JP5961712B1 - Wall type ground improvement method with displacement restraint wall - Google Patents

Abstract

An object of the present invention is to realize a wall-type ground improvement method including a displacement suppression wall that can effectively improve soft ground by suppressing the embankment of a structure and settlement of surrounding parts by a displacement suppression wall. Yes. Therefore, an unimproved layer is left on a support layer made of a hard layer according to the design level, and a plurality of walls are provided on the unimproved layer at predetermined intervals so as to be orthogonal to the embankment longitudinal direction. In the wall-type ground improvement method in which a wall-type improvement layer is formed, and a shallow-type improvement layer is formed on the wall-type improvement layer and then embankment is performed on the shallow-type improvement layer, the outer edge of the wall in the cross-banking direction In the vicinity of the portion, at least one row of displacement suppression walls having a gap between the constituent members is arranged. [Selection] Figure 1

Description

  The present invention relates to a wall-type ground improvement method provided with a displacement suppression wall, and more particularly, to an improvement method of a wall-type ground improvement method, and by providing a displacement suppression wall, the embankment of a structure and the settlement of surrounding parts are suppressed and soft. The present invention relates to a wall-type ground improvement method provided with a displacement restraint wall for improving the ground.

When constructing structures such as roads and dikes, for example, some use a wall-type ground improvement method.
When building the structure 101 by this wall-type ground improvement method, first, as shown in FIG. 9, the support layer 102 which consists of a hard layer is ensured.
At this time, the “support layer 102” can be interpreted as a general “hard ground”.
After securing the support layer 102, the unmodified layer 103 having a predetermined depth is left on the support layer 102.
The unimproved layer 103 may not be left depending on the design level.
On this unimproved layer 103, a plurality of cement-type walls 104 are arranged at predetermined intervals so as to be orthogonal to the embankment longitudinal direction A to form a wall-type improved layer 105.
For reference, the above-mentioned “deep layer mixing process” includes, for example, excavating earth and sand using a bucket, and then agitating and mixing it with cement milk in the earth and sand to lay a plurality of linear walls. A processing method is assumed in which the wall 104 and the earth and sand located between the walls 104 are formed to form an integral wall-type improvement layer 105.
Further, after the shallow layer improvement layer 106 is formed on the wall type improvement layer 105, the structure 101 is constructed by performing embankment 107 on the shallow layer improvement layer 106.
Furthermore, on this structure 101, a road, a dike, etc. are formed.
The “banking longitudinal direction A” refers to a direction that coincides with the longitudinal direction of a road or a dike formed on the structure 101.

  Moreover, regarding the ground improvement construction method, many technical contents are disclosed like the following patent documents 1-3 etc.

Japanese Patent Laid-Open No. 10-317307 JP 2010-37831 A JP 2014-196614 A

Incidentally, in the conventional wall-type ground improvement method, as is apparent from FIG. 9, when the structure 101 is constructed, earth and sand are located between the plurality of walls 104 constituting the wall-type improvement layer 105. .
At this time, consolidation settlement occurs due to the weight of the embankment 107 located above the unimproved layer 103.
In addition, when this consolidation settlement occurs, the peripheral part of the embankment 107 is also dragged, and there exists a problem that subsidence occurs in the peripheral part of the embankment 107 of the structure 101.

Further, as a structure for preventing the above-described inconveniences, a structure in which integral sheet piles are arranged at outer end portions of a plurality of walls constituting the wall type improvement layer can be considered.
However, although this sheet pile type has an integral structure, it can prevent the settlement of the surrounding area of the embankment 107, but the material cost increases and the cost increases. In addition to the disadvantage, the sheet pile blocks the flow of groundwater.

  An object of the present invention is to realize a wall-type ground improvement method including a displacement suppression wall that can effectively improve the soft ground by suppressing the embankment of the structure and the settlement of the surrounding portion by the displacement suppression wall.

