JP6427051B2 - Ground improvement foundation structure - Google Patents

Description

  The present invention relates to a ground improvement foundation structure constructed by an improvement body in which a ground and a cement-based solidifying material are mixed and stirred.

  In order to prevent the liquefaction of the ground at the time of an earthquake, a structure is known in which a wall made of a ground improvement body is made continuous so as to become a grid in plan view, and a liquefaction layer is enclosed reference).

  For example, in Patent Document 1, a lattice-like wall is constructed by continuously arranging two types of columnar modified bodies having different lengths. Here, a columnar reformer with a short length is formed to the depth of the liquefaction layer, and a columnar reformer longer than that is formed to a length that reaches the support layer.

  The long columnar reformer and the short columnar reformer are constructed so as to be integrated continuously in the lateral direction. In addition, a longer pile is placed in the center of the grid of the grid improvement body than in the longer columnar improvement body.

  In short, the ground improvement body disclosed in Patent Document 1 is a combination of an upper portion formed in a wall shape in the liquefaction layer and a lower portion protruding from the upper portion toward the support layer, and the load of the building is It is a stress transmission structure that it receives in the entire upper part as a distributed load and transmits it to the lower part.

  Moreover, in the liquefaction countermeasure structure disclosed in Patent Document 2, piles in which the core material is embedded at the intersections of the grids are constructed, and the piles are connected by the soil cement wall to form a grid in plan view It is formed. In short, the soil cement wall is supported by the piles joined at both ends.

  Furthermore, Patent Document 3 also discloses a foundation structure in which a soil cement column retaining wall and a supporting wall by a columnar improvement body arranged in a plan view lattice shape and a pile disposed in the center of the grid are combined. There is. And a support wall and a pile are provided under the foundation (solid foundation) of a building, and have a structure which receives a vertical load as distributed load and bears it in the whole.

  On the other hand, Patent Document 4 discloses a structure for preventing liquefaction of the ground in which the depth position of the top portion of the underground structure in the form of a lattice in plan view is separated from the bottom surface of the structure. In this structure, even when the structure sinks, the bottom of the structure is set so as not to contact the underground structure, and the load of the structure is transmitted to the ground surrounded by the underground structure, and the load is transmitted. We expect the liquefaction suppression effect by the effective stress of the ground increased by

JP, 2013-2077, A JP-A-7-150544 JP, 2010-222870, A JP, 2014-118752, A

  However, in the foundation structure disclosed in Patent Literature 1-3, the grid-like wall provided to prevent liquefaction also bears the vertical load. Therefore, the thickness, length and strength should be sufficient to bear the vertical load of the building. Also, the weight of the grid-like wall is added as a vertical load to be supported.

  On the other hand, the liquefaction preventing structure of Patent Document 4 is a structure of a design concept in which the ground is loaded with a vertical load, and the upper structure is not intended to be supported by a plurality of columnar modified bodies.

  Therefore, the present invention provides a ground improvement foundation structure that can be rationally and economically structured by clarifying an improvement that bears a vertical load and an improvement placed for suppressing liquefaction. It is intended to be provided.

  In order to achieve the above object, the ground improvement foundation structure of the present invention is a ground improvement foundation structure constructed by an improvement body in which the ground and a cement-based solidifying material are mixed and stirred, and the vertical load by the upper structure is And a wall-shaped modification provided between the columnar modification such that the lower ground of the upper structure is enclosed, wherein the depth of the columnar improvement is It is characterized in that it is deeper than the depth of the wall reformer.

  In addition, the ground improvement foundation structure of the present invention is a ground improvement foundation structure constructed by an improvement body in which the ground and a cement-based solidifying material are mixed and stirred as a foundation of an upper structure in which a frame is formed by columns and beams. A plurality of columnar modification provided at a flat position where the column base portion of the upper structure is installed, and a wall provided between the columnar improvement so as to surround the lower ground of the upper structure The depth of the columnar modification is deeper than the depth of the wall type modification.

  Here, it may be configured that an edge cut portion that reduces or blocks transmission of a shear force is formed between the columnar modified body and the wall-shaped modified body. Further, the rim cut portion can be formed by a pipe material having a smooth peripheral surface which is an outer shell of the columnar modified body.

