JP2019011678A - Ground improvement foundation structure - Google Patents

Abstract

To provide a ground improvement foundation structure capable of obtaining a rational and economical structure by defining a part for bearing a vertical load from a part disposed for restricting liquefaction.SOLUTION: A ground improvement foundation structure 1 is constructed of improvement bodies including subsoil and a cement-based solidification material which are mixed and stirred. The ground improvement foundation structure 1 includes: plural columnar improvement bodies 2, ... which are positioned in a plane on which a concentrated load P of an upper structure acts; and wall-like improvement bodies 3, ... which are formed between columnar improvement bodies so as to surround the lower subsoil of the upper structure. The depth of the columnar improvement bodies is deeper than the depth of the wall-like improvement bodies.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a ground improvement foundation structure constructed by an improved body obtained by mixing and stirring the ground and a cement-based solidified material.

  In order to prevent liquefaction of the ground at the time of an earthquake, a structure in which a ground improvement body is constructed so as to have a lattice shape in plan view and a liquefied layer is enclosed is known (Patent Documents 1-3, etc.) reference).

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

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

  In short, the ground improvement body disclosed in Patent Document 1 is a basic structure of a combination of an upper part formed in a wall shape in the liquefied layer and a lower part protruding from the upper part toward the support layer, and the load of the building is It has a stress transmission structure in which it is received as a distributed load throughout the upper part and transmitted to the lower part.

  Moreover, in the liquefaction countermeasure structure disclosed in Patent Document 2, a pile in which a core material is embedded at a position where the lattice intersects is constructed, and the piles are connected by a soil cement wall to form a lattice in plan view. Is formed. In short, a soil cement wall is supported by a pile joined to both ends.

  Further, Patent Document 3 discloses a foundation structure in which a soil cement column mountain retaining wall and a supporting wall made of columnar improvement bodies arranged in a lattice shape in plan view and a pile arranged at the center of the grid are combined. Yes. 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 a distributed load and bears as a whole.

  On the other hand, Patent Document 4 discloses a ground liquefaction countermeasure structure in which the depth position of the top portion of the underground structure having a lattice shape 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 that it does not touch the underground structure.The load of the structure is transmitted to the ground surrounded by the underground structure, and the load We expect the liquefaction suppression effect due to the effective stress of the ground increased by.

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

  However, in the basic structure disclosed in Patent Documents 1-3, a lattice-like wall provided to prevent liquefaction also bears a vertical load. For this reason, the thickness, length, and strength must be sufficient to bear the vertical load of the building. In addition, the self-weight of the grid-like wall is added as a vertical load to be supported.

  On the other hand, the liquefaction countermeasure structure of Patent Document 4 is a structure based on a design concept that bears a vertical load on the ground, and does not attempt to support the upper structure with a plurality of columnar improvements.

  Therefore, the present invention provides a ground improvement foundation structure that can be made a rational and economical structure by clarifying an improved body that bears a vertical load and an improved body that is arranged to suppress liquefaction. It is intended to provide.

  In order to achieve the above object, the ground improved foundation structure of the present invention is a ground improved foundation structure constructed by an improved body obtained by mixing and stirring the ground and a cement-based solidified material, and a vertical load caused by an upper structure is generated. A plurality of columnar improvement bodies provided in a planar position to act, and a wall-like improvement body provided between the columnar improvement bodies so as to surround a lower ground of the upper structure, the depth of the columnar improvement body is It is characterized by being deeper than the depth of the wall-shaped improvement body.

  In addition, the ground improved foundation structure of the present invention is a ground improved foundation structure constructed by an improved body obtained by mixing and stirring the ground and cement-based solidified material as a foundation of an upper structure in which a framework is formed by columns and beams. A plurality of columnar improvement bodies provided at a planar position where the column base portion of the upper structure is installed, and a wall shape provided between the columnar improvement bodies so that a lower ground of the upper structure is surrounded. An improvement body, wherein the depth of the columnar improvement body is deeper than the depth of the wall-like improvement body.

  Here, it can be set as the structure by which the edge cut part which reduces or interrupts | blocks transmission of a shearing force is formed between the said columnar improvement body and the said wall-shaped improvement body. Moreover, the said edge cut part can be formed with the tubular material with the smooth surrounding surface used as the outer shell of the said columnar improvement body.

