JPH09158212A - Foundation reinforcing structure for structure group - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a flowing load or the load of a surface layer from being transmitted to a foundation by constructing an underground wall continued so as to nip each foundation from mutually opposed directions and surround the ground between adjacent foundations, and fixing the underground wall to the foundation by an anchor. SOLUTION: A continued underground wall 12 is fixed to a foundation 22 by an anchor 13. The underground wall 12 is formed by connecting steel sheet piles, and arranged so as to nip the foundation 22 from two opposed directions and surround the ground between the foundations 22. As the steel sheet piles, those having a length such that the underground wall 12 penetrates through liquefied layer 24 are used. An underground beam 11 is integrally formed on the upper end of the underground wall 12. Further, the ground surrounded by the foundation 22 and the underground wall 12 is soil-improved. A pipe having a tip extending to the liquefied layer 24 is provided on the side ground of the foundation 22 to drain ground water. Thus, the foundation can be isolated from the peripheral surface layer by the underground wall 12, and the surface layer is moved in the side flowing direction along the undergroundwall 12 even if the ambient ground is liquefied, so that the transmission to each foundation can be prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field 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]

2. Description of the Related Art The ground near a river or the sea may have a non-liquefied layer, a liquefied layer located on the non-liquefied layer, and a surface layer located on the liquefied layer. In such a ground, the non-liquefied layer inclines diagonally downward toward the river or the sea in many cases, so when a liquefaction phenomenon occurs, the liquefied earth and sand will follow the slope of the non-liquefied layer. It may move toward the sea and move. In addition, liquefied earth and sand will flow even when the seawall and quay are broken and deformed during an earthquake, or when the surface ground of the liquefied layer is inclined.

On the other hand, there are some bridge piers such as viaducts, warehouse groups or collective housing groups in which a plurality of foundations are constructed in a substantially constant direction at predetermined intervals. For example, as shown in the schematic plan view of FIG.
Some 1, 32 are constructed almost at one direction toward the sea or river 37 at a predetermined interval. Kayo Basic 3
When liquefaction occurs in the ground where 0, 31, and 32 are constructed, a lateral fluidization phenomenon, that is, a phenomenon in which sediment in the liquefaction layer flows in parallel with the foundations that are arranged in a substantially constant direction, may occur. is there.

Conventionally, as a general countermeasure against liquefaction of ground,
A method of constructing a continuous underground wall that surrounds the entire circumference for each foundation of the structure, or as shown in Figs. 5 (a) and 5 (b), existing piles 5
An additional pile construction method is proposed in which additional piles 53 are hammered around 4 and the footings 52 are additionally hammered so as to be integrated with the additional piles 53.

[0005]

However, as shown in FIG. 6, when the ground is liquefied and the lateral flow occurs around the foundation 32, the surface layer of the ground is cracked from a corner of the foundation 32 in a substantially oblique direction. As can be seen from the damage example in which 35 has occurred, an excessive load of the surface layer 36 covering a wide area in the front and diagonal directions of the foundation 32 is transmitted to the foundation 32. The above-mentioned transmission of an excessive load of the surface layer cannot be prevented by the conventional method of reinforcing the basic unit, and may cause the foundation 32 and its upper structure to collapse. Even if the above-mentioned conventional construction method can prevent collapse, the additional pile 53
And the amount of additional hitting of the footing 52 becomes enormous, which requires a large cost and is uneconomical.

The present invention has been made in order to solve the above-mentioned problems, and an object thereof is to obtain a fluidized load from a liquefaction layer and a wide range of diagonal surfaces even if a lateral fluidization phenomenon occurs in the ground. An object of the present invention is to provide a foundation reinforcing structure for a group of structures that prevents the load of a layer from being transmitted to the foundation and prevents collapse of the foundation and its upper structure.

Another object of the present invention is to provide a foundation reinforcing structure for a group of structures capable of restraining the ground between the foundations relatively strongly and thereby suppressing liquefaction between the foundations. is there.

Another object of the present invention is to provide a foundation reinforcing structure for a group of structures which can improve the horizontal bearing capacity of each foundation.

Still another object of the present invention is to provide a foundation reinforcing structure of a structure group capable of efficiently curing earth and sand between foundations when a soil and sand hardening agent is injected to improve the ground between foundations. To do.

