JPH0645942B2 - Basic structure of PC egg digester - Google Patents

Description

TECHNICAL FIELD The present invention relates to a basic structure of a PC egg-type digester used in an anaerobic digestion method, which is one of sludge treatment facilities.

"Prior Art" Conventionally, as a basic structure of this type of PC egg digester, a group pile foundation shown in Figs. 3 to 7 is known.

FIG. 3 is a side sectional view of a PC egg-type digestion tank using a conventional group pile foundation, and FIG. 4 is a IV-IV sectional view of the group pile foundation.
5 to 7 are explanatory views of the vicinity of the foundation during construction. In the figure, reference numeral T is a PC egg-type digestion tank, which mainly comprises a group pile foundation part 1 built in the ground G and a digestion tank main body 3 supported above it by a ring foundation part 2. As an element.

The group pile foundation part 1 is constructed by driving steel pipe piles 1a, 1a, ... In the ground G in a ring shape at predetermined intervals in the circumferential direction and the radial direction, and at the same time, the upper part of the pile pile is provided with stability and a predetermined shape. A ring foundation 2 having a predetermined thickness is built to maintain strength, and a digester tank body 3 having an egg-shaped wall 4 is supported on the ring foundation 2 and the ring foundation 2 is supported. The part 2 is integrated so as to horizontally project from the wall part 4 in the ground, and the bottom plate parts 3a and 3b of the digestive tank body 3 having a conical shape are formed below the ring base part 2. .

Next, a construction method of the base portion of the PC egg-type digestion tank will be described with reference to FIGS. 4 to 7. First,
As shown in FIG. 4, steel pipe piles 1a, 1a, ... Supporting the ring foundation 2 by the medium excavation method are driven in a plurality of rows in an annular shape to provide the group pile foundation 1 in the ground G, and then the fifth As shown in the figure, a steel sheet pile 5 is provided on the outer peripheral portion of the group pile foundation part 1 for soil retention and water stoppage. After performing ground improvement by using the steel sheet pile 5, the inner side 6 of the steel sheet pile 5 is primarily excavated to a predetermined depth, and a 1: 1 method is used so that the ground improvement portion Gi serves as a mold for the bottom plate 3a of the digestion tank body 3. Secondary excavation (part of reference numeral 7) with a gradient. When the secondary excavation is completed, concrete is sprayed on the surface to form the bottom slab 3b, and as shown in FIG. 6, the PC steel materials 8, 8, ... On the bottom slab 3b.
Are arranged in a helical shape. Next, as shown in FIG. 7, a form 9 using a ring beam type steel garter is installed on the upper part of the bottom plate part 3b at a predetermined interval, and concrete is placed between them to form the bottom plate part 3a. To build. Next, the ring foundation 2 integrated with the upper portion of the bottom slab 3a is built on the group pile foundation 1 to complete the foundation of the PC egg digester.

"Problems to be Solved by the Invention" However, the PC egg digester using the conventional group pile foundation has the following problems.

(1) In order to excavate the bottom slab of the PC egg digester, it is necessary to carry out the steps of soil retention and water stoppage using steel sheet pile, etc., and it is necessary to improve the ground in the part that will be the formwork when the bottom slab is built. In addition, it is necessary to carry out secondary excavation of this ground improvement part according to the shape of the bottom slab with a 1: 1 gradient, the bottom slab construction by concrete spraying, the PC steel material of the bottom slab The need for a helical installation work, etc.
Many types of work are required, and many works that require precision and complicated works, which increase the construction cost and delay the construction period.

(2) A large amount of steel pipe piles are required to increase horizontal resistance.

(3) A thick-walled ring foundation is formed so as to horizontally project from the wall of the digestive tank body having an egg-shaped curved surface, and stress concentration is likely to occur on the outer peripheral surface of the connection portion.

The present invention has been made in view of the above problems, and simplifies the type of work required for the construction of a foundation portion, and excavates at a 1: 1 slope according to the shape of the bottom slab or helical of PC steel. The construction cost is reduced and the construction period is shortened by eliminating the need for complicated work that requires precision, such as the laying work, and a large amount of horizontal resistance is exerted with a small number of pile foundations, and the connection between the wall and foundation is made. It is an object of the present invention to provide a basic structure of a PC egg-type digestive tank in which stress concentration is unlikely to occur.