Therefore, in order to eliminate the above-mentioned inconveniences, the present invention leaves an unmodified layer on the support layer made of a hard layer according to the design level, and sets the unimproved layer on the unmodified layer so as to be orthogonal to the embankment longitudinal direction. In the wall-type ground improvement method in which a plurality of walls are arranged at intervals to form a wall-type improvement layer, and after forming a shallow layer improvement layer on this wall-type improvement layer, embankment is performed on this shallow layer improvement layer. , while the wall and the continuous wall structure, the outer end portion of the embankment transverse direction of the wall and the continuous wall structure, this is opposed to the outer end portion, and at least one of a gap between members constituting It is characterized by disposing displacement restraining walls in rows or more.

According to the present invention, the following effects can be obtained.
(1) It is possible to effectively improve the soft ground by suppressing the embankment of the structure and the settlement of the surrounding portion by the displacement restraining wall.
(2) Moreover, the flow of groundwater in the transverse direction of the wall-type improved layer is not obstructed by utilizing the gap between the members constituting the displacement suppression wall, and the ground between the walls is accelerated at the wall. Also effective for liquefaction countermeasures.

FIG. 1 is a schematic cross-sectional plan view of an arrangement state of a displacement suppression wall showing Embodiment 1 of the present invention. Example 1 FIG. 2 is a schematic cross-sectional front view of the disposition state of the displacement suppression wall. Example 1 FIG. 3 is a diagram illustrating land subsidence due to the presence or absence of a displacement suppression wall. Example 1 FIG. 4 is a schematic cross-sectional plan view of an arrangement state of a displacement suppression wall showing Embodiment 2 of the present invention. (Example 2) FIG. 5 is a schematic cross-sectional plan view of an arrangement state of a displacement suppression wall showing Embodiment 3 of the present invention. (Example 3) FIG. 6 is a schematic cross-sectional plan view of an arrangement state of a displacement restraint wall showing Embodiment 4 of the present invention. Example 4 FIG. 7: shows the schematic cross-sectional top view of the wall of the wall-type improvement layer of Example 5 of this invention, (a) is a schematic cross-sectional top view of the integrally formed wall, (b) is a plurality of discontinuous piles (C) is a schematic cross-sectional plan view of a wall made of a pile member that is continuous so that a plurality of parts overlap, and (d) is an integrally formed portion and a plurality of discontinuities. FIG. (Example 5) FIG. 8: is principal part explanatory drawing of the wall which consists of a pile member which continues so that some of the multiple pieces which show Example 6 of this invention may overlap. (Example 6) FIG. 9 is a schematic perspective view of the wall-type ground improvement method showing the prior art of the present invention.

  Embodiments of the present invention will be described below in detail with reference to the drawings.

1 to 3 show Embodiment 1 of the present invention.
1 and 2, reference numeral 1 denotes a structure constructed by the wall-type ground improvement method of the present invention.
As described in the prior art portion, the structure 1 secures the support layer 2 made of a hard layer, and then forms an unmodified layer 3 having a predetermined depth on the support layer 2.
Then, a plurality of cement-type walls 4 are arranged at a predetermined interval so as to be perpendicular to the embankment longitudinal direction A on the unimproved layer 3 to form a wall-type improved layer 5.
Further, the method is based on the wall-type ground improvement method in which the shallow layer improvement layer 6 is formed on the wall type improvement layer 5 and then the bank 7 is built on the shallow layer improvement layer 6.

And in the said structure 1 in Example 1 of this invention, the displacement suppression wall 8 of the at least 1 or more row | line | column which has a clearance gap between the members to comprise is arrange | positioned in the outer edge part vicinity of the embankment crossing direction B of the said wall 4. The configuration.
More specifically, the wall 4 will be described as, for example, three first walls 4-1, second wall 4-2, and third wall 4-3. As shown in FIG. The three walls 4-1, 4-2, 4-3 are arranged at predetermined intervals and so as to be orthogonal to the embankment longitudinal direction A, that is, the first to third walls 4-1, 4-2. , 4-3 is arranged so that the longitudinal direction thereof coincides with the embankment crossing direction B to form the wall type improvement layer 5.