[0010]

The present invention has been made in view of the above-mentioned object, and its gist is a basic reinforcing structure for a plurality of structures constructed at predetermined intervals in predetermined directions. Characterized in that a continuous underground wall is constructed by sandwiching the foundations from two opposite directions and surrounding a ground between the adjacent foundations, and the underground wall is fixed to the respective structures by a fixing means. It is in the basic reinforcement structure of the structure group.

In the foundation reinforcing structure of the structure group of the present invention, as the plurality of structures constructed at predetermined intervals in a predetermined direction, for example, there are bridge piers such as viaducts, warehouse groups or collective housing groups, These foundations are constructed in a substantially straight line and arranged in a certain direction at substantially equal intervals, or are formed in a certain direction while drawing a gentle curve.

In the present invention, when the ground around the foundation is liquefied and a lateral flow is generated, the underground wall is the laterally flown earth and sand and the surface layer on the earth and sand, and the earth and sand between the foundations and the earth and sand. As long as it is a wall that can insulate the upper surface layer, for example,
It is possible to employ a continuous underground wall with a sheet pile, a column row wall reinforced with a steel frame for an underground pillar formed with soil mortar, or a continuous underground wall formed with cast-in-place reinforced concrete, preferably by a sheet pile. Build an underground wall. An underground wall made of sheet pile has an advantage that it can be economically constructed with a compact construction machine that does not occupy a working space as compared with other underground walls. Here, the material of the sheet pile can be appropriately selected, for example, wood sheet pile,
It can be appropriately selected from reinforced concrete sheet piles, prestressed concrete sheet piles, pressurized concrete sheet piles, steel sheet piles and the like, and preferably steel sheet piles are used to construct a continuous underground wall. If steel sheet pile is used as the sheet pile, the joint can transmit tensile force,
There is an advantage that excess pore water pressure generated by liquefaction can be blocked.

In the present invention, as the fixing means for fixing the underground wall to each foundation, for example, anchor bolts or reinforcing bars can be used.

In the present invention, a connecting reinforcing member may be provided between the foundations for connecting them, and the connecting reinforcing member connects adjacent foundations to each other and applies a horizontal force acting on each foundation. It would be good if it could be transmitted to the next foundation. As such a connecting 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.

In the present invention, a soil hardening agent may be injected into the ground between predetermined foundations surrounded by the underground wall,
The earth and sand hardening agent may be any as long as it can form a water blocking film on the earth and sand to improve the strength of soil and prevent the ground from easily liquefying during an earthquake. As such earth and sand 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.

Further, in the present invention, one or more groundwater removing means may be provided on the underground wall, and the groundwater removing means is provided at least when the water pressure of the aquifer increases due to vibration in the ground or the like. Any means can be used as long as it can remove the water in the layer. As such groundwater removing means, for example, a columnar body formed of sand or gravel in the ground, a perforated pipe, a synthetic resin pipe or a screen pipe can be used.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS 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, and FIG. 2 is a chain line in FIG.
FIG. 4 is a vertical sectional view taken along line II-II, FIG. 3 is a horizontal sectional view taken along alternate long and short dash line III-III in FIG. 1, and FIG. 4 is a horizontal sectional view showing an embodiment different from FIGS. 1 to 3. Is. As shown in FIGS. 1 to 3, a bridge pier 21 to which the foundation reinforcement structure of the present invention is applied is supported by a foundation composed of a plurality of piles 23 and a footing 22 integrally formed on the piles 23, and is elevated above. It supports the road 20. The footing 22 of such an elevated road is constructed at a prescribed interval in a prescribed direction. For example, an elevated road that crosses a river is often provided in an arrangement that is orthogonal to the river. Some elevated roads extending to the coast are installed almost vertically to the sea.

According to the present invention, the bridge pier 21 is provided with a continuous underground wall 12 and an anchor bolt 13 as a fixing means for fixing the underground wall 12 to the footing 22 in the present invention. It is intended to reinforce.

Here, the underground wall 12 is formed by connecting a plurality of steel sheet piles (not shown) with their joints, and as shown in FIG. 3, the footings 22 of the pier 21 are opposed to each other in two directions. It is arranged so as to be continuous while surrounding the ground between the footings 22 adjacent to each other. At this time, the steel sheet pile has a length such that the underground wall 12 penetrates the liquefied layer 24 as shown in FIG.

On the upper end of the underground wall 12, an underground beam 11 made of reinforced concrete is integrally formed as a connecting reinforcing member for connecting adjacent footings 22, 22 to each other. 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 acts.

