JP4310502B1 - Reinforcement structure for embankment support ground - Google Patents

Abstract

The present invention provides a rational embankment supporting ground reinforcing structure capable of obtaining a sufficient reinforcing effect even at a low improvement rate.
A pile-shaped first ground improvement body 1 is formed in the embankment supporting ground 11 below the peripheral edge of the embankment 10, and a wall-like second ground improvement body 2 is formed on the inside thereof. A pile-shaped third ground improvement body 3 is formed inside. The depth of improvement of the second ground improvement body is set to be deeper than that of the first and third ground improvement bodies, and at least one or all of the first to third ground improvement bodies are the foundation ground. Not reached. A wall-shaped fourth ground improvement body 4 is formed in the embankment support ground further outside the first ground improvement body. The core material 5 is provided in the second ground improvement body. The tension member 6 is fixed on the upper part of the second ground improvement body to restrain outward deformation and displacement. Laying net material 7 is laid on the entire surface near the boundary between the embankment and the embankment supporting ground.
[Selection] Figure 1

Description

  The present invention is a rational method that can effectively prevent settlement and horizontal displacement of the embankment and its surrounding ground, and can effectively prevent lateral flow of the embankment supporting ground when creating the embankment on a soft embankment supporting ground. The present invention relates to a reinforcing structure for embankment supporting ground.

  As is well known, when creating embankments on soft ground, measures are taken to prevent subsidence beyond the allowable limit on the embankment and lateral flow and liquefaction on the original ground (embankment supporting ground). is required.

As a technique for that purpose, for example, in Patent Document 1, when embankment is constructed on soft ground, a large number of piles (off-the-shelf piles, cast-in-place piles, or ground improved piles by deep agitation mixed processing method) reach the support layer. As described above, a lateral flow prevention structure is disclosed in which a sandy embankment is provided between a soft ground and an embankment as well as a lattice shape, a continuous wall shape, and a cross-beam shape.
Japanese Patent Laid-Open No. 10-292360

  The lateral flow prevention structure shown in Patent Document 1 requires the construction of a large number of piles that reach the support layer. Therefore, the construction requires a large amount of work cost and work period, and in particular, the deep layer mixing process method When the ground improvement pile is constructed by this, the ground improvement rate becomes considerably high, so it is not so realistic.

  In view of the above circumstances, when the embankment support ground is reinforced by the technique of ground improvement by the deep agitation mixing method, sufficient reinforcement effect can be obtained even at a low improvement rate, and settlement of the embankment and its surrounding ground can be obtained. It is an object of the present invention to provide a rational reinforcement structure that can effectively prevent horizontal displacement and can effectively prevent lateral flow of the embankment support ground.

  The invention described in claim 1 is a reinforcement structure for a banking support ground when the banking is created on a soft banking support ground, and the pile-shaped first ground improvement is provided in the banking support ground below the peripheral edge of the banking. Forming a wall, forming a wall-like second ground improvement body in the embankment support ground along the direction intersecting the horizontal displacement direction of the embankment support ground assumed inside, and further supporting the embankment inside A pile-shaped third ground improvement body is formed in the ground.

  Invention of Claim 2 is the reinforcement structure of the embankment supporting ground of Claim 1, Comprising: The said 2nd ground improvement body of the said 2nd ground improvement body is rather than the improvement depth of the said 1st ground improvement body and a 3rd ground improvement body. The improvement depth is set to be deeper, and the lower end of at least one of the first to third ground improvement bodies does not reach the foundation ground.

  Invention of Claim 3 is the reinforcement structure of the embankment support ground of Claim 2, Comprising: None of the lower end of the said 1st-3rd ground improvement body has reached the foundation ground, It is characterized by the above-mentioned. .

  A fourth aspect of the present invention is the embankment supporting ground reinforcing structure according to the first, second or third aspect of the present invention, wherein a wall-like fourth reinforcing structure is provided in the outer embankment supporting ground further outside the first ground improvement body. It is characterized by forming a ground improvement body.

  The invention according to claim 5 is the embankment supporting ground reinforcing structure according to claim 1, 2, 3 or 4, wherein a core material is provided in the second ground improvement body. To do.

  The invention described in claim 6 is the reinforcement structure for the embankment supporting ground of the invention described in claim 1, 2, 3, 4 or 5, wherein the embankment inside the second ground improvement body and the embankment supporting ground A tensile material is disposed in the vicinity of the layer boundary along the assumed horizontal displacement direction of the embankment supporting ground, and one end of the tensile material is fixed on the upper part of the second ground improvement body, thereby the tensile material. Thus, the deformation and displacement of the second ground improvement body to the outside are restricted.