  Furthermore, the ground improvement foundation structure of the present invention is a ground improvement foundation structure constructed by an improved body obtained by mixing and stirring the ground and cementitious solidified material, and is provided at a planar position where a vertical load is applied by the upper structure. A plurality of columnar improvement bodies, and a wall-like improvement body provided so as to surround the outside of the columnar improvement body so that at least the lower ground of the upper structure is surrounded, the depth of the columnar improvement body is It is characterized by being deeper than the depth of the wall-shaped improvement body.

  And while making the front-end | tip of the said columnar improvement body reach the support layer of a ground, it is preferable to make the said wall-shaped improvement body the structure provided in the range of the liquefied layer located in a shallower layer than the said support layer.

  Moreover, the said wall-shaped improvement body is formed by making a short columnar improvement body continue, and the diameter of the said short columnar improvement body can be set as the structure smaller than the diameter of the said columnar improvement body. Furthermore, the structure by which a core material is embed | buried under the said columnar improvement body may be sufficient.

  In the ground improvement foundation structure of the present invention configured as described above, a columnar improvement body is provided at a planar position where a vertical load is applied by the upper structure. And the lower ground of an upper structure is surrounded by arrange | positioning a wall-shaped improvement body between columnar improvement bodies. Here, the depth of the columnar improvement body is deeper than the depth of the wall improvement body.

  For this reason, it is possible to clearly separate the columnar improvement body portion that bears the vertical load from the wall-like improvement body portion that is arranged to suppress liquefaction, and a rational and economical structure. Can be.

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

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

  As a result, the supporting force of the columnar improvement body can be set rationally and economically according to the vertical load of the superstructure. Moreover, such an edge cutting part can be easily provided by using a pipe material with a smooth peripheral surface such as a steel pipe.

  On the other hand, by providing the wall-like improved body so as to surround the outside of the columnar improved body so that the lower ground of the upper structure is surrounded, the portion of the columnar improved body that bears the vertical load and the liquefaction suppression Therefore, it becomes possible to clearly separate the portion of the wall-like improvement body arranged for the purpose, and a rational and economical structure can be obtained.

  Furthermore, by allowing the tip of the columnar improvement body to reach the support layer of the ground, it becomes possible to ensure the support force for the vertical load of the columnar improvement body and to limit the wall-like improvement body to the range of the liquefied layer By doing so, it can be set as the basic structure which can prevent liquefaction economically.

  Moreover, the dead weight of a wall-shaped improvement body can be reduced by making the diameter of the short column body of a wall-shaped improvement body smaller than the diameter of a columnar improvement body. Furthermore, if the cross-sectional area of the wall-shaped improved body is reduced and the rigidity is lowered, the shear force and bending stress transmitted to the columnar improved body are reduced even when the edge cut portion is not provided. Can be reduced.

  Moreover, since the compressive strength can be increased by embedding the core material in the columnar improved body, the cross-sectional area can be reduced and the dead weight can be reduced. Furthermore, by arranging a steel pipe having a high bending strength in the outer shell of the columnar improved body, the bending strength can be improved while reducing the weight of the columnar improved body.

It is the perspective view which showed schematic structure of the ground improvement foundation structure of this Embodiment. It is the top view which showed the structure of the ground improvement foundation structure of Example 1. FIG. 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 basic structure of Example 2, and a wall-shaped improvement body. It is the perspective view which showed schematic structure of the ground improvement foundation structure of Example 3. FIG. It is the perspective view which showed schematic structure of the ground improvement foundation structure of Example 4. FIG. It is the perspective view which showed schematic structure of the ground improvement foundation structure of Example 5. FIG. It is a figure which expands and demonstrates the structure of the ground improvement basic 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 schematically explaining the configuration of the ground improvement foundation structure 1 of the present embodiment.

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

  The liquefied layer G2 corresponds to a sandy soil layer below the groundwater level. Further, in this ground, a hard support layer G1 exists at a position deeper than the liquefied layer G2. Further, a soft ground layer or the like is interposed between the liquefied layer G2 and the support layer G1.

  The support layer G1 is a stratum having a hardness that can secure a tip support force when a tip of a deep foundation such as a pile is buried. The ground improvement basic structure 1 of this Embodiment is constructed | assembled by the improvement body which made the ground and the cement-type solidification material mix and stir.

  Such an improved body can be constructed by, for example, a deep mixing method or a soil cement method. In these methods, an improved body (soil cement) is constructed by mixing a slurry-like cement-based solidified material such as cement milk into the ground in which it has been cut and mixing and stirring.

