The present invention relates to a pile construction comprising a plurality of separate and distinct steel tube sections, which by being formed with male and female portions at their respective ends are adapted to be readily stacked end to end, one on the other, to form a continuous pile of a predetermined length-

Such pile constructions can be used for foundation reinforcement when building houses and similar objects. For this purpose the piles are driven through the ground until they strike the rock base. Sometimes friction piles are used, which do not need to be driven down to the rock base.-

One serious problem about joining separate tube sections to long piles is to obtain a joint with a sufficient stiffness, so that a relative displacement of adjacent tube sections is prevented. A further problem is to prevent corrosion damages on the pile. As the pile is driven through the ground its corrosion protection layer is scraped off by the material in the hole around the pile. In particular the part of the pile that penetrates the ground water level will thereby be exposed to the risk of corrosion damages.

Several different types of joining devices to connect pile sections have been proposed. Such a joining device may consist of a coupling body, that is attachable to a pile section. This coupling body has coupling details mounted thereon. One type of joining devices comprises a flat contact surface, which is disposed in a right angle towards the longitudinal axis of the pile, ^' .-lien two pile sections, each of which having a coupling body as described above, are connected these contact- surfaces are brought to a rigid contact with each other. The known

joining devices have that in common that they are expensive and sometimes sensitive to damages or difficult to apply.

It is an object of this invention to provide improved pile joints, that fulfil the requirement on stiffness and the shape of which makes possible that a transfer of forces is obtained to a sufficient extent. The shape of the joint makes also possible a fast and simple connecti of the separate tube sections. Furthermore is obtained that the risk corrosion damages on the driven pile is reduced. For this purpose the

< invention comprises the features defined in the claim.

The advantages of the invention will become readily apparent when considered in view of the drawing and description thereof in which:

Fig. 1 is a cross-section of the male end of a tube section.

Fig. 2 is a cross-section of the socket end of a tube section.

Each tube section 1 that is comprised in the pile construction is formed with a joining portion when the tube section is cast. One of the ends is formed as a male end 2, the outer surface _. 3 of which is conical inwards towards the centre of the section 1 towards its end ^* . The other end of the tube section 1 is formed as a socket 4, being wider than the remaining part of the section. The interior surface 5 of the socket is conical inwards towards the centre of the section 1 from its end. The conicity of the socket 4 corresponds to that of the male end 2. The socket end 4 of the tube section 1 is furthermore provided with a ^' shoulder 6, the purpose of which will become evident in the following. Reference numeral 7 refers to the driving direction of the pile.

'.hen the pile is driven through the ground the conical contact surface 3 of the male end 2 of each tube section 1 interact with the conical socket end _> of the preceding section 1 in the driving direction 7. The pile is composed of the number of tube sections 1 that are require to reach the rock base. The normal length of a tube section is ^** . metre The shape of the joint makes possible a sufficient stiffness of the pi even when using several tube sections 1. By means of the conical conta surfaces 3. 5 a correct joint between the sections is obtained, said joint being of such a nature that a sufficient transfer of forces is

( OM

VΪ . IP

made possible. To obtain this purpose the conicity must be so small

__, that self-locking is obtained. In a preferred embodiment of the invention the conicity is 1:15.

Since the socket end 4 is wider than the remaining part of each tube section, the tube section that is first driven through the ground will create a hole, which is wider than the tube section 1. This means that the subsequent tube section can be driven through the ground without its principle envelopesurface getting in contact with the ground material. It is thus avoided that the corrosion protection layer is scraped off. In this way a sufficient corrosion protection for the pile is obtained. This is of particular importance for the part of the pile that penetrates the ground water level, said part being particularly exposed to corrosion, After the pile has been driven to a stop, the ground material will be pressed to contact with the pile due .to the pressure in the ground.

^' hen the pile strikes the rock base, the male end 2 is driven against the shoulder 6 in the socket end 4 without eliminating the conical contact.

The invention is not limited to the embodiment described above, but can be varied within the scope of the claim.

O.V.PΪ

J . WIPO , y