Mandrel for soil compaction

A mandrel for forming a cavity at a target location, the mandrel comprising:

• a base part with a cylindrical-shaped structure, the base part positioned at a top end of the mandrel, the base part comprising:
• a shaft insertion hole on a top surface of the base part, the shaft insertion hole configured to receive a shaft of a mechanical vibratory hammer;
• a first middle part comprising a first top surface, a first bottom surface, and a first lateral surface between the first top surface and the first bottom surface, the first top surface attached to a bottom surface of the base part, the first middle part and the base part defining a first angle between a main plane of the bottom surface of the base part and a tangential plane of the first lateral surface, the first angle in a range between 130° and 150°;
• a second middle part with a cylindrical-shaped structure, the second middle part comprising a second top surface, a second bottom surface, and a second lateral surface, the second top surface attached to the first bottom surface, a main longitudinal axis of the second middle part perpendicular to the main plane of the bottom surface of the base part;
• a third middle part comprising a third top surface, a third bottom surface, and a third lateral surface, the third top surface attached to the second bottom surface, the third lateral surface and the second bottom surface defining a second angle between a main plane of the second bottom surface and a tangential plane of the third lateral surface, the second angle in a range between 130° and 150°;
• and
• a bore head positioned at a bottom end of the mandrel, a top surface of the bore head attached to the third bottom surface, the bore head configured to tamper through hard rock surfaces.

A method for soil compaction at a target location, the method comprising:

• positioning a mandrel above the target location, the mandrel comprising:
• a base part with a cylindrical-shaped structure, the base part positioned at a top end of the mandrel, the base part comprising:
• a shaft insertion hole on a top surface of the base part, the shaft insertion hole configured to receive a shaft of a mechanical vibratory hammer;
• and
• a cavity at the bottom surface of the base part, a diameter of the cavity ninety percent of a diameter of the base part, a depth of the cavity being 2 millimeters;
• a first middle part comprising a first top surface, a first bottom surface, and a first lateral surface between the first top surface and the first bottom surface, the first top surface attached to a top surface of the cavity, a diameter of the first top surface being 0.9 of the diameter of the cavity, the first middle part and the base part defining a first angle between a main plane of the bottom surface of the base part and a tangential plane of the first lateral surface, the first angle being 135°;
• a second middle part with a cylindrical-shaped structure, the second middle part comprising a second top surface and a second bottom surface, the second top surface attached to the first bottom surface, a diameter of the second top surface being equal to a diameter of the first bottom surface, a main longitudinal axis of the second middle part perpendicular to the main plane of the bottom surface of the base part;
• a third middle part comprising a third top surface, a third bottom surface, and a third lateral surface, the third top surface attached to the second bottom surface, a diameter of the third top surface being equal to a diameter of the second bottom surface, the third lateral surface and the second bottom surface defining a second angle between a main plane of the second bottom surface and a tangential plane of the third lateral surface, the second angle being 135°;
• a first plurality of diamond-shaped crushing blades attached around the first middle part and the second middle part, each respective diamond-shaped crushing blade from the first plurality of diamond-shaped crushing blades comprising a first edge and a second edge, each diamond-shaped crushing blade from the first plurality of diamond-shaped crushing blades attached at the respective first edge to the first lateral surface of the first middle part and attached at the respective second edge to the second lateral surface of the second middle part;
• and
• a second plurality of diamond-shaped crushing blades attached around the third middle part and the bore head, each respective diamond-shaped crushing blade from the second plurality of diamond-shaped crushing blades comprising a third edge and a fourth edge, each diamond-shaped crushing blade from the second plurality of diamond-shaped crushing blades attached at the respective third edge to the third lateral surface of the third middle part and attached at the respective fourth edge to the fourth lateral surface of the bore head;
• and
• a bore head positioned at a bottom end of the mandrel, a top surface of the bore head attached to the third bottom surface, a diameter of the top surface of the bore head being equal to a diameter of the third bottom surface, the bore head comprising a wedge-shaped tip at a bottom end of the bore head, the wedge-shaped tip configured to tamper through hard rock surfaces, the wedge-shaped tip comprises a first inclined surface and a second inclined surface, a bottom end of the first inclined surface attached to a bottom end of the second inclined surface, the first inclined surface and the second inclined surface defining a wedge angle between a main plane of the first inclined surface and a main plane of the second inclined surface, the wedge angle being 32°;
• generating a first conical-shaped cavity by driving the mandrel into the target location;
• extracting the mandrel from the conical-shaped cavity;
• generating a first aggregate filled conical-shaped cavity by filling the conical-shaped cavity with aggregate;
• generating a second conical-shaped cavity by driving the mandrel into the first aggregate filled conical-shaped cavity;
• extracting the mandrel from the second conical-shaped cavity;
• generating a second aggregate filled conical-shaped cavity by filling the second conical-shaped cavity with aggregate;
• compacting the second aggregate filled conical-shaped cavity by ramming a first hammering device onto a top surface of the second aggregate filled conical-shaped cavity;
• compacting the second aggregate filled conical-shaped cavity by ramming a second hammering device onto the top surface of the second aggregate filled conical-shaped cavity.