Vibration characterization of fully-closed high speed railway subgrade through frequency: Sweeping test

• Damage mechanisms of railway subgrade overlying on expansive soil are proposed.
• A new type of fully-closed railway subgrade structure (FCRS) was developed.
• Dynamic stress attenuation regularity was apparently affected by frequency range.
• Frequency and FCRS layer system affects acceleration attenuation regularity.
• The internal resonance frequency of FCRS was influenced by its layer system.

This paper presents the vibration characteristics of a new type fully-closed railway subgrade (FCRS) through field frequency – sweeping test. The FCRS, which uses semi-grid modified cement-based compound material as waterproof layer, is designed to solve serious subgrade damage problems induced by expansive soil. Dynamic stress sensors and accelerometers were installed at various locations in FCRS to monitor dynamic response. The results show that the attenuation regularities of dynamic stress and acceleration along subgrade depth were significantly affected by excitation frequency and semi-grid waterproof layer. The pronounced frequency of FCRS investigated in this paper was gently influenced by its layer system, and gradually changed from 20 Hz to 22 Hz as depth increased.