  The invention according to claim 7 is the reinforcement structure for the embankment supporting ground according to the invention according to claim 1, 2, 3, 4, 5 or 6, wherein the covering net is provided in the vicinity of the boundary between the embankment and the embankment supporting ground. It is characterized by laying materials.

According to the present invention, subsidence and displacement of the surrounding ground of the embankment is effectively suppressed by the pile-shaped first ground improvement body provided below the peripheral edge of the embankment, and the wall-like shape provided on the embankment supporting ground inside the embankment The subsidence near the center of the embankment and lateral lateral flow are effectively suppressed by the second ground improvement body, and the subsidence at the top of the embankment is effectively prevented by the third pile-shaped ground improvement body provided inside it. Deterred.
Therefore, according to the present invention, the first to third ground improvement bodies are provided with appropriate depth in each part of the embankment supporting ground according to the allowable limit of the amount of settlement and horizontal displacement required for each part of the embankment and the surrounding ground. By properly arranging so that, even if it is a low improvement rate as a whole, even if it does not provide each ground improvement body to reach a stable foundation ground, sufficient reinforcement effect for the whole embankment supporting ground can be obtained, In addition to the settlement of the embankment, settlement and horizontal displacement of the surrounding ground can be effectively prevented, and lateral flow can be effectively prevented from occurring on the embankment supporting ground.

In particular, the influence on the surrounding ground can be further suppressed by further providing a wall-like fourth ground improvement body on the outermost peripheral edge of the embankment (below the bottom edge) as necessary.
Further, by providing a core material on the upper part of the second ground improvement body or fixing a tensile material on the second ground improvement body, the bending deformation and lateral displacement of the second ground improvement body are restrained and the side It is possible to further improve the flow prevention effect.
Furthermore, it is more effective that the overlay load due to the embankment can be distributed over the entire embankment supporting ground by laying the covering net material entirely between the embankment and the embankment supporting ground.

1 to 2 show an embodiment of the present invention. In this embodiment, when the embankment 10 as the road ground is created on the soft ground, the embankment is formed by forming a ground improvement body by the deep agitation mixing processing method in the soft embankment supporting ground 11 that supports the embankment 10. The support ground 11 is reinforced to prevent settlement and horizontal displacement of the embankment 10, as well as to prevent settlement and horizontal displacement of the surrounding ground of the embankment 10, and to prevent lateral flow of the embankment support ground 11. In particular, the main purpose is to properly arrange the first to fourth ground improvement bodies 1 to 4 having different functions in appropriate positions.
In addition, although it is the embankment 10, in this embodiment, soil, sand, gravel, asphalt, concrete, etc. are assumed as embankment material, However, It does not specifically limit about embankment material.

The first ground improvement body 1 is formed in a pile shape in the embankment supporting ground 11 below the peripheral edge of the embankment 10 (from the vicinity of the shoulder to the vicinity of the buttocks), and is spaced in the length direction of the embankment 10. It is arranged so as to form a row, and mainly functions to support the slope of the embankment 10 and to suppress the subsidence by suppressing the influence on the surrounding ground. In other words, the first ground improvement body 1 enters the sliding soil mass formed by the arc-sliding surface in the embankment supporting ground 11 to prevent the slope failure of the slope and suppresses the settlement of the surrounding ground within an allowable value. To do.
Since this first ground improvement body 1 mainly supports the slope, its supporting load (upload of the embankment 10 itself) is smaller than that of a third ground improvement body 3 (described later) that supports the inside of the embankment 10. However, if importance is attached to reducing the settlement of the surrounding ground, since the allowable settlement amount of the surrounding ground is smaller (severe) than the allowable settlement amount of the embankment 10 itself, the first ground improvement body as shown in the illustrated example. It is preferable to make the required length of 1 longer (reaching deeper) than the third ground improvement body 3 installed in the embankment 10.
However, the stability of the embankment 10 may be mainly taken into account depending on the slope shape of the peripheral edge of the embankment and the layer thickness of the soft ground. In that case, the third ground improvement over the first ground improvement body 1 may be required. The body 3 may be longer.

The second ground improvement body 2 exhibits a function of suppressing the settlement of the central portion of the embankment and preventing lateral flow from the central portion of the embankment, and below the slope on the inner side of the first ground improvement body 1. It is arranged on the ground (especially the lower ground near the shoulder) and is formed in a wall shape along the length direction of the embankment 10 (perpendicular to the assumed direction of lateral flow). . In the example shown in the figure, the adjacent second ground improvement bodies 2 are arranged in a staggered manner by securing a slight gap in the length direction of the embankment 10 and slightly shifting in the width direction of the embankment 10, thereby allowing groundwater to pass between them. Water is available.
The length of the second ground improvement body 2 may be set so that the lateral flow can be effectively prevented, and by preventing the lateral flow, the settlement prevention effect at the center of the embankment can be expected. For that purpose, it is preferable to make it longer than the above-mentioned first ground improvement body 1, the third ground improvement body 3, and the fourth ground improvement body 4 described later, as in the illustrated example.

