JP2019031821A - Construction method of underground tank - Google Patents

Abstract

To provide a construction method of underground tank capable of reducing the construction period.SOLUTION: A construction method of an underground tank comprises: a first drilling step of drilling a continuous wall hole part 7A in which an underground continuous wall 5 is installed in the ground G; an underground continuous wall construction step of constructing the underground continuous wall 5 in the continuous wall hole 7A; a second drilling step of drilling a heater hole portion 7B for installing a side heater 6 on the outside the continuous wall hole portion 7A; a side heater setting step of installing the side heater 6 in the heater hole portion 7B; a tank body construction step of constructing a tank main body 10 having a bottom plate 2 and a cylindrical side wall 3 inside the underground continuous wall 5; and an embankment step of embanking so as to cover the outside of the tank body 10. The side heater setting step is carried out before the tank main body building step.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an underground tank construction method.

  Conventionally, low-temperature liquids such as liquefied natural gas (LNG) are stored in underground tanks buried in the ground. The underground tank includes a bottom plate, a side wall constructed around the bottom plate, and a roof covering an upper portion of the side wall. In order to prevent the ground around the underground tank from freezing due to the cold heat of the liquid in the underground tank, it is widely known that a side heater is installed on the side of the underground tank (outside the side wall). (See Patent Documents 1 to 3 below).

  The construction procedure for such underground tanks is to build a cylindrical underground continuous wall in the ground, excavate the interior of the underground continuous wall, and build a frame such as a bottom plate, side walls, and roof. Performing embankment. On the other hand, the side heater is installed by excavating (drilling) a hole for installing the side heater after the side wall is constructed, and installing the side heater in the hole when embankment is performed.

JP 2000-282495 A JP-A-62-83599 JP-A-6-221028

  However, the side heater drilling work overlaps with the roof construction work, and the side heater installation work overlaps with the embankment work, so the roof construction work and embankment work is the side heater drilling work. There is a problem that it is a critical path that affects the installation work (or the side heater drilling work or installation work affects the roof construction work or the banking work).

  Then, this invention is made | formed in view of the said situation, and provides the construction method of the underground tank which can shorten a construction period.

In order to achieve the above object, the present invention employs the following means.
That is, the underground tank construction method according to the present invention includes a continuous underground wall formed in the ground and formed into a cylindrical shape, and a tank body that is built inside the continuous underground wall and can store liquid. An underground tank construction method comprising: a side heater installed outside the continuous underground wall, wherein an annular continuous wall hole in which the underground continuous wall is installed in the ground A first drilling step for excavation; an underground continuous wall construction step for constructing the underground continuous wall in the continuous wall hole portion; and the side heater is installed outside the continuous wall hole portion. A second drilling step of excavating the heater hole, a side heater installation step of installing the side heater in the heater hole, a bottom plate and a cylindrical side wall inside the underground continuous wall; A tank body construction step for constructing a tank body having And a fill step of performing said second heater installation process is characterized in that it is carried out in the front of the tank body building process.

  In the construction method of the underground tank constructed in this way, the side heater installation process deviates from the critical path by performing the side heater installation process before the tank body construction process. Can be planned.

  The underground tank construction method according to the present invention includes a side heater extending step of extending the side heater installed in the side heater installation step upward by the height of the embankment, and the tank body construction. A side wall extending step of extending the side wall constructed in the process upward by the height of the embankment, and the side heater extending step and the side wall extending step after the tank body constructing step, and It is preferable to carry out before the embankment process.

  In the construction method of the underground tank configured as described above, the side heater and the side wall extended upward in the side heater extending step and the side wall extending step are reliably embedded in the embankment in the subsequent embankment step. Furthermore, since the side heater stretching step and the side wall stretching step are performed before the embankment step, the side heater stretching step deviates from the critical path, so that the work period can be shortened as compared with the conventional method.

  According to the construction method of the underground tank according to the present invention, the construction period can be shortened.

