JP4396836B2 - Structure for preventing lateral flow of ground - Google Patents

Description

  The present invention is a structure for preventing lateral flow of the ground by improving the ground. For example, a ground that can effectively obtain a horizontal resistance force for improving the ground to prevent the lateral flow of the ground due to landfill or embankment. It relates to an improved structure.

  When constructing various structures such as embankments, abutments, or roads on soft ground such as submarine ground and coastal reclaimed land, in addition to improving the ground directly under the structure as a countermeasure for ground subsidence, In order to prevent lateral flow, the ground will be improved with the expectation of horizontal resistance.

  In order to improve the ground to prevent such lateral flow, conventionally, for example, a method of sufficiently compacting, a method of driving drain material at regular intervals, a method of driving sheet piles or foundation piles at regular intervals, There are methods such as consolidation, all of which were intended to improve the target improvement area uniformly.

Moreover, as a construction method for preventing lateral flow of the ground, construction methods such as Patent Documents 1 to 3 have been proposed. The invention of Patent Document 1 embeds a foamed polystyrene board laminated on the soft ground at the back of a structure such as an abutment to prevent subsidence and lateral flow of the soft ground. In the invention of Patent Document 2, a plurality of piles are arranged at regular intervals from the surface through the soft ground and the consolidated ground below the region where the lateral flow of the soft ground due to liquefaction in the event of a large earthquake is expected. It has been cast. In Patent Document 3, a self-hardening material is poured into a casting casing driven into soft ground, and a plurality of forming plates are integrated to construct a cellular shell structure composed of thin walls. A method for forming a substructure has been proposed.
JP-A-4-73310 JP-A-10-131208 Japanese Patent Publication No. 61-28049

  If the improvement aimed at measures against lateral flow was applied uniformly over the entire target area, the construction period was long and the construction cost was expensive.

  In particular, at landfill airports where construction is planned in the future, it takes a considerable amount of time for positioning for improved pile construction as ground improvement, which has a great impact on the construction period and cost.

  The purpose of the present invention is to ensure that the improvement effect on the lateral flow of the ground is substantially equal to or more than the conventional construction method that is applied uniformly over the entire target area, and further reduces the improvement area of the ground compared to the conventional method, The object is to provide a structure for preventing lateral flow of ground that can reduce the construction period and cost.

The present invention is, with respect to soil improvement material, by applying the structurally very advantageous earth switch are those that permit the reduction of the subject improvement areas.

Claim 1 of the present invention is a lateral flow prevention structure that prevents lateral flow of the ground by ground improvement, and in a plan view, the target region of lateral flow prevention is left with a number of non-improved areas. by ground improvement, a number of ground improvement body unmodified regions are interspersed arrangement constructed in improving regional, and arches are formed by improved zone to the end of the flow direction of the non-modified region, arch plurality The lateral flow prevention structure is characterized in that all arches are formed in the same direction .

That is, the planar shape of the non-modified region, for example, as shown in FIG. 3, a semi-circular shape such that its arc is located at the end of the flow direction x, by improving area on one side in the flow direction x of the unmodified region Form an arch. The arch of the improvement zone is composed of an integrated soil cement column, a precast block frame, or an improvement block. The non-improved area is composed of the ground.

In the present invention, A over switch is formed with a plurality, the direction of the arch are the same direction, as shown in FIG. 3 In example embodiment, the planar shape of the unmodified area is the case of the semi-circular shape or the like, arch They are arranged in a staggered manner or aligned vertically and horizontally so that the crown portions (convex directions) are in the same direction. The crown portion of the arch is preferably in the direction toward the horizontal load F, but may be opposite to the load F.

Claim 2 of the present invention, in the lateral flow prevention structure of the ground of claim 1 Symbol placement, lateral flow prevention structure of the ground, characterized in that improved depth in improved zone is constant in the flow direction It is.

Claim 3 of the present invention, in the lateral flow prevention structure of the ground of claim 1 Symbol placement, lateral flow preventing Ground improvement depth in improved zone is characterized in that shallower along the flow direction It is a structure. That is, as the distance from the structure or the like increases, the improvement depth is reduced, for example, in a staircase shape, and the improvement area is reduced.

According to the present invention as described above, the improvement rate is significantly reduced by providing the non-improvement area in the improvement area as compared with the conventional method of improving the target improvement area uniformly. When acting horizontal load such soil improvement material, as shown in FIG. 3, is transmitted load in a portion corresponding to the arch of the foot, the second column in al, third column, ... and load Is transmitted and resists horizontal loads throughout the ground improvement body.

The present invention constructs a ground improvement body in which a large number of non-improvement areas are interspersed within the improved area by improving the ground for the lateral flow prevention target area while leaving a large number of non-improvement areas. since forming the arch by improved zone to the end of the flow direction of the band, the conventional method that more arch effect of soil improvement material, a horizontal resistance to lateral flow of the ground, uniformly construction throughout target area The ground improvement area can be reduced from the conventional level, and the construction period and cost can be greatly reduced.

Hereinafter, the present invention will be described based on the illustrated embodiments. FIG. 1 is a vertical sectional view showing an example of a structure to which the ground lateral flow prevention structure of the present invention is applied. Figure 2 is a view to lead a straight cross-sectional view of one embodiment of a lateral flow prevention structure of the ground of the present invention. Figure 3 is a plan view showing an example of a planar shape and plane placement arch according to the present invention.

