JPS5949973B2 - Construction methods for foundations such as abutments and piers - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for constructing foundations such as bridge abutments and piers that are supported by footings buried underground.

In elevated bridges constructed along river banks, etc., the ground is generally soft, so as shown in Figure 1, a box-shaped footing 1a with an open bottom is installed underground, and abutments or abutments are placed on top of it. The column portion 1b of the pier is erected.

In this case, the problem is how to construct the underground portion including the footing portion 1a.

Conventionally, a box-shaped footing member previously formed on the ground surface was deposited using the so-called caisson construction method. However, as is well known, this caisson construction method There is a problem that it involves dangerous work and that work efficiency is extremely poor.

This invention was made in view of the above-mentioned problems, and its purpose is to improve the foundation part of the bridge abutment or pier including the footing, especially the underground part, without using the conventional caisson construction method. The object of the present invention is to provide a construction method that can be installed more safely and efficiently than before.

Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIGS. 2a=h and 3a-h sequentially show each step of the method for constructing a bridge abutment and pier foundation according to the present invention.

In the method shown in the figure, first, Figure 2a and Figure 3a
As shown in Figure 2, an embankment 3 for the work site will be provided at the planned location of the foundation within the river 2.

Further, a working floor 4 is constructed on the embankment 3, and a guide trench 6 is provided on the ground surface at a position corresponding to the side wall of the footing 5 to be provided.

Then, as shown in Figures 2 and 3, an excavation is made from the ground surface to a position corresponding to the upper end of the side wall 5a of the footing 5 and along a position corresponding to the extending direction of the footing side wall 5a. A slotted hole 8 is provided.

Next, as shown in FIG. 2 C and FIG. Excavate further towards the appropriate location and extend it.

Here, the trench hole 8 can be excavated entirely from the ground surface using, for example, a Kelly excavator.

In addition, as the earth retaining member 9, ('!) steel plates having approximately the same length as the groove hole 8, (2) steel sheet piles, etc. are arranged closely in parallel.

In addition, in this embodiment, the above-mentioned slot holes 8 are not provided all at once.
Together with a continuous wall, which will be described later, it is provided in several parts, and finally the entire side wall part 5a of the footing part 5 is constructed.

As shown in FIGS. 2d and 3d, concrete with reinforcing bar cages inserted from the ground is poured into the groove 8 which has been extended to a position corresponding to the lower end of the footing side wall 5a as described above. A part of the side wall portion 5a of the footing 5 is formed.

Then, as shown in Figures 2e and 3e, a series of operations such as digging trenches 8, installing earth retaining members 9, and pouring reinforced concrete are repeated for other parts to form a closed ring. A whole side wall portion 5a having a cross section and being integrated is formed.

What should be noted here is that, as shown in FIG.
The lower end portion of the groove hole 8 is sandwiched between the outer inner wall surface of the groove hole 8 and the outer inner wall surface of the groove hole 8.

This strengthens the integrity of the top plate portion 5b and the side wall portion 5a, resulting in a footing structure suitable for cases where fluctuating loads are applied, such as on railway piers, and the opening 1
Even when digging 1, the earth retaining member 9 can effectively prevent the collapse of the earth.

After this, as shown in FIGS. 2f and 3f, the area surrounded by the earth retaining member 9 is excavated while providing a cutout 10, and an opening reaching from the ground surface to a position corresponding to the upper end of the footing 5 is created. Excavate 11.

Then, as shown in FIGS. 2g and 3g, a top plate part 5b is integrally provided at the bottom of the opening 11 to connect with the upper end of the footing side wall part 5a, and then an upper part of the top plate part 5b is installed. The pillar portion 5c of the pier is erected, the earth retaining member 9 and the cutout 10 are removed, and the opening 11 is backfilled.

Furthermore, by removing the aforementioned work land embankment 3, the pier foundation constructed in the river 2 can be completed, as shown in the second drawing and the 83rd drawing.

As described above, in the method for constructing bridge abutments and pier foundations according to the invention, when a footing, which is a foundation member of an abutment, a bridge pier, etc., is installed in the ground, first, from the ground surface to a position corresponding to the upper end of the side wall of the footing. A groove is provided which is opened and closed along a position corresponding to the extending direction of the footing side wall, and then an earth retaining hole having approximately the same length as the groove is provided along the outer inner wall surface of the groove. After installing the member, the groove hole is further excavated and extended toward a position corresponding to the lower end of the side wall of the footing. forming an integrated continuous wall having a cross section, the upper end of which protrudes to a position corresponding to the top plate of the footing, and the lower end of the earth retaining member being sandwiched between the outer inner wall surface of the groove; After this, the area surrounded by the earth retaining member is excavated while providing a cutting beam to create an opening that reaches from the ground surface to a position corresponding to the upper end of the footing, and the bottom of this opening is connected to the upper end of the side wall of the footing. The method is characterized in that a top plate portion is integrally formed, and then, a pillar portion of an abutment or a bridge pier is provided on the top of the top plate portion, the earth retaining member and the cut beam are removed, and the opening is backfilled. As a result, bridge abutments and pier foundations can be constructed safely and efficiently even in poor location conditions such as rivers, without relying entirely on the conventional caisson construction method, and by mostly working from the ground.

In addition, in the foundation constructed by this method, the top plate part is integrally formed with the side wall part of the closed cross section that has been converted into a body, and the upper end of the side wall part is formed to protrude from the top plate part, so it cannot be sunk. It has a rigidity equal to or greater than that of a caisson, and is suitable for railway bridge piers with large fluctuating loads. The bearing strength is different from other foundations, and there is no problem of corrosion of the casing left in the soil as part of the foundation.

[Brief explanation of drawings]

Figure 1 is a partially broken perspective view showing the foundation of the pier.
to h are sectional views showing each step of an embodiment of the construction method according to the present invention, and FIGS. 3a to 3h are plan views corresponding to the sectional views of FIGS. 2a to h, respectively. 1a...Footing part, 1b...Column part, 2...River, 3...Embankment, 4...
...Working floor, 5...Footing part, 5a
...Side wall part, 5b...Top plate part, 5c.
...Column part, 6...Guide trench, 8
...Groove, 9...Earth retaining member, 10...
...Kiribari, 11...Opening.

Claims (1)

[Claims] 1. When installing a footing, which is a base member for an abutment, a bridge pier, etc., underground, first, excavation is carried out from the ground surface to a position corresponding to the upper end of the footing side wall and along a position corresponding to the extension direction of the footing side wall. After providing a retaining member having approximately the same length as the groove along the outer inner wall surface of the groove, The extension section is further excavated and extended into the ground, and has an annular closed cross section that constitutes the side wall of the footing, and its upper end protrudes to a position corresponding to the top plate of the footing, and the above-mentioned An integrated continuous wall is formed by sandwiching the lower end of the earth retaining member with the outer inner wall surface of the groove, and then the part surrounded by the earth retaining member is excavated while providing a cut beam. An opening that reaches from the ground surface to a position corresponding to the upper end of the footing is provided, and a top plate portion that connects to the upper end of the footing side wall is integrally formed at the bottom of this opening, and then a bridge abutment or pier is installed on the top of the top plate portion. A method for constructing a foundation for an abutment, a bridge pier, etc., characterized by providing a pillar portion, removing the earth retaining member and the cut beam, and then leaning back the opening.