CCS cellular confinement systems for soft subgrade reconstruction and expansion projects

CCS cellular confinement systems for soft subgrade reconstruction and expansion projects

Provincial Highway Soft Subgrade Reconstruction & Expansion Project (Old‑New Subgrade Splicing)

1. Project Overview: 

This is a domestic provincial highway reconstruction and expansion project. The route passes through collapsible loess and silt soil strata, featuring numerous old‑new subgrade splicing sections with heavy daily traffic volume.

2. Engineering Pain Points: 

Huge stiffness difference between old and new subgrades; large settlement of the original subgrade, which easily triggers longitudinal cracks at splicing joints; limited design cushion thickness, and large‑scale deep excavation and replacement is prohibited.

3. Selected CCS Specification: 

HDPE textured cellular confinement system; height 150 mm; sheet thickness 1.5 mm; welding spacing 440 mm, non‑perforated.

4. Key Construction Points

1. Level and compact the subgrade base, then lay non‑woven geotextile.

2. Lay CCS in transverse direction, fully stretch the panels, fix with anchor nails, and connect modules via interlocks.

3. Fill with crushed‑stone aggregate and compact in layers to form a stiffness‑transition composite cushion, then construct the upper pavement base course.

5. Implementation Results

✅ The thickness of subgrade cushion is reduced by 50%, and earth excavation volume is greatly decreased.

✅ Effectively mitigates differential settlement between old and new subgrades; the occurrence rate of longitudinal splicing cracks drops significantly after opening to traffic.

✅ Soil shear strength increases by 2‑3 times, restraining pavement shoving and rutting distresses.

✅ Compared with conventional deep‑excavation replacement, the overall construction period is shortened by 25%.