Bi-Directional Load Testing Using Donut Super Cells for Hangzhou West Railway Station-Paper

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The Hangzhou West Railway Station project requires 1,580 drilled shafts to support its station and related structures. To verify the Phase I design and assess construction methods, engineers performed bi-directional static load tests on eight sacrificial, 1,000 mm diameter shafts, each embedded in weathered argillaceous siltstone. The shafts were 50–56.5 m long.<br /><br />Donut-shaped Super Cells installed within the shafts applied loads of up to 13,200 kN. Instrumentation measured shaft movement and load transfer, allowing the team to estimate axial resistance and equivalent top-down performance.<br /><br />The tests indicated that the upper soil layers contributed little resistance; most load capacity came from deeper gravel and weathered siltstone. Calculated axial compressive resistances ranged from approximately 19,532 to 27,005 kN—well above the 7,000 kN design requirement. The measured end resistance also exceeded the design estimate. However, side and end resistance were not fully mobilized in most tests, so the calculated capacities are lower-bound values. One shaft showed unusually large downward movement, possibly due to soft soil or sediment at its base.<br /><br />Overall, the tests confirmed that the shafts met and substantially exceeded the required axial capacity, and that the contractor’s installation methods were satisfactory. The results also provided a basis for refining the foundation design in later project phases.

Keywords

Hangzhou West Railway Station

drilled shafts

bi-directional static load test

axial resistance

foundation design

weathered argillaceous siltstone

load transfer

Super Cell

construction methods

axial compressive capacity