Method and apparatus for forming structures in the ground

Claim 1

A method of forming a sand drain in the ground comprising the steps: providing a mandrel having a straight stem and a detachable drive foot at or near its lower end, said drive foot having a cross-sectional area in the direction transverse to the mandrel axis which is larger than the transverse cross-sectional area of the solid portion of the mandrel stem; moving said mandrel stem downwardly to cause said drive foot to penetrate into the ground so that an elongated hole is formed, the area of which hole is larger than the cross-sectional body area of the mandrel, thus creating longitudinal space in the ground adjacent the mandrel stem behind said downward penetrating drive foot; causing a liquid to flow downwardly from the ground surface into said longitudinal space simultaneously with the downward mandrel penetration so that at least a portion of this space is immediately filled with liquid as soon as it is created, said liquid serving to prevent the soil or ground water from the walls of the hole from entering said space; withdrawing said mandrel from the ground while simultaneously causing an additional supply of liquid to flow into the hole in such a way that the volume of the mandrel being withdrawn is replaced with liquid, leaving the detachable drive foot fixed in the ground at the bottom of the liquid-filled hole; filling said liquid-filled hole with sand by pouring it in from the surface.

Claim 2

A method of forming a sand drain in the ground comprising the steps: providing a mandrel having a straight stem and a detachable drive foot at or near its lower end, said drive foot having a cross-sectional area in the direction transverse to the mandrel axis which is larger than the transverse cross-sectional area of the solid portion of the mandrel stem; moving said mandrel stem downwardly to cause said drive foot to penetrate into the ground so that an elongated hole is formed, the area of which hole is larger than the cross-sectional body area of the mandrel, thus creating longitudinal space in the ground adjacent the mandrel stem behind said downward penetrating drive foot; causing a liquid to flow downwardly from the ground surface into said longitudinal space simultaneously with the downward mandrel penetration so that at least a portion of this space is immediately filled with liquid as soon as it is created, said liquid serving to prevent the soil or ground water from the walls of the hole from entering said space; withdrawing said mandrel from the ground while simultaneously causing an additional supply of liquid to flow into the hole in such a way that the volume of the mandrel being withdrawn is replaced with liquid, leaving the detachable drive foot fixed in the ground at the bottom of the liquid-filled hole; filling said liquid-filled hole with sand by pouring it in from the surface.

Claim 3

A method of forming a sand drain in the ground comprising the steps: providing a mandrel having a straight stem with a hollow interior and a detachable drive foot at or near its lower end, said drive foot having a central opening and cross-sectional area in the direction transverse to the mandrel axis which is larger than the transverse cross-sectional area of the solid portion of the mandrel stem; moving said mandrel stem downwardly to cause said drive foot to penetrate into the ground so that an elongated hole is formed, having an area larger than the cross-sectional body area of the mandrel, thus creating longitudinal space in the ground adjacent the mandrel stem behind said downward penetrating drive foot, and so that some of the soil lying in the path of the downward penetrating mandrel enters the interior of said mandrel stem in the form of a soil plug, said soil plug inside said mandrel being carried out of the hole along with said mandrel stem; causing said longitudinal space to be filled with liquid simultaneously with the downward mandrel penetration so that at least a portion of this space is immediately filled with liquid as soon as it is created, said liquid serving to prevent the soil or ground water from the walls of the hole from entering said space; withdrawing said mandrel from the ground while simultaneously causing an additional supply of liquid to flow into the hole in such a way that the volume of the mandrel being withdrawn is replaced with liquid leaving the detachable drive foot fixed in the ground at the bottom of the liquid-filled hole; filling said liquid-filled hole with sand by pouring it in from the surface.

