JP3752238B2 - Structure construction method and structure - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a structure construction method and a structure.
[0002]
[Prior art]
Conventionally, in a structure having a direct foundation structure, a foundation that is a settlement prevention plate is directly formed on the ground. In addition, when the surface layer of the ground is soft and the support layer is below the soft layer, a method has been proposed in which an improved body is formed on the surface layer of the ground and a column is erected on the improved body (for example, a patent Reference 1).
[0003]
[Patent Document 1]
Japanese Patent Laid-Open No. 2001-81862
[Problems to be solved by the invention]
However, if a simple direct foundation type structure (bridge foundation, abutment, retaining wall, etc.) is installed on the ground, the horizontal strength may be insufficient during a large-scale earthquake.
[0005]
The present invention has been made in view of such problems, and the purpose of the present invention is to directly utilize the strength of the ground even when the surface layer of the ground is soft, and is excellent in economic efficiency and workability. An object of the present invention is to provide a method for constructing a structure of a foundation structure and a structure.
[0006]
[Means for Solving the Problems]
1st invention for achieving the objective mentioned above is the process (a) which installs the improvement body which is stronger than the said ground and deform | transforms integrally with the said ground on the surface layer of the ground, and a process (a) And a step (b) of installing a foundation on the upper surface of the improved body and a projecting portion provided on the lower surface penetrating into the improved body. .
[0007]
The ground is, for example, sandy ground or viscous ground. The improved body is formed by kneading a solid material such as a polymer, water glass, cement, or lime into earth and sand. A plurality of convex portions are provided on the lower surface of the foundation, that is, the surface in contact with the improved body, as necessary. On the foundation, for example, a leg portion of a temporary gantry straddling between the tracks is installed.
[0008]
In the first invention, an improved body having a strength greater than that of the ground and having a deformation coefficient equivalent to that of the ground is installed on the surface layer of the ground, and the maximum shear force of the boundary surface between the improved body and the ground is made larger than the shear strength of the ground. Then, the ground and the improved body are integrally deformed until the ground shears and breaks. Moreover, the adhesion between the foundation and the improved body is increased by increasing the shear strength of the improved body. In addition, adhesion is further increased by providing a convex portion on the lower surface of the foundation and penetrating the improved body.
[0009]
The second invention is a structure constructed by the construction method of the structure of the first invention. The structure of 2nd invention comprises the improvement body which was provided in the surface layer of the ground, the intensity | strength is larger than a ground, and deform | transforms integrally with the ground, and the foundation installed in the upper surface of the improvement body.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 shows a cross-sectional view of the structure A. As shown in FIG. 1, the structure A includes an improved body 5, a settlement prevention plate 7, a temporary gantry leg 15, a temporary gantry 19, a jetty 21, and the like. The improved body 5 is formed on the surface layer portion of the ground 1. The settlement prevention plate 7 is installed on the upper surface of the improved body 5. The temporary gantry base 15 is installed on the basis of the settlement prevention plate 7. The temporary gantry 19 is supported by the temporary gantry legs 15 and the jetty 21.
[0011]
Next, a construction method of the structure A will be described. As shown in FIG. 1, in the structure A, temporary gantry legs 15 are installed on the ground 1 between the tracks 23. FIG. 2 is a cross-sectional view of the ground 1 on which the improved body 5 is installed. FIG. 2 is a view showing the vicinity of the planned installation position of the temporary gantry leg 15 (portion shown by B in FIG. 1).
[0012]
The ground 1 is a loam ground. At this time, in order to install the improved body 5, first, the ground 1 in the range to be replaced with the improved body 5 is excavated to remove the earth and sand. The excavation is performed by manual excavation when the excavation amount is small, and by using a small backhoe or other general-purpose machines when the excavation amount is large.
[0013]
After excavating the ground 1, the excavation surface 3 is disturbed to apply a small amount of solidified material, and a mixture of the solidified material and aggregate is poured into the improved body 5. The thickness of the improved body 5 is determined using the crushed stone thickness when the foundation is directly installed as a reference value, for example, about 100 mm.
[0014]
The mixture of solidified material and aggregate is made of aggregate (sand, sand, asphalt glass, concrete glass, etc.) so that the deformation coefficient of the improved body 5 after hardening is about the same as that of the ground 1 and the strength is larger than that of the ground 1. It is created by mixing solidified material with the recycled aggregates used. By kneading the aggregate and the solidified material with a mixer, a mixture with relatively high uniformity can be obtained.