Thereafter, the outer end portions 4a-1, 4a-2, 4a-3 of the first to third walls 4-1, 4-2, 4-3 are respectively connected to the outer end portions 4a-1, 4a-2, The displacement restraint wall 8 is arranged at a predetermined distance S from 4a-3.
At this time, the displacement suppression walls 8 are, for example, three rows of first displacement suppression wall rows 8A, second displacement suppression wall rows 8B, and third displacement suppression wall rows 8C. 3 can be paraphrased as “displacement deterrent wall 3 rows” in FIG.

Regarding the “predetermined distance S”, the setting can be arbitrarily changed according to the ground condition.
And although it is possible to change each separation dimension at the time of arrange | positioning the 3rd 1st displacement suppression wall row 8A, the 2nd displacement suppression wall row 8B, and the 3rd displacement suppression wall row 8C. In the first embodiment of the present invention, the “predetermined distance S” is used without being changed.

If it adds, as will be clear from FIG. 1, the longitudinal direction of the first wall 4-1 is perpendicular to the embankment crossing direction B at the outer end 4a-1 of the first wall 4-1. That is, the first displacement is performed so that the longitudinal direction of the cross-sectional shape made of a rectangular shape matches the embankment longitudinal direction A and is separated from the outer end 4a-1 of the first wall 4-1 by a predetermined distance S. The first displacement suppression wall 8A-1 of the suppression wall row 8A is arranged.
Further, the outer end portion 4a-2 of the second wall 4-2 has a predetermined distance S from the outer end portion 4a-2 of the second wall 4-2, similarly to the first wall 4-1. The second displacement suppression wall 8A-2 of the first displacement suppression wall row 8A is disposed so as to be separated from each other.
Further, the outer end portion 4a-3 of the third wall 4-3 has an outer end portion of the third wall 4-3, similar to the first wall 4-1 and the second wall 4-2 described above. The third displacement suppression wall 8A-3 of the first displacement suppression wall row 8A is arranged so as to be separated from 4a-3 by a predetermined distance S.
Then, the first to third displacement restraints of the second displacement restraint wall row 8B are separated from the first displacement restraint wall row 8A by a predetermined distance S outside the first displacement restraint wall row 8A. Walls B-1, 8B-2, and 8B-3 are respectively arranged.
Further, outside the second displacement suppression wall row 8B, the first to third of the third displacement suppression wall row 8C are separated from the second displacement suppression wall row 8B by a predetermined distance S. Displacement restraining walls 8C-1, 8C-2, 8C-3 are respectively arranged.

And each 1st-3rd displacement suppression wall 8A-1, 8A-2, 8A-3 and 1st-3rd which are the members which the said 1st-3rd displacement suppression wall row | line | column 8A, 8B, 8C comprises. When the displacement restraint walls 8B-1, 8B-2, 8B-3 and the first to third displacement restraint walls 8C-1, 8C-2, 8C-3 are arranged, the first to third walls 4-1 are arranged. , 4-2, 4-3 so as to oppose the first and second gaps 9-1, 9-2, and these first and second gaps 9-1, 9-. Predetermined first and second gaps 10-1 and 10-2, which are gaps between constituent members, are ensured to be smaller than 2.
That is, as shown in FIG. 1, with respect to the first gap portion 9-1 that appears by the first wall 4-1 and the second wall 4-2, the first displacement suppression wall row 8A has a first Between the first displacement suppression wall 8A-1 and the second displacement suppression wall 8A-2, and between the first displacement suppression wall 8B-1 and the second displacement suppression wall 8B-2 in the second displacement suppression wall row 8B. The first gap 10-1 extending in the embankment crossing direction B is interposed between the first displacement suppression wall 8C-1 and the second displacement suppression wall 8C-2 of the third displacement suppression wall row 8C. Secure.
Similarly, with respect to the second gap portion 9-1 appearing by the second wall 4-2 and the third wall 4-3, the second displacement suppression wall 8A of the first displacement suppression wall row 8A. -2 and the third displacement suppression wall 8A-3, between the second displacement suppression wall 8B-2 and the third displacement suppression wall 8B-3 of the second displacement suppression wall row 8B, and The second gap 10-2 extending in the embankment crossing direction B is secured between the second displacement suppression wall 8C-2 and the third displacement suppression wall 8C-3 of the third displacement suppression wall row 8C.

