JPH07103559B2 - Construction method for steel pipe piles - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for driving a steel pipe pile used as a foundation pile for supporting a marine structure, for example.

<Prior art> When using steel pipe piles as foundation piles for offshore structures, the pile diameter, pile length, and number of piles are planned according to the soil properties of the seabed at the construction site.

By the way, in general, since the pile opposes the pulling out only by the peripheral frictional force, the resistance against the pulling out force is small.

Therefore, when resistance to the pulling force is required, sufficient pulling strength can be obtained by securing a sufficient pile length of the steel pipe pile during construction and reaching the deep part of the ground during the driving.

However, especially when it is used as a foundation pile for offshore structures, it is necessary to secure the height from the sea bottom to the sea surface and the height from the sea surface to the structure in addition to the driving depth.
The pile length is also limited by the size of construction machinery such as a pile driver.

For this reason, in many cases, it is not possible to actually drive into the ground to a sufficient depth.

Therefore, in the past, the number of piles was increased to compensate for the fact that the pile length could not be secured.

<Problems to be solved by the invention> However, when the number of piles is increased, the man-hours for placing work are increased, the number of joints with the structure above the pile is increased, and the amount of concrete on the structure side is also increased. There were drawbacks such as.

The present invention solves the above problems and enables anchoring of a cast steel pipe pile by a simple process without the need for casing casting work, and a sufficient pull-out resistance can be obtained with a small number of cast pipes. The purpose of the present invention is to provide a method for driving a steel pipe pile.

<< Means for Solving the Problem >> In order to achieve the above-mentioned object, the present invention, on the outer periphery of a steel pipe pile, joins a plurality of guide pipes protruding from the tip of the pile in parallel, and driving the steel pipe pile against the ground. After the completion, an anchor material is inserted into the guide pipe, one end of this anchor material is fixed to the lower ground of the steel pipe pile, and the other end is fixed to the upper structure.

<Operation> According to the above configuration, since the anchor material fixed between the ground and the upper structure is provided on the outer periphery of the steel pipe pile, the steel pipe pile opposes the pushing force and also withstands the pulling force. Anchor material opposes.

<< Embodiment >> An embodiment of the present invention will be described in detail below with reference to the drawings.

1 and 2 show a steel pipe pile used in the method of the present invention.

On the outer circumference of the steel pipe pile 1 in the figure, a pair of guide pipes 2 are arranged parallel to each other at 180 ° intervals along the longitudinal direction and integrally joined by welding.

The diameter and the pile length of the steel pipe pile 1 are set depending on the soil properties of the seabed on which it is laid, constraints on construction, etc., and the reinforcing ribs 3 in the shape of a cross are formed on the inner circumference of the tip. It is provided.

Each of the guide pipes 2 is made of a steel pipe, and the upper end thereof is located at a position lower than the top of the steel pipe pile 1 by an actual size of about 1,000 mm to prevent deformation due to hammering.

In addition, the tip 2a of the guide tube 2 protrudes from the tip of the steel pipe pile 1 by about 500 mm in actual size to prevent cavitation of the tip of the steel pipe pile 1 due to stirring during punching, which will be described later, and to cut out diagonally. The penetration resistance at the time of driving is reduced.

Further, the inside of the tip portion 2a is joined to a triangular reinforcing rib 4 whose lower portion is joined to the reinforcing rib 3 to prevent the tip portion 2a from buckling due to the driving pressure.

The diameter of the guide tube 2 is set to an actual size in the range of 162.5 to 216.3 mm in consideration of insertion of a drill bit and injection of a solidifying material.

As shown in FIG. 3, the steel pipe pile 1 having the above-described configuration is driven to a predetermined depth of the seabed ground E by an impact hammer of a pile driving ship. After the driving of the predetermined number of steel pipe piles 1 is completed, the skeleton 5 of the offshore structure is built on top of the steel pipe piles 1.

Each of the steel pipe piles 1 is driven in an inclined state so as to face the frame 5 in a V-shape in order to give a resistance force to a horizontal force.

In addition, after building the skeleton 5 or after constructing the scaffold, a bit for piercing is introduced from the upper part of the guide pipe 2, and the ground E is pierced by projecting at the tip of the guide pipe 2 and an anchor material such as a steel rod is provided. After inserting 7 into the guide tube 2, by injecting a solidifying material through the guide tube 2 and hardening the solidifying material,
The lower end of the anchor material 7 is fixed to the lower ground of the steel pipe pile 1.

Then, when the fixing of the lower end of the anchor material 7 is completed, the upper end of the anchor material 7 is fixed to the skeleton 5 side, and at this time, tension is introduced into the anchor material 7.

Therefore, in the completed construction state, the combination of the pushing resistance force obtained corresponding to the driving depth of the steel pipe pile 1 and the pulling resistance force of the anchor material 7 makes it possible to pull the steel pipe pile 1 without increasing its length. Power increases.

In this embodiment, two guide pipes 2 are provided for each steel pipe pile, and two anchor members 7 are provided, but if more anchor pipes 7 are provided, the pullout resistance can be further increased.

Further, it goes without saying that the present invention can be applied not only to foundation piles for offshore structures but also to construction of various structures using steel pipe piles.

<< Effects of the Invention >> As described in detail with reference to the embodiments above, in the method for placing a steel pipe pile according to the present invention, since the anchor material can be constructed on the side portion of the steel pipe pile using the guide pipe as a guide, This can be carried out more easily than the construction method in which the anchor portion is formed by casting the casing or the like.

In addition, with this construction method, the resistance to pulling out when steel pipe piles of the same length are driven can be increased, the number of piles driven against the planned strength can be reduced, and it is not necessary to use excessively long steel pipe piles. It is possible to reduce the size of pile driving ships and other pile driving machines, which is advantageous in terms of economic efficiency and construction period compared to the past.

[Brief description of drawings]

FIG. 1 is a side view of a steel pipe pile used in the present invention, FIG. 2 is a perspective view showing the bottom of the steel pipe pile, and FIGS. 3 and 4 are explanatory views showing a driving method using the steel pipe pile. Is. 1 …… Steel pipe pile, 2 …… Guide pipe 2a …… Tip part, 7 …… Anchor material

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-48-2820 (JP, A) JP-A-62-268423 (JP, A) JP-B-55-21135 (JP, B2) JP-B-63- 49765 (JP, B2) Ernst Bax, Kashima Kenkyu Shuppankai, published in 1969, "Basic construction methods for field engineers" p. 319

Claims (1)

[Claims] 1. A plurality of guide pipes projecting from the tip of the pile are joined in parallel to the outer periphery of the steel pipe pile, and an anchor material is inserted into the guide pipe after completion of the operation of placing the steel pipe pile on the ground. A method for placing a steel pipe pile, characterized in that one end of the material is fixed to the lower ground of the steel pipe pile and the other end is fixed to the upper structure.