Sichuan Province Highway High-Fill Roadbed Reinforcement Project

Project situation:

At the site of the provincial highway expansion and reconstruction project on the western margin of the Sichuan Basin, a 850-meter-long valley section with fill height reaching 12-18 meters is undergoing geological challenges. The 2-3 meter thick saturated silty clay layer at the base has posed serious difficulties for traditional layered compaction methods—predicted post-construction settlement exceeds the design limit of 30mm, and the risk of slope instability during the rainy season increases by 40%. We Zhonglong Engineering team applied biaxial stretch geogrid (PP material, longitudinal ultimate tensile strength ≥50kN/m), successfully overcoming the deformation problem of weak foundation.

Project Stages:

The base treatment phase: after removing the surface silt, workers laid 4-meter-wide double tensile grids, using U-shaped nails in a 0.8m×0.8m matrix for high-density anchoring. Once the 30cm-thick gravel drainage cushion layer was filled, the first layer of reinforcement had formed a stable foundation.

The subsequent layered reinforcement work: after each 1.2m layer of soil was compacted by a heavy-duty roller, a new grid layer was immediately laid. The joints used a patented clip connection technology to ensure a tensile strength retention rate of ≥95%. The grid edges were left with ≥2 meters of folded segments, providing structural margin for slope reinforcement

Slope protection phase: for every 3-meter fill increase, a stepped anchoring groove (1.5m deep x 1.0m wide) was set, with the grid folded end embedded and then filled with cement mortar. This innovative mode increased the slope's resistance to scour by 300%.

Excellent Performance in the Rainy Season

Monitoring data six months after completion confirmed the reliability of the technology: the maximum settlement along the entire section was only 14 mm, less than half of the design allowable value; no longitudinal cracks appeared along the shoulder. More importantly, during the period of continuous heavy rainfall, the construction section achieved "zero collapse, zero repair" . Economic benefits are also evident—saving 800,000 yuan in maintenance costs compared to traditional methods.