"Means for Solving Problems" In the present invention, a wall portion is formed in an egg shape, and a base portion integrally provided on the bottom portion of the wall portion is embedded in the ground.
A basic structure of a C egg-type digestion tank, in which a large number of steel sheet piles are continuously connected in a closed ring in the ground to form a tubular pile foundation part and the bottom surface of the foundation part is formed. The base portion is formed horizontally and the outer peripheral surface is vertically formed to provide the foundation portion on the upper portion of the pile foundation portion, and the bottom outer peripheral surface of the egg-shaped wall portion is continuous with the vertical outer peripheral surface of the foundation portion in the ground. It is characterized by being made possible.

In this case, a foundation pillar that supports the bottom surface of the foundation portion may be provided inside the pile foundation portion.

"Embodiment" FIGS. 1 and 2 show an embodiment of the present invention, which is a side sectional view of a PC egg-type digestion tank using the foundation structure of the present invention, and FIG. 2 is a pile foundation. It is a II-II sectional view of a part.

In the figure, reference numeral T is a PC egg-type digester tank, and this PC egg-type digester tank T is a pile foundation portion 1 built in the ground G in a tubular shape.
0 and the digestion tank body 1 supported by the pile foundation part 10
3 is the main component. The digester tank body 13 is
A base 11 having a circular outer shape on the bottom of the egg-shaped wall 12
Are integrally formed, and the bottom surface 11a of the base portion 11 thereof is
Is formed horizontally, and the outer peripheral surface 11o is formed vertically.

The pile foundation portion 10 is constructed in a tubular shape by connecting a large number of steel pipe sheet piles 10a, 10a ... Having various joints in the ground G in a closed ring shape as shown in FIG. The diameter of the pile foundation 10 (each steel pipe sheet pile 10a,
The diameter of a virtual circle connecting the centers of 10a, ...
It is set to be substantially the same as the outer diameter dimension of. The wall 12 of the digester tank body 13 is formed in an oval shape, and the outer peripheral surface 12o of the digester tank main body 13 is an inner peripheral surface 12i in the ground G.
While forming a curved surface that gradually expands with respect to the outer peripheral surface 10o of the base portion 11, the inner peripheral surface 12i has a conical shape inside the base portion 11. It is formed so as to be smoothly continuous with the wall surface of the bottom slab portion 11i formed in. Further, the foundation portion 11 has a reinforced concrete structure and is fixed to the steel pipe sheet piles 10a, 10a, ... By means of a dowel reinforcement (not shown).

Next, a method of constructing the base portion of the PC egg digester tank T will be described.

First, steel pipe sheet piles 10a, 10a having various joints in the ground G,
The pile foundation portion 10 is built by driving the ... In a closed circular shape having an outer diameter substantially the same as the outer diameter of the foundation portion 11. Next, after excavating the inside of the pile foundation portion 10, the excavated surface is subjected to abandoned concrete, and then a reinforcing bar is laid in a predetermined shape on the excavated concrete, and then a ring beam type steel is further arranged at a predetermined interval above the reinforcing bar. Place the form using the garter made,
Next, concrete is poured into the interior of the digestion tank body 13 to complete the foundation portion 11. Finally, the foundation part 11
The egg-shaped wall portion 12 is built by a predetermined method while forming a curved surface that is smoothly continuous with the wall surface on the upper part of the.

Therefore, in the foundation structure of the PC egg-type digester tank of the present invention, when excavating the foundation portion 11, the pile foundation portion 10 constructed in advance can be provided with soil retaining and water stopping functions. It is not necessary to install another steel sheet pile just for that, and since the bottom slab portion 11i is formed inside the foundation portion 11, it is not necessary to improve the ground of the portion that will be the formwork when building it. At the same time, it is not necessary to excavate the ground G with a 1: 1 normal gradient according to the shape of the bottom slab 11i or to spray concrete on the slope, and the foundation 11 can have a reinforced concrete structure. Since many work types are unnecessary, such as the construction work of helically arranging PC steel on the bottom slab 11i is unnecessary, the complicated work requiring precision is reduced, and the construction cost is reduced and the construction period is shortened. It can be realized.

