JP3687805B2 - Foundation reinforcement structure of structures - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a foundation reinforcing structure for a plurality of existing structure groups or new structure groups constructed in a predetermined direction at predetermined intervals.
[0002]
[Prior art]
The ground near a river or the sea may include a non-liquefied layer, a liquefied layer located thereon, and a surface layer located on the liquefied layer. In such a ground, the non-liquefied layer is inclined obliquely downward toward the river or the sea in many cases, so when a liquefaction phenomenon occurs, the liquefied sediment will flow into the river according to the inclination of the non-liquefied layer. Or may flow toward the sea. The liquefied soil also flows when the revetment or quay breaks during an earthquake and changes its shape, or when the surface ground of the liquefied layer is inclined.
[0003]
On the other hand, some bridge piers such as viaducts, warehouse groups or apartment houses have a plurality of foundations constructed at predetermined intervals in a substantially constant direction. For example, as shown in the schematic plan view of FIG. 6, some of the foundations 30, 31, and 32 of the elevated road are constructed in one direction toward the sea or the river 37 at a predetermined interval. When liquefaction occurs in the ground where the foundations 30, 31, and 32 are constructed in this way, the lateral fluidization phenomenon, that is, the phenomenon in which the sediment of the liquefied layer flows in parallel with the foundation arranged in a substantially constant direction. May happen.
[0004]
Conventionally, as a general countermeasure against ground liquefaction, there is a construction method that builds a continuous underground wall that surrounds the entire circumference of each foundation of the structure, or an existing pile as shown in Figs. 5 (a) and 5 (b). An additional pile construction method has been proposed in which an additional pile 53 is hit around 54, and a footing 52 is increased to be integrated with the additional pile 53.
[0005]
[Problems to be solved by the invention]
However, as shown in FIG. 6, when the ground is liquefied around the foundation 32 and lateral flow occurs, a damage example in which a crack 35 is generated in a substantially oblique direction from the corner of the foundation 32 on the surface layer of the ground. As can be seen, an excessive load on the surface layer 36 over a wide range in the front and diagonal directions of the foundation 32 is transmitted to the foundation 32.
Transmission of an excessive load on the surface layer as described above cannot be prevented by a conventional method of reinforcing a simple foundation, and may cause the foundation 32 and its superstructure to collapse. Even if the above-mentioned conventional construction method can prevent collapse, the number of additional piles 53 and the additional hitting amount of footing 52 become enormous, requiring a great deal of cost and being uneconomical.
[0006]
The present invention has been made to solve the above-mentioned problems, and its purpose is that even if a lateral fluidization phenomenon occurs in the ground, the flow load from the liquefied layer and the load on the surface layer over a wide range in the oblique direction. It is intended to provide a foundation reinforcing structure for a group of structures that prevents the foundation and its superstructure from collapsing.
[0007]
Another object of the present invention is to provide a foundation reinforcing structure for a group of structures that can relatively strongly restrain the ground between the foundations and thereby suppress liquefaction between the foundations.
[0008]
Another object of the present invention is to provide a foundation reinforcing structure for a group of structures that can improve the horizontal strength of each foundation.
[0009]
Furthermore, another object of the present invention is to provide a foundation reinforcing structure for a group of structures that can efficiently harden the sand between the foundations when the earth and sand hardening agent is injected to improve the ground between the foundations. is there.
[0010]
[Means for Solving the Problems]
The present invention has been made in view of the above-mentioned object, and the gist thereof is a plurality of structures such as a plurality of bridge piers, warehouse groups, or apartment houses that are constructed so as to be arranged in a predetermined direction at predetermined intervals. in the basic, viewed sandwiched from two directions opposite to each foundation and adjacent said building the ground the circumference unnecessarily continuous underground wall between the foundation fixed to the each foundation by fixing means該地the wall In addition , the present invention provides a foundation reinforcing structure for a group of structures, characterized in that a connection reinforcing member for connecting the foundations is provided .
[0011]
In the foundation reinforcing structure of the structure group of the present invention, examples of the plurality of structures constructed at predetermined intervals in a predetermined direction include a bridge pier such as a viaduct, a warehouse group, or an apartment house group. Are constructed approximately at regular intervals or at predetermined different intervals, and are arranged in a straight line in a certain direction, or are arranged in a certain direction while drawing a gentle curve.
