JP2009275358A - Improvement structure of building bearing ground, and construction method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To hold a building without the occurrence of differential settlement even on relatively soft ground, and to enhance resisting toughness against a lateral force of an earthquake etc. <P>SOLUTION: In this improvement structure of building bearing ground, a surface course improvement section 5 composed of a soil improvement material is formed on the surface course of the building bearing ground. The surface course improvement section 5 is equipped with a horizontal section 5a with a required thickness, which is formed on a surface layer section GL of ground E, and an underground wall section 5b which is integrally provided in a suspended state in the lower section of the horizontal section 5a. The underground wall section 5b is integrated in such a manner as to continue into the bottom of the horizontal section 5a. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an improved structure of a building support ground in which the ground supporting the foundation portion is improved in advance according to the ground properties on which the building is constructed, and a construction method thereof.

  When a building such as a house is constructed on a relatively soft ground, if the building is constructed directly on the ground, the ground immediately below the building may be consolidated due to the loading load of the building, which may cause uneven settlement. Therefore, conventionally, as shown in FIG. 8 (a), an area ground E corresponding to the projected area of the building is excavated to a predetermined depth, and a ground improvement material is placed in the ground to improve the surface layer improvement part a. A construction method for constructing and constructing the foundation b and the building body c on the top is known.

  In addition, as another construction method, after laying multiple piles that reach the stable depth of the ground directly under the building and building the foundation on the ground surface on this pile. The building itself may be constructed.

  In the case of the former surface improvement part a, even if it is a homogeneous and robust structure, if the ground E is soft, the building c is simply floated on the ground E via the surface improvement part a. As shown in FIG. 8 (b), there is a possibility that the uneven settlement phenomenon may occur in the surface improvement part a due to the uneven load of the building c itself and the unevenness of the soil E. It is also vulnerable to shaking such as earthquakes.

  The latter method is suitable for large buildings such as buildings, but is not common for detached houses and supports the foundation slab at multiple points. If a subsidence phenomenon occurs, the pile may bear the full load of the foundation and the building body, and there is a risk of subsidence due to subsidence between the piles due to secular change.

  Therefore, the present invention solves the above-mentioned problems, and its purpose is to maintain a building without causing uneven settlement even on relatively soft ground, and toughness against horizontal forces such as earthquakes. It is intended to provide an improved structure for building support ground and its construction method.

    In order to achieve the object, the present invention provides a structure for improving a building support ground in which a surface improvement part 5 (10, 20) made of a ground improvement material is formed on a surface layer of the building support ground, the surface improvement part 5 (10, 20) is a horizontal portion 5a (10a, 20a) having a required thickness formed in the surface layer portion GL of the ground E, and an underground wall portion integrally provided in a suspended state at the lower portion of the horizontal portion 5a (10a, 20a). 5b (10b, 20b), and the underground wall 5b (10b, 20b) is continuously integrated with the bottom of the horizontal part 5a (10a, 20a).

  The ground improvement material is formed of a backfill material obtained by adding a solidification material to excavation residual soil obtained by excavating the surface layer improvement portion.

  The ground improvement material may be formed of a concrete material made of a concrete block, a wrinkle concrete, a reinforced concrete, or the like.

  The surface layer improvement portion is formed in a box shape in which the underground wall portion is integrally provided in a suspended state at a lower portion of a peripheral edge portion of the horizontal portion.

  Further, the surface layer improving portion is integrally provided with the underground wall portion in a suspended state at a lower portion of the peripheral edge portion of the horizontal portion, and is continuous with the underground wall portion of the peripheral edge portion of the horizontal portion. It is characterized by having an underground beam part that is integrated into the lower surface in the shape of an approximate rice field.

  It is desirable to locate the crossing position in the underground beam portion at the planned center-of-gravity position of the building to be constructed on the surface improvement part and the foundation thereof.

Further, the present invention provides a method for constructing an improved structure for building support ground, wherein the ground of the building projection surface to be constructed is excavated to a predetermined depth, and the ground improvement material is buried back to the ground surface in the excavated interior. By doing so, the surface layer improvement part provided with the horizontal part of required thickness and the underground wall part integrally provided in the hanging state in the lower part of a horizontal part is characterized.
The excavation depth and excavation shape are such that a groove portion having a depth and shape corresponding to the underground wall portion is excavated and formed at the bottom of the concave portion having a required depth corresponding to the horizontal portion.

  Therefore, according to the improvement structure of the building support ground according to the present invention, the underground wall portion protruding from the bottom portion of the surface improvement portion becomes a resistance force to the force to incline the horizontal portion of the surface improvement portion. Settling can be prevented. It also works against resistance against horizontal forces such as earthquakes, improving seismic resistance.