  Specifically, the ground is cut in place by a stirring blade attached to the tip of an auger that is driven to rotate by a hydraulic motor, and the cement milk discharged from the tip of the auger and the ground that has been cut are mixed and stirred by the stirring blade. Let The part which became the soil cement by this mixing and stirring is solidified by a chemical solidification reaction of the cement-based solidified material, and is formed into an improved body having a higher compressive strength than the original ground.

  On the other hand, the superstructure of the present embodiment is a building such as a house in which a framework is formed by beams and columns. For example, a frame structure that is a structural member is formed by bridging a beam between columns arranged at intervals.

  The columns and beams constituting the frame structure can be formed of a steel material such as an H-shaped steel, a grooved steel (C-shaped steel), or a square steel pipe. Further, the frame structure may be a steel structure that joins a column and a beam with bolts, or a rigid frame structure that rigidly joins a column and a beam 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 planar positions illustrating the concentrated loads P,... In FIG. 1 indicate the four corners where the column bases of the building are installed. And the columnar improvement body 2 is constructed | assembled in the position where this concentrated load P acts.

  This columnar improvement body 2 is a columnar improvement body constructed by the above-described deep mixing method. And the front-end | tip of the columnar improvement body 2 is reached to the support layer G1 of a ground.

  The support force of the columnar improvement body 2 constructed in this way is represented by the sum of the frictional resistance between the peripheral surface of the columnar improvement body 2 and the ground and the tip resistance of the portion embedded in the support layer G1. .

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

  Specifically, the short columnar bodies 31,... That are constructed to have a length that matches the depth of the liquefied layer G2 are constructed so as to be a continuous body by wrapping both sides.

  In the present embodiment, the columnar improvement body 2 and the short columnar body 31 have the same diameter and material. On the other hand, the depth of the columnar improvement body 2 is different in that it is deeper than the depth of the wall-like improvement body 3 (in other words, the short columnar body 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 as described above, the columnar improvement is performed in accordance with the planar position of the column base portion where the vertical load due to the building as the upper structure acts as the concentrated load P,. Body 2, ... is provided.

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

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

  When the liquefied layer G2 is surrounded by the improved bodies (2, 3) in this way, even if the ground is shaken by an earthquake, the inside surrounded by the improved body is relatively prevented from being deformed, and the gap between the soil particles is reduced. The increase in water pressure will be suppressed. As a result, the occurrence of liquefaction is suppressed.

  For this reason, the wall-shaped improvement body 3 should just be provided with the horizontal rigidity of the grade which can suppress the deformation | transformation which causes generation | occurrence | production of liquefaction. On the other hand, all of the vertical loads of the building (concentrated loads P,...) Are supported by the columnar improvement bodies 2.

  In short, the supporting force of the columnar improvement body 2 arranged at the position where the concentrated load P is applied is formed so as to have a strength capable of bearing the concentrated load P with only one columnar improvement body 2. For this reason, the depth of the columnar improvement body 2 becomes deeper than the depth of the wall-like improvement body 3, and reaches the support layer G1 if necessary.

  In this way, the columnar improvement bodies 2,... That bear the vertical load (P,...) And the wall improvement bodies 3,. If it can be divided, it becomes possible to make a rational and economical structure.

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

  Furthermore, the support force with respect to the vertical load of the columnar improvement body 2 can be reliably ensured by causing the tip of the columnar improvement body 2 to reach the ground support layer G1. And liquefaction can be prevented economically by constructing the wall-like improved body 3 limited to the range of the liquefied layer G2.

  Hereinafter, Example 1 of a form different from the above-described embodiment will be described with reference to FIG. The description of 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 has shown the top view of 1 A of ground improvement foundation structures actually constructed | assembled. The superstructure 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,. This building unit U1 is a rectangular parallelepiped ramen structure in which columns and beams 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 columnar bodies 31A,... Constituting the wall-shaped improved body 3A are illustrated by white circles, and the columnar improved bodies 2A are illustrated by circles with diagonal lines. The depth of the wall-like improved body 3A (short column body 31A) was 3 m, and the depth of the columnar improved body 2A was 5 m.

  In this ground improvement basic structure 1A, the improvement 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 the boundary between the left and right building units U1, U1 The improved bodies (2A, 3A) are continuously arranged at the positions.