  Furthermore, the ground improvement foundation structure of the present invention is a ground improvement foundation structure constructed by an improvement body in which the ground and the cement-based solidifying material are mixed and stirred, and provided at a planar position on which the vertical load by the upper structure acts. And a wall-shaped modification provided so as to surround the outside of the columnar modification so as to surround at least the lower ground of the upper structure, the depth of the columnar It is characterized in that it is deeper than the depth of the wall reformer.

  The top end of the columnar reformer preferably reaches a support layer of the ground, and the wall-shaped reformer is preferably provided in the range of a liquefied layer located in a shallower layer than the support layer.

  In addition, the wall-shaped improved body is formed by continuously forming the short columnar improved body, and the diameter of the short columnar improved body may be smaller than the diameter of the columnar improved body. Furthermore, the core material may be embedded in the columnar improved body.

  The ground improvement foundation structure of this invention comprised in this way provides a columnar improvement body in the plane position to which the vertical load by an upper structure acts. And, the lower ground of the upper structure is surrounded by arranging the wall-shaped reformer between the columnar reformers. Here, the depth of the columnar modification is deeper than the depth of the wall-shaped modification.

  For this reason, it is possible to clearly separate the portion of the columnar improved body that bears the vertical load and the portion of the wall-shaped improved body that is disposed for liquefaction suppression, and a rational and economical structure. Can be

  In addition, in the case of an upper structure in which a frame is formed by columns and beams, the vertical load is concentrated on the flat position where the column base is installed, so the position where the columnar improved body should be installed is determined. easy.

  Furthermore, if an edge cutting portion that reduces or blocks transmission of shear force is formed between the columnar improved body and the wall-shaped improved body, the weight of the wall shaped improved body is transmitted to the columnar improved body. The burden load will not increase significantly.

  As a result, it is possible to rationally and economically set the supporting force of the columnar improved body in accordance with the vertical load of the upper structure. Moreover, such an edge cut part can be easily provided by using a tube material with smooth surrounding surfaces like a steel pipe.

  On the other hand, also by providing the wall-shaped improved body so as to surround the outer side of the columnar improved body so that the lower ground of the upper structure is enclosed, the portion of the columnar improved body which bears the vertical load and the liquefaction suppression In order to be able to be clearly separated from the part of the wall-like body to be arranged, it is possible to make a rational and economical structure.

  Furthermore, by allowing the tip of the columnar reformer to reach the support layer of the ground, it is possible to ensure the supporting force against vertical load of the columnar reformer, and the wall-shaped reformer is limited to the range of the liquefied layer. By doing this, it is possible to provide a foundation structure that can economically prevent liquefaction.

  In addition, the weight of the wall-shaped improved body can be reduced by making the diameter of the short column of the wall-shaped improved body smaller than the diameter of the column-shaped improved body. Furthermore, when the cross-sectional area of the wall-shaped modified body decreases and the rigidity decreases, the shear force and bending stress transmitted to the columnar modified body are reduced even when the rim cut portion is not provided. Can reduce the burden of

  In addition, since the compressive strength can be enhanced by embedding the core material in the columnar modified body, the cross-sectional area can be reduced to reduce the own weight. Furthermore, by disposing a steel pipe having high bending strength in the outer shell of the columnar modified body, it is possible to improve the bending resistance while reducing the dead weight of the columnar modified body.

BRIEF DESCRIPTION OF THE DRAWINGS It is the perspective view which showed schematic structure of the ground improvement foundation structure of this Embodiment. FIG. 2 is a plan view showing the configuration of the ground improvement foundation structure of Example 1; It is the perspective view which showed schematic structure of the ground improvement foundation structure of Example 2. FIG. It is the top view which expanded and showed the structure of the connection part of the columnar improvement body of the ground improvement foundation structure of Example 2, and a wall-like improvement body. FIG. 14 is a perspective view showing a schematic configuration of a ground improvement foundation structure of Example 3; FIG. 16 is a perspective view showing a schematic configuration of a ground improvement foundation structure of Example 4; It is the perspective view which showed schematic structure of the ground improvement foundation structure of Example 5. FIG. It is a figure which partially enlarges and demonstrates the structure of the ground improvement foundation structure of Example 5, Comprising: (a) is a side view, (b) is a top view. It is sectional drawing which showed schematic structure of the ground improvement foundation structure of Example 6. FIG.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1: is a perspective view for demonstrating typically the structure of the ground improvement foundation structure 1 of this Embodiment.