Further, since the pile foundation part 10 is formed by integrally connecting the steel pipe sheet piles 10a, 10a, ... In a cylindrical shape, it has a large horizontal resistance force as a whole, and many piles such as a group pile foundation are provided. In addition, the wall 12 of the digestive tank main body 13 having an egg-shaped curved surface is gradually thickened and is connected to the thick-walled base portion 11, and the outer peripheral portion 12o and the inner peripheral surface 12i are connected to each other.
Peripheral surface 11o having a circular cross section and a conical bottom plate portion 11i
The inner peripheral surface is continuous with a smoothly changing curved surface, and the shape is such that stress concentration is unlikely to occur near the connecting portion.

Further, the bottom surface 11a of the foundation portion 11 is provided inside the pile foundation portion 10.
By providing the foundation pillars 14 for supporting the piles as shown by the chain line in FIG. 1, for example, the supporting force of the foundation can be increased, and a pile foundation using steel sheet piles instead of the steel pipe sheet piles 10a can be provided. It is also possible to install a foundation pillar in the inside of the force and to bear it.

"Effects of the Invention" As described above, the present invention provides a cylindrical pile foundation by integrating a large number of steel sheet piles, and a bottom surface of the foundation integrally provided on the bottom of the egg-shaped wall portion. Formed horizontally and the outer peripheral surface is formed vertically, this foundation part is provided on the upper part of the pile foundation part, and the bottom outer peripheral surface of the egg-shaped wall part is the vertical outer peripheral surface of the foundation part in the ground. Since it is a continuous structure, it is possible to simplify the work type for constructing the foundation without installing steel sheet piles used only for soil retention and water stoppage and ground improvement near the bottom slab, and at the same time, the bottom slab It is possible to eliminate complicated work that requires precision, such as excavation of the ground at a 1: 1 slope that matches the shape of the section and construction work for helically arranging PC steel, reducing construction costs and shortening the construction period. Can be achieved. Further, it is possible to exert a large horizontal force with a small number of piles in the pile foundation portion, and further it is possible to prevent stress concentration from occurring in the connection portion between the wall portion and the foundation portion.

[Brief description of drawings]

1 and 2 show one embodiment of the present invention. FIG. 1 is a side sectional view of a PC egg-type digestion tank using the foundation structure of the present invention, and FIG. 2 shows a pile foundation portion. It is a figure which shows II-II of FIG.
Sectional views, FIGS. 3 to 7 are for explaining the conventional technique, FIG. 3 is a side sectional view of a PC egg-type digestion tank using a group pile foundation, and FIG. 4 is a group pile foundation. FIG.
IV-IV sectional view of the figure, Fig. 5 is a side sectional view of the ground near the bottom slab during construction, Fig. 6 is a plan view of a PC steel material helically arranged in the bottom slab, and Fig. 7 is excavation. It is a side sectional view near the bottom slab part under construction in the ground. G: Ground, 10: Pile foundation, 10a: Steel pipe sheet pile,
11 ... Foundation, 11a ... Bottom, 11o ... Wall outer peripheral surface, 12 ... Wall, 12o ... Wall outer peripheral surface, 14 ...
… Basic pillars.

Claims (2)

[Claims] 1. A base structure of a PC egg-shaped digestive tank in which a wall is formed in an oval shape, and a base integrally provided at the bottom of the wall is embedded in the ground. A cylindrical pile foundation is provided by continuously connecting and integrating steel sheet piles in a closed annular shape in the ground, and the bottom surface of the foundation is formed horizontally and the outer peripheral surface is formed vertically. A base portion is provided on the upper portion of the pile foundation portion, and the bottom outer peripheral surface of the egg-shaped wall portion is continuous with the vertical outer peripheral surface of the foundation portion in the ground. Foundation structure. 2. The foundation structure for a PC egg-type digestive tank according to claim 1, further comprising a foundation pillar provided inside the pile foundation portion for supporting a bottom surface of the foundation portion.