  That is, the ground below the unit building U is surrounded by two rectangles in plan view. And the column base part U11, ... of all the building units U1, ... will be installed right above the columnar improvement body 2A or its vicinity. Moreover, in the ground improvement basic structure 1A of the first embodiment, a plurality (three) of the columnar improvement bodies 2A, 2A, 2A are continuously arranged.

  The ground improvement foundation structure 1A of the first embodiment configured as described above is provided with the columnar improvement bodies 2A,... At the plane position where the vertical load by the unit building U acts. And the lower ground of the unit building U is surrounded by the improved body by arranging the wall-shaped improved body 3A between the columnar improved bodies 2A and 2A. Here, the depth of the columnar improvement body 2A is deeper than the depth of the wall-like improvement body 3A.

  For this reason, it becomes possible to clearly separate the portion of the columnar improvement body 2A that bears the vertical load and the portion of the wall-like improvement body 3A that is arranged to suppress liquefaction, which is rational and economical. Structure.

  For example, in a conventional foundation structure in which a vertical load is supported via a solid foundation by an improved body constructed in a grid shape, the vertical load acts as a distributed load on the entire range of the grid-like improved body. For this reason, all the improved bodies are provided with both the liquefaction prevention function and the vertical load support function, and the total extension of the improved bodies becomes longer.

  On the other hand, the total extension of the improved body can be reduced by clearly separating the portion bearing the vertical load (columnar improvement body 2A) and the portion arranged for liquefaction suppression (wall-like improvement body 3A). It becomes possible to make about half of the conventional basic structure. As a result, the construction cost and the construction period can be greatly reduced.

  Other configurations and functions and effects are substantially the same as those of the above-described embodiment or other examples, and thus description thereof is omitted.

  Hereinafter, Example 2 of a form different from the above-described embodiment will be described with reference to FIGS. The description of 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 cut portion that reduces or blocks transmission of shearing force is formed between the columnar improvement body 2B and the wall-like improvement body 3B. The edge cut portion is formed by a pipe material having a smooth peripheral surface that serves as an outer shell of the columnar improvement body 2B.

  For example, as the edge cutting portion, a steel pipe 21 used for a ground excavation casing or a pile can be used. FIG. 4 is an enlarged plan view showing a configuration of a connection portion between the columnar improvement body 2B and the wall-like improvement body 3B of the ground improvement foundation structure 1B.

  As shown in FIG. 4, the short columnar body 31 </ b> B constituting the wall-shaped improvement body 3 </ b> B has a continuous integrated structure wrapped on the short columnar body 31 </ b> B adjacent on both sides. On the other hand, the steel pipe 21 is interposed between the columnar improvement body 2B and the wall-like improvement body 3B.

  Although the wall-like improved 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 that the transmission of shearing force is reduced or blocked. Can be considered.

  Further, on the inner corner side of the columnar improvement body 2B covered with the steel pipe 21, the end portions of the wall improvement bodies 3B and 3B on both sides thereof are formed to be continuous. In short, the wall-shaped improvement bodies 3B and 3B constituting each side are directly connected so that the 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 making the steel pipe 21 function as an edge cutting part, what is necessary is just to make it the same length (depth) as the wall-shaped improvement body 3B.

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

  Moreover, a bending strength can be improved by arrange | positioning the steel pipe 21 with high bending strength to the outer shell of the columnar improvement body 2B. For this reason, what is necessary is just to determine the length which arrange | positions the steel pipe 21 according to the desired performance.

  In the ground improvement foundation structure 1B of the second embodiment configured in this way, a steel pipe 21 is interposed between the columnar improvement body 2B and the wall-like improvement body 3B as an edge cut portion that reduces or blocks transmission of shearing force. ing.

  For this reason, since the weights of the wall-like improvement bodies 3B, 3B on both sides of the columnar improvement body 2B are hardly or not transmitted to the columnar improvement body 2B, the burden load on the columnar improvement body 2B can be suppressed. That is, the columnar improvement 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 superstructure.

  Other configurations and functions and effects are substantially the same as those of the above-described embodiment or other examples, and thus description thereof is omitted.

  Hereinafter, Example 3 of a form different from the above-described embodiment will be described with reference to FIG. The description of 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 in which the diameter of the columnar improvement body 2C and the diameter of the short columnar body 31C constituting the wall improvement body 3C are different will be described. As described above, when a portion that bears a vertical load (columnar improvement body 2C) and a portion that is arranged to suppress liquefaction (wall-like improvement body 3C) are separated, the rigidity required for each is also increased. Because it is different, the diameter can be changed.