  The ground improvement foundation structure 1 of the present embodiment is constructed on the ground as a foundation of a building to be an upper structure such as a house or a small-scale apartment house. In the ground, there is a liquefied layer G2 which may be liquefied in the upper layer.

  The sandy soil layer below the groundwater level corresponds to the liquefied layer G2. Furthermore, on this ground, a hard support layer G1 is present at a position deeper than the liquefaction layer G2. A soft ground layer or the like is interposed between the liquefaction layer G2 and the support layer G1.

  The support layer G <b> 1 is a stratum having a hardness enough to secure a tip supporting force when the tip of a deep foundation such as a pile is embedded. The ground improvement foundation structure 1 of the present embodiment is constructed by an improved body in which the ground and the cement-based solidifying material are mixed and stirred.

  Such an improved body can be constructed, for example, by a deep mixing treatment method or a soil cement method. In these construction methods, a slurry-like cement-based solidifying material such as cement milk is mixed into the ground in situ and then mixed and stirred to construct an improved body (soil cement).

  Specifically, the ground is cut in situ by a stirring blade attached to the tip of an auger rotationally driven by a hydraulic motor, and the cement milk discharged from the tip of the auger and the ground ground are mixed and stirred by the stirring blade Let The portion that has become soil cement by this mixing and agitation is consolidated by the chemical solidification reaction of the cement-based solidifying material, and is formed as an improved body with higher compressive strength than the original ground.

  On the other hand, the upper structure of the present embodiment is a building such as a house in which a frame is formed by beams and columns. For example, by bridging beams between spaced columns, a frame structure is formed which is a structural member.

  The columns and beams that constitute this framework structure can be formed of steel materials such as H-shaped steel, channel steel (C-shaped steel) or square steel pipe, for example. The frame structure may be a steel frame structure in which a column and a beam are joined by bolts, or may be a frame structure in which a column and a beam are rigidly joined by welding.

  Vertical loads such as the weight of a building in which a frame structure is formed by such columns and beams are intensively transmitted from the column base to the foundation. In the diagram schematically shown in FIG. 1, concentrated loads P,...

  That is, the plane positions whose concentrated loads P,... Are illustrated in FIG. 1 indicate the four corners where the pillars of the building are installed. Then, the columnar improved body 2 is constructed at the position where the concentrated load P acts.

  The columnar improved body 2 is a cylindrical improved body constructed by the above-described deep layer mixing treatment method or the like. Then, the tip of the columnar reformer 2 reaches the support layer G1 of the ground.

  The bearing capacity of the columnar modified body 2 constructed in this manner is represented by the sum of the frictional resistance between the circumferential surface of the columnar modified body 2 and the ground and the tip resistance of the portion embedded in the support layer G1. .

  On the other hand, a wall-shaped modified body 3 is provided between the columnar modified bodies 2 and 2. The wall-shaped improved body 3 is constructed by continuing a cylindrical improved body constructed by the deep mixing treatment method described above or the like.

  Specifically, short columns 31 which are improvement bodies constructed to a length according to the depth of the liquefaction layer G2 are constructed so as to be continuous bodies by respectively lapping both sides.

  In the present embodiment, the columnar modified body 2 and the short column body 31 have the same diameter and material. On the other hand, the depth of the columnar modified body 2 is different in that it is deeper than the depth of the wall-shaped modified body 3 (in other words, the short column 31).

  Next, the operation of the ground improvement foundation structure 1 of the present embodiment will be described.

  In the ground improvement foundation structure 1 of the present embodiment configured in this manner, the column improvement is performed in accordance with the planar position of the column base acting as the concentrated load P,. Body 2, ... is provided.

  And, by arranging the wall-shaped reformer 3 between the columnar reformers 2 and 2, the lower ground of the building is surrounded in a rectangular parallelepiped shape by the column-modified bodies 2, ... and the wall-shaped reformer 3, ... To be

  Here, since FIG. 1 is a diagram schematically written, the ground is surrounded in a rectangular shape in a plan view, but the present invention is not limited to this, and may be surrounded in a lattice in a plan view.

  Then, when the liquefaction layer G2 is surrounded by the improved bodies (2, 3) in this way, even if the ground shakes due to an earthquake, the inside surrounded by the improved bodies is relatively restrained from deformation and the gaps between the soil particles The rise in water pressure will be suppressed. As a result, the occurrence of liquefaction can be suppressed.

