EXPERIMENTAL STUDY ON INFRASOUND MONITORING DURING SOIL SHEAR FAILURE

When a soil landslide is near the landslide stage, infrasound waves are generated. Infrasound monitoring can be used as a technical means to determine whether a soil landslide is in the approaching stage Considering that the landslide's mechanical method is mainly shear failure, in order to ascertain the response characteristics of infrasound signals during the process of soil landslides, a combined infrasound-force-displacement monitoring system for soil shear experiments was designed and an infrasound monitoring test for soil failure was carried out. Based on the automatic picking up of infrasound events, combined with the theory of progressive failure of cohesive soil, the micro-acoustic mechanism during the shearing process is analyzed. The results show that: (1) The infrasound signals emitted during shear failure of cohesive soil are mainly derived from three aspects: first, from the mutual compression of clay particles in the elastic phase, and then from the tensile fracture of clay colloidal particles in the elastic-plastic phase, finally, it comes from the friction between soil particles during strain softening. (2) The amplitude of the infrasound signal shows a certain regularity at different stages of soil shear loading. The amplitude of the infrasound signal during the elastoplastic phase is the largest. The amplitude of the infrasound signal during the strain softening phase is minimal. The amplitude of the infrasound signal corresponding to the elastic phase is between the elastoplastic phase and the strain softening phase (3) There is a strong correlation between the shear force and the infrasound signal. The peak envelope of the infrasound event matches the shear force trend line. At the same time, the mean square power peak of the infrasound signal is ahead of the thrust peak. The average time is 22.95 s. The research has important theoretical reference value for further using infrasound to carry out monitoring and stability evaluation of soil landslides.