JP2014156714A - Ground reinforcing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a ground reinforcing method capable of inexpensively and easily preventing subsidence or sinkage of ground for a long period of time.SOLUTION: A net sheet 3 is superimposed on a head 2a of a pile 2 driven into a ground layer 1, and therefore, pressure of a covering layer 5 applied to the ground layer 1 can be dispersed by the net sheet 3. Accordingly, a pressure load locally applied to the ground layer 1 can be greatly reduced, and uneven subsidence or sinkage of the ground layer 1 can be prevented for a long period of time. That is, subsidence of the ground layer 1 can be prevented, and therefore, subsidence and sinkage of the covering layer 5 can be prevented. Further, even when a heavy-weight building or a vehicle is locally placed on the covering layer 5, the pressure applied to the ground layer 1 can be dispersed by the net sheet 3, and therefore, subsidence or sinkage of the ground layer 1 can be prevented for a long period of time, and a crack in the covering layer 5 or tilting of the building can be prevented.

Description

  The present invention particularly relates to a ground reinforcement method for stabilizing and strengthening soft ground.

Conventionally, there is a ground reinforcement method in which a large number of piles are placed on the ground to improve the strength of the ground and prevent the ground from sinking or sinking. However, in the ground reinforcement method using only piles, when a heavy load such as a building or a vehicle is applied to the ground for a long time, the ground may sink or sink. In particular, there was a tendency for the settlement and depression to be greater between the piles than the surroundings where the piles were placed (near the piles).
In order to solve this problem, there is a ground reinforcement method for placing a ground improvement body on a ground portion at a position corresponding to the planar shape of a building after placing a pile as in Patent Document 1 on the ground. In this method, the subsidence and depression of the ground are prevented by the pile and the ground improvement body created by the solidification method.

JP-A-6-294137

However, in each of the above-mentioned patent documents, the ground improvement body is created by a solidification processing method that chemically improves the properties and strength of the soil by mixing the solidified material such as concrete or lime with soft soil, However, there is a problem that a large amount of materials related to the construction method is required and the construction cost is increased.
The present invention has been made to solve the above-mentioned problems, and its purpose is to prevent ground subsidence and depression over a long period of time at low cost without using a solid processing method or the like. The purpose is to provide a reinforcement method.

In order to achieve the above object, in the invention according to claim 1, after placing a large number of piles on the ground layer so that the pile heads are exposed from the ground layer, the pile heads and the ground layer The gist is to disperse the pressure of the coating layer through the pressure dispersion by laying a pressure dispersion on the substrate and then laminating the coating layer so as to cover the pressure dispersion.
By setting it as such a structure, the pressure of the coating layer added to a ground layer will be disperse | distributed by a pressure dispersion body, and the local (that is, non-uniform) subsidence and depression of a ground layer are prevented.
Further, in the invention described in claim 2, in addition to the configuration of the invention described in claim 1, the pressure dispersion body is formed with a group of through holes that are evenly or substantially equally distributed in the surface direction. The gist.
By setting it as such a structure, the rain water etc. which permeate | transmit from a coating layer are drained to a ground layer from the through-hole group of a pressure dispersion body. It is preferable that a large number of through-hole groups are evenly or substantially evenly distributed in the surface direction. Here, “equal or substantially equal” not only means that all the areas of the pressure dispersion body are arranged with the same interval, but there may be locally uneven portions. is there. The material and shape of the piles are not limited, but they are best made of plastic that is lightweight and does not rot.
The gist of the invention described in claim 3 is that, in addition to the configuration of the invention described in claim 1 or 2, the pressure dispersion is a sheet body having a thick and net-like appearance.
By having such a configuration, it has stable drainage and sufficient dispersion ability of pressure.
In addition, the gist of the invention described in claim 4 is that, in addition to the configuration of any one of claims 1 to 3, the pressure dispersion body is a flexible sheet body.
By setting it as such a structure, when laying a pressure dispersion body on a ground layer, even if there exists distortion in a ground layer surface, it can arrange | position, deforming a pressure dispersion body along the ground layer surface.
Moreover, in the invention of Claim 5, in addition to the structure of any one of Claims 1 to 4, the gist is that the pressure dispersion body is fixed to the pile head by a fixing member.
By setting it as such a structure, the shift | offset | difference of the pressure dispersion body with respect to a ground layer is prevented.
The gist of the invention described in claim 6 is that, in addition to the structure of any one of the inventions of claims 1 to 5, the coating layer is made of a material that solidifies with time.
Thereby, the pressure is more preferably dispersed in the pressure dispersion body.

