A concrete pier foundation having a plurality of sleeved tower anchor bolts embedded therein and a spiral loop encasement providing lateral shear reinforcement is provided. The spiral loop encasement surrounds at least a lower portion of the concrete pier and is formed by hoop steel wrapped around the perimeter of the tower anchor bolt cage. In proper soils or rock the spiral loop encasement can eliminate the need for corrugated metal pipes, reducing the cost and complexity of construction.

A retrofit reinforcing structure addition and method for an existing gravity spread foundation for a wind turbine or the like having a central pedestal and a spread section is provided. The retrofit structure addition includes a collar formed around the pedestal of the spread foundation. The collar is formed by a shape sustaining member, such as a CMP, placed around the pedestal to define an annular ring between the CMP and the pedestal that is filled with cementitious material. Radial bolts extend horizontally through the collar and into the side of the pedestal. Soil and/or rock anchor bolts extend vertically through the collar, the spread portion of the foundation and into the underlying soil and/or rock substrate. The radial and anchor bolts are post-tensioned to ensure that the cementitious material of the collar remains in compression and the bolts are always in static tension, strengthening the original gravity spread foundation and extending the fatigue life thereof.

A retrofit reinforcing structure addition and method for an existing gravity spread foundation for a wind turbine or the like haying a central pedestal and a spread section is provided. The retrofit structure addition includes a collar formed around the pedestal of the spread foundation. The collar is formed by a shape sustaining member, such as a CMP, placed around the pedestal to define an annular ring between the CMP and the pedestal that is filled with cementitious material. Radial bolts extend horizontally through the collar and into the side of the pedestal. Soil and/or rock anchor bolts extend vertically through the collar, the spread portion of the foundation and into the underlying soil and/or rock substrate. The radial and anchor bolts are post-tensioned to ensure that the cementitious material of the collar remains in compression and the bolts are always in static tension, strengthening the original gravity spread foundation and extending the fatigue life thereof.

A concrete pier foundation having a plurality of sleeved tower anchor bolts embedded therein and a spiral loop encasement providing lateral shear reinforcement is provided. The spiral loop encasement surrounds at least a lower portion of the concrete pier and is formed by hoop steel wrapped around the perimeter of the tower anchor bolt cage. In proper soils or rock the spiral loop encasement can eliminate the need for corrugated metal pipes, reducing the cost and complexity of construction.

A reinforced tensionless concrete pier foundation for supporting a tower and a method of constructing the same is provided, the foundation having an outer CMP and an inner CMP with an annular space therebetween in which a plurality of sleeved tower anchor bolts are embedded, and the pier foundation including at least one reinforcement structure that at least partly encircles the outer CMP to provide one or more of increased lateral stiffness, increased shear resistance and overturning (upset) moment capacity, reduced bending, displacement, and deflection of the top of the pier, and improved conditioning, containment, skin friction and lateral bearing capacity of the surrounding soil and/or rock substrate that supports the tensionless pier.

A retrofit reinforcing structure addition and method for an existing gravity spread foundation for a wind turbine or the like having a central pedestal and a spread section is provided. The retrofit structure addition includes a collar formed around the pedestal of the spread foundation. The collar is formed by a shape sustaining member, such as a CMP, placed around the pedestal to define an annular ring between the CMP and the pedestal that is filled with cementitious material. Radial bolts extend horizontally through the collar and into the side of the pedestal. Soil and/or rock anchor bolts extend vertically through the collar, the spread portion of the foundation and into the underlying soil and/or rock substrate. The radial and anchor bolts are post-tensioned to ensure that the cementitious material of the collar remains in compression and the bolts are always in static tension, strengthening the original gravity spread foundation and extending the fatigue life thereof.

Disclosed herein are a construction structure and method for an underground facility. The construction structure for an underground facility includes: a facility body including a foundation constructed by pouring concrete, and a cover member extending in the front-back direction and having both ends configured to extend downward and be fixed to the top surface of the foundation to form a tunnel-shaped space therebelow; and a soil cover layer formed to cover the facility body with soil. The construction method for an underground facility includes: forming a pit in the ground; constructing a foundation on the bottom surface of the pit; constructing a cover member to cover the top of the foundation; and constructing a soil cover layer by covering the pit with soil to cover the cover member.

A retrofit reinforcing structure addition and method for an existing gravity spread foundation for a wind turbine or the like having a central pedestal and a spread section is provided. The retrofit structure addition includes a collar formed around the pedestal of the spread foundation. The collar is formed by a shape sustaining member, such as a CMP, placed around the pedestal to define an annular ring between the CMP and the pedestal that is filled with cementitious material. Radial bolts extend horizontally through the collar and into the side of the pedestal. Soil and/or rock anchor bolts extend vertically through the collar, the spread portion of the foundation and into the underlying soil and/or rock substrate. The radial and anchor bolts are post-tensioned to ensure that the cementitious material of the collar remains in compression and the bolts are always in static tension, strengthening the original gravity spread foundation and extending the fatigue life thereof.

A reinforced tensionless concrete pier foundation for supporting a tower and a method of constructing the same is provided, the foundation having an outer CMP and an inner CMP with an annular space therebetween in which a plurality of sleeved tower anchor bolts are embedded, and the pier foundation including at least one reinforcement structure that at least partly encircles the outer CMP to provide one or more of increased lateral stiffness, increased shear resistance and overturning (upset) moment capacity, reduced bending, displacement, and deflection of the top of the pier, and improved conditioning, containment, skin friction and lateral bearing capacity of the surrounding soil and/or rock substrate that supports the tensionless pier.

A post-tensioned tube foundation for supporting a structure subject to high upset forces is described herein. The post-tensioned tube foundation includes an outer CMP, an inner CMP, and a tubular concrete base positioned between the inner CMP and the outer CMP. The outer CMP includes an inner surface that defines a cavity extending between a first open end and an opposite second open end. The outer CMP is positioned within an excavated hole defined along a ground surface. The inner CMP is positioned within the cavity of the outer CMP such that an annular space is defined between the inner CMP and the outer CMP. The tubular concrete base is positioned within the annular space defined between the inner CMP and the outer CMP. A plurality of bracing beams extend radially outwardly from the tubular concrete base.