[0012]
In the present invention, when the ground around the foundation is liquefied and lateral flow occurs, the underground wall in the present invention is the laterally flowing earth and sand and the surface layer thereon, and the earth and sand between each foundation and the surface thereon. Any wall body that can insulate the layer, for example, a continuous underground wall made of sheet pile, a column wall made of steel reinforced underground columns made of soil mortar, or a continuous underground wall made of cast-in-place reinforced concrete Etc., and preferably the underground wall is constructed by a sheet pile. The underground wall by the sheet pile has an advantage that it can be economically constructed by a compact construction machine that does not take a work space compared to other underground walls.
Here, the material of the sheet pile can be selected as appropriate, and can be appropriately selected from, for example, a wood sheet pile, a reinforced concrete sheet pile, a prestressed concrete sheet pile, a pressurized concrete sheet pile, a steel sheet pile, and preferably continuous with a steel sheet pile. To build underground walls. In addition, when a steel sheet pile is used as the sheet pile, there is an advantage that a tensile force can be transmitted by the joint and excess pore water pressure generated by liquefaction can be cut off.
[0013]
In the present invention, as a fixing means for fixing the underground wall to each foundation, for example, an anchor bolt or a reinforcing bar can be used.
[0014]
In the present invention, a connecting reinforcing member that connects these foundations may be provided between the foundations. The connecting reinforcing members connect adjacent foundations and apply horizontal forces acting on the foundations to the adjacent foundations. It only needs to be able to communicate to. As such a connection reinforcing member, for example, a wire rope, a strand, a steel frame, a reinforcing bar, a reinforced concrete, or a tie rod can be used.
[0015]
Further, in the present invention, earth and sand hardening agent may be injected into the ground between the predetermined foundations surrounded by the underground wall, and this earth and sand hardening agent forms a water stop film on the earth and sand to improve the strength of soil quality. However, any material can be used as long as the ground is not easily liquefied during an earthquake. As such a soil hardening agent, for example, a cement-based solidifying agent such as cement grout, a water glass-based solidifying agent, or a resin-based solidifying agent such as urea or acrylamide can be used.
[0016]
Further, in the present invention, one or more groundwater draining means may be provided on the underground wall, and the groundwater draining means is at least water in the aquifer when the water pressure of the aquifer increases due to vibration in the ground. Any means can be used as long as it can be eliminated. As such a groundwater draining means, for example, a columnar body, a perforated pipe, a synthetic resin pipe, or a screen pipe formed in the ground by sand or gravel can be used.
[0017]
【Example】
Embodiments of the present invention will be described below with reference to the accompanying drawings.
1 is a cross-sectional view showing a foundation reinforcing structure of the present invention applied to a pier foundation, FIG. 2 is a vertical cross-sectional view taken along the alternate long and short dash line II-II in FIG. 1, and FIG. 3 is an alternate long and short dash line III in FIG. FIG. 4 is a plan sectional view taken along line -III, and FIG. 4 is a plan sectional view showing an embodiment different from those shown in FIGS.
As shown in FIGS. 1 to 3, the pier 21 to which the foundation reinforcing structure of the present invention is applied is supported by a foundation comprising a plurality of piles 23 and footings 22 integrally formed thereon, and is elevated at the top. The road 20 is supported. Such elevated road footings 22 are constructed at predetermined intervals in a predetermined direction. For example, elevated roads crossing rivers are often arranged so as to be orthogonal to the rivers. Some elevated roads that extend to the coast are arranged almost perpendicular to the sea.
[0018]
By providing the bridge pier 21 with a continuous underground wall 12 and anchor bolts 13 as fixing means for fixing the underground wall 12 to the footing 22 as main parts in the present invention, the foundation structure is reinforced. It is intended.
[0019]
Here, the underground wall 12 is formed by connecting a plurality of steel sheet piles (not shown) with the joints, and sandwiching the footing 22 of the pier 21 from two opposite directions as shown in FIG. It arrange | positions so that the ground between the adjacent footings 22 may be surrounded. At this time, a steel sheet pile having a length that allows the underground wall 12 to penetrate the liquefied layer 24 as shown in FIG. 1 is used.
[0020]
Further, an underground beam 11 made of reinforced concrete is integrally formed at the upper end of the underground wall 12 as a connection reinforcing member for connecting the adjacent footings 22 and 22. In this underground beam 11, reinforcing bars are arranged so as to be structurally continuous in the axial direction so as not to be broken even if tensile stress is applied.
[0021]
Furthermore, the ground may be improved by injecting a cement-based solidifying agent such as cement grout into the ground surrounded by the footings 22 and 22 and the underground walls 12 and 12. Furthermore, a pipe (not shown) whose tip reaches the liquefied layer is provided on the ground between the underground walls 12 and 12 or the ground on the side of the underground wall 12 or the footing 22 so as to drain the groundwater. Also good.