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

  The ground improvement foundation structure 1C of the third embodiment configured as described above is configured so that the thickness of the wall-shaped improvement body 3C (the diameter of the short column body 31C) is smaller than the diameter of the columnar improvement body 2C. The weight of the improved body 3C can be reduced.

  Further, when the cross-sectional area of the wall-like improved body 3C is reduced and the rigidity is lowered, the shearing force and bending stress transmitted to the columnar improved body 2C are reduced even when the edge notch is not provided. The burden on the improved body 2C can be reduced. That is, if the rigidity of the wall-like improved body 3C is lowered, the stress that can be transmitted thereby is reduced, so that even if it is transmitted to the columnar improved body 2C, the load is not significantly increased.

  Other configurations and functions and effects are substantially the same as those of the above-described embodiment or other examples, and thus description thereof is omitted.

  Hereinafter, Example 4 of a form different from the above-described embodiment will be described with reference to FIG. The description of 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, a core material 22 such as a small-diameter steel pipe or a shape steel is embedded in the axial position (center position) of the columnar improvement body 2D. On the other hand, the configuration of the wall-like improved body 3D constructed by continuously connecting the short columnar bodies 31D,... Is the same as that of the wall-like improved body 3 described in the above embodiment.

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

  Since the ground improvement foundation structure 1D of the fourth embodiment configured in this way can increase the compressive strength by embedding the core material 22 in the columnar improvement body 2D, it reduces the cross-sectional area and reduces its own weight. be able to. And if self-weight can be reduced, since the required supporting force (required supporting strength) of columnar improvement body 2D can also be made small, the further rational and economical design is also attained.

  Other configurations and functions and effects are substantially the same as those of the above-described embodiment or other examples, and thus description thereof is omitted.

  Hereinafter, a fifth embodiment different from the above-described embodiment and examples will be described with reference to FIGS. Note that the description of the same or equivalent parts as those described in the above embodiment or other examples will be given with the same terms or the same reference numerals.

  In the fifth embodiment, a ground improvement foundation structure 1E provided with wall-like improvement bodies 3E,... So as to surround the outsides of the columnar improvement bodies 2E,. That is, the ground improvement foundation structure 1E is surrounded by a plurality of columnar improvement bodies 2E provided at a plane position where a vertical load is applied by the upper structure (for example, the unit building U), and at least the lower ground of the upper structure. As described above, the wall-shaped improvement bodies 3E,... Provided so as to surround the outside of the columnar improvement bodies 2E,.

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

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

  FIG. 8B is an enlarged plan view showing a corner portion of the unit building U. As shown in this figure, short column bodies 31E,... Are provided outside the outer edge of the unit building U. This short column 31E is provided in the range of the liquefied layer G2 at a relatively shallow position, and is shorter than the columnar improvements 2E,.

  These short column bodies 31E,... Are continuously provided so as to surround the ground below the unit building U as shown in FIG. That is, the unit building U and the four columnar improvement bodies 2E,... Below the unit building U, which are built on a substantially rectangular site in plan view, are four-side wall-like improvement bodies 3E formed in a substantially rectangular shape in plan view. It will be surrounded by ...

  In this way, by arranging the columnar improvement bodies 2E,... That support the vertical load of the unit building U inside the wall-like improvement bodies 3E,. The shear rigidity of the columnar improvement bodies 2E,... Can be rationally reduced.

  Further, the ground inside the wall-like improved body 3E,... Is suppressed from liquefaction, and the peripheral frictional resistance between the wall-like improved body 3E,. High support performance against load can be obtained.

  Moreover, although the case where the wall-shaped 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 entire site where the unit building U is built, such as a garden or a parking lot, can be surrounded by the wall-like improved bodies 3E,. By adopting such a configuration, it is possible to take measures against liquefaction even for peripheral equipment attached to the house.

  Other configurations and functions and effects are substantially the same as those of the above-described embodiment or other examples, and thus description thereof is omitted.

  Hereinafter, a sixth embodiment, which is a modification of the fifth embodiment, will be described with reference to FIG. Note that the description of the same or equivalent parts as those described in the above embodiment or other examples will be given with the same terms or the same reference numerals.

  In this sixth embodiment, the ground improvement foundation structure 1F in which the wall-shaped improvement bodies 3F,... Are provided so as to surround the outside of the columnar improvement bodies 2F,.