  In FIG. 1, a ground improvement body 3 is constructed immediately below a structure composed of a revetment (abutment) 1 and a landfill (filling) 2, and the lateral flow prevention structure of the present invention, that is, in front of the ground improvement body 3, that is, A ground improvement body 4 that expects horizontal resistance is constructed.

Viewed in a flat plane, the target area of the lateral flow prevention, a number of by ground improvement leaving unmodified region, as shown in FIG. 2, a number of unmodified region 6 a point in the improved area 5 standing placed soil improvement material 4 Ru constructed.

Further, the improvement depth of the improvement region 5 can be constant with respect to the flow direction x, but is not limited thereto, and as shown in FIG. 2 , the improvement depth of the improvement region 5 is set along the flow direction x. For example, it may be shallowed stepwise or inclined in the direction in which the horizontal load F acts (as it moves away from the structure).

Compared with the conventional method for uniformly improving the subject improved range of lateral flow prevention, according to the number of ground improvement body 4 unmodified region 6 is scattered arrangement of the present invention, an improved area of the ground 5 ( Volume) can be reduced by 40%, for example. Moreover, if the improvement depth of the improvement area | region 5 is gradually made shallow as it leaves | separates from a structure, the improvement area 5 (volume) of a ground can further be reduced.

In FIG. 3 , the planar shape of the non-improved area 6 is a semi-circular shape in which the arch 7 by the improved area 5 is convex toward the horizontal load F (the crown portion of the arch 7 is convex in the opposite direction). and it may also be), the unmodified region 6 that are staggered. Not limited to the illustrated example of this, it is possible with the planar arrangement other planar shape. Further, the size of the arch 7 can be changed depending on the distance from the load F. For example, the closer to the load F, the smaller the arch 7 is, and the farther from the load F, the larger the arch 7 is.

If such a large number of unmodified region 6 acts horizontal load F to ground improvement body 4 which is interspersed arranged, as shown by thick arrows in FIG. 3, the load F is transmitted to the portion corresponding to the arch of the foot 7 Is done. Furthermore, the load F is transmitted to the second row, the third row,..., And the ground improvement body 4 as a whole resists the horizontal load F. By such an arch effect, the horizontal resistance force against the lateral flow of the ground can be ensured substantially equal to or higher than that in the conventional construction method in which the construction is uniformly performed over the entire target region.

  The improvement area 5 of the ground improvement body 4 is usually formed of a number of so-called soil cement columns, and in order to exhibit the arch effect as described above, it is necessary to integrate the soil cement columns. An integrated ground improvement body 4 can be constructed by using agitation and jet agitation.

  In addition to this, there is also a method by on-site assembly of a precast arch-shaped block frame unit (made of steel, concrete, etc.) as a means of shortening the construction period. The construction procedure in this case is as follows. (1) Excavate the target improvement area. (2) Install an arched block frame connecting several block frame units. (3) The excavated soil generated in (1) is subjected to cement solidification, etc. to increase its strength and fill the block frame. In addition, you may provide a frame part by the site construction which drives a sheet pile instead of such a block frame.

  Furthermore, when the improvement block described in the specification of Japanese Patent Application No. 2003-158068 is used, the tip surface in the underground direction is formed in an arch shape. The ground improvement body 4 can also be constructed by being integrated so as to become the arch 7. In this case, there are advantages such as (a) being strong against a vertical load, (b) being able to secure horizontal resistance at low cost, and (c) being able to further shorten the work period.

  In addition, although the above demonstrated the case where the side flow prevention structure of this invention was installed in front of the ground improvement body directly under a structure, it is not restricted to this, The structure of this invention is also used for the side flow prevention of other ground. Can be applied. Further, it goes without saying that the present invention is not limited to the above illustrated examples.

Ru vertical sectional view showing an example of a structure lateral flow prevention structure is applied of the ground of the present invention. It is a vertical sectional view showing one embodiment of the ground lateral flow prevention structure of the present invention. Is a plan view showing an example of a planar shape and plane placement arch according to the present invention.

1 …… Revetment (Abutment)
2 ... Reclamation (filling)
3 ... Ground improvement body directly under the structure 4 ... Ground improvement body as a lateral flow prevention structure of the present invention 5 ... Improvement zone 6 ... Non-improvement zone 7 ... Arch F ... Horizontal load

Claims (3)

This is a lateral flow prevention structure that prevents lateral flow of the ground by ground improvement.In plan view, the target area of lateral flow prevention is improved within the improved area by leaving many unimproved areas. A ground improvement body in which a large number of non-improvement areas are scattered is constructed, and an arch by the improvement area is formed at the end of the flow direction of the non-improvement area . A lateral flow prevention structure for the ground characterized in that the directions are the same . In lateral flow prevention structure of claim 1 Symbol placement of the ground, lateral flow prevention structure of the ground, characterized in that improved depth in improved zone is constant in the flow direction. In lateral flow prevention structure of claim 1 Symbol placement of the ground, lateral flow prevention structure of the ground improvements depth in improved zone is characterized in that shallower along the flow direction.

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