It is a typical longitudinal section showing an underground tank concerning one embodiment of the present invention. It is a typical top view showing an underground tank concerning one embodiment of the present invention. It is a figure which shows the underground continuous wall construction process of the construction method of the underground tank which concerns on one Embodiment of this invention. It is a figure which shows the side part heater installation process of the construction method of the underground tank which concerns on one Embodiment of this invention. It is a figure which shows the tank main body construction process of the construction method of the underground tank which concerns on one Embodiment of this invention. It is a figure which shows the side part heater extending process and side wall extending process of the construction method of the underground tank which concerns on one Embodiment of this invention. It is a figure which shows the embankment process of the construction method of the underground tank which concerns on one Embodiment of this invention.

The construction method of the underground tank which concerns on one Embodiment of this invention is demonstrated using drawing.
First, the underground tank will be described.
FIG. 1 is a schematic longitudinal sectional view showing an underground tank according to an embodiment of the present invention. FIG. 2 is a schematic plan view showing an underground tank according to an embodiment of the present invention.
As shown in FIG.1 and FIG.2, the underground tank 1 which concerns on this embodiment is used as an LNG storage tank, for example. The underground tank 1 includes a tank main body 10, an underground continuous wall 5 constructed along the outer peripheral surface of the tank main body 10, and a side heater 6 provided outside the underground continuous wall 5. .

  The tank body 10 includes a bottom plate 2 having a substantially circular shape in plan view installed below the ground G surface, a substantially cylindrical side wall 3, and a dome-shaped roof 4 supported by the upper end 3 a of the side wall 3, have.

  The bottom slab 2 is made of reinforced concrete, and is constructed on the crushed stone layer 11 provided on the ground G excavated. A bottom heater (not shown) for adjusting the temperature in the underground tank 1 is installed inside the bottom plate 2.

  The side wall 3 is made of reinforced concrete, and the lower end 3 b is rigidly joined to the outer edge 2 a of the bottom plate 2. The bottom plate 2 and the side wall 3 form a bottomed cylindrical shape. On the inner surfaces of the bottom plate 2 and the side wall 3, a cold insulating material and a membrane material (not shown) are installed.

  Since the outer periphery of the upper side of the side wall 3 is embanked during construction of the underground tank 1, the underground tank 1 is configured to be disposed underground.

  The roof 4 is made of reinforced concrete, has a circular shape in plan view, and is connected to the upper end 3 a of the side wall 3.

  The ground G on the outer periphery on the lower end 3 b side of the side wall 3 is provided with an underground continuous wall 5 having an annular shape in plan view in a shape along the outer peripheral surface of the side wall 3.

  The underground continuous wall 5 has a function of preventing the ground G from collapsing and a water stop function as a soil retaining. The underground continuous wall 5 is constructed deeper than the bottom slab 2 of the underground tank 1, and the lower end portion 5 b reaches the hardly permeable layer (cold clay layer) 13. The underground continuous wall 5 is constructed of, for example, reinforced concrete.

  A plurality of side heaters 6 are installed outside the underground continuous wall 5. The side heaters 6 are arranged at intervals in the circumferential direction of the underground continuous wall 5. The side heater 6 is for suppressing freezing and expansion of the ground G. In the present embodiment, the side heater 6 has a substantially circular shape in plan view. For example, the side heater 6 has a double structure for flowing warm water.

Next, the construction method of the above-described underground tank 1 will be described.
In advance, ground improvement work or ground surface layer excavation work for lowering the surface layer portion of the ground G so as to be lower than the surrounding ground G is performed.

(First drilling process)
A continuous wall groove (continuous wall hole) 7 </ b> A is provided along the planned location of the underground continuous wall 5. In plan view, the continuous wall groove 7A has an annular shape.

(Underground continuous wall construction process)
FIG. 3 is a diagram illustrating an underground continuous wall construction process.
As shown in FIG. 3, the underground continuous wall 5 is constructed by a well-known technique in which concrete is placed by placing reinforcing bars in the continuous wall groove 7A.

(Second drilling process)
As shown in FIG. 2, a heater hole (heater hole) 7 </ b> B is provided along a planned installation location of the side heater 6 by a boring machine or the like. In plan view, the heater hole 7B has a circular shape. A plurality of heater holes 7B are provided outside the continuous wall groove 7A, that is, outside the continuous wall groove 7A in the radial direction, with an interval in the circumferential direction of the continuous wall groove 7A.

