JP2010007459A - Structure for preventing lateral flow of ground - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a structure for preventing the lateral flow of the ground that can reduce a construction period and a construction cost by reducing an improved area of the ground after securing an improving effect on the lateral flow of the ground almost equally to or better than a conventional method of uniform construction over the whole object area. <P>SOLUTION: The lateral flow preventing structure for preventing the lateral flow of the ground by soil improvement is installed in front of a soil improving body directly under a structure, for instance. Unimproved areas 6 of elliptic shape or the like in a plan view are interspersed in the improved area 5, and arches 7 are formed in a flow direction x in the improved area 5 by the shape of the unimproved areas 6. The arches of the improved area 5 are composed of precast block frames, blocks for improvement or sheet piles. Horizontal load F is resisted by the whole of such a soil improving body 4. <P>COPYRIGHT: (C)2010,JPO&INPIT

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.

Japanese Patent Laid-Open No. 04-073310 Japanese Patent Laid-Open No. 10-131208 Japanese Examined Patent Publication No. 61-028049 Japanese Patent Laid-Open No. 11-280056 Japanese Patent Laid-Open No. 51-045405

  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 makes it possible to reduce the target improvement area by applying an arch that is very structurally advantageous to the ground improvement body.

  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 improving the ground, a ground improvement body in which a large number of non-improvement areas are scattered in the improvement area is constructed, and an arch by the improvement area is formed at the end in the flow direction of the non-improvement area. The side arch is constructed of a precast block frame, a block for improvement, or a sheet pile.

  That is, for example, as shown in FIG. 4, the planar shape of the non-improved region is a semicircular shape or an oval (ellipse) shape whose arc is located at the end of the flow direction x, and the flow direction x of the non-improved region. An arch with an improved area is formed on one side or both sides. The improvement area arch is composed of a precast block frame or an improvement block. The non-improved area is composed of the original ground.

  Claim 2 of the present invention is the lateral flow prevention structure of the ground according to claim 1, wherein a plurality of the arches are formed and the directions of the arches are the same direction. It is a prevention structure. For example, as shown in FIG. 4 (a), the planar shape of the non-improved area is a semicircular shape, and the arch crown (convex direction) is arranged in a staggered manner or vertically and horizontally so that it is in the same direction. Align and arrange. The crown portion of the arch is preferably in the direction toward the horizontal load F, but may be opposite to the load F.

  According to a third aspect of the present invention, in the lateral flow prevention structure of the ground according to the first aspect, the pair of arches are arranged symmetrically with respect to one non-improved region. Anti-flow structure. For example, as shown in FIGS. 4 (b) and 4 (c), the planar shape of the non-improved zone is an ellipse or an ellipse that is long in the flow direction x, and a pair of arches are arranged symmetrically in the flow direction x. Is done. In the illustrated example, a plurality of such a pair of arches are arranged in a staggered manner, or arranged vertically and horizontally.

  According to a fourth aspect of the present invention, in the ground lateral flow prevention structure according to any one of the first to third aspects, the improvement depth in the improvement region is made constant in the flow direction. It is a ground side flow prevention structure.

  Claim 5 of the present invention is the ground lateral flow prevention structure according to any one of claims 1 to 3, wherein the improvement depth in the improvement region is shallow along the flow direction. This is a structure for preventing lateral flow of ground. 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 a horizontal load acts on such a ground improvement body, as shown in FIG. 4, the load is transmitted to a portion corresponding to the foot of the arch, and further, the load is transmitted to the second row, the third row,. Resist horizontal load 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 the arch by the improved zone is formed at the end of the flow direction of the area, the horizontal resistance against the lateral flow of the ground is almost equal to that of the conventional method, which is applied uniformly over the entire target area due to the arch effect of the ground improvement body. The ground improvement area can be reduced as compared with the prior art while ensuring the same or more, and the construction period and cost can be greatly reduced.

It is a vertical sectional view showing an example of a structure to which the lateral flow prevention structure of the ground of the present invention is applied. It is one Embodiment by the arch of the lateral flow prevention structure of the ground of this invention, (a) is a top view, (b) is a vertical sectional view. It is a top view which compared the conventional construction method and this invention. It is a top view which shows the various examples of the planar shape and planar arrangement | positioning of the arch according to this invention.

  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. FIG. 2 is a plan view and a vertical sectional view showing an embodiment of an arch of the ground lateral flow prevention structure of the present invention. FIG. 3 is a plan view comparing the conventional method with the present invention. FIG. 4 is a plan view showing various examples of the planar shape and planar arrangement of the 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.

  As shown in FIG. 2 (a), when seen in plan view, the target area of the lateral flow prevention is improved in the ground while leaving a large number of non-improved areas. The ground improvement bodies 4 in which are dotted are arranged. In the illustrated example of FIG. 2 (a), the planar shape of the non-improved area 6 is a long oval along the flow direction (direction in which the horizontal load F acts) x, and both ends of the non-improved area 6 in the x direction. A substantially arc-shaped arch 7 is formed by the improved region 5.

  Further, the improvement depth of the improvement zone 5 can be made constant with respect to the flow direction x, but not limited to this, as shown in FIG. 2 (b), the improvement depth of the improvement zone 5 is set to the flow direction x. For example, the horizontal load F may be made shallower in a stepped or inclined manner in the direction in which the horizontal load F acts (as the distance from the structure increases).

  As shown in FIG. 3, according to the ground improvement body 4 in which a large number of non-improvement areas 6 of the present invention are interspersed as compared with the conventional method of uniformly improving the target improvement area of the lateral flow prevention. The ground improvement area 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.

  As shown in FIG. 4, the planar shape and planar arrangement of the non-improved area 6 can be various. In FIG. 4 (a), 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 reverse direction). This non-improved area 6 is staggered. In FIG. 4 (b), the planar shape of the non-improved area 6 is a substantially oval shape having arches 7 by the improved area 5 at both ends in the major axis direction (flow direction x). Arranged. In FIG. 4 (c), the substantially oval non-improved areas 6 are arranged in a staggered manner. In addition, the planar shape and planar arrangement of the non-improved area 6 are not limited to this illustrated example, and other planar shapes and planar arrangements are possible. 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.

  When the horizontal load F acts on the ground improvement body 4 in which such a large number of non-improvement areas 6 are scattered, the load F is transmitted to a portion corresponding to the foot of the arch 7 as indicated by a thick arrow in FIG. 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.

  In the present invention, in order to shorten the construction period, on-site assembly of a precast arch-shaped block frame unit (made of steel, concrete, etc.) is performed. 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.

1 ... Revetment (Abutment)
2 ... Landfill (embankment)
DESCRIPTION OF SYMBOLS 3 ... Ground improvement body just under structure 4 ... Ground improvement body as side flow prevention structure of this invention 5 ... Improvement area 6 ... Non-improvement area 7 ... Arch F ... Horizontal load

Claims (5)

  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, an arch by the improvement area is formed at the end of the flow direction of the non-improvement area, and the arch of the improvement area is a precast block frame, A lateral flow prevention structure comprising an improvement block or a sheet pile.   2. The ground lateral flow prevention structure according to claim 1, wherein a plurality of the arches are formed and the directions of the arches are the same.   2. The ground lateral flow prevention structure according to claim 1, wherein a pair of arches are arranged symmetrically with respect to one non-improved region.   The lateral flow of the ground according to any one of claims 1 to 3, wherein the improved depth in the improved zone is constant in the flow direction. Prevention structure.   The lateral flow prevention structure of the ground according to any one of claims 1 to 3, wherein the improved depth in the improved area is shallow along the flow direction. Anti-flow structure.

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