  In the fifth embodiment, the ends of the columnar improvement bodies 2E,... Reach the hard support layer G1, but in the present embodiment 6, the tips of the columnar improvement bodies 2F,. The non-liquefied layer G3 which is not as hard (rigid) as the support layer G1 is supported. Here, in the ground shown in FIG. 9, a surface layer G4, a liquefied layer G2, a non-liquefied layer G3, and a support layer G1 are laminated in order from the top.

  And the unit building U is constructed | assembled on the solid foundation U2 used as the foundation provided on the surface layer G4. And the upper end of columnar improvement body 2F and ... is connected with the lower surface of the four corners used as the edge of the solid foundation U2.

  On the other hand, the wall-like improvement bodies 3F,... Are provided from the surface layer G4 to the liquefied layer G2 so as to surround the outside of the columnar improvement bodies 2F,. The short column bodies 31F,... Constituting the wall-shaped improved body 3F do not need to be provided up to the deepest portion of the liquefied layer G2, and may be up to the middle.

  In short, when the foundation directly under the structure such as the unit building U is a solid foundation U2, the effective stress of the ground is increased by using the pressure (ground pressure) from the bottom of the solid foundation U2, and liquefaction occurs. It is possible to increase the suppression power of

  Moreover, even if the settlement has occurred, the load can be dispersed by the solid foundation U2, so that the amount of settlement can be suppressed as much as possible. Further, by preventing the ends of the columnar improvement bodies 2F,... From reaching the support layer G1, the ratio of the load of the unit building U to the ground load increases, and the liquefaction suppression effect can be further enhanced.

  Other configurations and functions and effects are substantially the same as those of the above-described embodiment or other examples, and thus description thereof is omitted.

  The embodiment of the present invention has been described in detail above with reference to the drawings. However, the specific configuration is not limited to this embodiment or example, and the design changes are within the scope of the present invention. Are included in the present invention.

  For example, in the above-described embodiment and examples, the tip ends of the columnar improvement bodies 2 and 2A-2E are made to reach the support layer G1, but the present invention is not limited to this. If it can be ensured, the tip need not reach the support layer G1.

1,1A-1F Ground improvement foundation structure 2,2A-2F Columnar improvement body 21 Steel pipe (edge cutting part)
22 Core material 3, 3A-3F Wall-shaped improvement body 31, 31A-31F Short column body G1 Support layer G2 Liquefaction layer P Concentrated load (vertical load)
U unit building (superstructure)
U11 Column base

Claims (7)

A ground improvement foundation structure constructed by an improved body obtained by mixing and stirring the ground and cementitious solidified material,
A plurality of columnar improvement bodies provided in a plane position where a vertical load is applied by the superstructure;
A wall-like improvement body provided between the columnar improvement bodies so as to surround the lower ground of the upper structure,
A foundation structure for ground improvement, wherein the depth of the columnar improvement body is deeper than the depth of the wall improvement body. As the foundation of the upper structure in which a framework is formed by columns and beams, it is a ground improvement foundation structure constructed by an improved body in which the ground and cement-based solidified material are mixed and stirred,
A plurality of columnar improvements provided at a planar position where the column base of the superstructure is installed;
A wall-like improvement body provided between the columnar improvement bodies so as to surround the lower ground of the upper structure,
A foundation structure for ground improvement, wherein the depth of the columnar improvement body is deeper than the depth of the wall improvement body.   The ground improvement foundation structure according to claim 1 or 2, wherein an edge notch for reducing or blocking transmission of shear force is formed between the columnar improvement body and the wall improvement body. . A ground improvement foundation structure constructed by an improved body obtained by mixing and stirring the ground and cementitious solidified material,
A plurality of columnar improvement bodies provided in a plane position where a vertical load is applied by the superstructure;
A wall-like improvement body provided so as to surround the outside of the columnar improvement body so that at least the lower ground of the upper structure is surrounded,
A foundation structure for ground improvement, wherein the depth of the columnar improvement body is deeper than the depth of the wall improvement body.   The tip of the columnar improvement body reaches the ground support layer, and the wall improvement body is provided in a range of a liquefied layer located shallower than the support layer. The ground improvement foundation structure as described in any one of.   6. The wall-like improvement body is formed by continuing a short columnar improvement body, and the diameter of the short columnar improvement body is smaller than the diameter of the columnar improvement body. Ground improvement foundation structure as described in any one of Claims.   The ground improvement foundation structure according to any one of claims 1 to 6, wherein a core material is embedded in the columnar improvement body.