  The third ground improvement body 3 is formed in a pile shape like the first ground improvement body 1 inside the second ground improvement body 2, and has a slight interval in the length direction of the embankment 10. And staggered so as to form a line. These third ground improvement bodies 3 mainly suppress the settlement of the embankment top, but as described above, the allowable settlement amount of the embankment 10 itself is often larger than the allowable settlement amount of the surrounding ground. Therefore, in that case, the required length of the third ground improvement body 3 may be shorter than the length of the first ground improvement body 1 as in the illustrated example.

  The fourth ground improvement body 4 is provided on the outside of the first ground improvement body 1, in particular, on the lower ground of the buttock, and this is the length of the embankment 10 as with the second ground improvement body 2. It is formed in a wall shape along the vertical direction. The fourth ground improvement body 4 may be provided when the surrounding ground subsidence or displacement is severely limited (when the allowable subsidence amount or the allowable displacement amount is particularly small), and the length required for this may be set. .

Further, in the present embodiment, a core material 5 made of H-shaped steel is provided in the upper part of the second ground improvement body 2, and a tensile material 6 made of PC steel material is fixed to the core material 5. ing.
The tension member 6 is disposed inside the second ground improvement body 2 on both sides, in the vicinity of the boundary between the embankment 10 and the embankment supporting ground 11, along the width direction of the embankment 10 (assumed direction of occurrence of lateral flow). Both ends thereof are tightly connected to the heads of the core member 5 provided on the second ground improvement bodies 2 on both sides.
Therefore, the second ground improvement body 2 has the bending rigidity sufficiently increased by the core material 5 and the outward deformation and displacement are surely restrained by the tension material 6, and only the second ground improvement body 2. Thus, even when the lateral flow pressure cannot be sufficiently resisted, the lateral flow can be surely prevented.

  Furthermore, in this embodiment, the laying net material 7 is laid all over the boundary between the embankment 10 and the embankment supporting ground 11, and the overlay load due to the embedding 10 is applied to the entire embankment supporting ground 11 by the laying net material 7. To be distributed.

According to said structure, the 1st-4th ground improvement bodies 1-4 are each parts in the embankment support ground 11 according to the allowable subsidence amount and allowable horizontal displacement amount requested | required of each part of the embankment 10 and its surrounding ground. Therefore, even if the improvement rate is sufficiently low, a sufficient reinforcing effect for the whole embankment supporting ground 11 can be obtained, and the subsidence of the surrounding ground as well as the embedding of the embankment 10 can be obtained. Horizontal displacement and lateral flow of the embankment supporting ground 10 can be effectively prevented.
In the present embodiment, the improvement rate of the ground improvement body (the ratio of the ground improvement body area in the unit area of the ground in plan view) is the construction range of each of the first to fourth ground improvement bodies 1 to 4 or The improvement rate is set to 5 to 20% as a whole. However, it is also conceivable that only the construction range of the first ground improvement body 1 is improved to 5 to 20%, or only the construction range of the second ground improvement body 2 is set to 5 to 20%.
Therefore, according to the present invention, even if the improvement rate is sufficiently low compared with the conventional method shown in Patent Document 1, a further reinforcing effect can be obtained, and the ground improvement body (deep stirring mixing treatment as in the conventional method) can be obtained. It is not necessary to provide piles to reach the stable foundation ground 12 (the ground that can stably support both the embankment and the soft embankment supporting ground), and a thick sandy embankment between the embankment and the embankment supporting ground. Since it is not necessary to provide a layer, it can be carried out at a much lower cost and in a shorter construction period than the conventional method, and is extremely rational.

  In designing the 1st to 4th ground improvement bodies 1 to 4, the FEM analysis method etc. are utilized, and the placement and length of each ground board improvement body are confirmed while confirming whether they fall within the allowable subsidence and allowable displacement. The form may be set optimally.

Moreover, the 4th ground improvement body 4 in the said embodiment can also be abbreviate | omitted depending on the allowable subsidence amount and allowable displacement amount of a surrounding ground.
Moreover, in the said embodiment, although the core material 5 was provided in the 2nd ground improvement body 2, and the tension | tensile_strength material 6 was fastened with respect to the 2nd ground improvement body 2 via the core material 5, When the ground improvement body 2 itself has sufficient bending rigidity, either the core material 5 or the tension material 6 is omitted, or only the core material 5 is provided and the tension material 6 is omitted, or the core material 5 is The tension member 6 may be directly fixed to the second ground improvement body 2 by omitting it.
When the tension member 6 is tightened, a pair of second ground improvement bodies 2 on both sides of the embankment 10 are mutually coupled as shown in the figure, so that both are used as a fixing body of the tension material 6 or the embankment 10 When the width of the ground is wide, the second ground improvement body 2 and the third ground improvement body 3 are used as the tensile material by using the third ground improvement body 3 in the central portion of the embankment as a fixing body at the other end of the tensile material. 6 may be tightened, and various forms of the fixing body at the other end of the tensile material are conceivable.
Furthermore, in the above embodiment, the laying net material 7 is laid all over, but if it is unnecessary, it may be omitted.