  For this reason, the wall-shaped improved body 3 should just be provided with horizontal rigidity to such an extent that the deformation which causes generation | occurrence | production of liquefaction is suppressed. On the other hand, all of the vertical loads of the building (concentrated loads P,...) Are supported by the columnar modified bodies 2,.

  In short, the supporting force of the columnar improved body 2 disposed at the application position of the concentrated load P is formed so as to be a resistance that can bear the concentrated load P with only one columnar improved body 2. For this reason, the depth of the columnar modified body 2 is deeper than the depth of the wall-shaped modified body 3 and reaches the support layer G1 if necessary.

  In this way, the portion of the columnar improved body 2, ... that bears the vertical load (P, ...) and the portion of the wall-shaped improved body 3, ... placed for suppressing liquefaction are clarified If it can be divided, it is possible to make it a rational and economical structure.

  In addition, in a building in which a frame is formed by columns and beams, the vertical load acts as a concentrated load P on the planar position where the column base is installed, so the position where the columnar improved body 2 should be installed Is easy to judge.

  Furthermore, by causing the tip of the columnar reformed body 2 to reach the support layer G1 of the ground, it is possible to ensure the supporting force of the columnar improved body 2 against the vertical load. And liquefaction can be prevented economically by constructing wall form improvement object 3 by restricting to the range of liquefaction layer G2.

  Hereinafter, Example 1 of a mode different from the above-described embodiment will be described with reference to FIG. The same or equivalent parts as the contents described in the above embodiment will be described with the same terms or the same reference numerals.

  Example 1 shows a plan view of the ground improvement foundation structure 1A that is actually constructed. The upper structure constructed on the ground improvement foundation structure 1A is a unit building U.

  The unit building U is constructed by installing a plurality of building units U1,... Adjacent to each other. The building unit U1 is a rectangular parallelepiped rigid frame structure in which a column and a beam are rigidly joined by welding.

  FIG. 2 illustrates a unit building U in which six building units U1,... Here, the planar position of the corner portion of each building unit U1 is the planar position of the column base U11.

  In FIG. 2, the short columns 31A,... Constituting the wall-shaped modified body 3A are illustrated by white circles, and the columnar modified body 2A is illustrated as a shaded circle. Further, the depth of the wall-shaped modified product 3A (short column 31A) is 3 m, and the depth of the columnar modified product 2A is 5 m.

  In this ground improvement foundation structure 1A, the improved bodies (2A, 3A) are continuously arranged along the outer periphery of the unit building U so as to be substantially rectangular in plan view, and with the boundaries of the left and right building units U1, U1. In the above position, the modification (2A, 3A) is continuously arranged.

  That is, the ground under the unit building U is surrounded by two rectangles in plan view. Then, the column base portions U11,... Of all the building units U1,... Are installed immediately above or in the vicinity of the columnar modified body 2A. In addition, in the ground improvement foundation structure 1A of the first embodiment, a plurality of (three) columnar modification bodies 2A, 2A, 2A are continuously arranged.

  In the ground improvement foundation structure 1A of the first embodiment configured as described above, the columnar improvement bodies 2A,... Are provided at the planar positions on which the vertical load by the unit building U acts. Then, by arranging the wall-shaped reformer 3A between the columnar reformers 2A and 2A, the lower ground of the unit building U is surrounded by the reformer. Here, the depth of the columnar modified body 2A is deeper than the depth of the wall-shaped modified body 3A.

  For this reason, it is possible to clearly divide the portion of the columnar improved body 2A that bears the vertical load and the portion of the wall-shaped improved body 3A disposed for liquefaction suppression, which is rational and economical. Structure.

  For example, in a conventional foundation structure in which vertical loads are supported via a solid foundation by grid-like modified bodies, vertical loads act as distributed loads over the entire range of grid-like grids. For this reason, all the improvement bodies are equipped with both a liquefaction preventing function and a vertical load supporting function, and the total extension of the improvement bodies becomes long.

  On the other hand, the total extension of the improved body can be achieved by clearly dividing the portion that carries the vertical load (the columnar improved body 2A) and the portion that is disposed for liquefaction suppression (the wall-shaped improved body 3A). It will be possible to make it about half of the conventional foundation structure. As a result, the construction cost and the construction period can be significantly reduced.

  In addition, about another structure and an effect, since it is substantially the same as the said embodiment or another Example, description is abbreviate | omitted.

