Zhoukou–Nanyang Expressway Project, Henan Province-By application category

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Zhoukou–Nanyang Expressway Project, Henan Province

Application of Steel Pipe Screw Piles in Cutting Slope Reinforcement of Expansive Soil

Overall summary of the project

The Zhoukou–Nanyang Expressway is a key section of the Shangqiu–Nanyang Expressway, serving as a vital rapid transportation corridor connecting eastern and southwestern Henan Province. The project spans approximately 195 kilometers in total, including around 100 kilometers of plain sections and 95 kilometers of rolling hill sections. It stands as a representative expressway project built in plain and rolling hill terrain.

For this project, SSP provided technical support for the design and construction of screw pile slope reinforcement, and completed the manufacturing and supply of steel pipe screw piles required for the works. The company delivered both products and integrated solutions for the reinforcement of expansive soil cutting slopes.

Project Background

Project Challenge

he project route passes through Pingdingshan, Zhumadian, Nanyang and other areas, where expansive soil is widely distributed in Henan Province. Expansive soil features swelling upon water absorption and shrinkage after dehydration, which tends to cause long-term stability risks, deformation control troubles and high maintenance hazards to expressway cutting slopes. Therefore, the project required a reinforcement solution that can meet slope stability requirements, reduce construction disturbance, improve construction efficiency, and balance long-term durability and project economy simultaneously.

SSP provided a steel pipe screw pile slope reinforcement solution for this project.

Anchoring and bearing of screw piles: Special rotary driving equipment is used to screw screw piles into stable soil or rock layers of the slope. The helical flights of the piles fully engage with the surrounding soil. Combined with shaft friction and flight end bearing capacity, the piles gain powerful resistance against uplift, sliding and overturning to firmly hold back sliding soil masses. Integrated load transfer system: When lateral earth pressure occurs on slope soil, loads transfer step by step: slope soil → retaining/protective structure → screw pile body → deep stable strata, which inhibits slope sliding, collapse and slumping. Coordinated protection: Supporting facilities including slope hydroseeding and drainage holes address rainwater infiltration and soil softening, fundamentally cutting down slope failure risks. A three-in-one protection system combining pile load bearing, slope surface protection and drainage & anti-seepage is formed to reinforce expansive soil cutting slopes.

Compared with traditional cement grouted rock bolts and other technologies, the screw-in construction of screw piles avoids large-scale excavation, reduces disturbance to the original slope structure and improves on-site construction efficiency. It is more applicable to infrastructure projects with strict requirements on construction period, environmental disturbance control and site construction organization. The complete design covers eight standardized steps: site reconnaissance, data collection, working condition analysis, structural calculation, component selection, drawing deepening, checking and rechecking, and final scheme confirmation. The process is clear with high professionalism and safety performance. Structural calculation is the core link. Professional geotechnical calculation is carried out to guarantee the piles and overall structure meet all load requirements and eliminate collapse and sliding risks.

Project Value

Low-disturbance construction: The screw-in installation reduces excavation and imposes less impact on existing slopes.

Reliable structural reinforcement: The steel pipe shaft and helical flights work together to provide effective support for slope protection.

High construction efficiency: The relatively simple construction process meets the schedule requirements of large-scale infrastructure projects.

Wide adaptability: Applicable to various scenarios including expansive soil slopes, road subgrades, platform foundations, photovoltaic foundations and industrial foundations.

Complete supporting supply: SSP can provide customized manufacturing services in accordance with project drawings, dimensions, surface treatment and construction requirements.