In the first embodiment of the present invention, the first to third displacement suppression wall rows 8A are disclosed in FIG. 1 so that the first and second gaps 10-1 and 10-2 are in a straight line state. 8B and 8C have been described, but a special configuration in which the arrangement positions of the first to third displacement suppression wall rows 8A, 8B, and 8C are shifted is also possible.
For example, the arrangement position of the second displacement suppression wall row 8B is shifted in the embankment longitudinal direction A with respect to the first displacement suppression wall row 8A, and the first and second gaps 10-1 and 10-2 are straight lines. It is intended not to be in a state.
Then, even if it is not a linear state as a special configuration, the first and second gaps in a connected state can be secured, so that the flow of groundwater is not hindered.

In addition, the first to third displacement suppression wall rows 8A and 8B are arranged at outer end portions 4a-1, 4a-2 and 4a-3 of the first to third walls 4-1, 4-2 and 4-3. , 8C, it is possible to arbitrarily set the depths of the first to third displacement suppression wall rows 8A, 8B, 8C.
In Embodiment 1 of the present invention, as shown in FIG. 2, the depth gradually increases from the first displacement suppression wall row 8A toward the second displacement suppression wall row 8B and the third displacement suppression wall row 8C. Is set to be large.
At this time, the lower end of the deepest third displacement suppression wall row 8C located at the outermost portion and reaching the support layer 2 is used.

Further, the first to third displacement restraining wall rows 8A and 8B are arranged at outer end portions 4a-1, 4a-2 and 4a-3 of the first to third walls 4-1, 4-2 and 4-3. , 8C, the shallow layer improvement layer 6 is formed on the wall type improvement layer 5 of the first wall 4-1, the second wall 4-2, and the third wall 4-3, and this The shallow improvement layer 6 is also formed integrally with the first to third displacement suppression wall rows 8A, 8B, and 8C.
At this time, the shallow layer improvement layer 6 can also be supported by a geotextile.
Then, after the shallow layer improvement layer 6 is formed, when embankment 7 is performed on the shallow layer improvement layer 6, the first to third displacement suppression wall rows 8A and 8B from the wall type improvement layer 5 side. The structure 1 is constructed by inclining so that the height position of the upper surface of the embankment 7 gradually decreases toward the 8C side.

  Next, the operation will be described.

If the said structure 1 provided with the said 1st-3rd displacement suppression wall row | line | column 8A, 8B, 8C of "3 displacement suppression wall rows" is constructed | assembled, the said 1st-3rd wall 4-1, 4-2, 4- 3 and the earth and sand of the first and second gap portions 9-1 and 9-2 which are revealed by the first to third walls 4-1, 4-2 and 4-3. Layer 5 is formed.
At this time, the unimproved layer 3 below the wall-type improved layer 5 is an unimproved region, and consolidation subsidence occurs due to the weight of the embankment 107 and the like due to use over time.
In addition, at the occurrence of consolidation settlement of the unimproved layer 3 or the like, dragging of the peripheral portion of the embankment 107 is prevented.
Further, the flow of groundwater in the transverse direction of the wall-type improved layer 5 is not inhibited.

Here, the embankment 7 of the structure 1 and the subsidence state of the peripheral part will be described.
In the case of a structure that does not have the first to third displacement restraint wall rows 8A, 8B, and 8C as in the prior art, that is, a "no displacement restraint wall" structure, as shown by a solid line in FIG. The ground surface subsidence of about −25 (cm) occurs at a distance (5 m) from the heel at the boundary (position of interest).
In contrast, the first ends of the first to third walls 4-1, 4-2, 4-3, which are Embodiment 1 of the present invention, are connected to the first ends of the first end walls 4a-1, 4a-2, 4a-3. In the case of the structure 1 of the “three rows of displacement restraint walls” comprising the third row of displacement restraint walls 8A, 8B, 8C, as shown by the broken line in FIG. If it is disclosed numerically, the ground surface subsidence of about −2 (cm) occurs at a distance of 5 (m) from the slope at the road boundary (target position).
The first to third displacement suppression wall rows 8A, 8B, and 8C have a standard range of 2/3 from the base of the structure 1 to the top.