Claim 4

A method of forming a sand drain in the ground comprising the steps: providing a mandrel having a straight stem with a hollow interior and a detachable drive foot at or near its lower end, said drive foot having a central opening and cross-sectional area in the direction transverse to the mandrel axis which is larger than the transverse cross-sectional area of the solid portion of the mandrel stem; moving said mandrel stem downwardly to cause said drive foot to penetrate into the ground so that an elongated hole is formed, having an area larger than the cross-sectional body area of the mandrel, thus creating longitudinal space in the ground adjacent the mandrel stem behind said downward penetrating drive foot, and so that some of the soil lying in the path of the downward penetrating mandrel enters the interior of said mandrel stem in the form of a soil plug, said soil plug inside said mandrel being carried out of the hole along with said mandrel stem; causing said longitudinal space to be filled with liquid simultaneously with the downward mandrel penetration so that at least a portion of this space is immediately filled with liquid as soon as it is created, said liquid serving to prevent the soil or ground water from the walls of the hole from entering said space; withdrawing said mandrel from the ground while simultaneously causing an additional supply of liquid to flow into the hole in such a way that the volume of the mandrel being withdrawn is replaced with liquid leaving the detachable drive foot fixed in the ground at the bottom of the liquid-filled hole; filling said liquid-filled hole with sand by pouring it in from the surface.

Claim 8

A method of forming a sand drain in the ground comprising the steps: providing a mandrel with a straight hollow tubular stem and a detachable drive foot at or near its lower end, the exterior dimensions of said drive foot in the direction transverse to the mandrel axis being larger than the exterior diameter of the mandrel stem, said detachable drive foot also having a central opening; moving said mandrel stem downwardly to cause said drive foot to penetrate into the ground so that an elongated hole is formed with a cross-sectional shape the same as the exterior shape of said drive foot and larger than said mandrel stem, thus creating longitudinal space in the ground adjacent the exterior surface of said mandrel stem behind said downward penetrating drive foot, some of the soil lying in the path of the downward penetrating mandrel entering the interior of the mandrel stem through said drive foot central opening in the form of a soil plug; causing said longitudinal space that is exterior of said mandrel stem to be filled with liquid simultaneously with downward mandrel penetration, said liquid serving to prevent soil or ground water from the walls of the hole from entering said space, said liquid being a flowable mixture of sand and self-disintegrating mud; withdrawing said mandrel stem from the ground, said soil plug inside the mandrel being carried out of the ground with the mandrel stem, while simultaneously causing an additional supply of the same liquid to flow into the hole in such a way that the voLume of the mandrel and soil plug being withdrawn is replaced with the liquid, leaving the detachable drive foot fixed in the ground at the bottom of the liquid-filled hole.

Claim 9

A method of forming a sand drain in the ground comprising the steps: providing a mandrel with a straight hollow tubular stem and a detachable drive foot at or near its lower end, the exterior dimensions of said drive foot in the direction transverse to the mandrel axis being larger than the exterior diameter of the mandrel stem, said detachable drive foot also having a central opening; moving said mandrel stem downwardly to cause said drive foot to penetrate into the ground so that an elongated hole is formed with a cross-sectional shape the same as the exterior shape of said drive foot and larger than said mandrel stem, thus creating longitudinal space in the ground adjacent the exterior surface of said mandrel stem behind said downward penetrating drive foot, some of the soil lying in the path of the downward penetrating mandrel entering the interior of the mandrel stem through said drive foot central opening in the form of a soil plug; causing said longitudinal space that is exterior of said mandrel stem to be filled with liquid simultaneously with downward mandrel penetration, said liquid serving to prevent soil or ground water from the walls of the hole from entering said space, said liquid being a flowable mixture of sand and self-disintegrating mud; withdrawing said mandrel stem from the ground, said soil plug inside the mandrel being carried out of the ground with the mandrel stem, while simultaneously causing an additional supply of the same liquid to flow into the hole in such a way that the voLume of the mandrel and soil plug being withdrawn is replaced with the liquid, leaving the detachable drive foot fixed in the ground at the bottom of the liquid-filled hole.