(Side heater installation process)
FIG. 4 is a diagram illustrating a side heater installation process.
As shown in FIG. 4, the side heater 6 is installed in the heater hole 7B. In the present embodiment, the lower end 6b side (referred to as the lower heater 6X) of the side heater 6 is installed. In other words, the upper end 6a side of the side heater 6 shown in FIG. 1 is not yet installed at this stage.

(Tank body construction process)
FIG. 5 is a diagram showing a tank body construction process.
As shown in FIG. 5, the bottom plate 2 and the lower end 3b side (referred to as the lower side wall 3X) of the bottom plate 2 and the side wall 3 are known by excavating the inside of the underground continuous wall 5 and placing concrete by placing reinforcing bars. To construct. In other words, the upper end 3a side of the side wall 3 shown in FIG. 1 is not constructed again at this stage.

(Side heater stretching process and side wall stretching process)
FIG. 6 is a diagram illustrating a side heater stretching step and a side wall stretching step.
As shown in FIG. 6, the upper side 6a side (referred to as the upper heater 6Y) of the side heater 6 is connected to the upper side of the lower heater 6X installed in the side heater installation process, and the entire side heater 6 is constructed. To do. Also, the side wall 3 is constructed by constructing the upper end 3a side (referred to as the upper side wall 3Y) of the side wall 3 above the lower side wall 3X constructed in the tank body construction process. Thereafter, the roof 4 (see FIG. 1) is constructed. The height of the upper heater 6Y and the upper side wall 3Y corresponds to the height of embankment Ga (see FIG. 7) described later.

(Filling process)
FIG. 7 is a diagram illustrating the embankment process.
As shown in FIG. 7, embankment is performed to a height near the upper end portion 3 a of the side wall 3 so that the outer peripheral surface of the side wall 3 is buried in the ground. In FIG. 1, the embankment ground G is shown as Ga.

  According to the construction method of the underground tank 1 configured as described above, the side heater installation process is deviated from the critical path by performing the side heater installation process before the tank body construction process. The construction period can be shortened.

  Further, the side heater (upper heater 6Y) and the side wall (upper side wall 3Y) extending upward in the side heater extending step and the side wall extending step are reliably embedded in the embankment in the subsequent embedding step. Furthermore, since the side heater stretching step and the side wall stretching step are performed before the embankment step, the side heater stretching step deviates from the critical path, so that the work period can be shortened as compared with the conventional method.

  The various shapes and combinations of the constituent members shown in the above-described embodiments are merely examples, and various modifications can be made based on design requirements and the like without departing from the gist of the present invention.

DESCRIPTION OF SYMBOLS 1 ... Underground tank 2 ... Bottom slab 3 ... Side wall 4 ... Roof 5 ... Underground continuous wall 6 ... Side heater 7A ... Continuous wall groove (hole for continuous wall)
7B ... Heater hole (Heater hole)
10 ... Tank body 11 ... Crushed stone layer G ... Ground

Claims (2)

An underground continuous wall constructed in the ground and formed into a cylindrical shape, a tank body constructed inside the underground continuous wall and capable of storing liquid, and a side installed outside the underground continuous wall An underground tank construction method comprising:
A first drilling step of excavating an annular continuous wall hole in which the underground continuous wall is installed in the ground;
An underground continuous wall construction step of constructing the underground continuous wall in the hole for the continuous wall;
A second drilling step of excavating a heater hole in which the side heater is installed outside the continuous wall hole;
A side heater installation step of installing the side heater in the heater hole;
A tank body construction step for constructing a tank body having a bottom plate and a cylindrical side wall inside the underground continuous wall;
A banking step of banking to cover the outside of the tank body,
The underground heater construction method, wherein the side heater installation step is performed before the tank body construction step. A side heater extending step of extending the side heater installed in the side heater installing step upward by the height of the embankment;
A side wall extending step of extending the side wall constructed in the tank main body construction step upward by the height of the embankment,
The underground tank construction method according to claim 1, wherein the side heater stretching step and the side wall stretching step are performed after the tank body construction step and before the embankment step.

Images