  Hereinafter, a second embodiment different from the above-described embodiment will be described with reference to FIGS. The same or equivalent parts as the contents described in the above embodiment will be described with the same terms or the same reference numerals.

  In the ground improvement foundation structure 1B of the second embodiment, an edge cutting portion that reduces or blocks transmission of a shear force is formed between the columnar improvement body 2B and the wall-like improvement body 3B. This rim cut portion is formed of a tube whose surface is smooth as the outer shell of the columnar reformed body 2B.

  For example, the steel pipe 21 used for a casing, a pile, etc. for ground excavation can be used as an edge cut part. FIG. 4: is the top view which expanded and showed the structure of the connection part of the columnar improvement body 2B of the ground improvement foundation structure 1B, and the wall-like improvement body 3B.

  As shown in FIG. 4, the short pillars 31B constituting the wall-shaped modified body 3B are lapped by the short pillars 31B adjacent to each other on both sides to form a continuous integral structure. On the other hand, the steel pipe 21 is interposed between the columnar modified body 2B and the wall-shaped modified body 3B.

  Although the wall-like modified body 3B is in close contact with the steel pipe 21, the adhesion between the soil cement and the steel pipe 21 is smaller than the adhesion between the soil cements, so transmission of shear force is reduced or blocked. It can be considered.

  Further, on the inner corner side of the columnar modified body 2B covered with the steel pipe 21, the ends of the wall-shaped modified bodies 3B and 3B on both sides thereof are formed so as to be continuous. In short, the wall-like reformed bodies 3B and 3B constituting each side are directly connected to each other so that groundwater does not flow into the ground surrounded by the ground improvement foundation structure 1B from the portion where the edge is cut by the steel pipe 21. Make it continuous.

  Moreover, in the present Example 2, the outer shell is coat | covered with the steel pipe 21 over the full length of the columnar improvement body 2B. Here, if it is only for the steel pipe 21 to function as the edge cutting part, it may be made the same length (depth) as the wall-shaped improved body 3B.

  On the other hand, by covering the entire length of the columnar reformed body 2B with the steel pipe 21, the compressive strength can be enhanced. As a result, the required supporting force can be reduced by reducing the cross-sectional area of the columnar reformed body 2B to reduce its own weight.

  Further, by disposing the steel pipe 21 having high bending strength in the outer shell of the columnar reformed body 2B, it is possible to improve the bending resistance. Therefore, the length for arranging the steel pipe 21 may be determined according to the desired performance.

  In the ground improvement foundation structure 1B according to the second embodiment configured as described above, the steel pipe 21 is interposed between the columnar modification 2B and the wall-shaped modification 3B as an edge cutting portion that reduces or blocks transmission of shear force. ing.

  For this reason, the self-weights of the wall-shaped modified bodies 3B, 3B on both sides of the columnar modified body 2B become difficult to be transmitted to the columnar modified body 2B or are not transmitted, so that the load on the columnar modified body 2B can be suppressed. That is, the columnar modified body 2B can be rationally and economically designed and constructed in accordance with the concentrated load P acting due to the vertical load of the upper structure.

  In addition, about another structure and an effect, since it is substantially the same as the said embodiment or another Example, description is abbreviate | omitted.

  Hereinafter, a third embodiment different from the above-described embodiment will be described with reference to FIG. The same or equivalent parts as the contents described in the above embodiment will be described with the same terms or the same reference numerals.

  In the third embodiment, a ground improvement foundation structure 1C will be described in which the diameter of the columnar modified body 2C and the diameter of the short columns 31C constituting the wall-shaped modified body 3C are different. As described above, in the case of dividing the portion carrying the vertical load (the columnar improved body 2C) and the portion disposed for suppressing liquefaction (the wall-shaped improved body 3C), the rigidity required for each is also obtained. Because they are different, the diameter can be changed.

  For example, the diameter of the columnar improved body 2C is about 600 mm, and the diameter of the short column 31C is about 300 mm to 400 mm. Since the wall shape improving body 3C only needs to secure the necessary horizontal rigidity as a whole, the required thickness (diameter of the short column 31C) is not so large.

  The ground improvement foundation structure 1C according to the third embodiment configured as described above has a wall shape by making the thickness (diameter of the short column 31C) of the wall shape improved body 3C smaller than the diameter of the column improved body 2C. The weight of improved body 3C can be reduced.