[0015]
FIG. 3 is a table showing applicability of various solidification materials determined from experiments. In the experiment, sand was procured from outside the field as an aggregate, or a mixture of sand and loam, and a cement, lime, water glass, or polymer was used as a solidifying material, and an improved body was formed. The applicability to soft and soft loam ground was judged. Regarding the deformation coefficient and strength, the conditions of the improved body 5 (the deformation coefficient is close to the ground 1 and the strength is larger than the ground 1) were used as criteria.
[0016]
As shown in FIG. 3, the closest to the loam ground having a relatively soft deformation coefficient is an improved body using a polymer-based solidified material. Further, the strength is sufficiently high in an improved body using a water glass-based or polymer-based solidifying material. In addition, from a comprehensive evaluation including workability and economic efficiency, it is desirable to use a polymer-based solidified material used in the injection system construction method when forming an improved body on a relatively soft loam ground.
[0017]
FIG. 4 is a diagram showing a stress-strain relationship between a polymer improved body (an improved body obtained by kneading Toyoura sand and a polymer-based solidified material) and ROHM (collected in Kanagawa Prefecture), and FIG. 5 shows a polymer improved body and a ROHM. It is a figure which shows the result of a one surface shear test (constant pressure). By mixing sand and polymer-based solidified material in an appropriate amount, the rigidity is almost equal to ROHM as shown in FIG. 4, and the shear strength τ (= c + σ _V tanφ) is significantly higher than ROHM as shown in FIG. A polymer modification can be obtained.
[0018]
FIG. 6 is a cross-sectional view in a state in which the settlement prevention plate 7 is installed, and FIG. 7 is a perspective view of the settlement prevention plate 7. After the improved body 5 is formed on the ground 1, as shown in FIG. 6, a settlement prevention plate 7 that is the foundation of the structure is installed on the improved body 5.
[0019]
As shown in FIGS. 6 and 7, the settlement prevention plate 7 includes, for example, a plate-shaped main body 13 and a plurality of square bars 14 that form convex portions. The main body 13 is a steel plate or the like, and the square bar 14 is a square steel. A corrugated treatment 9 is performed on the lower surface of the settlement prevention plate 7 by welding square bars 14 to the main body 13 at predetermined intervals. When the square bar 14 is used for the corrugation 9, welding to the main body 13 is easy as compared with round steel. In addition, since the load transmitted from the settlement prevention plate 7 is shared by the surface, the structure is less likely to break than when round steel is used.
[0020]
The subsidence prevention plate 7 is installed such that the surface subjected to the corrugation 9 is in contact with the improved body 5. By increasing the shear strength of the improved body 5, adhesion between the improved body 5 and the subsidence prevention plate 7 is ensured even when the corrugated treatment 9 is not performed, and the adhesion between the subsidence prevention plate 7 and the improved body 5 comes off. The phenomenon that the horizontal supporting force is lost can be avoided, but by attaching the square bar 14 to the inside of the improved body 5, the adhesion between the settlement prevention plate 7 and the improved body 5 can be further increased.
[0021]
FIG. 8 is a cross-sectional view in a state in which the temporary gantry base 15 is installed on the settlement prevention plate 7. After the settlement preventing plate 7 is installed on the improved plate 5, the temporary gantry base 15 is installed on the settlement preventing plate 7 as shown in FIGS. 1 and 5. Then, one side of the gantry 25 of the temporary gantry 19 is supported by the temporary gantry leg 15. As shown in FIG. 1, a work pier 21 is installed along the track 23 on the side of the track 23. The gantry 25 is disposed across the track 23, and the side not supported by the temporary gantry leg 15 is attached to the pier 21.
[0022]
Next, a model experiment for confirming the horizontal supporting force of the settlement prevention plate installed on the loam ground will be described. FIG. 9 shows a cross-sectional view of the countermeasure-type foundation 27 that is an experimental model. As shown in FIG. 9, the countermeasure-type foundation 27 is obtained by forming an improved body 5a on the surface layer of the loam ground 1a and installing a subsidence prevention plate 7a on which the corrugated treatment 9a is applied. There are two types of experimental models: a countermeasure-type foundation 27 shown in FIG. 9 and a non-measurement foundation in which a subsidence prevention plate of only the main body 13a not subjected to the corrugated treatment 9a is installed on the loam ground 1a not forming the improved body 5. Produced.
