Shaking table test on damage mechanism of bedrock and overburden layer slope based on the time-frequency analysis method.

To systematically analyze the damage caused by bedrock and overburden layer slope under seismic action, a set of large-scale shaking table test was designed and completed. Interpolation of the acceleration amplification coefficient, Hilbert-Huang transform and transfer function was adopted. The damage mechanisms of the bedrock and overburden layer slopes under seismic action are systematically summarized in terms of slope displacement, acceleration field, vibration amplitude, energy, vibration frequency, and damage level. The results show a significant acceleration amplification effect within the slope under seismic action and a localized amplification effect at the top and trailing edges of the slope. With an increase in the input seismic intensity, the difference in the vibration amplitude between the overburden layer and bedrock increased, low-frequency energy of the overburden layer was higher than that of the bedrock, and the vibration frequency of the overburden layer was smaller than that of the bedrock. These differences cause the interface to experience cyclic loading continuously, resulting in the damage degree of the overburden layer at the interface being larger than that of the bedrock, reduction of the shear strength, and eventual formation of landslides. The displacement in the middle of the overburden is always greater than that at the top. Therefore, under the action of an earthquake and gravity, the damage mode of the bedrock and overburden layer slope is such that the leading edge of the critical part pulls and slides at the trailing edge, and multiple tensile cracks are formed on the slope surface.

Clean Preparation of Formed Coke from Semi-coke by the Carbonated Consolidation Process.

In order to address the low thermal efficiency of low-rank coal combustion and the accompanying serious environmental issues, formed coke was prepared using a carbonization consolidation method with low-rank coal semi-coke. The test for briquetting and carbonation consolidation conditions revealed that the optimal parameters were a briquetting pressure of 93.63 MPa, moisture content of 16%, Ca(OH)2 binder amount of 10%, and a CO2 concentration of 30% at 20 °C. Under these conditions and a carbonation consolidation time of 60 min, high-quality formed coke was produced, exhibiting a compressive strength of 1256.2 N/a, redrying strength of 286.2 N/a, and a dropping strength of 10.6 number/a. The combustion characteristics of the prepared formed coke were investigated, revealing that ignition temperatures (345.39 °C), burnout temperatures (495.57 °C), and peak of the maximum weight loss rate temperatures (437.93 °C) are slightly higher than those of bituminous coal. The low calorific value of the briquette was 20.4 MJ/kg. During the combustion process, the emission concentrations of SO2, NOX, and solid particles from the formed coke were significantly lower than those of bituminous coal, indicating that it is a cleaner energy source. Moreover, adding Ca(OH)2 effectively reduced SO2 emissions and achieved sulfur fixation and emission reduction.