The seventh session of the Geotechnical College series event "My Technology, My Presentation" was held today, focusing mainly on the technology of precast hollow pile internal tamping carrier piles. This session was moderated by Dean Wang Tao of the Geotechnical College, with Deputy Director Xu Tong of the Deep Foundation National Key Laboratory Geotechnical Center as the keynote speaker. The event aims to promote the exchange and sharing of innovative technologies, advance the application and commercialization of scientific and technological achievements, and inject new vitality and momentum into the development of the foundation engineering field.

Dean Wang Tao of the Geotechnical College, China Foundation Engineering Technology Alliance, moderated the event

The precast hollow pile internal tamping carrier pile technology involves driving a precast hollow pile with a closed bottom into the soil to a certain depth, then using a 3.5t column hammer to repeatedly tamp and fill a cement-sand mixture through the central hole of the pile toward the pile bottom. Under lateral confinement, the soil within a certain range below the pile bottom is compacted, forming an expanded foundation at the bottom of the pipe pile composed of a tamped-expanded body, compacted soil, and influenced soil. This expanded foundation is called the "carrier." The upper load is transferred through the pipe pile to the carrier and spread to the bearing stratum. Its advantages are:

Reliable quality and high bearing capacity

The pile shaft uses precast hollow pipe piles, ensuring pile integrity and avoiding defects such as diameter reduction and pile breakage common in traditional construction processes. The process is simple with reliable control measures, and it changes the load-bearing mode of pile foundations. Piles of the same dimensions achieve characteristic bearing capacity 2-3 times higher than conventional technology.

Short construction period and high efficiency

It reduces construction difficulty and greatly improves construction efficiency, thereby shortening the construction period. No curing period is required after construction is completed, and subsequent construction does not require pile head breaking—truly achieving immediate driving, immediate pressing, and immediate use.

Strong economic efficiency

Compared with conventional technology, precast hollow pile internal tamping carrier piles have shorter pile lengths and fewer piles, thus saving construction owners more than 10%-30% in cost.

Green and environmentally friendly

Construction requires no soil excavation and produces no mud, keeping the construction site clean and tidy.‍

The successful application of this technology not only improves the efficiency of engineering construction but also enhances the stability and safety of the projects. The precast hollow pile internal tamping carrier pile technology has achieved remarkable results in just a few years and has been widely applied in various engineering cases, opening up a new development path for the foundation engineering industry. The final settlement calculated according to the calculation method provided in the "Technical Standard for Carrier Piles" is slightly larger than the final settlement predicted by settlement observation, indicating that the deformation of carrier piles calculated by the equivalent solid method has certain guiding significance. The technical core of the carrier pile lies in the "carrier," which is completely different from traditional pile foundations: a carrier pile is not a pile in the traditional sense, but an expanded foundation formed by a compaction method, combining the technology of column hammer tamping fill material and dynamic compaction densification of soil. This carrier-centered technological innovation is not only ingeniously conceived and easy to control in quality, but also highly integrates theory and practice, demonstrating an original breakthrough. As the stress level gradually decreases, the strength and stiffness of the materials used in carrier piles also gradually decrease, achieving a "soft landing" transition and fully utilizing the carrier to expand the contact area with the soil, thereby effectively expanding the foundation. This points the way forward for the development of geotechnical engineering and is a model for us to learn from.

Sharing guest: Deputy Director Xu Tong of the Deep Foundation National Key Laboratory Geotechnical Center

The presentation on precast hollow pile internal tamping carrier pile technology further deepened and expanded the application of this technology in the engineering field. Deputy Director Xu Tong of the Deep Foundation National Key Laboratory Geotechnical Center shared the technology's R&D history, key technologies, and successful cases, while bringing entirely new ideas and methods to the design and construction of foundation engineering. Through the platform of "My Technology, My Presentation," experts and scholars from various fields jointly discussed how to further leverage the advantages of carrier pile technology, promote continuous innovation and improvement of foundation engineering technology, and contribute to the development of foundation engineering technology!

The "My Technology, My Presentation" series is a platform for sharing innovative technologies and promoting industry development. Through sharing their own technological achievements, alliance members have promoted the upgrading and innovation of industry technologies and the dissemination of innovative thinking. Each session has attracted the attention of numerous industry experts and scholars, building a bridge for exchange and cooperation in the field of foundation engineering technology.