[0023]
The loam ground 1a is obtained by installing the loam (consolidation degree 90%) shown in FIG. 4 in a model soil tank (W × L × H = 400 × 2800 × 400 mm). The improved body 5a was formed using the polymer improved body (W × L × H = 400 × 2800 × 100 mm) shown in FIG. The subsidence prevention plate 7a is formed by welding a square steel (28 × 28 mm) at a pitch of 100 m to the lower surface of a main body 13a (W × L = 400 × 400 mm) of an iron plate and applying a waveform processing 9a.
[0024]
A loading board 31 for applying a vertical load is placed on the main body 13a of the settlement prevention plate 7a, and two wires 29 for applying a horizontal load are attached to the side portion 33 of the main body 13a. In the experiment, as shown in FIG. 9, the arrow 29 is applied via the wire 29 while applying the expected upper pressure (σ _V = about 42.7 kPa) in the direction indicated by the arrow A through the loading board 31 in the direction indicated by the arrow A. A horizontal load was applied step by step from the direction shown in B, and the horizontal displacement of the settlement prevention plate 7a was measured.
[0025]
FIG. 10 is a diagram showing the relationship between horizontal load and horizontal displacement. The horizontal axis in FIG. 10 indicates normalized horizontal displacement, and the vertical axis indicates stress when the horizontal load is increased stepwise. The solid line 35 is the measurement result of the countermeasure-type foundation, and the broken line 37 is the measurement result of the non-measurement foundation. As shown in FIG. 10, the horizontal resistance tends to converge to a constant value after increasing to the limit horizontal resistance on the non-measure basis. On the other hand, in the countermeasure-type foundation 27, it further increases after rising to the limit horizontal resistance, and gradually decreases after reaching the maximum horizontal resistance.
[0026]
FIG. 11 is a diagram showing the basic form and the rate of increase in horizontal resistance. As shown in FIG. 11, in the countermeasure-type foundation 27, the limit horizontal resistance and the maximum horizontal resistance both increased to 1.9 times that of the countermeasure-free foundation. In the non-measure foundation, it was confirmed that the subsidence prevention plate slides on the loam ground. However, in the countermeasure type foundation, the shear is not the boundary between the improved body 5a and the loam ground 1a, but the loam ground 1a. Occurred inside.
[0027]
In the present embodiment, in the structure shown in FIG. 6, the strength of the improved body 5 is made greater than the strength of the ground 1 to increase the adhesion between the improved body 5 and the settlement prevention plate 7, and the shear strength τ _{i of the} improved body 5. > Maximum shear stress τ _{BI at} the boundary surface between the subsidence prevention plate 7 which is the foundation and the improved body 5> Shear strength τ _{E of the} ground. Further, the deformation coefficient E _i and deformation coefficient E _E of the ground 1 of the improved body 5 is substantially the same level, the maximum shear stress tau _IE> shear strength of ground tau _E boundary surfaces of the improved body 5 and the ground 1. As a result, the maximum shear stress τ _f of the foundation becomes τ _E , and in the event of a large-scale earthquake, the improved body 5 on which the subsidence prevention plate 7 is mounted and the ground 1 behave as one body. As shown in FIG. 17 and 17a pass through the ground 1.
[0028]
In the conventional direct foundation, when the ground shear strength τ _E is larger than the maximum shear stress τ _{BE at} the interface between the foundation and the ground, the maximum shear stress τ _f of the foundation becomes τ _BE and the horizontal resistance problem between the foundation and the ground arises. However, in this embodiment, as shown in the experimental results of FIGS. 10 and 11, the horizontal proof stress of the foundation such as the settlement prevention plate can be improved.
[0029]
However, in FIG. 6, for example, the extreme deformation coefficient of deformation coefficient E _i >> subsidence prevention plate 7 of the improved body 5 to construct a modified body 5 has a high rigidity E _E using mortar, shear strength of the soil τ _E > When the maximum shear stress τ _{IE at} the boundary surface between the improved body 5 and the ground 1 is reached, the maximum shear stress τ _f of the foundation is τ _IE , and the conventional ground-foundation friction problem is between the ground 1 and the improved body 5. It simply replaces the problem of friction and does not solve the essence of the horizontal resistance problem. Therefore, carefully determine the formulation and specifications of the improved product.
