Abstract: A tamper device includes a shaft for driving a tamper head. A tamper head is attached to the end of the shaft for tamping a lift of aggregate in a cavity formed in a ground surface. A shield extends upwardly a predetermined height from the tamper head an amount sufficient to prevent sidewalls of the cavity from failing and collapsing. Methods of constructing aggregate columns with thicker lifts are also disclosed.

Abstract: A system and method of determining lift deflection during construction of aggregate columns allows for real time monitoring of construction to ensure meeting defined parameters. The amount of deflection of a tamper head during tamping is determined multiple times for each lift. When the amount of deflection matches a predetermined value, tamping is stopped.

Abstract: A slotted mandrel is used in displacement pier construction. Longitudinal slots are formed in the sides of the hollow mandrel which allow for the introduction of aggregate efficiently into the mandrel from a hopper through which the mandrel passes while being driven into the ground. Water may also be employed with the aggregate. Once in the ground the mandrel is raised to release the aggregate (and water if present) into the formed hole in lifts and a mandrel head then compacts the aggregate in the hole. This apparatus and method obviates the need for complicated and expensive hoppers that are raised with the mandrel or the use of expensive aggregate delivery systems.

Abstract: A primary earth penetrating mandrel formed of a hollow shell steel plate octagonal in cross-section has an upper end and a blunt lower end joined by an upwardly and outwardly tapered wall. The mandrel is driven downwardly in the earth to simultaneously form a vertical tapered cavity while compacting the sidewall of the cavity to provide structural integrity. The mandrel is then moved upwardly from the bottom of the cavity and aggregate is deposited in the bottom of the cavity following which the mandrel is lowered so that its blunt lower end engages the deposited aggregate and densifies the aggregate by vertical vibratory action and static force with these steps being repeated until the pier top is near the surface of the earth at which time the upper aggregate portions are densified by either the primary mandrel or a secondary mandrel having a substantially larger lower end surface than the lower end surface of the primary mandrel.

Abstract: A primary earth penetrating mandrel formed of a hollow shell steel plate octagonal in cross-section has an upper end and a blunt lower end joined by an upwardly and outwardly tapered wall. The mandrel is driven downwardly in the earth to simultaneously form a vertical tapered cavity while compacting the sidewall of the cavity to provide structural integrity. The mandrel is then moved upwardly from the bottom of the cavity and aggregate is deposited in the bottom of the cavity following which the mandrel is lowered so that its blunt lower end engages the deposited aggregate and densifies the aggregate by vertical vibratory action and static force with these steps being repeated until the pier top is near the surface of the earth at which time the upper aggregate portions are densified by either the primary mandrel or a secondary mandrel having a substantially larger lower end surface than the lower end surface of the primary mandrel.

Abstract: A method and apparatus for forming a support aggregate pier having compacted aggregate lifts in a soil matrix, includes an elongate, hollow tube with a bulbous leading end bottom head element that is forced or lowered into the soil matrix. The hollow tube includes a mechanism for releasing aggregate from the lower head element of the tube as the tube is lifted in predetermined increments. The same hollow tube is then lowered or pushed in predetermined increments to vertically compact the released aggregate in thin aggregate lifts, while forcing a portion of the compacted aggregate transaxially into the soil matrix at the sidewalls of the cavity. The process may be repeated to form a series of compacted aggregate lifts comprising an aggregate pier or the process may include forming only a single lift for the aggregate pier while densifying adjacent matrix soils and imparting lateral stress in these soils.

Abstract: A primary earth penetrating mandrel formed of a hollow shell steel plate octagonal in cross-section has an upper end and a blunt lower end joined by an upwardly and outwardly tapered wall. The mandrel is driven downwardly in the earth to simultaneously form a vertical tapered cavity while compacting the sidewall of the cavity to provide structural integrity. The mandrel is then moved upwardly from the bottom of the cavity and aggregate is deposited in the bottom of the cavity following which the mandrel is lowered so that its blunt lower end engages the deposited aggregate and densifies the aggregate by vertical vibratory action and static force with these steps being repeated until the pier top is near the surface of the earth at which time the upper aggregate portions are densified by either the primary mandrel or a secondary mandrel having a substantially larger lower end surface than the lower end surface of the primary mandrel.