By forming the underground beam portion in a substantially tabular shape in addition to the underground wall portion, the resistance force is further increased, and it is further effective in preventing the uneven settlement, and the earthquake resistance is further improved.
Moreover, it becomes a preferable structure when the loading load of a building is supported by the underground beam part and is distributed over the entire horizontal part.

  Moreover, according to the construction method which concerns on this invention, said improved structure can be efficiently constructed irrespective of the state and scale of a construction site.

FIGS. 1A to 1E show the construction procedure of the improved structure according to the first embodiment of the present invention.
First, prior to work, the ground composition is confirmed by, for example, Swedish sounding, etc., so that the material composition of the surface improvement material, the casting thickness, etc. are set according to the ground characteristics and the planned building. The building to be constructed is assumed to be a square as an example, and hereinafter, the building projected area is assumed to be a square.

  Based on the above design plan, first, as shown in (a), after the land allocation for the projected area of the planned building, as shown in (b), a small backhoe is placed in the ground E inside the building construction site. 1 is introduced and excavated. The excavation depth D depends on the ground properties and the projected area of the building, but in the case of normal alluvial soil, it is about 0.5 to 1.0 m from the ground surface GL. The excavated residual soil 2 is accumulated in the vicinity of the excavation site.

  After excavating to the planned depth and leveling, the backhoe 1 is removed from the site, and then, as shown in FIG. Excavate deep roots and excavate the bases that cross the center of the site in a cross shape (see Fig. 3). The excavation depth of the root insertion portion may be a depth from the surface portion GL to about 2 m in addition to the excavation depth D.

  After completion of the dredging operation, the excavated residual soil 2 is used as local soil, and lime / cement slurry is added to this soil and mixed with, for example, the mixer 3 to sequentially manufacture the soil cement as an improved material. The mixing ratio is set according to the ground properties, but the appropriate mixing ratio is about 3 to 10% (weight) of the cement added to the remaining soil 2.

  Next, as shown in (d), the soil cement kneaded by the mixer 3 is placed in the root portion through the tremy tube 3a and the like, and a rolling machine such as a rammer 4 (tamper in a flat portion) is used. By sequentially repeating the rolling and leveling operations until reaching the ground surface portion GL, the surface layer improving portion 5 having a predetermined thickness is finally completed in the building site. The surface layer improvement portion 5 has a surface that is flush with the ground surface portion GL, and as shown in FIG. 3 as well, a horizontal portion 5a having a thickness corresponding to the planned excavation depth D, and a lower part of the circumference of the horizontal portion 5a. The underground wall portion 5b that is integrally suspended and the underground beam portion 5c that is integrally suspended by crossing in a cross shape at the lower portion of the horizontal portion 5a are provided.

  After that, as shown in FIG. 2, all the construction is completed by constructing the foundation 6 on the surface improvement part 5 according to the initial plan and constructing the building body 7 on the upper part. As shown in FIG. 3, the center of gravity (G) of the building main body 7 and the foundation 6 is approximately on the crossing position of the underground beam 5c, and the load is supported by the underground beam portion 5c and the load is applied to the horizontal portion 5a. This is suitable for dispersion throughout.

  In the present embodiment, even when a force that tilts the horizontal portion 5a is applied due to the settlement of the ground E, the levelness is maintained by the embedded portion including the underground wall portion 5b and the underground beam portion 5c. Further, even when a horizontal force such as an earthquake is applied, the level of the horizontal portion 5a is maintained by the toughness of the root portion, so that the earthquake resistance of the building body 7 is also improved.

  4 and 5 show a second embodiment. In the present embodiment, the projected area of the building is not a square but a deformed rectangular shape in which a part of the rectangle is cut out, the surface improvement part 10 is formed with a required thickness in the ground E, and the top end thereof is the ground part GL. It consists of a matching horizontal portion 10a and an underground wall portion 10b that is integrally suspended from the lower periphery of the horizontal portion 10a. The foundation and the building body are constructed on the upper portion of the surface improvement portion 10 in the same manner as in FIG. It has come to be.

  In this structure, as shown in FIG. 5 (a), even if the horizontal component of ground subsidence is applied to the surface improvement part 10 as indicated by the arrow, it is added to the underground wall part 10b integrated in the lower part, Due to the toughness of the underground wall, the level of the horizontal portion 10a is maintained. Similarly, even when a horizontal force such as an earthquake is applied, the level of the horizontal portion 10a is maintained by the toughness of the underground wall portion 10b.