[0030]
In this embodiment, the ground 1 which is a loam ground is excavated and the mixture 5 in which the solidified material and the aggregate are mixed is poured into the improved body 5, but the field agitation in which the solidified material is mixed in the ground 1. Thus, the improved body 5 may be formed. In this case, it is necessary to solve problems such as the approach of heavy construction equipment into narrow spaces, construction speed, and uniformity of stirring and mixing. Alternatively, a mixture of a solidified material and an aggregate may be squeezed out and rolled to create an improved body.
[0031]
The ground 1 is not limited to the loam ground but may be sandy ground or soft rock. In FIG. 3, the evaluation of the polymer system was high as the solidifying material used when creating the improved body 5. However, depending on the ground conditions, the chemical solution is used to form the improved body having the same conditions as in the present embodiment. Other solidification materials such as water glass used in the pouring method, cement used in the shallow or deep mixed processing method, or lime used in soft ground countermeasures may be effective. For example, when the ground is soft rock, it is conceivable to use an epoxy-based solidifying material.
[0032]
The square bar 14 that forms a convex portion on the lower surface of the settlement prevention plate 7 shown in FIG. 7 and the like is for increasing adhesion between the foundation secured by using the improved body 5 having a high shear strength and the improved body. It is a thing, it is not essential. Moreover, you may provide a convex part in the lower surface of foundations, such as the subsidence prevention board 7, using members other than the square bar 14. FIG.
[0033]
FIG. 12 is a perspective view of another foundation 39. As shown in the foundation 39 in FIG. 12, the convex portion may be formed by welding a single pile 43, a piece-shaped member 45, etc. to the main body 41. In addition, it is desirable that the length 45 of the convex portion is usually 2 to 3 cm and about 5 cm at the maximum.
[0034]
In the present embodiment, the subsidence prevention plate 7 that is the basis of the temporary gantry base 15 in the rail pile driving method has been described as an example, but the structure constructed on the improved body 5 is not limited thereto. For example, the present invention can also be applied to other structures that need to be studied for sliding, such as bridge foundations, abutments, and retaining walls.
[0035]
【The invention's effect】
As described above in detail, according to the present invention, even when the surface layer of the ground is soft, the ground strength can be utilized to the maximum, and the construction method of the structure of the direct foundation structure that is excellent in economic efficiency and workability. And can provide structure.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a structure A. FIG. 2 is a cross-sectional view of a ground 1 on which an improved body 5 is installed. FIG. 3 is a table showing applicability of various solidification materials determined from experiments. Fig. 5 is a diagram showing the relationship between stress and strain of ROHM. Fig. 5 is a diagram showing the results of a one-surface shear test (constant pressure) of the improved polymer and ROHM. FIG. 8 is a cross-sectional view of the subsidence prevention plate 7 with the temporary base 15 installed thereon. FIG. 9 is a cross-sectional view of the experimental base 27 as an experimental model. FIG. 10 is a horizontal load. FIG. 11 is a diagram showing the relationship between the horizontal displacement and FIG. 11 is a diagram showing the basic form and the rate of increase in horizontal resistance. FIG. 12 is a perspective view of another foundation 39.
DESCRIPTION OF SYMBOLS 1 ......... Ground 5, 5a ......... Improvement bodies 7, 7a ......... Settling prevention plates 9, 9a ...... Wave processing 13, 13a ......... Main body 14 ......... Square bar 17 ......... Shear surface 23 ……… Track

Claims (4)

A step (a) of installing an improved body on the surface layer of the ground that is stronger than the ground and deforms integrally with the ground; and
After the step (a), on the upper surface of the improved body, a step (b) of installing a foundation penetrating the improved body with a base provided on the lower surface;
A structure construction method characterized by comprising: The method for constructing a structure according to claim 1, wherein the improved body is formed using a water glass-based solidifying material .   The method of constructing a structure according to claim 1, further comprising a step (c) of installing a leg portion of a temporary gantry straddling between the tracks on the foundation.   The structure constructed | assembled by the construction method of the structure described in any one of Claims 1-3.

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