Thereby, in Example 1 of this invention, outer edge part 4a-1, 4a-2, 4a-3 of the embankment crossing direction B of the said 1st-3rd walls 4-1, 4-2, 4-3. The outer end portions 4a-1, 4a-2, 4a-3 are opposed to each other, and have predetermined first and second gaps 10-1, 10-2 that are gaps between constituent members. By arranging the displacement restraining walls 8, for example, three rows of the first displacement inhibiting wall row 8A, the second displacement inhibiting wall row 8B, and the third displacement inhibiting wall row 8C, the following effects can be obtained. be able to.
(1) Between the first displacement suppression wall row 8A, the second displacement suppression wall row 8B, and the third displacement suppression wall row 8C, which are the displacement suppression walls 8, the first to third walls 4-1 , 4-2, 4-3, the first and second gaps 10-1, 10-2 are set to be smaller than the first and second gaps 9-1, 9-2. Thereby, the embankment 7 of the said structure 1 and the settlement of a surrounding site | part can be suppressed by the said displacement suppression wall 8, and the soft ground can be improved effectively.
(2) The first and second gaps provided between the first displacement suppression wall row 8A, the second displacement suppression wall row 8B, and the third displacement suppression wall row 8C, which are the displacement suppression walls 8. The flow of groundwater such as the unimproved layer 3 positioned below the first to third walls 4-1, 4-2, 4-3 of the wall-type improved layer 5 using 10-1 and 10-2 Is not inhibited, and the first to third walls 4-1, 4-2, 4-3 are also effective for liquefaction countermeasures.
(3) Furthermore, even if the support layer 2 of the structure 1 is inclined, the first displacement suppression wall row 8A, the second displacement suppression wall row 8B, which is the displacement suppression wall 8, Since the displacement-inhibiting wall row 8C of 3 becomes a resistance to hold the entire earth and sand located in the unimproved layer 3 and the like, the soft ground can be sufficiently improved regardless of the inclined state of the support layer 2.

FIG. 4 shows Embodiment 2 of the present invention.
In the second embodiment, portions having the same functions as those in the first embodiment will be described with the same reference numerals.

  In the first embodiment, the first to third displacement restraints are provided at the outer end portions 4a-1, 4a-2, 4a-3 of the first to third walls 4-1, 4-2, 4-3. The structure 1 of the “displacement deterrence wall 3 row” including the wall rows 8A, 8B, and 8C is used. This is in the point of construct 11.

That is, the displacement suppression wall 8 includes first to third displacement suppression walls 8-1, 8-2, and 8-3 having a rectangular cross section.
Similarly to the first embodiment described above, the first and second gap portions 9-1 and 9-2 that are exposed by the first to third walls 4-1, 4-2, and 4-3 are opposed to each other. Thus, predetermined first and second gaps 10-1 and 10-2 are ensured.
For this reason, "displacement restraint wall 1 row | line | column provided with the said displacement restraint wall 8 in the outer end part 4a-1, 4a-2, 4a-3 of the said 1st-3rd walls 4-1, 4-2, 4-3. In the case of the structure 11 in FIG. 3, as indicated by a one-dot chain line in FIG. 3, the ground subsidence is about −15 (cm) at a distance of 5 (m) from the nose at the road boundary (position of interest). Has occurred.