[0022]
As the connecting reinforcing member, the strand 15 may be stretched between the footings 22 and 22, as shown in FIG. At this time, the arrangement position of the strand 15 can be determined as appropriate. For example, the strand 15 may be provided at a position separated by a predetermined length from the underground wall 12 as shown in FIG. It may be provided at the upper end of the middle wall 12.
[0023]
When liquefaction occurs and lateral flow occurs in the surrounding ground of the footing 22 having the above-described foundation reinforcing structure, the ground surrounded by the underground walls 12 and 12 and the footings 22 and 22 is Since the inner wall 12 is insulated from the outer peripheral surface layer, the oblique cracks as shown in FIG. 6 do not occur, so that only the outer peripheral surface layer of the underground wall 12, 12 becomes the underground wall 12, 12. Accordingly, the load on the outer peripheral surface layer can be prevented from being transmitted to the footing 22.
[0024]
In addition, the underground wall 12 formed of a plurality of steel sheet piles connects adjacent footings 22 and 22 and has a tensile strength greater than or equal to a predetermined level in the horizontal direction. Even if the footing 22 is subjected to pressure in the horizontal direction, the pressure is successively transmitted to the adjacent footing 22 through the underground wall 12, so that the proof strength of the footing 22 and the pier 21 against the lateral flow load can be improved. it can. Furthermore, since the underground beam 11 is provided at the upper end of the underground wall 12, the transmission of the horizontal pressure between the footings 22 and 22 can be more effectively performed.
[0025]
Furthermore, since the ground between the footings 22 and 22 is relatively strongly restrained by the underground wall 12, liquefaction of the ground between the footings 22 and 22 can be suppressed. Furthermore, since the ground between the footings 22 and 22 is surrounded by the underground wall 12, the soil can be improved efficiently by injecting a soil hardener between the footings 22 and 22.
[0026]
【The invention's effect】
In the foundation reinforcing structure of the present invention, the ground surrounded by the adjacent foundation and the underground wall is insulated from the outer surface layer by the underground wall. Even if this occurs, the outer surface layer moves in the direction of lateral flow along the underground wall, preventing transmission to each foundation.
[0027]
Further, in the foundation reinforcing structure of the present invention, the underground walls connect adjacent foundations, so that even if some foundations are subjected to pressure in the horizontal direction due to lateral fluidization in the surrounding ground, Since the pressure is transmitted to the next foundation one after another through the wall, the foundation and the structure on the foundation can improve the resistance to the lateral flow load.
[0028]
Furthermore, since the foundations are connected by the connection reinforcing member, the horizontal pressure between the foundations can be transmitted more effectively.
[0029]
Furthermore, since the ground between each foundation is restrained by the underground wall, liquefaction of the ground between each foundation can be suppressed.
[0030]
Moreover, since the ground between each foundation is surrounded by the underground wall, if the earth and sand hardening agent is inject | poured between this foundation, ground improvement can be performed efficiently.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a basic reinforcing structure of a group of structures according to the present invention.
FIG. 2 is a longitudinal sectional view taken along one-dot chain line II-II in FIG.
3 is a plan sectional view taken along one-dot chain line III-III in FIG.
4 is a plan sectional view showing an embodiment different from those shown in FIGS. 1 to 3; FIG.
5A is a side sectional view showing a conventional example, and FIG. 5B is a plan sectional view of FIG. 5A.
FIG. 6 is a schematic plan view showing a state in which a lateral flow load acts on a conventional foundation group.
[Explanation of symbols]
11 Reinforced concrete underground beam (reinforcement member)
12 underground wall 13 anchor (fixing means)
15 Strand (Connecting reinforcement member)
21 Pier (structure)
22 Footing (basic)

Claims (3)

On the basis of a plurality of structures such as a plurality of piers, warehouse groups or apartment houses, each constructed to be arranged in a certain direction at predetermined intervals,
The look clamping the two directions opposite to each foundation, build and adjacent the ground the circumference unnecessarily continuous underground wall between the foundation, is fixed to the each foundation by fixing means該地in the wall, each A foundation reinforcing structure for a group of structures, characterized in that a connecting reinforcing member for connecting the foundations is provided .   The foundation reinforcing structure for a structure according to claim 1, wherein a soil hardener is injected into a ground between predetermined foundations surrounded by the underground wall.   2. The foundation reinforcing structure for a group of structures according to claim 1, wherein one or more groundwater draining means are provided on the underground wall.

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