Further, a cement-based solidifying agent such as cement grout may be injected into the ground between the footings 22, 22 and the ground surrounded by the underground walls 12, 12 to improve the ground. Furthermore, the ground between the underground walls 12, 12 or the underground wall 12
A pipe (not shown) whose tip reaches the liquefied layer may be provided on the ground on the side of the footing 22 or the ground to drain groundwater.

The underground beam 11 is used as the connecting reinforcing member.
Alternatively, as shown in FIG. 4, the strand 15 may be stretched between the footings 22 and 22. At this time, the arrangement position of the strand 15 can be appropriately determined, but for example, it may be provided at a position separated by a predetermined length from the underground wall 12 as shown in FIG. It may be provided on the upper end of the inner wall 12.

When liquefaction occurs and lateral flow occurs in the ground around the footing 22 having the above-mentioned basic reinforcement structure, the ground surrounded by the underground walls 12, 12 and the footing 22, 22. Is insulated from the outer peripheral surface layer by the underground wall 12, no oblique cracks as shown in FIG. 6 occur, and therefore only the outer peripheral surface layer of the underground walls 12, 12 is formed. , 12 in the lateral flow direction, and the load of the outer surface layer can be prevented from being transmitted to the footing 22.

An underground wall 1 formed of a plurality of steel sheet piles
No. 2 connects adjacent footings 22 and 22 and has a tensile strength more than a predetermined level in the horizontal direction, so that lateral fluidization occurs in the surrounding ground and some footings 22 receive horizontal pressure. Also, since the pressure is successively transmitted to the adjacent footing 22 through the underground wall 12, the footing 22 and the pier 21 can be improved in proof stress against a lateral flow load. Furthermore, since the underground beam 11 is provided at the upper end of the underground wall 12, the horizontal pressure can be transmitted between the footings 22, 22 more effectively.

Further, 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, this footing 2
If the earth and sand hardening agent is injected between 2 and 22, the ground can be improved efficiently.

[0026]

In the foundation reinforcing structure of the present invention, the ground surrounded by the foundation and the underground wall which are adjacent to each other is insulated from the outer surface layer by the underground wall, so that the surrounding ground is liquefied. Even if the lateral flow occurs, the outer surface layer moves in the lateral flow direction along the underground wall and can prevent the transmission to each foundation.

Further, in the foundation reinforcing structure of the present invention, since underground walls connect adjacent foundations to each other, even if some foundations are subjected to horizontal pressure due to lateral fluidization in the surrounding ground. Since the pressure is sequentially transmitted to the adjacent foundation through the underground wall, the foundation and the structure on the foundation can improve the proof stress against lateral flow load.

Furthermore, since the bases are connected by the connecting reinforcing member, the horizontal pressure can be transmitted between the bases more effectively.

Furthermore, since the ground between the foundations is constrained by the underground wall, liquefaction of the ground between the foundations can be suppressed.

Since the ground between the foundations is surrounded by the underground wall, the soil can be efficiently improved by injecting the earth and sand hardening agent between the foundations.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a basic reinforcing structure of a structure group of the present invention.

FIG. 2 is a vertical sectional view taken along one-dot chain line II-II in FIG.

3 is a plan sectional view taken along the alternate long and short dash line III-III in FIG.

FIG. 4 is a plan sectional view showing an embodiment different from FIGS. 1 to 3;

5A is a side sectional view showing a conventional example, and FIG. 5B is a sectional view of FIG.
FIG.

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 Underground beam (reinforcement member) by reinforced concrete 12 Underground wall 13 Anchor (fixing means) 15 Strand (reinforcement member) 21 Pier (structure) 22 Footing (foundation)

Claims (4)

[Claims] 1. A foundation reinforcing structure for a plurality of structures, each of which is constructed at a prescribed interval in a prescribed direction, wherein each foundation is sandwiched from two opposing directions, and the ground between adjacent foundations is surrounded. A foundation reinforcing structure for a group of structures, characterized in that a continuous underground wall is constructed and the underground wall is fixed to each of the foundations by a fixing means. 2. The foundation reinforcing structure for a group of structures according to claim 1, further comprising a connecting reinforcing member for connecting the foundations. 3. The earth and sand hardening agent is injected into the ground between predetermined foundations surrounded by the underground wall.
Foundation reinforcement structure of the described structure. 4. The foundation reinforcing structure for a group of structures according to claim 1, wherein the underground wall is provided with one or more means for removing groundwater.