Then, the following effects can be obtained as in the case of the above-described first embodiment.
(1) Between the displacement suppression walls 8, than the first and second gap portions 9-1 and 9-2 that appear by the first to third walls 4-1, 4-2, and 4-3. By setting the first and second gaps 10-1 and 10-2 to be smaller, the displacement restraint wall 8 suppresses the embankment of the structure 11 and the settlement of the surrounding area, thereby improving the soft ground. Can be done automatically.
(2) The first to third walls 4-1 and 4- of the wall-type improvement layer 5 using the first and second gaps 10-1 and 10-2 provided between the displacement restraining walls 8. The flow of groundwater such as the unimproved layer 3 located below 2 and 4-3 is not obstructed, and the first to third walls 4-1, 4-2 and 4-3 are used for liquefaction countermeasures. Also works.
(3) Furthermore, even if the support layer of the structure 11 is inclined, the displacement restraint wall 8 becomes a resistance so as to hold the entire earth and sand located in the unmodified layer 3 or the like. Regardless of the inclination of the layer, the soft ground can be sufficiently improved.

  FIG. 5 shows Embodiment 3 of the present invention.

  The feature of the third embodiment is that a displacement restraining wall 28 is provided at outer end portions 4a-1, 4a-2, 4a-3 of the first to third walls 4-1, 4-2, 4-3. The construction 21 of the “one row of displacement restraint walls” provided is constructed, and the longitudinal directions of the first to third displacement restraint walls 28-1, 28-2, 28-3 of the displacement restraint wall 28 are defined in the first direction. ~ The third wall 4-1, 4-2, and 4-3 are configured to match the longitudinal direction.

That is, when constructing the structure 21, as shown in FIG. 5, the first to third displacement restraining walls 28- having a rectangular cross section which is the displacement restraining walls 28 of "one row of displacement restraining walls". 1, 28-2, and 28-3, while the longitudinal directions of these first to third displacement restraining walls 28-1, 28-2, and 28-3 are set to the first to third walls 4-1, It matches with the embankment crossing direction B which is the longitudinal direction of 4-2 and 4-3.
At this time, the width dimension of the first to third walls 4-1, 4-2, 4-3 and the width dimension of the first to third displacement suppression walls 28-1, 28-2, 28-3 are arbitrary. However, in the third embodiment of the present invention, the contact area is made large with substantially the same width dimension.

As a result, compared with the above-described second embodiment, the first and second gap portions 9-1 and 9-2 appear by the first to third walls 4-1, 4-2 and 4-3. The predetermined first and second gaps 30-1 and 30-2 facing each other are enlarged to the same dimensions as the first and second gaps 9-1 and 9-2, but the first to third walls The first to third displacement restraining walls 28-1, 28-2, 28-3 are arranged on the outer ends 4a-1, 4a-2, 4a-3 of 4-1, 4-2, 4-3. Since the contact area is large, the following effects can be obtained.
(1) Similar to the first and second gap portions 9-1 and 9-2 that are exposed by the first to third walls 4-1, 4-2, and 4-3 between the displacement suppression walls 28. By setting the first and second gaps 30-1 and 30-2 in various dimensions, the displacement restraining wall 28 having a large contact area suppresses the settlement of the embankment of the structure 21 and the surrounding portion and is soft. The ground can be improved effectively.
(2) The first to third walls 4-1 and 4- of the wall-type improvement layer 5 using the first and second gaps 30-1 and 30-2 provided between the displacement suppression walls 28. The flow of groundwater such as the unimproved layer 3 located below 2 and 4-3 is not obstructed, and the first to third walls 4-1, 4-2 and 4-3 are used for liquefaction countermeasures. Also works.
(3) Furthermore, even if the support layer of the structure 21 is inclined, the displacement restraining wall 28 becomes a resistance so as to hold the entire earth and sand located in the unmodified layer 3 and the like. Regardless of the inclination of the layer, the soft ground can be sufficiently improved.

  FIG. 6 shows Embodiment 4 of the present invention.

  In the first to third embodiments described above, the cross-sectional shape of the displacement suppression walls 8 and 28 is rectangular, but the feature of this fourth embodiment is that the cross-sectional shape of the displacement suppression wall 38 is circular. It is in.