  According to the inventions of the above-mentioned claims, it is possible to easily prevent ground subsidence and depression over a long period of time at low cost.

BRIEF DESCRIPTION OF THE DRAWINGS It is a front sectional view which shows the composition of the ground in embodiment of this invention, (a) is the state which struck the pile, (b) is the state which has arrange | positioned the net body sheet, (c) comprised the coating layer. State. (A) is an expanded sectional view of the A section in FIG.1 (b), (b) is an expanded sectional view of the A section in FIG.1 (c). The top view which shows a ground structure. (A) is a perspective view of a pile, (b) is a front view of a pile, (c) is a bottom view of the pile. The perspective view which shows the fixing member of another Example.

Hereinafter, the ground reinforcement method of the present invention will be described with reference to the drawings.
First. The pile 2 used for this construction method and the net body sheet 3 as a pressure dispersion body will be described. As shown in FIGS. 4 (a) to 4 (c), the pile 2 is composed of an integrally molded product of plastic, such as polycarbonate, which is difficult to biodegrade. The body portion 2a of the pile 2 is formed in a cross shape in cross section and has four ribs 2c. In the figure, a disc-shaped head 2b is integrally formed at the upper part of the body 2a, and the lower part has a tapered point 2d so that it can be driven easily. The pile 2 is held on the ground with its head 2b exposed.
As shown in FIGS. 1 and 3, the net body sheet 3 is formed of a high-strength plastic that is difficult to biodegrade using a flexible polyolefin or the like as a raw material. In the present embodiment, as an example, the net sheet 3 is formed with a thickness of about 2 mm, and a planar square-shaped through-hole 3 a with a length of 30 mm is formed. Further, between the adjacent through holes 3a, there are a vertical connecting portion 3b extending in the vertical direction and a horizontal connecting portion 3c extending in the horizontal direction, and the width of both connecting portions 3a, 3b is about 3 mm. A portion where the two connecting portions 3a and 3b intersect is an intersecting portion 3d. The mesh sheet 3 is manufactured by resin molding, and each part is integrally formed.

Now, a method for forming an improved ground using such a pile 2 and a net sheet 3 will be described.
As shown in FIG. 1 (a), in this embodiment, when performing ground improvement, first, a large number of piles 2 are equidistantly spaced at regular intervals on the ground 1 in the construction area with dedicated equipment (breakers, monkens, power shovels, etc.). Type in.
Next, after driving the pile 2 into the ground 1, a net body sheet 3 as a pressure dispersion body is laid on the ground 1 as shown in FIG. At this time, since the head 2 b of the pile 2 is exposed from the ground 1, the net body sheet 3 is placed on the head 2 b of the pile 2.
After laying the net body sheet 3 on the ground layer 1, as shown in FIG. 2 (a), a stainless steel metal nail as a fixing member from the intersecting portion 3d of the net body sheet 3 facing the head 2b of the pile 2 4 is struck, and the net body sheet 3 is connected and fixed to the head 2a of the pile 2. By hitting the metal nail 4, the movement of the net body sheet 3 in the horizontal direction and the vertical direction with respect to the pile 2 is restricted. After hitting the metal nail 4, as shown in FIGS. 1 (c) and 2 (b), a mixed material in which gravel and cement are mixed is put on the mesh sheet 3, and a leveling means such as a road roller is used. The ground is leveled to form a covering layer (leveling layer) 5. Since the mixed material is also filled into the through holes 3 a of the net body sheet 3 in the leveling operation, the net body sheet 3 is taken into a part of the coating layer 5. The covering layer 5 gradually changes to a firm and hard layer as the cement takes moisture and solidifies with time. Thereafter, an upper layer such as asphalt or concrete may be formed on the coating layer 5 as necessary.

