Provided is a method for burying a precast pile in which a borehole and a buried precast pile are strongly integrated, the end bearing capacity and the circumferential frictional force of the precast pile are increased, and the extraction resistance strength thereof is improved. Provided is a method for burying a precast pile in which a foaming agent having an expanding effect is added to the cement milk or mortar in advance, whereby the soil cement formed around the base of the precast pile in the borehole is caused to expand.

Soil displacement piles having a shaft and one or more soil displacement assemblies secured to the shaft are provided. If more than one soil displacement assembly is utilized, each soil displacement assembly is separated by a longitudinal distance. Each soil displacement assembly has an upper helical plate, a lower helical plate separated from the upper helical plate by a longitudinal plate distance, and at least one soil displacement plate positioned relative to the shaft, the upper helical plate and the lower helical plate.

The invention relates to a method of building a foundation (1) comprising a steel monopile (2) and a precast concrete part (3) on top of the monopile (2), comprising:arranging a support structure (12) inside the monopile (2), the support structure (12) having a plurality of rods (16) extending radially with respect to a longitudinal axis of the monopile; bringing the concrete part (3) above the monopile (2), with supporting columns (13) interposed between the support structure (12) and the concrete part (3), wherein reinforcement bars (14) protruding from a bottom surface (9) of the precast concrete part (3) extend downwardly beyond the support structure (12) by passing between the rods (16) of the support structure (12); arranging tendons (15) between the support structure (12) and the concrete part (3) and tensioning the tendons (15); andpouring concrete into an upper part of the monopile (2).

The present invention provides a wave-shaped grouting bulb (100) for securing an underground bearing capacity of a steel bar (10), the bulb comprising a plurality of protrusions (120), which have a predetermined maximum diameter (D1) and are formed along the longitudinal direction of a cylindrical pillar part (110) extending downward, wherein the neighboring protrusions (120) are formed to be spaced from each other by a predetermined formation distance (s). The present invention has an advantageous effect of improving a skin friction force and resistance to compression and pullout in the grouting bulb integrated with the steel bar and thus enhancing structural stability in the micropile body.

The present invention provides a wave-shaped grouting bulb (100) for securing an underground bearing capacity of a steel bar (10), the bulb comprising a plurality of protrusions (120), which have a predetermined maximum diameter (D1) and are formed along the longitudinal direction of a cylindrical pillar part (110) extending downward, wherein the neighboring protrusions (120) are formed to be spaced from each other by a predetermined formation distance (s). The present invention has an advantageous effect of improving a skin friction force and resistance to compression and pullout in the grouting bulb integrated with the steel bar and thus enhancing structural stability in the micropile body.

A hybrid foundation structure includes a first perforation hole formed in the ground, at least one second perforation hole formed adjacent to the first perforation hole on a side surface of the first perforation hole, and a first pile and a second pile formed by mixing and injecting soil and soil solidifying agent into the first perforation hole and the second perforation hole.

A hybrid foundation structure includes a first perforation hole formed in the ground, at least one second perforation hole formed adjacent to the first perforation hole on a side surface of the first perforation hole, and a first pile and a second pile formed by mixing and injecting soil and soil solidifying agent into the first perforation hole and the second perforation hole.

A method for the construction of composite under-reamed pile, including: implementing a jet grouting and agitation at a pre-designed position to form a composite cemented-soil foundation; constructing the pile hole with a drilling rig, during which bulb cavities are formed when the pile structure includes bulbs; cleaning the pile hole, lifting down a reinforcing cage, lowering a concrete pouring conduit to the pile hole, and lifting the pouring conduit while pouring the concrete; the hardened concrete becoming a pile stem in the pile hole and a bulb in the bulb cavity. Thus, this construction method can completely eliminate the hole collapse risk at the bulb cavity position during drilling; the combined structure of the bulb and the composite cemented-soil foundation can greatly improve the bearing capacity of pile foundation, significantly reduce the settlement risk and the cost of the pile foundation, as well as shorten construction period.

A method for the construction of composite under-reamed pile, including: implementing a jet grouting and agitation at a pre-designed position to form a composite cemented-soil foundation; constructing the pile hole with a drilling rig, during which bulb cavities are formed when the pile structure includes bulbs; cleaning the pile hole, lifting down a reinforcing cage, lowering a concrete pouring conduit to the pile hole, and lifting the pouring conduit while pouring the concrete; the hardened concrete becoming a pile stem in the pile hole and a bulb in the bulb cavity. Thus, this construction method can completely eliminate the hole collapse risk at the bulb cavity position during drilling; the combined structure of the bulb and the composite cemented-soil foundation can greatly improve the bearing capacity of pile foundation, significantly reduce the settlement risk and the cost of the pile foundation, as well as shorten construction period.

A concrete variable cross-section prefabricated square pile comprises pile bodies of large cross-section sections and small cross-section sections alternately arranged along a longitudinal direction. Lateral transition surfaces are formed between side surfaces of the large cross-section sections and adjacent small cross-section sections; at least part of the lateral transition surfaces have a front edge and/or a rear edge that are offset from a vertical direction in a lateral projection, and a vertical projection of an intersection line between the lateral transition surface and a first horizontal plane is located outside a vertical projection of an intersection line between the lateral transition surface and a second horizontal plane; the first horizontal plane is a horizontal plane located above in any two horizontal planes, and the second horizontal plane is a horizontal plane located below in any two horizontal planes.