That is, when constructing the structure 31, as shown in FIG. 6, the first to third displacement restraining walls 38- having a circular cross-section that is the displacement restraining walls 38 of the "displacement restraining wall 1 row". 1, 38-2, 38-3 are provided.
At this time, the width dimension of the first to third walls 4-1, 4-2, 4-3 and the diameter dimension of the first to third displacement restraining walls 38-1, 38-2, 38-3 are arbitrarily set. However, in the fourth embodiment of the present invention, the first to third displacement restraining walls 38-1, 38-2, 38-3 are slightly larger in diameter. .
When forming the first to third displacement restraint walls 38-1, 38-2, 38-3 of the displacement restraint wall 38, for example, a cement-type cement mill is placed in the earth and sand while excavating the earth and sand. This can be done by pouring and stirring to make a cylindrical pile.

Accordingly, predetermined first and second facing the first and second gap portions 9-1 and 9-2 that are exposed by the first to third walls 4-1, 4-2, and 4-3. The gaps 40-1 and 40-2 can be made smaller than the first and second gap portions 9-1 and 9-2, and the outside of the first to third walls 4-1, 4-2, and 4-3. Since the first to third displacement restraining walls 38-1, 38-2, 38-3 are arranged at the end portions 4a-1, 4a-2, 4a-3, the following effects can be obtained.
(1) Between the displacement suppression walls 38, than the first and second gap portions 9-1 and 9-2 that are exposed by the first to third walls 4-1, 4-2, and 4-3. By setting the first and second gaps 40-1 and 40-2 so as to be small, the displacement suppression wall 38 suppresses the embankment of the structure 31 and the settlement of the surrounding portion, thereby improving the soft ground. Can be done automatically.
(2) The first to third walls 4-1 and 4- of the wall-type improvement layer 5 using the first and second gaps 40-1 and 40-2 provided between the displacement suppression walls 38. The flow of groundwater such as the unimproved layer 3 located below 2 and 4-3 is not obstructed, and the first to third walls 4-1, 4-2 and 4-3 are used for liquefaction countermeasures. Also works.
(3) Further, even if the support layer of the structure 31 is inclined, the displacement suppression wall 38 becomes a resistance so as to hold the entire earth and sand located in the unmodified layer 3 and the like. Regardless of the inclination of the layer, the soft ground can be sufficiently improved.

  FIG. 7 shows Embodiment 5 of the present invention.

  In the first to fourth embodiments described above, the wall 4 is described as a continuous wall structure as shown in FIG. 7A, but the feature of the fifth embodiment is that the wall structure is improved.

At this time, the wall structure is improved, for example, as shown in FIGS.
That is, in the case of the discontinuous cylindrical wall 41 shown in FIG. 7B, a plurality of cylindrical members 41 having a circular cross-sectional shape are arranged at predetermined intervals.
In the case of the continuous cylindrical wall 51 shown in FIG. 7C, a plurality of cylindrical members 42 having a circular cross-sectional shape are arranged side by side so as to overlap each other by a small size.
Further, in the case of the combined wall 61 shown in FIG. 7D, for example, a so-called combined wall structure in which a discontinuous cylindrical wall 63 is disposed at an intermediate portion of the continuous wall 62 disclosed in the first to third embodiments. Form.
The cylindrical members 41 and 42 and the discontinuous cylindrical wall 63 will be described. When forming by the “deep mixing process”, cement-based cement milk is injected into the earth and sand while excavating the earth and sand, for example. Agitation is performed to form a plurality of cylindrical members.

Thereby, the wall structure can be the discontinuous cylindrical wall 41, the continuous cylindrical wall 51, and the combined wall 61 described above, and can be appropriately selected according to the formation state when constructing a structure, The versatility can be increased to improve workability and reduce costs.
Moreover, even if the discontinuous cylindrical wall 41, the continuous cylindrical wall 51, and the combined wall 61 having the configuration of the fifth embodiment of the present invention are used in a structure including the displacement suppression wall, groundwater such as an unmodified layer is used. There is no problem in the flow of

  FIG. 8 shows Embodiment 6 of the present invention.

  The feature of the sixth embodiment resides in that the strength of the continuous cylindrical wall 71 is improved when the wall structure is improved.

