JPS62202125A - Underwater foundation work using steel plate shell - Google Patents

Abstract

PURPOSE:To enhance the economical advantage and exactness of underwater foundation work by a method in which the heads of plural piles driven into the space of a double steel plate shell set concentrically are fixed by filling concrete, and footing concrete is then placed to connect the filling concrete. CONSTITUTION:Large-diameter steel plate shells 1 and 2 of different diameters are set concentrically into the ground 6 under water, and plural piles 3 are driven into the space between the inner and outer shells 1 an 2. The heads of the piles 3 are fixed by concrete 4 packed into the space between the shells 1 and 2. Under a condition that water is left in the inner shell 1, footing concrete 5 for connecting the concrete 4 is placed on the water to integrally connect the cylindrical portion surrounded by the piles 3 and the shells 1 and 2 and the footing above them to form an underwater foundation. The construction work can thus be simplified and the construction period can be shortened without the needs for large-scale temporary equipments.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an underwater foundation construction method using steel plate cells, and is used, for example, in construction of bridge pier foundations.

[Conventional technology and problems] In recent years, there has been an increase in the number of cases in which bridge piers are installed in or under the sea in the construction of coastal roads in conjunction with the development of urban road networks or in the construction of connecting bridges in conjunction with the construction of offshore artificial islands. .

Construction methods for constructing foundations for such underwater structures often require the following points in particular:

■ Not affected much by waves and water currents ■ Short on-site construction period ■ Safe construction ■ Does not require large-scale temporary equipment ■ Does not cause water pollution ■ Economical Construction methods include the cofferdam method using double sheet piles, the caisson method, the steel pipe sheet pile well method, which uses wells made by connecting steel pipes with joints, and the footings installed at the heads of many piles that rise above the water surface. Multi-column foundation construction method,
Other steel plate cell caisson construction methods (Japanese Unexamined Patent Publication No. 59/1989) that combine steel plate cells and underground continuous walls constructed within the cells.
-8835) or concentrically cast steel plate cells with different diameters, and then fill in the inside of the steel plate cells and place rising concrete between the inner and outer steel plate cells, and place upper concrete on the middle fill part and the top of the rising concrete. There are underwater foundation construction methods (Japanese Unexamined Patent Publication No. 59-138621), but all of them have advantages and disadvantages in terms of construction efficiency, etc. For example, in the multi-column foundation construction method, the footing concrete is constructed above the water surface, resulting in a so-called top-heavy condition, which increases the moment generated in the piles during an earthquake, necessitating the use of larger diameter piles.

The purpose of the construction method of the present invention is to economically and reliably construct the foundations of such underwater structures.

[Means for solving problems]

In the construction method of this invention, prefabricated large-diameter cylindrical steel plate cells 1 and 2 of different diameters are concentrically rooted in the underwater ground 6, and the steel plate cells 1 and 2 inside and outside of this double steel plate cell,
The heads of the multiple piles 3 driven between the inner and outer steel plate cells 1
, 2 is fixed by filling the gap with filler concrete 4. Note that there are two methods for forming the double steel plate cells: one is to integrate the inner and outer steel plate cells 1 and 2 in advance and then drive them, and the other is to drive the inner and outer single steel plate cells 1 and 2 individually.

As a driving method, a vibration driving method using a crane ship and a device that links multiple vibrohammers has already been put into practical use.

Next, while leaving water in the inner steel plate cells 1, a footing concrete 5 is placed on the water surface to connect the filler concrete 4, and the footing concrete 5 is surrounded by the piles 3 and the inner and outer steel plate cells 1 and 2. The cylindrical part and the footing part above it are integrated with concrete.

Through the above steps, an underwater foundation is formed, and a superstructure such as a bridge pier can be constructed on top of the underwater foundation.

The steel plate cells 1 and 2 are not limited to cylindrical ones, but may have an oval cross section as shown in FIG. 2.

〔Example〕

Next, embodiments of the present invention will be described based on the drawings.

Figures 1(a) and 1(t) are structural conceptual diagrams when the construction method of the present invention is used for an underwater pier foundation.

Piles 3 sufficient to withstand the required vertical force and horizontal force are driven between the inner and outer steel plate cells 1 and 2, which are concentrically driven into the underwater ground 6.

The space between the steel plate cells 1 and 2 is filled with filler concrete 4, and the head of the pile 3 is fixed by this filler concrete 4.

A circular footing concrete 5 is placed on top of the filler concrete 4 to cover the cylindrical part surrounded by the inner and outer steel plate cells 1.2, and a pier 7 rises from the footing concrete 5. .

In this example, the piles 3 are driven only between the inner and outer steel plate cells 1°2, but in order to increase the foundation strength, a footing with a pile head is placed inside the inner steel plate cell 1 as shown in Fig. 7. Additional piles 3' fixed to the concrete 5 may be driven.

