JPS615114A - Ground improvement work for preventing liquefaction - Google Patents

Abstract

PURPOSE:To prevent the liquefaction of the ground by a method in which a treating machine with a stirring blade is penetrated into and drawn out of the ground while being turned, a solidifying chemical grout is injected through the treating machine to solidify the ground in a form of lattice, band, etc. CONSTITUTION:The stirring blade Pa of a deep layer mixing and treating machine P is penetrated into and drawn out of the ground 1 to be liquefied while being turned. During the penetrating period, a solidifying chemical grout is supplied and discharged in the neighborhood of the blade Pa with stirring to form improved ground 2, e.g., solidified latticed wall, banded wall, etc. A superstructure 3 is constructed on the improved ground 2.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a ground improvement method for ground that may cause liquefaction, such as sand, shirasu ground, etc. (hereinafter referred to as liquefaction ground).

Conventionally, when constructing structures on ground that has the potential for liquefaction, compaction is used to increase density as a measure to prevent liquefaction of the ground in the event of an earthquake.

In this case, the specific means of increasing density is BiFlo.
There are flotation methods, vibro-composer methods, etc., but these methods have environmental problems such as noise and vibration,
There are concerns as to whether compaction can really prevent liquefaction, and problems such as increased costs.

Therefore, the present invention penetrates and pulls out the liquefied ground while rotating a processing machine with stirring blades, and at this time, a caking agent is supplied and mixed through the processing machine, and the ground is formed into a lattice shape. By consolidating to an appropriate depth in a belt shape or other appropriate planar shape, an improved ground as a whole consisting of a composite ground of consolidated and unconsolidated areas (natural ground) can be created, and the rigidity of the entire ground can be improved. By increasing the height of the ground, reducing the deformation of the ground in response to seismic motion, and reducing the shear strain in the unconsolidated portion of the improved ground, it is possible to prevent or reduce the rise in pore water pressure and reduce the risk of damage to structures due to liquefaction of the ground. This is to prevent damage. In addition, even if there are local excess gaps in the unconsolidated ground (natural ground) around the outer periphery of the improved ground, it is possible to place the consolidated portions densely around the outer periphery of the improved ground, making it difficult for water to pass through the improved ground. This prevents the excess pore water pressure that has locally risen in the outer periphery from reaching the inner area during a short period of time during continuous seismic motion, prevents the expansion of the liquefaction area, and prevents or significantly damages the structure. It is intended to reduce

Hereinafter, the present invention will be explained in detail based on the drawings.

Fig. 1 is a cutaway perspective view after construction is completed, and in the figure, l is the liquefied ground, 2 is the improved ground provided on the liquefied ground, and 3 is the ground structure built on the improved ground. It is.

The improved ground 2 is treated with a deep mixing treatment machine P as shown in Fig. 2.
is used to penetrate and pull out the stirring blade Pa while rotating it into the liquefied ground, and at the time of penetration, a caking agent is supplied and discharged near the stirring blade, stirring and mixing it into the liquefied ground. The lattice walls shown in Figures 1 and 2, the strip walls shown in Figure 4, other honeycomb-shaped walls, square walls, triangular walls, and peripheral walls that match the outer periphery of ground structures. etc., and create an improved ground as a whole. Further, the top of the improved ground 2 is placed underground in consideration of the penetration of the ground structure 3.

After constructing the improved ground 2 as shown above, the top of the improved ground 2 is excavated to the top of the improved ground 2, and the above-ground structure 3 is constructed on the improved ground 2. Note that the top of the improved ground 2 may be placed as appropriate.

Experiments have confirmed that it is extremely superior both statically and dynamically, and is also superior in terms of cost.

According to the present invention, the rigidity of the improved ground as a whole can be increased, the deformation of the ground due to earthquake motion can be reduced, and the shear strain in the unconsolidated portion of the improved ground can be reduced,
This can prevent or reduce the rise in excess pore water pressure in the internal region, and prevent damage to structures due to liquefaction of the ground.

Furthermore, even if there are local excess pores in the unconsolidated ground (natural ground) around the outer periphery of the improved ground, it is possible to prevent the excess pore water pressure in the core from being transmitted to the inner region, thereby preventing the expansion of the liquefaction area. damage to structures can be prevented or significantly reduced.

Furthermore, there is no need for stakes, and there is no need to drive stakes.
It does not cause environmental problems such as noise and vibration, shortens the construction period, saves resources, reduces costs, and achieves the intended purpose.

[Brief explanation of the drawing]

Drawings (illustrating the liquefaction prevention ground improvement method of the present invention, Fig. 1 is a cutaway perspective view showing the structure after construction, Fig. 2 is a
The explanatory drawings, FIGS. 3 and 4 showing the construction state are perspective views each illustrating the shape of the improved ground.

Claims (1)

[Claims] Penetration and extraction are carried out while rotating a treatment machine with stirring blades into the ground that may liquefy. At this time, a caking agent is supplied through the treatment machine and mixed, forming the ground into a grid or band shape. , Liquefaction prevention characterized by creating an improved ground as a whole consisting of a composite ground of a consolidated part and an unconsolidated part (natural ground) by consolidating to an appropriate depth in other appropriate planar shapes. Ground improvement method.