That is, when the continuous cylindrical wall 71 is formed by arranging a plurality of circular cylindrical members 72 having a circular cross-sectional shape so as to overlap each other by a small size, the cylindrical members 72 are formed at both end portions 71 a of the continuous cylindrical wall 71. Arrange multiple.
More specifically, when both end portions 71a of the continuous columnar wall 71 are formed, the first columnar member 72-1 is arranged on both sides with respect to the first columnar member 72-1 of the base row portion located in the central portion. That is, the second and third cylindrical members 72-2 and 72-3 are formed so as to sandwich the front and rear sides in the embankment longitudinal direction A.

Thereby, the wall structure can be the continuous cylindrical wall 71 in which both end portions 71a are formed in a plurality of rows by the second and third cylindrical members 72-2 and 72-3, and when constructing a structure, the continuous cylindrical wall The contact area with the soft ground located in the peripheral part of the wall 71 can be increased, the frictional force of the continuous cylindrical wall 71 is increased, and the settlement is reduced.
And since it is not necessary to make the whole area | region of the said continuous cylindrical wall 71 into multiple rows | lines, it is also possible to aim at improvement of workability | operativity, cost reduction, etc.
In addition, if the continuous cylindrical wall 71 according to the sixth embodiment of the present invention is used in a structure including the displacement suppression wall, both end portions 71a of the continuous cylindrical wall 71 function as a diaphragm. It is possible to hold the earth and sand more firmly, and does not hinder the flow of groundwater such as unmodified layers.

  In addition, this invention is not limited to the said Examples 1-6, A various application modification is possible.

For example, in the present invention, at least one row or more of the displacement suppression walls disposed so as to face the outer end portion of the wall is described as being three rows in the first embodiment, while being described as one row in the second embodiment. It is also possible to make the displacement suppression wall have a special configuration of two rows or four rows or more.
Then, it is possible to achieve the above-described remarkable effect due to the displacement suppression wall.

  Further, in the first embodiment of the present invention, when the displacement suppression walls are arranged in three rows, the depths of the first to third displacement suppression wall rows are gradually different, and the third displacement suppression wall located outside. Although the lower end of the row has been described as a configuration that reaches the support layer, the lower end of the third displacement suppression wall row extends to the vicinity of the support layer without contacting the support layer, and other than the third displacement suppression wall row A special configuration such as a configuration in which the lower ends of the second and / or third displacement suppression wall rows are in contact with the support layer, and a configuration in which all of the lower ends of the first to third displacement suppression wall rows are in contact with the support layer; It is also possible to do.

  Furthermore, in the sixth embodiment of the present invention, the improvement of the wall structure has been described. However, it is also possible to adopt a special configuration in which the described configuration is applied to a displacement suppression wall.

DESCRIPTION OF SYMBOLS 1 Construction constructed by wall-type ground improvement method 2 Support layer 3 Unimproved layer 4 Wall 4-1 First wall 4a-1 Outer end 4-2 Second wall 4a-2 Outer end 4-3 Third wall 4a-3 Outer end 5 Wall type improvement layer 6 Shallow layer improvement layer 7 Embankment 8 Displacement prevention wall 8A First displacement prevention wall row 8B Second displacement prevention wall row 8C Third displacement prevention wall row 9-1 First 1 Gap 9-2 Second Gap 10-1 First Gap 10-2 Second Gap A Filling Longitudinal Direction B Filling Crossing Direction S Predetermined Distance

Claims (1)

A wall-type improved layer is formed by leaving an unmodified layer on the support layer made of a hard layer according to the design level, and arranging a plurality of walls on the unmodified layer at predetermined intervals so as to be orthogonal to the embankment longitudinal direction. In the wall-type ground improvement method in which a shallow layer improvement layer is formed on the wall type improvement layer and then embankment is performed on the shallow layer improvement layer, the wall has a continuous wall structure. The outer end of the wall in the crossing direction of the embankment is structured to dispose at least one row of displacement restraining walls facing the outer end and having a gap between constituent members. Wall type ground improvement method with displacement restraint walls.

Images