Furthermore, since the said embodiment is an application example to the embankment 10 long in one direction as a road ground, the embankment cross section is symmetrical as a whole, and therefore all of the first to fourth ground improvement bodies 1 to 4. However, the present invention is not limited to the above-described embodiment, and the allowable settlement required for the embankment and the surrounding ground is also required depending on the form, scale, and use of the embankment. Depending on the amount and the allowable displacement, it is possible that appropriate design changes and applications can be made within the scope of the present invention with respect to the specific configuration of the details as well as the specifications and arrangement of the local board improvement body. Needless to say, for example, in the case of a landform where one side is a mountain and the other side is a lowland, and the earth is rubbed and embanked, the third, second and first ground improvement bodies in order from the mountain side to the lowland side or 3rd, 2nd, 1st Sometimes a side configured to the fourth ground improvement body.
Then, in each embodiment of the present invention, it is explained that none of the lower ends of the first to fourth ground improvement bodies 1 to 4 are in contact with the foundation ground 12, and that point is also characterized by the above. From the viewpoint of reaching the foundation ground at the lower end of the ground improvement body in each embodiment, the lower ends of the first, third and fourth ground improvement bodies do not reach the foundation ground, and the lower end of the second ground improvement body becomes the foundation ground. The first, third, and fourth lower ends of the first and third ground improvement bodies that have reached the lower end of the second and fourth ground improvement bodies have reached the foundation ground. The first to fourth ground improvement bodies, wherein the lower end of any one of the ground improvement bodies does not reach the foundation ground and the lower ends of the other ground improvement bodies including the second ground improvement body reach the foundation ground. It can take various forms depending on the design conditions such that all the lower ends of the base have reached the foundation ground.

It is sectional drawing which shows embodiment of the reinforcement structure of the embankment support ground of this invention. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 1st ground improvement body 2 2nd ground improvement body 3 3rd ground improvement body 4 4th ground improvement body 5 Core material 6 Tensile material 7 Laying net material 10 Filling 11 Filling support ground (soft ground)
12 Foundation ground

Claims (7)

Reinforcement structure of embankment support ground when creating embankment on soft embankment support ground,
A pile-shaped first ground improvement body is formed in the embankment supporting ground below the peripheral edge of the embankment,
A wall-shaped second ground improvement body is formed in the embankment supporting ground along the direction intersecting the horizontal displacement direction of the embankment supporting ground assumed inside thereof,
Furthermore, the reinforcement structure of the embankment supporting ground characterized by forming a pile-shaped 3rd ground improvement body in the embankment supporting ground inside it. It is the reinforcement structure of the embankment supporting ground according to claim 1,
The improvement depth of the second ground improvement body is set to be deeper than the improvement depth of the first ground improvement body and the third ground improvement body, and the first to third ground improvement bodies A reinforcement structure for embankment supporting ground, wherein the lower end of at least one ground improvement body does not reach the foundation ground. It is the reinforcement structure of the embankment supporting ground according to claim 2,
A reinforcement structure for embankment supporting ground, wherein none of the lower ends of the first to third ground improvement bodies reaches the foundation ground. A reinforcement structure for embankment supporting ground according to claim 1, 2 or 3,
A reinforcing structure for embankment supporting ground, wherein a wall-like fourth ground improving body is formed in the embankment supporting ground further outside said first ground improving body. A reinforcing structure for embankment supporting ground according to claim 1, 2, 3 or 4,
A reinforcing structure for embankment supporting ground, wherein a core material is provided in the second ground improvement body. A reinforcement structure for embankment supporting ground according to claim 1, 2, 3, 4 or 5,
A tensile material is disposed in the vicinity of the boundary between the embankment and the embankment supporting ground inside the second ground improvement body along the assumed horizontal displacement direction of the embankment supporting ground, and one end of the tensile material is A reinforcing structure for embankment supporting ground, wherein the second ground improvement body is fixed to the upper part of the second ground improvement body to restrain deformation and displacement of the second ground improvement body to the outside by the tensile material. The embankment supporting ground reinforcing structure according to claim 1, 2, 3, 4, 5 or 6,
A reinforcement structure for embankment supporting ground, characterized by laying a covering net material over the entire surface near the boundary between embankment and embankment supporting ground.

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