With the configuration described above, the following effects are achieved in the present embodiment.
(1) The covering layer 5 applied on the ground layer 1 by laminating the net body sheet 3 on the head 2a of the pile 2 driven into the ground layer 1 and integrating the net body sheet 3 with the covering layer 5 Can be dispersed by the mesh sheet 3. In particular, since the coating layer 5 of the present embodiment is solidified with time, it is suitable for dispersing pressure on the net sheet 3. Thereby, the pressure load applied locally on the ground layer 1 can be greatly reduced, and the ground layer 1 can be prevented from sinking or sinking unevenly over a long period of time. And since the subsidence and depression of the ground layer 1 can be prevented, the subsidence and depression of the coating layer 5 can be prevented. Furthermore, even if a heavy building or vehicle is placed locally on the covering layer 5, the pressure applied to the ground layer 1 by the mesh sheet 3 can be dispersed, so that the ground layer 1 sinks or sinks over a long period of time. As a result, the covering layer 5 can be prevented from sinking or sinking, and for example, cracking of the ground surface, inclination of the building, or the like can be prevented.
(2) By using the net sheet 3 having the through-hole 3a, rainwater or the like that permeates from the coating layer 1 side can be drained from the through-hole 3a to the ground layer 1 to reduce the influence of the rainwater or the like on the coating layer 1 In addition, the drainage of the coating layer 5 can be improved.
Further, the mixed material enters into the through holes 3a and the frictional force (shear resistance) of the coating layer 5 with respect to the ground layer 1 increases, so that the displacement of the coating layer 5 with respect to the ground layer 1 can be further prevented.
(3) The net body sheet 3 sinks into the ground layer 1 by driving into the ground layer 1 with the head 2a of the pile 2 exposed, and placing the net body sheet 3 on the head 2a. Is prevented, and the settlement and depression of the coating layer 5 can be prevented more reliably.
(4) By connecting and fixing the net body sheet 3 to the head 2 a of the pile 2 with the metal nail 4, it is possible to prevent the net body sheet 3 from being displaced with respect to the pile 2. Thereby, even if concrete is poured when constructing the covering layer 5, the net work sheet 3 does not move with respect to the ground layer 1 due to the fluid pressure, and workability can be improved. Moreover, since the shift | offset | difference of the net body sheet | seat 3 with respect to the ground layer 1 is suppressed, by extension, the shift | offset | difference of the coating layer 5 with respect to the ground layer 1 can be prevented.
Moreover, by connecting and fixing the net body sheet 3 to the head 2a of the pile 2, it is possible to prevent the pile 2 from sinking into the ground layer 1 by its own weight, and to more reliably prevent the covering layer 5 from sinking or sinking. Can be prevented.
(5) By forming the mesh sheet 3 from a flexible thin sheet, the mesh sheet 3 is deformed along the surface of the ground layer 1 even if the surface of the ground layer 1 is distorted. The distortion of the ground layer 1 can be allowed, and the ground can be improved over a wide range.
(6) By forming the pile 2 with plastic and making the trunk | drum 2a into the cross-shaped cross section, weight can be reduced significantly, maintaining intensity | strength rather than the columnar iron pile and wooden pile of the same size. As a result, the transportation cost can be reduced and the construction work at the time of driving the pile can be simplified.

