Instrumentation for Determination of Guardrail-Soil Interaction

A series of steel posts (W150 × 12.6) and timber posts (15.2 × 20.3 cm) were instrumented with soil pressure transducers to assess the soil-post load response to a 1,388-kg bogie striking the post at 33 km/hr. Soil pressure measurements demonstrated the dramatic effects of soil shear strength and modulus on the responses of both timber and wood posts. The differences in the failure mechanisms between stiff and soft cohesive soils and noncohesive soils are demonstrated by both stress distributions and total stresses measured by the pressure transducers. The measurement system has potential applications for measurement of loads during impact testing of guardrail systems and as a tool for developing more appropriate models of soil behavior during impact loading.