  In addition, as shown in FIG.5 (b), you may form the taper-shaped reinforcement connection part 10c in the junction part of the horizontal part 10a and the underground wall part 10b. As shown in the first embodiment, the connecting portion 10c can be easily implemented because it is only necessary to cut out the edge of the groove in a taper shape at the time of digging. Can also be increased.

  6 and 7 show a third embodiment. This embodiment is a deformed rectangular shape as in the second embodiment, and the surface layer improvement portion 20 is formed in the ground E with a required thickness, and a horizontal portion 20a whose top end coincides with the ground surface portion GL, and a horizontal portion. It is integrated with the underground wall portion 20b vertically suspended from the lower periphery of the portion 20a and the lower surface of the horizontal portion 20a, and both ends thereof are integrated with the underground wall portion 20b and are cross-shaped with each other. The underground beam part 20c integrated by crossing is provided. By placing the crossing position of the underground beam portion 20c immediately below the center of gravity G of the building main body, the load on the building can be dispersed and supported on average.

  In the present embodiment, as shown in FIG. 7 (a), even if the horizontal component of ground subsidence is applied to the surface improvement part 20 as indicated by the arrow, the underground wall part 20b integrated in the lower part thereof and In addition to the underground beam part 20c, the level of the horizontal part 20a is maintained by the toughness of the underground wall part 20b and the underground beam part 20c. Similarly, even when a horizontal force such as an earthquake is applied, the level of the horizontal portion 20a is maintained by the toughness of the underground wall portion 20b and the underground beam portion 20c, which is stronger than the second embodiment. It becomes a structure.

  In this embodiment as well, as shown in FIG. 7B, a tapered reinforcing connecting portion 20d is formed at the joint between the horizontal portion 20a, the underground wall portion 20b, and the underground wall portion 20c. In this case, the integrated strength is further increased. Needless to say, a reinforcing connecting portion may also be provided in the first embodiment.

(A)-(e) is sectional explanatory drawing which shows the construction procedure of the surface layer improvement part by 1st Embodiment of this invention. It is sectional explanatory drawing which shows the building constructed | assembled on the improved ground. It is a top view of the completed surface layer improvement part. It is a top view of the surface layer improvement part by 2nd Embodiment of this invention. (A), (b) is sectional drawing in the BB line of FIG. It is a top view of the surface layer improvement part by 3rd Embodiment of this invention. (A), (b) is sectional drawing in CC line of FIG. (A), (b) is sectional explanatory drawing which shows the malfunction by the conventional surface layer improvement part.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Backhoe 2 Excavation residual soil 3 Mixer 3a Tremy tube 4 Ramma 5, 10, 20 Surface improvement part 5a, 10a, 20a Horizontal part 5b, 10b, 20b Underground wall part 5c, 20c Underground beam part 10c, 20d Reinforcing connection part 6 Foundation 7 Building E Ground GL Ground part

Claims (7)

In the improved structure of the building support ground in which the surface improvement part made of ground improvement material is formed on the surface layer of the building support ground,
The surface improvement portion includes a horizontal portion having a required thickness formed on the surface portion of the ground, and an underground wall portion integrally provided in a suspended state at a lower portion of the horizontal portion, and the underground wall portion is a horizontal portion. Improved structure of building support ground, characterized by being integrated continuously at the bottom.   The structure for improving a building support ground according to claim 1, wherein the ground improvement material is formed of a backfill material in which a solidification material is added to excavation residual soil obtained by excavating the surface layer improvement portion. .   The building support ground improvement structure according to claim 1, wherein the ground improvement material is formed of a concrete material made of concrete block, lap concrete, reinforced concrete, or the like.   The building support according to any one of claims 1 to 3, wherein the surface layer improving portion is integrally provided with the underground wall portion in a suspended state at a lower portion of a peripheral portion of the horizontal portion. Improved structure of the ground.   The surface layer improving portion is integrally provided with the underground wall portion in a suspended state at a lower portion of the peripheral portion of the horizontal portion, and is continuously provided on the lower surface of the horizontal portion. The improved structure for a building support ground according to any one of claims 1 to 3, further comprising an underground beam portion integrated in an approximately rice field shape.   6. The building support ground improvement structure according to claim 5, wherein a crossing position in the underground beam portion is located at a planned center of gravity position of a building to be constructed on the surface improvement portion and its foundation. In the construction method of the improved structure of the building support ground that forms the surface improvement portion made of the ground improvement material on the surface layer of the building support ground,
The ground of the building projection surface to be constructed is excavated to a predetermined depth, and the ground improvement material is backfilled and solidified inside the excavated interior, so that it is suspended in the horizontal part of the required thickness and the lower part of the horizontal part The construction method of the improved structure of the building support ground characterized by forming a surface layer improvement part provided with the underground wall part integrally provided in the.

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