Abstract: A method for ground improvement with hardened inclusions includes providing a device having a plurality of tines extending downwardly from a top plate in a manner to achieve displacement of ground material downward and radially outward. The device is mechanically driven into the ground to achieve predetermined depths of penetration by the tines and to create cavities at the location the tines are advanced. The device is at least partially retracted and hardening cementitious material backfill is added into the cavities for forming a plurality of hardened inclusions within the cavities.

Abstract: Extensible shells and related methods for constructing a support pier are disclosed. A shell can define an interior for holding granular construction material and define an opening for receiving the granular construction material into the interior. The shell can be flexible such that the shell expands when granular construction material is compacted in the interior of the shell. A method may include positioning the shell in the ground and filling at least a portion of the interior of the shell with the granular construction material. The granular construction material may be compacted in the interior of the shell to form a support pier.

Abstract: An apparatus and method for forming a support pier having a single or multiple compacted aggregate lifts in a soil matrix, wherein the apparatus includes a vertical, hollow tube with a bulbous leading end or head element that is forced into the soil matrix. The hollow tube includes a mechanism for releasing aggregate from the lower head element of the tube as the tube is lifted incrementally. The same hollow tube is then utilized to compact the released aggregate. The process may be repeated to form a series of compacted lifts comprising a pier.

Abstract: A system for constructing a support column includes a mandrel with an upper portion and a tamper head. A feed tube extends through the mandrel for feeding flowable material to the head. The tamper head includes a lower enlarged chamber with a reducing surface at an upper portion for compacting material and restricting upward flow of aggregate. The tamper head is of a size providing an enclosed region for allowing cementitious materials to be placed therein. The system allows a support column including a cementitious inclusion on top of an expanded base to be built.

Abstract: An apparatus and method for ground improvement includes a device having a plurality of tines extending downwardly from a top plate in a manner to achieve displacement of ground material downward and radially outward. The device is mechanically driven into the ground to achieve predetermined depths of penetration by the tines. The device is retracted and driven repeatedly to achieve densification. Optionally, voids made by the device can be filled with a flowable media.

Abstract: A tamper device includes a shaft for driving a tamper head. A tamper head is attached to the end of the shaft for tamping a lift of aggregate in a cavity formed in a ground surface. A shield extends upwardly a predetermined height from the tamper head an amount sufficient to prevent sidewalls of the cavity from failing and collapsing. Methods of constructing aggregate columns with thicker lifts are also disclosed.

Abstract: A system and method for installing aggregate piers is provided. A cylindrical hollow mandrel is driven to a desired depth. Aggregate is fed through the mandrel in steps. The mandrel is raised and driven to tamp the aggregate. Physical members in a tamping head of the mandrel allow aggregate to remain in a cavity formed by the mandrel, and prevent aggregate from entering the mandrel during driving.

Abstract: A tamper head having an elongated pyramidal or conical shape is used to construct rammed aggregate piers. The pyramidal or conical shape of the tamper head is more efficient at building up lateral earth pressure and provides for greater economy in the construction of the piers than available with existing methods that rely on tamper heads with flat bottoms and beveled sides.

Abstract: A slotted mandrel is used in displacement pier construction. Longitudinal slots are formed in the sides of the hollow mandrel which allow for the introduction of aggregate efficiently into the mandrel from a hopper through which the mandrel passes while being driven into the ground. Water may also be employed with the aggregate. Once in the ground the mandrel is raised to release the aggregate (and water if present) into the formed hole in lifts and a mandrel head then compacts the aggregate in the hole. This apparatus and method obviates the need for complicated and expensive hoppers that are raised with the mandrel or the use of expensive aggregate delivery systems.

Abstract: A primary earth penetrating mandrel formed of a hollow shell steel plate octagonal in cross-section has an upper end and a blunt lower end joined by an upwardly and outwardly tapered wall. The mandrel is driven downwardly in the earth to simultaneously form a vertical tapered cavity while compacting the sidewall of the cavity to provide structural integrity. The mandrel is then moved upwardly from the bottom of the cavity and aggregate is deposited in the bottom of the cavity following which the mandrel is lowered so that its blunt lower end engages the deposited aggregate and densifies the aggregate by vertical vibratory action and static force with these steps being repeated until the pier top is near the surface of the earth at which time the upper aggregate portions are densified by either the primary mandrel or a secondary mandrel having a substantially larger lower end surface than the lower end surface of the primary mandrel.