This paper explores a new approach for assessing the stability of a hazardous rock block on a slope using vibration feature parameters. A physical model experiment is designed in which a thermally sensitive material is incorporated into the potential failure plane of the hazardous rock, and the complete process of hazardous rock collapse caused by strength deterioration is simulated by means of constant-temperature heat transfer. Moreover, the vibration response of the hazardous rock is monitored in real time by laser vibrometry. The experimental results show that five vibration feature parameters, including the mean frequency, the center frequency, the peak frequency, the mean frequency standard deviation, and the root mean square frequency, are well-correlated with rock stability. Furthermore, through principal component analysis, the five vibration feature parameters are synthesized into a principal component factor (PCF) as a representative assessment parameter. The results of the analysis demonstrate that the variation in the PCF exhibits three characteristic stages, i.e., “stationary-deviation-acceleration,” and can effectively identify the stability evolution trend and collapse precursor behavior of hazardous rock block.

As one of the dynamic disasters of deep mining, rockburst significantly affects the safety of underground environment especially at great depth. First, the elastic energy and dissipative energy are deduced to characterize rockburst process separately employing the theoretical analysis and test technique. Then, a series of split-Hopkinson pressure bar system tests are conducted. After calculation, the percentage of fractured dissipative energy occupied in total input dynamic energy is obtained. Subsequently, the dynamic mechanical parameters of rock specimens and dynamic impact factors are fitted. Finally, a three-dimensional model is developed using the mechanical property of the host rock, constitutive model, and in situ geostress. The contours of energy and the damage conditions of host rock are predicted, and the tendentiousness of rockburst is estimated.

The stiffness ratio of frame to core tube has an important influence on the seismic behavior of frame-core tube hybrid structure which is a high-rise building structure system widely used in the world. In this paper, nine models of concrete-filled steel tubular frame-concrete core tube super-high-rise hybrid structures with different stiffness ratios are established by using finite element method, and the effect of stiffness ratio on inter-story displacement angle, top displacement and base shear force of super high-rise buildings under frequent earthquakes is studied. The results show that, with the increase of stiffness ratio, the inter-story displacement angle, the top displacement and the base shear force change complicatedly, the maximum base shear force increase, and the maximum inter-story displacement angle and the maximum top displacement first increase then peak, and that the strengthening layer with outrigger obviously improves the deficiency of lateral stiffness caused by height. This study provides a reference for reasonable determination of stiffness ratio and optimization of structural seismic design.

The study on the change of rock pore structure during the weathering of purple mudstone is of guiding significance to the stability of the bank slope of the three gorges reservoir. In this paper, the pore changes in the wet and dry circulation of purple mudstone in the three gorges reservoir area are studied by means of nuclear magnetic resonance (NMR). The results show that the simulated weathering of wet and dry circulation has a great influence on the purple mudstone. With an increase in the number of dry-wet cycles, the purple mudstone pore volume ratio significantly changed. Originally, it consisted of a small pore structure with a single pore diameter of 0.01–0.1 µm and changed to a variety of pore structures with various pore diameters of 0.001–100 µm. With the increase in the number of dry-wet cycles, the micropores (0.001–0.1 µm) were transformed into macropores (0.1–1 µm). The area of the second peak of the three samples (large pores 0.1–1 µm) increased from 0.9413, 0.9974, and 0.6779 to 0.9871, 1.1498, and 0.9901, respectively.

Nano-porous silica aerogels are synthesized by two steps by the supercritical condition. By synthesized process, tetra-ethyoxysilane is used as raw material, isopropanol and H2O which is distilled after ion exchange was used as solvent, HCl and NH4OH are used as hydrolysis and condensation catalysts, glycerol is used as drying control chemical agent. Silica aerogels are obtained by supercritical drying condition after aging, surface modification and exchanging solvent. The effect of water, PH, temperature, and so on, are analysed at supercritical drying condition. The resulting aerogels are characterized by means of X-ray diffraction and scanning electron microscopy. It is found that the aerogels made by this method have high porosity, specific surface area and the structure is sponge with narrow particle and pore size distribution.