In this study, dynamic pressure response of base structure of Fu Yingzi tunnel along Zhangjiakou to Tangshan was simulated through field large-scale excitation test under the class V rock conditions when the heavy haul trains with axle weights of 250 kN, 270 kN, and 300 kN passed. Dynamic pressure attenuation values at measuring points were presented when axle weight was reduced. According to the earth pressure time history chart of field measurement, horizontal and vertical distributions of dynamic pressure of the measuring points in each structural plane were analyzed. The results indicate that dynamic pressure of each measuring point in heavy haul line of double line tunnel is greater than passenger train line, and the dynamic pressure of the corresponding measuring points below the railway track under different axle load of heavy haul trains is greater than other measuring points. Stress concentration is found to appear in the structure and surrounding rock at corresponding heave haul position, which is more likely to cause the structure to crack or hole generation in wall rock under the condition of broken rock compared with the test results on the surface of class IV grade surrounding rock. Train load attenuates drastically due to cushioning of the bed structure and inverted arch filling as it vertically transfers, but there is only small attenuation in inverted arch. Current designed basement structure thickness cannot meet the demand of lifting axle load.

heavy-haul railway;base structure;field test;dynamic pressure response