  In addition, when the cross-sectional area of the wall-shaped modified body 3C is reduced and the rigidity is reduced, the shear force and bending stress transmitted to the columnar modified body 2C are reduced even when the rim cut portion is not provided. The burden on improved body 2C can be reduced. That is, if the rigidity of the wall-shaped modified body 3C is reduced, the stress that can be transmitted thereby is also reduced, so that even if it is transmitted to the columnar modified body 2C, the burden does not increase significantly.

  In addition, about another structure and an effect, since it is substantially the same as the said embodiment or another Example, description is abbreviate | omitted.

  Hereinafter, a fourth embodiment different from the above-described embodiment will be described with reference to FIG. The same or equivalent parts as the contents described in the above embodiment will be described with the same terms or the same reference numerals.

  In the ground improvement foundation structure 1D of the fourth embodiment, the core material 22 such as a small diameter steel pipe or a shaped steel is embedded at the axial position (center position) of the columnar reformed body 2D. On the other hand, the configuration of the wall-shaped improved body 3D constructed by continuously forming the short columns 31D, ... is the same as the wall-shaped improved body 3 described in the above embodiment.

  The core material 22 is pushed into the soil cement column formed by mixing and stirring the cement milk and the ground ground with a stirring blade before the soil cement is solidified. The core material 22 has a length substantially the same as that of the columnar modified body 2D.

  In the ground improvement foundation structure 1D of the fourth embodiment configured as described above, the compressive strength can be increased by embedding the core material 22 in the columnar improvement body 2D, so the cross-sectional area is reduced to reduce the self weight. be able to. And if self-weight can be reduced, the necessary bearing capacity (necessary bearing capacity) of columnar reformer 2D can also be made small, so that further rational and economical design becomes possible.

  In addition, about another structure and an effect, since it is substantially the same as the said embodiment or another Example, description is abbreviate | omitted.

  Hereinafter, a fifth example different from the above-described embodiment and example will be described with reference to FIGS. In addition, about the description of the same thru | or equivalent part as the content demonstrated in the said embodiment or another Example, the same term or the same code | symbol is attached | subjected and demonstrated.

  In the fifth embodiment, a ground improvement foundation structure 1E will be described in which the wall-shaped reformers 3E,... Are provided so as to surround the outer sides of the columnar reformers 2E,. That is, in the ground improvement foundation structure 1E, at least the lower ground of the upper structure is surrounded by a plurality of columnar improved bodies 2E, ... provided at the planar position on which the vertical load by the upper structure (for example, unit building U) acts. .. Are mainly provided so as to surround the outer sides of the columnar modified bodies 2E,...

  As shown in FIG. 8A, the columnar modified body 2E is provided at the four corners that are the edge of the unit building U with a length such that the tip reaches the support layer G1. On the other hand, the wall-shaped modified body 3E is provided outside the columnar modified body 2E where the vertical load of the unit building U does not directly act.

  That is, the columnar modified body 2E and the wall-shaped modified body 3E (short columnar body 31E) are separated so as to reduce or block the transmission of shear force, and the edges are cut.

  FIG. 8B is a plan view showing a corner of the unit building U in an enlarged manner. As shown to this figure, short pillars 31E, ... are provided in the outer side from the outer edge of the unit building U. As shown in FIG. The short pillars 31E,... Are provided in the range of the liquefied layer G2 at a relatively shallow position, and are shorter than the columnar reformed members 2E,.

  These short columns 31E, ... are continuously provided to surround the ground below the unit building U, as shown in FIG. That is, the unit building U and the four columnar modified bodies 2E below it, which are built on a site having a substantially rectangular shape in plan view, have wall-shaped improved bodies 3E,. It will be surrounded by.

  By arranging the columnar modified bodies 2E,... Supporting the vertical load of the unit building U inside the wall-shaped reformed bodies 3E,. The shear rigidity of the columnar reformed body 2E, ... can be rationally reduced.

  Furthermore, the ground on the inner side of the wall-shaped reformed body 3E, ... is suppressed from liquefaction, and the circumferential friction resistance between the wall-shaped reformed body 3E, ... and the ground adhering to it is added and vertical High support performance against load can be obtained.

  Moreover, although the case where wall shape improvement body 3E, ... was provided in the vicinity of the outer edge of the unit building U was demonstrated here, it is not limited to this. For example, the whole site on which the unit building U is built, such as a garden or a parking lot, can be surrounded by the wall-shaped modified body 3E,. With such a configuration, it is possible to take measures against liquefaction also for peripheral equipment attached to the house.

