Study Of The Water-inrush Mechanism And Prediction Of The Water-resisting Floor

As a heterogeneous material,the deformation and failure of coal and rock is a fundamental problem in the study of rock mechanics properties.Based on laboratory conditions,mortar samples are used for analogous test and analysis,in order to make breakthroughs.In this paper,the compressive strength characteristics of mortar specimens with different mortar ratio and the same loading rate under uniaxial compression conditions.The formation of the local zone and the evolution of the crack in the process of deformation and failure,and the acoustic emission characteristics,and the results of integrated acoustic emission and digital speckle under uniaxial compression conditions are studied under the conditions of uniaxial compression,with different mortar ratio and the same loading rate.A new index K for predicting the breaking time of mortar specimens is put forward.The whole process of deformation and failure of different sandwich mortar materials is analyzed,and the energy sources of the instability breaking of the sample are discussed by using the simple physical model and the FLAC simulation technology.The main results are summarized as follows:(1)During the deformation and failure process of mortar specimens,the characteristics of acoustic emission events are basically consistent with the characteristics of acoustic emission energy.Acoustic emission events count and acoustic emission energy can be used to characterize the process of internal damage evolution during the deformation and failure process of mortar specimens.combined with the test data.An index K for predicting the failure time of the mortar specimen is presented,and the phenomenon of "rebound" appears obviously in the change of K value.indicating that the mortar specimen will be destroyed soon.(2)Under uniaxial compression,the peak strength of the sandwich mortar specimen under the same loading rate,whether it is cast iron sandwich mortar or pine sandwich mortar,increases with the mass ratio of cement to sand,and the peak strength of the sandwich mortar specimen is higher than that of the mortar sample.And the peak strength of cast iron sandwich mortar with the same ratio is greater than that of pine wood mortar.(3)Using the digital speckle experiment,the localized deformation and breaking process of the mortar specimens under different sandwich conditions are discussed and analyzed.It is pointed out that the localized deformation and the crack evolution of the mortar specimens are greatly influenced by the sandwich materials,and the different evolution modes of the different "heterogeneity" are not the same.(4)Based on the energy instability criterion,a simple physical model is used and the FLAC simulation is used to make a related discussion.It is pointed out that the energy of the failure of the specimen is derived from the specimen itself.