In this structure, the footing concrete 5 is constructed near the water surface, similar to the multi-column foundation construction method, resulting in a so-called top-heavy condition. For this reason, in multi-column foundations, the moment generated in the piles during an earthquake is large.
Although a pile with a large diameter is required, in the structure according to the present invention, since the pile head is fixed near the underwater ground surface, the moment generated on the pile 3 does not become large, and therefore the pile diameter can be made relatively small.

FIG. 2 shows the case where the inner and outer steel plate cells 1 and 2 have an oval cross section. That is, when the inner steel plate 1' is filled with filler material such as earth and sand, a large moment is generated in the cell shell in the straight section, but in this invention, filling is not performed and the space between the inner and outer steel plate cells 1' and 2' is Interfill concrete 4
Because it is a concrete structure, an oval shape is also possible.Especially if it is installed upright in the flow direction, there is less impact on the fluid and water flow applied to the foundation, and it is also possible to arrange the desk economically according to the load conditions. The effect is a dog.

3 to 6 show the construction procedure according to the construction method of the present invention, and the work is carried out in the following steps.

■ The steel plate cells 1 and 2 manufactured in advance are transported to the pouring site, and after positioning, are poured into the underwater ground 6 to the required depth (see Fig. 3). The height of the top of the outer steel plate cell 2 is set at a level higher than the water surface in order to serve as the outer peripheral formwork of the filler concrete 4 to be constructed later and to avoid being affected by waves during construction.

■ After the inner and outer steel plate cells 1 and 2 are poured, steel plate cell 1
, drive multiple piles 3 between the two (see Figure 4). At this time, the inner and outer steel plate cells 1 and 2 can serve as guides for the pile 3. Furthermore, the driving of the piles 3 may be carried out prior to the driving of the steel plate cells 1 and 2. Next, after the required reinforcement is placed between the inner and outer steel plate cells 1 and 2, the filling concrete 4 is placed. (See Figure 5).

This construction will be carried out underwater. In addition, when the level of the bottom surface of the footing is below the water surface, water is drained until the water level in the steel plate cells 1 and 2 becomes below the level of the bottom surface of the footing. At this time, if necessary, provide support to reinforce the cell walls.

If the top of the inner steel plate cell 1 is the same as the top of the outer steel plate cell 2 as shown in Figure 8, by pouring filler concrete 4 up to the height of the top of the steel plate cells 1 and 2, the cell There is no need to reinforce the cell walls when draining the water inside.

■Next, after constructing the support for the footing concrete and the bottom formwork, the reinforcement for the footing is arranged, and the footing concrete 5 is placed.

Figure 7 shows the case where an additional pile 3' is constructed inside the aforementioned inner steel plate cell 1, and Figure 8 shows the case where the top of the inner steel plate cell 1 is made the same as the top of the outer steel plate cell 2. This shows an example.

〔Effect of the invention〕

The inner and outer steel plate cells serve as a formwork for pouring concrete to fix the pile head, and because large-scale temporary equipment is not required and the construction process is simplified, the construction period is shortened and economical.

In addition, since the pile head is fixed and integrated with the filler concrete, the bending moment acting on the pile is not so large, and the pile diameter can be made smaller than in the multi-column foundation method.

Furthermore, as long as there is no filling in the inner steel plate cells, the cross-sectional shape can be oval or any other economical cross-sectional shape depending on the load conditions. Also, depending on the cross-sectional shape, it is possible to reduce the influence on water flow.

[Brief explanation of drawings]

Figure 1 (a) is a front view (the right half is a sectional view) showing the structure of an underwater foundation constructed by the construction method of this invention.
) is an I-I cross-sectional view, Figure 2 is a cross-sectional view of an underwater foundation showing a modified example, Figures 3 to 6 are cross-sectional views showing the construction procedure,
FIG. 7 and FIG. 8 are sectional views of other embodiments, respectively. 1.2... Steel plate cell, 3... Pile 4... Filling concrete, 5... Footing concrete, 6... Underwater ground, 7... Pier Figure 1 (a) Figure 2g Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Written Amendment to Procedures 11 March 4, 20061 Mr. Michibu Uga, Commissioner of the Patent Office, 1
, Indication of the case Patent application filed on February 26, 1986 (3) 3. Person making the amendment Relationship to the case Patent applicant 4, agent address ■ 107 Higashij Shiroto-ku Akasaka 6-5-21 No. Shadow - Akasaka Telephone (586) 8741

Claims (2)

[Claims] (1) The heads of multiple piles driven between the inner and outer steel plate cells of a double steel plate cell concentrically rooted in the underwater ground are fixed by filling the space between the inner and outer steel plate cells with filler concrete. Then, while leaving water in the inner steel plate cell, footing concrete is placed on the water surface to connect the filler concrete, thereby forming a cylindrical part surrounded by the pile and the inner and outer steel plate cells and its upper part. An underwater foundation construction method using steel plate cells, which is characterized by integrating the footings with concrete. (2) An underwater foundation construction method using steel plate cells according to claim 1, wherein the inner and outer steel plate cells have an oval cross section.