JP2015172305A - Soft ground improvement method for widening of embankment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a soft ground improvement method for widening of embankment, which can prevent a decrease in stability of the whole embankment, the deformation and settlement of the existing embankment and the widening of embankment, associated with consolidation settlement or shear deformation of a bearing stratum, and ground uplift on the front side of the widening of embankment, in the case of execution of work for the widening of embankment.SOLUTION: In a soft ground improvement method for widening of embankment, ground improvement piles 2B are arranged in a column row under the widening of embankment, and a plate-like body 2A having resistance to bending is constructed on the ground improvement piles 2B.

Description

  The present invention relates to a soft ground improvement method for belly embankment.

  FIG. 2 is a schematic diagram of construction of a conventional belly-filled embankment.

  In this figure, 100 is a supporting ground (soft viscous soil, liquefied ground), 101 is an existing embankment that constructs the current track 102, 103 is a belly embankment that is attached to the existing embankment 101 that constructs the new track 104. It is.

  When constructing an abdominal embankment in a double track construction, etc., the stability of the entire embankment decreases, the subsidence of the supporting ground or the deformation or subsidence of the abdominal embankment due to consolidation or shear deformation, and the front side of the abdominal embankment There is concern about the uplift of the ground.

  Fig. 3 is a drawing substitute photo showing the damage of the belly embankment in the Tokachi-oki earthquake, Fig. 4 is a drawing substitute photo showing the damage of the belly embankment in the Great East Japan Earthquake, and Fig. 5 is the construction of the belly embankment on the soft ground. It is a drawing substitute photograph shown.

  In this way, it can be said that there are many cases of damage at the time of an earthquake in the case of an embankment embankment (weak spot).

  When improving the ground directly under an existing embankment in service as a business line, there is a possibility that the business line track may be deformed, so it is generally avoided. For this reason, countermeasures for soft ground are often limited to support ground directly under a belly embankment.

  When improving soft ground, ground improvement piles represented by agitation and mixing piles are often used. However, when ground improvement piles are limited to support ground directly under a belly embankment, this ground improvement Not only the vertical load but also the horizontal (lateral) load by the belly embankment acts on the pile. However, the ground improvement pile is a member that supports a load in the vertical direction as a compressive force, and has a low resistance to a horizontal (side) external force.

  Considering the above, it is considered that the effect is low even if the conventional method is placed only on the support ground directly under the belly embankment.

  On the other hand, the inventors of the present application have already proposed a method for constructing embankment on soft ground and an embankment structure thereof (see Patent Document 1 below).

  In addition, a ground reinforcement method (see Patent Document 2 below) in which a three-dimensional structure in which hollow plastic sheets are assembled in a lattice shape on a soft ground has been proposed.

Japanese Patent No. 4874739 Japanese Patent Laid-Open No. 5-17948

  The conventional construction method as described above is considered to be effective on general soft ground. The inventors of the present application, when constructing an abdominal embankment in a double track construction, etc., the deterioration of the stability of the whole embankment, the consolidation subsidence of the supporting ground or the deformation / subsidence of the abdominal embankment accompanying shear deformation, There is concern about the uplift of the ground on the front side of the belly embankment. In addition, it was not easy to improve the existing embankment used as a railway embankment, and the measure was limited to the underfill or the existing embankment, so that the embankment was strengthened.

  In view of the above situation, the present invention, when constructing a belly-filled embankment, can prevent a decrease in the stability of the whole embankment and subsidence of the support ground after starting operation after construction, for a belly-filled embankment An object is to provide a soft ground improvement method.

In order to achieve the above object, the present invention provides
[1] In the soft ground improvement method for belly embankment, a ground improvement pile is arranged in a column under the belly embankment, and a plate-like body having resistance to bending is placed on the ground improvement pile. It is characterized by construction.

  According to the present invention, the ground improvement under the belly embankment is made strong against bending and inclination by arranging the ground improvement piles in a columnar shape, and further, the pitching interval (improvement rate) of the columnar improvement body In order to lower the height, a plate-like body is installed on it. For example, by constructing a composite structure using geotextile and cement-improved gravel in the form of a plate, it is possible to construct a member against bending, and to suppress subsidence in the line direction and the direction perpendicular to the line of the belly embankment.

It is a schematic diagram of the soft ground improvement and embankment reinforcement construction method for belly embankment which shows the Example of this invention. It is a schematic diagram of the construction of the conventional fill with embankment. It is a drawing-substituting photograph showing the damage of the belly embankment in the Tokachi-oki earthquake. It is a drawing substitute photograph which shows the damage of the embankment embankment in the Great East Japan Earthquake. It is a drawing substitute photograph which shows the mode of construction of the embankment embankment on a soft ground.

  The soft ground improvement method for belly embankment according to the present invention is that a ground improvement pile is arranged in a column array under the belly embankment, and a plate-like body having resistance to bending is placed on the ground improvement pile. Install.

  Hereinafter, embodiments of the present invention will be described in detail.

  FIG. 1 is a schematic view of a soft ground improvement / banking reinforcement construction method for a belly-filled embankment according to an embodiment of the present invention, FIG. 1 (a) is a sectional view thereof, and FIG. 1 (b) is a plan view thereof. .

  In these drawings, 1 is a supporting ground, 2A is a plate-like body (shallow improvement body) for improving the ground under a belly-filled embankment, and 2B is also a belly-filled under-surface constructed under the plate-like body 2A. The ground improvement piles (stir mixed piles) for improving the ground of 3 are the existing embankment, 4 is the existing railway, 5 is the belly embankment, and 6 is the new railway. Here, if the ground improvement piles 2B are discretely present, in order to avoid the fact that the whole is inclined and the effect is reduced. I try to be strong. Furthermore, “slip-out” can be prevented by using the plate-like improvement by the plate-like body 2A in combination.

  Further, by placing this improved column array in the vicinity of the existing embankment buttocks in the direction of the track, a further deformation suppressing effect can be expected.

  Moreover, when it is desired to further suppress the deformation, geotextiles may be inserted into the embankment embankment in combination with the natural ground reinforcement earth method.

Incidentally, when soft about is not badly, or using a geotextile in alone instead of cement improved tills slab, to construction applications manner or with cement improved tills slabs without using the tubular elements improved body alone Is also possible.

  In addition, this invention is not limited to the said Example, Based on the meaning of this invention, a various deformation | transformation is possible and these are not excluded from the scope of the present invention.

  The soft ground improvement method for the belly-filled embankment of the present invention improves the stability of the whole embankment and prevents ground subsidence by constructing a structure for ground improvement under the belly-filled embankment. It can be used as a construction method.

DESCRIPTION OF SYMBOLS 1 Support ground 2 Structure for ground improvement under belly embankment 2A Plate body (shallow improvement body)
2B Ground improvement pile (stir mixed pile)
3 Existing Embankment 4 Existing Railway Line 5 Stomach Embankment 6 New Railway Line

Claims (1)

  A soft ground for belly-filled embankment characterized in that a ground improvement pile is arranged in a column array under the belly-filled embankment and a plate-like body having resistance to bending is constructed on the ground-improved pile. Improved construction method.

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