Claim 14

A method of forming a sand drain in the ground comprising the steps: providing a mandrel having a straight stem and a detachable drive foot at or near its lower end, said drive foot having a cross-sectional area in the direction transverse to the mandrel axis which is larger than the transverse cross-sectional area of the solid portion of the mandrel stem; attaching one end of a porous conduit to said drive foot, said porous conduit having a length approximately equal to that of the sand drain being formed; moving said mandrel stem downwardly to cause said drive foot to penetrate into the ground so that an elongated hole is formed, the area of which hole is larger than the cross-sectional body area of the mandrel, thus creating longitudinal space in the ground adjacent the mandrel stem behind said downward penetrating drive foot and carrying said porous conduit into the ground inside said elongated hole; causing liquid to flow into said space simultaneously with downward mandrel penetration so that at least a portion of the space is immediately filled with liquid as soon as it is created, said liquid serving to prevent soil or ground water from the walls of the hole from entering said space, said liquid being a flowable mixture of sand and self-disintegrating mud; withdrawing said mandrel stem from the ground while simultaneously causing an additional supply of the same liquid to flow into the hole in such a way that the volume of the mandrel being withdrawn is replaced with the liquid, leaving the detachable drive foot fixed in the ground at the bottom of the liquid-filled hole and leaving said porous conduit centrally located in the liquid-filled hole extending at least to the ground surface.

Claim 15

A method of forming a sand drain in the ground comprising the steps: providing a mandrel having a straight stem and a detachable drive foot at or near its lower end, said drive foot having a cross-sectional area in the direction transverse to the mandrel axis which is larger than the transverse cross-sectional area of the solid portion of the mandrel stem; attaching one end of a porous conduit to said drive foot, said porous conduit having a length approximately equal to that of the sand drain being formed; moving said mandrel stem downwardly to cause said drive foot to penetrate into the ground so that an elongated hole is formed, the area of which hole is larger than the cross-sectional body area of the mandrel, thus creating longitudinal space in the ground adjacent the mandrel stem behind said downward penetrating drive foot and carrying said porous conduit into the ground inside said elongated hole; causing liquid to flow into said space simultaneously with downward mandrel penetration so that at least a portion of the space is immediately filled with liquid as soon as it is created, said liquid serving to prevent soil or ground water from the walls of the hole from entering said space, said liquid being a flowable mixture of sand and self-disintegrating mud; withdrawing said mandrel stem from the ground while simultaneously causing an additional supply of the same liquid to flow into the hole in such a way that the volume of the mandrel being withdrawn is replaced with the liquid, leaving the detachable drive foot fixed in the ground at the bottom of the liquid-filled hole and leaving said porous conduit centrally located in the liquid-filled hole extending at least to the ground surface.

Claim 16

A method of creating a sand-filled cavity below ground comprising the steps: providing a mandrel having a straight stem and a detachable drive foot at or near its lower end, said drive foot having a cross-sectional area in the direction transverse to the mandrel axis which is larger than the transverse cross-sectional area of the solid portion of the mandrel stem; moving said mandrel stem downwardly to cause said drive foot to penetrate into the ground so that an elongated cavity is formed, the area of which is larger than the cross-sectional body area of the mandrel, thus creating longitudinal space in the ground adjacent the mandrel stem behind said downward penetrating drive foot; simultaneously filling said cavity with a fluid mixture of sand a viscous liquid, which fluid mixture has sufficient pressure to prevent collapse of the cavity, said viscous liquid having the characteristic that its viscosity decreases with time and gradually approaches the viscosity of water, said mixture within said cavity being left in place while the viscosity of said liquid decreases, thereby eventually leaving the cavity filled only with sand and a liquid having a viscosiTy essentially that of water.

Claim 17

A method of creating a sand-filled cavity below ground comprising the steps: providing a mandrel having a straight stem and a detachable drive foot at or near its lower end, said drive foot having a cross-sectional area in the direction transverse to the mandrel axis which is larger than the transverse cross-sectional area of the solid portion of the mandrel stem; moving said mandrel stem downwardly to cause said drive foot to penetrate into the ground so that an elongated cavity is formed, the area of which is larger than the cross-sectional body area of the mandrel, thus creating longitudinal space in the ground adjacent the mandrel stem behind said downward penetrating drive foot; simultaneously filling said cavity with a fluid mixture of sand a viscous liquid, which fluid mixture has sufficient pressure to prevent collapse of the cavity, said viscous liquid having the characteristic that its viscosity decreases with time and gradually approaches the viscosity of water, said mixture within said cavity being left in place while the viscosity of said liquid decreases, thereby eventually leaving the cavity filled only with sand and a liquid having a viscosiTy essentially that of water.