The stress-strain

resistivity and temperature variations of backfill materials in the whole process of uniaxial compression are studied using a self-designed synchronous monitoring system

which is composed of the loading control system

strain measurement system

the resistivity collection system and the thermal infrared (TIR) observation unit. The precursory anomaly characteristics of the stress-strain

resistivity and TIR are observed before backfill body failure. The sensitivity and difference of different monitoring systems to the same failure event are also compared. The results show that the time-space evolution process of the resistivity and TIR is quite close to the whole process from compression deformation to failure of backfill body

showing apparent staged characteristics. The precursory information point of resistivity occurs prior to the TIR and the stress points. The resistivity variation has an apparently anti-symmetry feature in the process of compression

compared to the stress-strain relation and temperature variation. The variation of resistivity can give a detailed description of the internal structure change at every phase during compression. However

the TIR information mainly represents the surface temperature evolution during the process of compression before plastic yielding of the backfill. The multiparameter methodology used to evaluate the precursory information during loading process can overcome the disadvantages of early-warning approach

say low reliability and inaccuracy. The proposed method is an effective one in determining the stable state of backfill body.