Research on the acoustic emission characteristics and instability correlation effect of the dynamic response of waste dump slopes.

Due to the fluidity of the loose medium inside the waste dump slope, the traditional monitoring system cannot fully reflect the misalignment and slip between particles inside the medium, and it is also difficult to capture the precursor information of the slip of the loose accumulation body. To reveal the dynamic evolution process of the slope instability of the waste dump slope, the coupling test system of the slope instability of the waste dump slope was used to carry out the study of the acoustic emission characteristics of the slope instability dynamic response of the dump slope under the action of vibration, and to quantitatively analyse the staged characteristics of the acoustic emission parameter evolution of the dump slope under the action of different vibration frequencies and its instability initiation node. The results show that with the increase of vibration frequency, the damage mode of the slope model gradually changes from sliding of small particles to large-scale landslides, and presents the stage process of "vibration compaction → vibration equilibrium → dynamic instability"; Under the action of low-frequency and high-amplitude, the slope model mainly shows that the tiny particles and the basement gravel slip, which is difficult to capture with the naked eye, while under the action of high-frequency and low-amplitude, the slope surface is damaged in a large area, and the overall model is unstable; The dynamic instability of the waste dump slope is accompanied by obvious acoustic emission activities, and the changes of the characteristic parameters of acoustic emission reveal, to a certain extent, the evolution of the internal state of the slope in the process of dynamic instability of the waste dump slope and its stage characteristics; The amplitude and energy efficiency of acoustic emission in the time domain show obvious fractal characteristics in the dynamic instability of the waste dump slope.

Triaxial testing on water permeability evolution of fractured shale.

A sound understanding of the water permeability evolution in fractured shale is essential to the optimal hydraulic fracturing (reservoir stimulation) strategies. We have measured the water permeability of six fractured shale samples from Qiongzhusi Formation in southwest China at various pressure and stress conditions. Results showed that the average uniaxial compressive strength (UCS) and average tensile strength of the Qiongzhusi shale samples were 106.