JP2928938B2 - Caisson laying method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a caisson sinking technique, and more particularly, to a caisson sinking method suitable for sinking at a large depth.

<Conventional technology> When a caisson is sunk to a large depth, auxiliary methods such as loading and press-fitting have been used in addition to the caisson's own weight, but the loading / unloading of the load and refilling of press-fit jacks are complicated. Easy to be.

Therefore, as measures to solve such inconveniences, air, water, bentonite, etc. are blown out from the surface of the caisson to reduce the frictional resistance between the caisson and the ground, or to reduce the NF sheet between the caisson and the ground. A method of interposing a friction sheet has been proposed.

<Problems to be Solved by the Present Invention> The above-described conventional caisson laying technique has the following problems.

<B> In the method of blowing out air, water, bentonite, etc., there is a risk that the ground is easily loosened and land subsidence is induced.

<B> In the case of using a low-friction sheet, the frictional resistance between the low-friction sheet and the caisson body increases as the immersion depth increases, so that the low-friction sheet is easily broken.

<C> For the caisson such as an annular shape that generates frictional force on both the inside and outside of the caisson, the inconvenience of the above <A> and <B> has been a bottleneck for construction.

<D> If the caisson to be laid is long, the caisson is connected at the site in parallel with the laying work.

However, since it takes time to assemble and disassemble the formwork, and there is a shortage of skilled formworkers, a proposal for an improvement plan is desired.

<E> Also, due to such a situation, the caisson is being laid at a large depth, and the construction period and costs are increasing.

<Object of the present invention> The present invention has been made to solve the above problems, and an object of the present invention is to provide a caisson squatting method suitable for deep sunking and excellent in workability. It is in.

<Means for Solving the Problems> That is, the present invention uses a mold having a low coefficient of friction and formed of a high-strength material, and constructs a caisson by positioning the form on the peripheral surface of the caisson body. A caisson squatting method in which a caisson is sunk while the formwork is attached. A method of laying a caisson, wherein the caisson is sunk while being interposed between a ground and a mold forming an outer peripheral surface of the caisson body.

<Description of the Present Invention> Hereinafter, the present invention will be described with reference to the drawings.

<A> Form used The present invention is different from the related art in that the material of the form 2 used for molding the caisson 1 and that the form 2 is used as a component of the caisson 1.

That is, in the present invention, the mold 2 formed of a high specific strength inorganic material having a small coefficient of friction and high strength is used.

<B> Material example As the material of the mold 2, for example, HMC (Heat Melamine Com
posite).

If the material simply satisfies the condition that the coefficient of friction is small, there are Teflon plates and various materials. However, when the caisson is laid, it is damaged by being rubbed by sand or gravel, and the characteristic of a low coefficient of friction cannot be maintained.

However, HMC has excellent compressive strength of 700 to 1200 kgf / cm ² , and has a smooth surface and an extremely small friction coefficient.

More specifically, it is processed into a thin plate with a thickness of about 2 cm at a factory, etc.
To produce

<Operation> Next, a caisson laying method will be described with reference to FIG.

<A> Assembling of the formwork The known formwork 2 is used to frame the caisson 1 frame width.

When the frame of the formwork 2 is performed, a vertical flap 3 and a horizontal flap 4 are used, and a reinforcing bar 5 is further arranged inside.

The pitch of these butterflies 3 and 4 can be widened by the strength of the mold 2.

<B> Casting concrete Next, concrete 6 is cast inside the formwork 2 to extend the side portion 11 of the caisson 1.

After the concrete 6 has hardened, the vertical flutter 3 and the horizontal flutter 4 are removed.

The mold 2 is left fixed to the side surface 11 of the caisson 1 integrally.

<C> Settlement of caisson In parallel with the construction work of the side part 11, the blade part of the caisson 1
At 12, excavation work is performed and caisson 1 is laid down.

A high-strength mold 2 having a small coefficient of friction is attached to the entire outer periphery of the side portion 11 of the caisson 1.

Therefore, even if the intruded ground is sand layer or gravel layer,
The caisson 1 can be laid with low frictional resistance without damaging the caisson.

The formwork 2 may be attached also to the outer peripheral surface of the blade opening 12 of the caisson 1 which comes into contact with the ground.

<D> When the penetration resistance is expected to increase When the penetration ground of the caisson 1 is a cohesive soil layer, the friction resistance between the ground and the formwork 2 increases and the penetration resistance of the caisson 1 may increase. is expected.

Therefore, in such a case, as shown in FIG.
A roll in which a metal low-friction sheet 7 having a small coefficient of friction has been wound is housed in the outer peripheral side of the cutting edge 12 so as to be able to be pulled out, and the drawing end of the low-friction sheet 7 is fixed to the ground side. When the caisson 1 is laid down, the low friction sheet 7 is pulled out in accordance with the amount of the caisson 1 laid down, and the pulled out low friction sheet 17 is sequentially interposed between the ground and the formwork 2.

By pulling out the low-friction sheet 12 from the side of the cutting edge 12, the low-friction sheet 7 is prevented from rubbing against the ground while the caisson 1 penetrates, and is broken. The low friction sheet 7 and the formwork 2 can exhibit their low friction performance to the maximum extent.

Since the low-friction sheet 7 and the mold 2 have a small coefficient of friction with each other, the caisson 1 can be laid with extremely low penetration resistance.

When the low-friction sheet 7 is used in combination, the frictional resistance is significantly smaller than when the low-friction sheet 7 is in direct contact with the concrete.

<Effects of the Present Invention> The present invention is as described above, and the following effects can be obtained.

<A> A low friction sheet is interposed between the ground and the formwork, and the caisson can be sunk with a small penetration force while maximizing the low friction performance of the low friction sheet and the formwork. it can.

<B> A caisson can always be laid with a stable small penetration force without being affected by the nature of the ground.

<C> The low-friction sheet does not rub against the ground while the caisson is penetrating and is not damaged.

<D> Conventionally, it was necessary to adopt an auxiliary method to reduce the frictional resistance between the caisson and the ground by spraying water, air, benton, etc. from the surface of the caisson, but such an auxiliary method is unnecessary in the present invention Becomes

[Brief description of the drawings]

 Fig. 1: Overall view showing caisson sunk means according to the present invention Fig. 2: Partial sectional view of lower part of caisson

Claims (1)

(57) [Claims] 1. A caisson is constructed by using a mold having a small coefficient of friction and formed of a high-strength material, and positioning the mold on the peripheral surface of a caisson body. In the method of sinking a caisson to be sunk, a low-friction sheet is retractably housed in an outer peripheral portion of a blade portion of the caisson, and the low-friction sheet pulled out in accordance with the sinking of the caisson is removed from the ground and an outer peripheral surface of the caisson body. A method of laying a caisson, wherein the caisson is laid down while being interposed between the formwork to be formed.