Abstract: Though many tests proved that thin-walled circular pipes will collapse under bending due to local buckling, the bending stability of this kind of pipes in soil hasn’t been studied so far. The behaviors of highway guardrail posts under lateral loads were studied experimentally. It was found that the stability of the thin-walled circular pipe piles under lateral loads depends mainly on the strength of the soil and the characteristic loads on the load-displacement curves all increase with the strength of the soil. Compared with rigid piles loaded laterally, thin-walled circular pipe piles embedded shallowly can be regarded as rigid piles before buckling. Large local deformation occurs only near buckling of pile. The admissible load of pile is linear with the limit cone penetration resistance of CPT representing the strength of soil. Finally, based on cone limit penetration resistance of CPT, a reduced model of soil reaction distribution on pile was proposed; and the soil reaction coefficient in model was back-calculated by the experimental data.

Key words: thin-walled circular pipe piles embedded shallowly, rigid piles, stability, CPT, local buckling