The present invention may be embodied as follows.
-It may replace with the net body sheet | seat 3 as a pressure dispersion which has water permeability, and may be actualized with the board member in which many through-holes which consist of a plastic, wood, a metal, etc. which do not have water permeability were formed.
-It may replace with the net body sheet | seat 3 as a pressure dispersion body which has flexibility, and may be actualized with the plate member which consists of a plastic which does not have flexibility, and does not have water permeability, a wood, a metal.
-It is also possible to use a pile having a shape and material other than the pile 2 as described above.
-Pile 2 does not necessarily need to be driven at equal intervals.
-You may embody, without using the metal nail 4 as a fixing member.
In the above embodiment, the coating layer 5 is embodied by a mixed material in which gravel and cement are mixed. However, the coating layer may be embodied by gravel, sand, embankment or the like. Alternatively, concrete may be poured to form the covering layer 5. Moreover, you may make it use solidifying agents, such as a lime type | system | group and a gypsum type | system | group, other than cement type (or mixing with cement type) as a solidifying agent.
-You may make it use the field material (soil, gravel) as the coating layer 5. FIG.
As means for leveling the covering layer 5, means other than those described above can be used. For example, the work may be performed manually.
-You may materialize the shape of the through-hole 3a of the net sheet | seat 3 as a pressure dispersion body with various shapes, such as a planar rectangle and a round shape. Moreover, in the said embodiment, although the net body sheet 3 was integrally formed by resin molding, the strip | belt-shaped (string shape) member which consists of the same material as the net body sheet 3 is arrange | positioned in the vertical direction and a horizontal direction. However, it may be embodied by a net sheet formed by knitting them. Further, a scouring fiber structure in which hard fibers are partially bound may be used. That is, any non-biodegradable (or hardly biodegradable) material having flexibility and a mass capable of dispersing the pressure of the coating layer 5 and having water permeability is suitable.
-You may embody using wooden or metal piles. Further, it may be embodied by a columnar or other shaped pile.
As the fixing member, an inverted U-shaped staple 7 having two driving portions 7a as shown in FIG. 5 may be used. In the said embodiment, when connecting and fixing the net body sheet 3 as a pressure dispersion body to the head 2a of the pile 2, the metal nail 4 as a fixing member was driven in from the cross | intersection part 3d of the net sheet body 3. . On the other hand, in the staple 7 of FIG. 5, the longitudinal connecting portion 3b or the lateral connecting portion 3c of the mesh sheet 3 is disposed between the driven portions 7a, and the staple 7 is piled from the upper portion of the connecting portion 3b (3c). The net body sheet 3 is connected and fixed to the head 2a by driving into the head 2a. In this case, the mesh sheet 3 can be connected and fixed to the head 2a even in a portion where the head 2a and the intersection 3d of the mesh sheet 3 do not face each other, improving the workability of the connection and fixing work. can do.
-You may make it use the net | network sheet | seat 3 of multiple sheets in piles. A three-dimensional structure is built in the coating layer 5 and the pressure is further dispersed.
In addition, the present invention may be implemented in a modified form without departing from the spirit of the present invention.

  DESCRIPTION OF SYMBOLS 1 ... Ground layer, 2 ... Pile, 3 ... Net body sheet as pressure dispersion, 4 ... Metal nail as fixing member, 5 ... Covering layer.

Claims (6)

  After placing a large number of piles on the ground layer so that the pile heads are exposed from the ground layer, a pressure dispersion body is laid on the pile head and the ground layer, and then the pressure dispersion body is covered The ground reinforcing method is characterized in that the coating layer is laminated so that the pressure of the coating layer is dispersed through the pressure dispersion body.   The ground reinforcing method according to claim 1, wherein the pressure dispersion body is formed with a group of through holes that are evenly or substantially evenly distributed in the surface direction.   The ground reinforcing method according to claim 2, wherein the pressure dispersion body is a sheet body having a thick and net-like appearance.   The ground reinforcement method according to any one of claims 1 to 3, wherein the pressure dispersion is a flexible sheet.   The ground reinforcement method according to any one of claims 1 to 4, wherein the pressure dispersion body is fixed to the pile head portion by a fixing member. The ground reinforcement method according to any one of claims 1 to 5, wherein the coating layer is made of a material that solidifies with time.

Images