  In addition, about another structure and an effect, since it is substantially the same as the said embodiment or another Example, description is abbreviate | omitted.

  A sixth embodiment which is a modification of the fifth embodiment will be described below with reference to FIG. In addition, about the description of the same thru | or equivalent part as the content demonstrated in the said embodiment or another Example, the same term or the same code | symbol is attached | subjected and demonstrated.

  In the sixth embodiment, as in the fifth embodiment, a ground improvement foundation structure 1F will be described in which the wall-shaped improved bodies 3F,... Are provided so as to surround the outer sides of the columnar improved bodies 2F,.

  In the fifth embodiment, the tip of the columnar improved body 2E,... Reaches the hard support layer G1. However, in the sixth exemplary embodiment, the tip of the columnar improved body 2F,. It is made to support on the non-liquefied layer G3 which does not have the hardness (rigidity) of the support layer G1. Here, in the ground illustrated in FIG. 9, a surface layer G4, a liquefied layer G2, a non-liquefied layer G3, and a support layer G1 are sequentially stacked from the top.

  And the unit building U is constructed on the solid foundation U2 used as the foundation part provided on the surface G4. Then, the upper ends of the columnar modified bodies 2F,... Are connected to the lower surfaces of the four corners which are the edge portions of the solid foundation U2.

  On the other hand, the wall shape improving bodies 3F,... Are provided from the surface layer G4 to the liquefying layer G2 so as to surround the outer sides of the columnar improving bodies 2F,. It is not necessary to provide the short pillars 31F,... Constituting the wall-like modified body 3F to the deepest part of the liquefaction layer G2, and may be halfway.

  In short, when the foundation immediately below a structure such as a unit building U is a solid foundation U2, the pressure (ground pressure) from the bottom surface of the solid foundation U2 is used to increase the effective stress of the ground to generate liquefaction. Can be enhanced.

  Further, even if the settlement has occurred, the load can be dispersed by the solid foundation U2, so that the amount of settlement can be minimized. Furthermore, by not causing the tip of the columnar reformed bodies 2F,... To reach the support layer G1, the rate at which the load of the unit building U becomes the load of the ground increases, and the liquefaction suppressing effect can be further enhanced.

  In addition, about another structure and an effect, since it is substantially the same as the said embodiment or another Example, description is abbreviate | omitted.

  As mentioned above, although the embodiment of the present invention has been described in detail with reference to the drawings, the specific configuration is not limited to the embodiment or the example, and a design change which does not deviate from the scope of the present invention. Is included in the present invention.

  For example, in the above embodiment and examples, the front ends of the columnar modified members 2 and 2A to 2E are made to reach the support layer G1, but the present invention is not limited thereto. If it can be secured, the tip may not reach the support layer G1.

1,1A-1F ground improvement foundation structure 2,2A-2F columnar improvement body 21 steel pipe (margin)
22 Core material 3, 3A-3F Wall-shaped reformer 31, 31A-31F Short column G1 Support layer G2 Liquefied layer P Concentrated load (vertical load)
U unit building (upper structure)
U11 pillar base

Claims (4)

A ground improvement foundation structure constructed by an improvement body in which the ground and a cement-based solidifying material are mixed and stirred,
A plurality of columnar modified bodies provided at a planar position on which the vertical load by the upper structure acts,
And a wall-shaped improver provided between the columnar improvers so as to surround the lower ground of the upper structure;
Said depth of the columnar improved body deeply than the depth of the wall-like improved body, and between the columnar improved body and the wall-like improved body, edge switching unit to reduce or block the transmission of the shear force is formed To be
The ground improvement foundation structure according to the present invention, wherein the rim cut portion is formed of a smooth tube material which is to be an outer shell of the columnar reformer . The tip of the columnar improved body together to reach to the supporting layer of the ground, according to claim 1, wherein the wall-like improved body and which are located in the range of liquefaction layer located shallow than the support layer Ground improvement foundation structure. The wall-like improved body is formed by successive improvements of short columnar, the diameter of the short columnar improved body to claim 1 or 2, characterized in that less than the diameter of the columnar improved body Ground improvement foundation structure described. Soil Improvement substructure according to any one of claims 1 to 3, characterized in Tei Rukoto core material embedded in the columnar improved body.