressure acts as a force to heap excavated soil above the ground, but most of it acts as lateral pressure on existing structures, and this lateral pressure can cause the existing structures to move or cause cracks. .

This kind of influence on existing structures due to earth pressure is not limited to the deep mixing method, but also when building earth retaining structures by piling when constructing a new structure in close proximity to an existing structure. arise.

This invention was made in view of the above-mentioned problems, and its purpose is to reduce soil damage when construction work that expands the ground volume, such as deep mixing treatment, is carried out near existing structures. An object of the present invention is to provide a method for protecting an existing structure that can prevent the influence of pressure from exerting on the existing structure.

(Means for Solving the Problems) In order to achieve the above object, the present invention involves constructing work that expands the ground volume, such as pile driving or deep mixing method, in the vicinity of existing structures. At this time, an excavated hole or an excavated trench filled with a stabilizing liquid is formed around the existing structure.

(Function) According to the method for protecting an existing structure with the above configuration, even if the earth pressure increases due to deep mixing treatment or pile driving, for example, an excavation hole or excavation filled with stabilizing liquid can be used around the existing structure. Since the groove is formed, an increase in earth pressure acting on the existing structure is absorbed by raising the level of the stabilizing liquid.

(Embodiments) Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 shows an embodiment of the method for protecting an existing structure according to the present invention.

The method shown in the figure is applied to constructing a new structure 14 almost directly above an underground tunnel 12 that has already been constructed in soft ground 10.

Prior to construction of the new structure 14, due to the soft ground,
Ground improvement at the site where the new structure 14 is planned to be constructed is performed by, for example, a drain method.

Before ground improvement, column-shaped walls 16 are constructed along both sides of the underground tunnel 12 at predetermined intervals to protect the underground tunnel 12.

The columnar walls 16 are formed by a deep mixing method, and are made by mixing cement using a stirring and mixing device disclosed in, for example, Japanese Utility Model Publication No. 58-17787 or Japanese Utility Model Application Publication No. 169326/1983 by the present applicant. A compacting material such as milk is press-fitted and mixed with excavated sand to form a compact in the soil.

In the present invention, prior to constructing the column-shaped walls 16, excavated holes 20 filled with a stabilizing liquid 18 made of bentonite slurry or the like are formed at appropriate intervals around the underground tunnel 12.

The excavated hole 20 is formed to have a circular cross section or a narrow groove shape, and is located approximately on the center line between the outside of the underground tunnel 12 and the inside of the wall 16 created by deep mixing, and its depth is at least deeper than the deepest position of the underground tunnel 12, more preferably closer to the creation depth of deep mixing, and the excavation hole 2 is at least deeper than the deepest position of the underground tunnel 12, and more preferably closer to the depth of deep mixing.
0, it is possible to prevent the phenomenon of disk bulging that is applied to the bottom surface of the underground tunnel 12 by bypassing the lower end of the excavation hole 20 due to the rise of the earthen wall when constructing the wall body 16.

Further, the stabilizing liquid 18 in the excavated hole 20 is kept at a water level slightly lower than the ground surface.

Now, if the excavation hole 20 filled with the stabilizing liquid 20 is prepared as described above, when constructing the wall body 16, the penetration of the stirring mixing device and the stirring of the rotary blades, the press-in of cement milk, and the solidification are performed. Even if the earth pressure increases due to factors such as the volume IIM, the increased earth pressure is prevented from acting on the underground tunnel 12 as lateral pressure.

In other words, between the wall 16 and the underground tunnel 12 there is an excavation hole 2.
0 intervenes, so when the rising soil reaches the wall of the borehole 20, it acts as a lateral pressure that pushes one wall of the borehole 20 toward the other wall, but this lateral pressure
It is released by raising the water level of the stabilizing liquid 18 in the tunnel 0, and is not transmitted to the side of the underground tunnel 12.

Furthermore, it goes without saying that the excavated hole 20 may be in the form of a continuous groove.

FIG. 2 shows a further embodiment of the protection method according to the present invention.

The protection method, which is not shown in the figure, is to perform deep mixing treatment on the back of the abutment 32 in order to prevent the abutment 30 and its foundation 32 from becoming unstable when the river bed soil is excavated and removed as shown in the imaginary line. This example shows the case where it is applied when constructing.

The back surface of the abutment 10 including the foundation 12 is solidified by deep mixing treatment as in the above embodiment! l! 34, but
Prior to this, an excavated hole 20 filled with the stabilizing liquid 18 is formed around the abutment 32.

In this embodiment, the excavation hole 20 is excavated to approximately the same depth as the consolidated ground 34, and the lateral displacement of the foundation 32 and abutment 30 due to the expansion of the ground volume when forming the consolidated ground 5JI 34 is avoided. The pores 20 and the stabilizing liquid 18 can absorb it and prevent its influence.

In addition, in the above embodiment, the case where the new structure 14 is built horizontally directly above the underground tunnel 12 and the case where the consolidated ground 34 is formed on the back of the abutment 30 are illustrated, but it is also possible to build a new structure on the side of these It can also be applied when constructing medium-sized structures, for example when driving piles for earth retaining.

(Effects of the Invention) As described above in detail in the embodiments, the method for protecting an existing structure according to the present invention is relatively effective in that a drilling hole is formed by filling a stabilizing liquid around the existing structure. With a simple configuration, when constructing a new structure or improving the ground, it is possible to reliably eliminate the adverse effects of rising earth pressure due to expansion of the ground.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing one embodiment of the method of the present invention, and FIG. 2 is a sectional view showing another embodiment of the method. 10... Soft ground 12... Underground tunnel 1
4...New structure 16...Wall body 18...
Stabilizing liquid 20...Drilling hole patent applicant
Obayashi Co., Ltd. Composition Manager Patent Attorney - Ken Iro Affair Figure 1 Figure 2

Claims (1)

[Claims] An existing structure characterized by forming an excavated hole or excavated trench filled with a stabilizing liquid around the existing structure when carrying out construction using the deep mixing method or driving piles in the vicinity of the existing structure. How to protect things.