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The 11th session of the Geotechnical Institute's series event "My Technology, I'll Explain" opens today! For this session, we are honored to invite two senior experts in the field of foundation engineering: Wang Shuguang, Deputy Chief Engineer of Jianyan Foundation Engineering Co., Ltd., and Si Jianbo, Chairman of Shaanxi Longyue Foundation Engineering Co., Ltd. This session focuses on "DDC and SDDC Pile Construction Methods."!

It is understood that the SDDC construction method represents a major advance in ground treatment technology. It is a deep in-hole super-heavy tamping method, and together with the DDC method, it is a leader among deep ground treatment methods. By adopting the SDDC method, dense piles with high bearing capacity and strongly compacted soil between piles can be formed, showing remarkable results in treating foundation soil layers and fill materials. Numerous engineering examples have proven that, especially in soft soil areas such as miscellaneous fill, soft red clay, and collapsible loess foundations, DDC technology demonstrates excellent technical performance and significant economic benefits.

However, as building technology advances rapidly and quality requirements continue to rise, we must clearly recognize the shortcomings of the current DDC method and further improve the requirements for its construction technology and quality. With this understanding, after years of research and practice, Shaanxi Longyue has actively proposed and explored an innovative solution combining the SC method with traditional pile foundation types. This innovative scheme aims to address the challenges faced when constructing high-rise buildings in areas with thick fill, ensuring that the foundation bearing capacity can meet the needs of the superstructure and enhancing the sustainability of the project.

In the live broadcast, Chairman Si shared many application cases of the SDDC method in different projects, among which the remarkable results achieved in the "Lanzhou CDC SDDC Pile Foundation Treatment" project were particularly noteworthy.

Considering that the site is a loess high-fill site with a fill thickness of 18.5 m to 25 m, and the backfill is mainly loess with a small amount of construction waste and domestic waste distributed unevenly, it is an under-consolidated self-weight collapsible site with very obvious collapsibility. To strengthen the foundation and improve bearing capacity, the SDDC pile composite foundation scheme was adopted to reinforce the site. The designed guide hole diameter is 1.2 m, the formed pile diameter is 1.8 m, the pile length is 32.0 m, and the pile spacing is 2.8 m. The pile compaction coefficient is required to be no less than 0.97, the soil-between-piles compaction coefficient no less than 0.93, and the characteristic value of the composite foundation bearing capacity to reach 260 kPa.

During the treatment process, a 12 t tamper was used for deep in-hole heavy tamping, with 4 blank tamping blows at the hole bottom, a layered tamping fill amount of 1.5 m³, 6-8 tamping blows, and a lifting height of 10 m. After the ground treatment was completed, a 2000 kN·m tamping energy was used for full compaction of the site. Testing showed that after treatment, the compaction coefficient of the soil between piles reached 0.94, the average pile compaction coefficient reached 0.97, and the composite foundation bearing capacity increased to 276.5 kPa. By adopting the SDDC treatment method, collapsibility was successfully eliminated.‍

Application Cases

We believe that the combined application of the SDDC method and traditional pile foundation types will have broad development prospects in the field of foundation engineering and will contribute to improving construction quality. We welcome industry colleagues to participate in this session to jointly discuss technological innovation and support the development and progress of foundation engineering!

Walking among foundations,

Joining hands to create a vast future;

The institute's students have lofty aspirations,

Together forging a grand plan for a brilliant future.‍

If fate brings us together again,

To explore the path of knowledge together;

Youth soars and dreams ignite,

Geotechnical students persevere tirelessly!‍

Live Broadcast Review

** Session: New Technology for Rebar Connection of Large-Diameter Long Pile Foundations

Session 2: Fully Digital Hot-Melt Anchor Technology

Session 3: Construction Technology and Engineering Application Research of Jet-Expanded Conical Frustum Pressure-Grouted Piles

Session 4: The Tomorrow of Dynamic Compaction

Session 5: High-Strength Composite Foundation — Brief Introduction to the Construction Technology of the Along-Track Column-Hammer Rock-Breaking Compaction Pile Method

Session 6: Technical Principles and Application Prospects of Geotechnical Curing Agents

Session 7: Precast Hollow Pile Internal Tamping Bearing Pile Technology

Session 8: Design Theory, Method and Treatment Technology for Variable-Stiffness Leveling of High-Rise Building Foundations

Session 9: Design and Construction of Visualized Squeezed-Expanded Branch-Plate Cast-in-Place Concrete Piles

Session 10: Discussion of Models for Calculating Complex Foundation Pits and Ground Treatment Projects with Jianyan Foundation Software

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