JPH0699940B2 - Method of constructing underground skeleton and formwork for underground skeleton construction - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method of constructing an underground skeleton for constructing a skeleton of a construction structure in the ground and a formwork for constructing an underground skeleton.

<Prior Art> Conventionally, when constructing a skeleton of a building structure such as a building in the ground, root cutting work is generally performed. To perform this root cutting work, first build a mountain retaining wall to support the earth pressure and water pressure acting from the ground around the root cutting, and while performing the support work sequentially inside the mountain retaining wall, The ground is excavated to the required depth. The formwork was supported by the floor surface and wall surface in the excavation mine excavated as described above, and concrete was placed to construct the underground structure.

<Problems to be solved by the invention> In the conventional method of constructing an underground skeleton, when root cutting work is performed up to the flooring surface, construction of mountain retaining wall → excavation → support work → conventional excavation → support work ... Since it has to be repeated, the construction period for the construction of the underground structure tends to be long as a whole, and thus the construction cost is increased.

In addition, when excavating the ground, groundwater is often contained in the ground, and before excavation, by the groundwater reduction method such as the Dapwell method and the Wellpoint method,
Although the groundwater level is being lowered to the excavated surface, when the groundwater level is lowered, subsidence of the surrounding ground may occur, which may cause environmental problems.

The present invention has been made to solve the above-mentioned drawbacks, and its purpose is to shorten the construction period from root cutting to construction of an underground skeleton, reduce the construction cost, and further reduce the surrounding ground such as ground subsidence. It is intended to provide a method for constructing an underground skeleton and a formwork for constructing an underground skeleton that do not adversely affect the above.

<Means for Solving the Problems> The present invention has been made in view of the above objects, and the gist thereof is a method of constructing a skeleton of a building structure in the ground. A first step of excavating the ground into a predetermined shape while supporting, and a second step of suspending a water-permeable formwork for constructing a skeleton in the excavation mine excavated in the first step. A third step of pouring concrete into the formwork installed in the muddy water by the second process, thereby draining the muddy water entering the formwork to the outside of the formwork by the water permeability of the formwork And a fourth step of discharging the muddy water filled in the excavation mine after the concrete poured in the third step is hardened.

Another aspect of the present invention is a formwork installed in muddy water for constructing an underground structure, wherein the formwork is a rebar cage assembled in a desired shape, and a formwork of the outer peripheral portion of the rebar cage. Among them, for the construction of the underground skeleton, which consists of at least a form plate provided on the inner surface of the structure to be constructed, and which has water permeability for discharging the muddy water in the form to the outside. On the formwork.

The material of the mold plate having water permeability is preferably expanded metal, lath metal or the like, and the mold plate is provided with a large number of water permeates for draining muddy water, or the mold plate itself is meshed. It is preferable that the structure has water permeability such that muddy water inside the mold can be discharged at the time of placing concrete.

<Examples> A method for constructing an underground skeleton and a formwork for constructing an underground skeleton according to the present invention will be described with reference to the accompanying drawings.

As shown in FIGS. 1a and 1b, the concrete formwork 10 is
It has a reinforcing bar cage 14 (see FIG. 3) in which a column reinforcing bar 11 extending in the vertical direction, a beam reinforcing bar 12 extending in the horizontal direction, and a hoop reinforcing bar 13 are manufactured into a desired underground structure by welding and wire binding, etc. It is composed of a form plate 15 provided on the inner surface of the underground skeleton except for the mine wall side of 14. The form plate 15 is attached to the rebar cage via a spacer 17. The mold plate 15 is provided with a large number of water passage holes 16 for draining muddy water in the mold plate 15 to the outside, and as will be described later, the mold 10 installed in muddy water is used.
When pouring concrete into the mold, the mud water and concrete in the form 10 can be easily replaced. In particular, when using a conventional non-water-permeable form, muddy water was trapped by the concrete placed in the corners, etc. By providing it, such a defect can be eliminated.

Next, a method of constructing an underground skeleton using the concrete formwork 10 will be described in the order of steps.

First, root cutting work is performed to build the underground structure (second
Figure). For this rooting work, a reverse circulation type excavator 18 or the like is used, and the groundwater level 0.
Excavation is carried out by applying a mud pressure of ² kg / cm ² and supporting the lateral pressure of the trench wall. After excavating into a desired shape, the formwork 10 is suspended in the muddy water of the excavation pit 19 using a crane or the like (FIG. 3). At this time, muddy water enters the formwork 10 installed in the excavation pit through the water passage holes 16 of the formwork plate 15. Next, the tremie pipe 20 is inserted into the vicinity of the lower part of the mold 10 installed in the muddy water, and concrete is poured (FIG. 4). When pouring concrete in muddy water, keeping the lower end of the tremie pipe 20 always buried in concrete,
It is necessary to pull out gradually. In this way, by sequentially placing concrete in the mold 10, muddy water in the mold 10 is drained to the outside of the mold 10 through the water holes 16 of the mold plate 15,
The replacement of concrete with muddy water in the mold 10 is favorably performed. The form plate 15 is not provided on the side surface of the formwork 10 on the mine wall 21 side, and concrete is directly placed on the mine wall 21. Further, after the cast concrete is hardened, the formwork plate 15 is removed, all the muddy water in the excavation pit 19 is discharged, and the construction process of the underground skeleton 22 is completed.

<Effect> According to the present invention, after excavating while supporting the lateral pressure of the groove wall by the mud pressure, the water-permeable mold is suspended in the mud,
Since the method of placing concrete in the formwork and constructing the underground skeleton is adopted, there is no need for mountain fastening and support work, so the construction period from root cutting to underground skeleton construction can be shortened, and construction The cost can be reduced.

In addition, by using a water-permeable form, slime is discharged out of the form along with muddy water when pouring concrete, preventing the inclusion of slime in the pouring concrete,
It is possible to prevent a decrease in concrete strength due to inclusion of impurities.

Furthermore, even in the corners where concrete is difficult to turn around in a conventional non-water-permeable formwork, concrete can be placed in every corner of the formwork because drainage is performed through the water-permeable formwork. Exerts the excellent effect of.

[Brief description of drawings]

FIG. 1a is a plan view of the mold 10, and FIG. 1b is a broken line in FIG. 1a.
The enlarged views in Ib, FIGS. 2 to 5 are schematic cross-sectional views showing the process of constructing an underground skeleton. 10 …… Formwork, 14 …… Reinforcing cage, 15 …… Formwork plate, 16 …… Water passage hole, 21 …… Mine wall, 22 …… Skeletal structure.

Claims (2)

[Claims] 1. A method of constructing a skeleton of a building structure in the ground, comprising a first step of excavating the ground into a predetermined shape while supporting a lateral pressure of a groove wall by mud pressure, and the first step. The second step of suspending the water-permeable formwork for constructing the skeleton in the excavation mine that was excavated in the step of (3), and the concrete is placed in the formwork installed in the muddy water by the second step. By this, the third step of draining the muddy water that has entered the mold to the outside of the mold by the water permeability of the mold, and the hardening of the concrete poured in the third step, and then filling the excavation mine The method for constructing an underground skeleton, which comprises a fourth step of discharging the collected muddy water. 2. A formwork to be installed in mud water for constructing an underground structure, wherein the formwork is at least a rebar cage assembled in a desired shape and a formwork on the outer peripheral portion of the rebar cage. An underground skeleton construction characterized in that it consists of a form plate provided on the inner surface of the structure to be constructed, and that this form plate has water permeability for discharging muddy water in the form to the outside. Formwork.