Stability and Reinforcement of Guardrail Post in Central Separate Belt of Expressways Based on MCPT

Abstract

In China there are no clear prescriptions to the compaction degree of the subsoil around guardrail posts in the current highway safety specification. So the bearing capacity of guardrail posts can not satisfy the actual requirement due to the presence of the plant soil in the central separate belt. A series of laterally loading tests of posts embedding in the silty clay are carried out. The linear relation is found between the critical load representing lateral bearing capacity of posts and the limit cone tip resistance of the miniature penetrometer representing soil strength in the miniature cone penetration test (MCPT). Assuming that the soil reaction on the post is related directly to the cone limit penetration resistance, a model of soil reaction distribution corresponding to the critical load is put forward and the unknown parameter in model is calculated inversely by test data. According to this model and the embedding conditions of posts in situ, an effective method of using one steel plate to reinforce the post is presented and verified by tests. Now this reinforcement method has been applied to guardrail posts of some expressways of China.