| The increase of the excavation depth of the full cycle blasting in open pit mines results in the extremely complex slope environment,especially the research on the response characteristics of the mine slope under the blasting load in the alpine region has always been the bottleneck problem in the cross field of blasting engineering and geotechnical engineering.In this paper,the response characteristics of the complex environment slope in the alpine region are studied by means of the measurement of the wave impedance of the variable medium rock,the field slope monitoring experiment and the numerical simulation.The main research contents and conclusions are as follows:(1)The relationship between multistage piecewise temperature and rock wave impedance is revealed.Firstly,The saturated rock specimens were placed in A(10℃ ～ 24℃)and B(-20℃ ～ 40℃)levels environments after saturated rock specimens were tested,and the rock wave impedance was measured by RSM-SY6.The relationship between multistage piecewise temperature and rock wave impedance was studied.It shows that the decrease of temperature leads to the increase of rock wave impedance value of B levels,which indicates that the decrease of temperature enhances the rock integrity after freezing in rock pore,and then improves the rock wave impedance value.(2)The quantify expression method of blasting vibration propagation model is proposed,and the corresponding relationship between rock freezing depth and blasting vibration attenuation coefficient is established.Based on blasting vibration monitoring experiment on rock slope,the propagation law models of blasting vibration at A and B levels were established respectively,and the freezing depth of rock strata in water-rich mining areas was monitored by self-developed devices.The correlation coefficients of blasting vibration attenuation at A and B levels are determined.It is found that the attenuation coefficients K and a of blasting vibration are negatively correlated with freezing depth.With the increase of freezing depth,the probability of energy dissipation caused by refraction and reflection of blasting seismic wave in water is reduced,and the deceleration rate of peak vibration speed is slowed down,and the damage effect on rock slope is increased.(3)The calculation model of blasting vibration energy of rock slope is constructed,and the energy distribution law of blasting vibration frequency band under the condition of temperature range change is found.The blasting vibration energy of A and B levels is calculated by differential empirical mode decomposition and the method of HHT.The distribution characteristics of vibration energy are analyzed,and the main frequency bands of blasting vibration energy under the condition of B levels are obtained.It is found that the blasting vibration energy of the B levels slope presents a trend toward the lowfrequency band,indicating that the frequency band of the energy concentration and the natural frequency of the rock slope are matched,affecting the safety and stability of rock slope.(4)The adjustment and distribution characteristics of stress state of rock slope with extremely range temperature change are analyzed.The characteristics of displacement change and stress adjustment distribution of A and B slope are analyzed by means of the numerical simulation method.The blasting load causes the horizontal stress of the slope gradually concentrate at the bottom of the slope,and The horizontal stress under condition B is more significant.It shows that there exists stress release in slope under B levels condition,which may lead to slope instability.The research results provide technical support for the safe operation of the mine and the formulation of slope protection scheme. |
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