Contemplated are simplification and cost reduction in arrangement of connecting a pair of steel pipes to each other. A joint mechanism for a pair of steel pipes 1A, 1B include inner joints 10A, 10B and an outer joint 20 disposed circumferentially across and between the inner joints 10A, 10B. The outer joint 20 incudes inward key portions 23 engageable with outward circumferential grooves 13 of the inner joints 10A, 10B. The outer joint 20 is formed of a plurality of unit members 12 disposed side by side around the inner joints 10A, 10B. A standard unit member 21A includes an engaging projecting portion 24 whereas the inner joints 10A, 10B respective include an engaging sunk portion 14 engageable with the engaging projecting portion for preventing detachment of the standard unit member 21A to the outside. A wall face constituting the engaging sunk portion 14 includes a cutout portion 15A, 15B which allows insertion of the standard unit member 21A to a position where the engaging projecting portion 24 is engageable with the engaging sunk portion 14.

A foundation pile includes a first flange section, a second flange section, and a web section. The first flange section, second flange section, and web section are formed from a single length of material and each comprises at least two layers of the material. A second end of the length of material is wrapped 180-degrees around a first end of the length of material to form a wrapped-around portion in the length of material and a three-layered overlapping region in the first flange section. One or more tabs protrude perpendicularly from the first end of the length of material, such that the tabs are not bent relative to the first end. The one or more tabs extend into respective one or more slots in the length of material adjacent the second end of the length of material. The respective one or more slots are formed in the wrapped-around portion.

A foundation pile includes a first flange section, a second flange section, and a web section. The first flange section, second flange section, and web section are formed from a single length of material and each comprises at least two layers of the material. A second end of the length of material is wrapped 180-degrees around a first end of the length of material to form a wrapped-around portion in the length of material and a three-layered overlapping region in the first flange section. One or more tabs protrude perpendicularly from the first end of the length of material, such that the tabs are not bent relative to the first end. The one or more tabs extend into respective one or more slots in the length of material adjacent the second end of the length of material. The respective one or more slots are formed in the wrapped-around portion.

Method and apparatus for enhancing capacity of piles and/or anchors, which can include any type of piles and/or anchors, including but not limited to micropiles and soil nail, by disposing a tube or casing into the earth and then laterally expanding at least a portion of the casing, in plastic deformation, using an expansion member such that an enlarged area is formed in the casing. The casing can then optionally be left in place and filled with a filler material and/or can optionally be forcibly pulled out of the ground, thus compacting and thereby densifying the surrounding soil, and the thusly formed enlarged hole can be filled with a filler material and used as an anchor and/or pile. Optionally, in one embodiment, existing piles and/or anchors can be re-used by lowering an expansion member into them and creating one or more laterally expanded areas.

The present invention relates to a foundation structure vertically installed on the ground, and comprising: an upper support layer 10 formed on the ground in the vertical direction; and a lower support layer 20 formed so as to extend downward from the upper support layer 10 and such that the width thereof is less than that of the upper support layer 10. The disclosed upper support layer 10 and the lower support layer 20 are structures formed from soil solidified by means of feeding and mixing an earth and soil-solidifying agent therein, and therefore are efficient and prevent overload due to boring equipment.

The present invention relates to a foundation structure vertically installed on the ground, and comprising: an upper support layer 10 formed on the ground in the vertical direction; and a lower support layer 20 formed so as to extend downward from the upper support layer 10 and such that the width thereof is less than that of the upper support layer 10. The disclosed upper support layer 10 and the lower support layer 20 are structures formed from soil solidified by means of feeding and mixing an earth and soil-solidifying agent therein, and therefore are efficient and prevent overload due to boring equipment.

A driven pile comprising a substantially cylindrical shaft, wherein the shaft provides a first pile end and a second pile end, wherein a socket is arranged on the driven pile in the region of the second pile end, wherein the socket or the driven pile has an abutment in the region of the second pile end so that a further driven pile can be inserted with a first pile end as far as a maximum insertion depth defined by the abutment, wherein the socket and/or the driven pile in the region of the second pile end provides or provide in the interior at least one undercut portion extending at least substantially to the abutment.

A driven pile comprising a substantially cylindrical shaft, wherein the shaft provides a first pile end and a second pile end, wherein a socket is arranged on the driven pile in the region of the second pile end, wherein the socket or the driven pile has an abutment in the region of the second pile end so that a further driven pile can be inserted with a first pile end as far as a maximum insertion depth defined by the abutment, wherein the socket and/or the driven pile in the region of the second pile end provides or provide in the interior at least one undercut portion extending at least substantially to the abutment.

A composite structure for a pile foundation for anchoring a tower structure (e.g., an offshore wind turbine) in ground, which includes a hollow pile introduced into the ground at an erection site of the tower structure and a corner post which is connected to the tower structure and which, on a connection side, is arranged within the pile. The pile and the corner post are fixedly bonded to one another in a bonding region by a cured bonding material. At least one bonding means for transmitting shear forces is fixedly arranged on the pile and/or on the corner post in the bonding region. The bonding means has at least one aperture which is filled with the bonding material or, together with the corner post or pile, forms the aperture that is filled with the bonding material. The aperture encloses the bonding material by an angular range of 90 or more.

A composite structure for a pile foundation for anchoring a tower structure (e.g., an offshore wind turbine) in ground, which includes a hollow pile introduced into the ground at an erection site of the tower structure and a corner post which is connected to the tower structure and which, on a connection side, is arranged within the pile. The pile and the corner post are fixedly bonded to one another in a bonding region by a cured bonding material. At least one bonding means for transmitting shear forces is fixedly arranged on the pile and/or on the corner post in the bonding region. The bonding means has at least one aperture which is filled with the bonding material or, together with the corner post or pile, forms the aperture that is filled with the bonding material. The aperture encloses the bonding material by an angular range of 90 or more.