Safety Analysis On The Dynamic Stability Of High Rock Slope Induced By Blasting Vibration

Most of high rock slope are excavated by blasting. During the process of rock excavation by blasting,as a result of the actions of blast stress wave and explosion product,the dynamic stability of high rock slope and blast-induced damage zone is occurred in the preserved rockmass after the excavation.The influence of blasting vibration on the dynamic stability of high rock slope is a complex dynamic problem in rock engineering, which relates to geology, explosion mechanics and rock dynamics, etc. It's a key technical problem that is urgently waiting to be solved in the construction of some large hydropower stations located at the high-mountain-and-gorge areas in the southwest and northwest of China. To do further study on the problem is of both high theoretical and practical importance.A series of research works have been done in the thesis, such as the characteristics of blasting vibration, the numerical analysis methods of the dynamic stability of high rock slope, the dynamic response of high rock slope and the safety criteria of slope induced by blasting vibration, etc. Combined with the excavation blasting of the slope of Jingping Hydro-power station cascade-1, the follwing contents are analyzed, the following achievements have been obtained:(1) To analyze influence of blasting vibration on the dynamic stability of high rock slope and summarize the analyze methods of rock high slope excavated by blasting from domestic and foreign.(2) An equivalent method for the acting of blasting load in the simulation of blasting vibtation is put forward. It is concluded that, it is feasible to use the method of acting equivalent blasting load on the cross section including row of boreholes to simulate blasting vibration in middle-and-far field, but it is good method of using ALE in close field.(2) Based on the time history analysis method, using reservation ratios of shearing strength analyzing the dynamic stability of high rock slope under blasting vibration . The variation of frequency spectrum, amplitude and phase of blasting vibration could be taken into account in the method proposed. The dynamic stability factor varying with time is obtained. It is indicated that the influence of the frequency of blasting vibration should be taken into account during analysis, and it is reasonable to analyze the dynamic stability of slope.(3) Using LSDYNA software analyzing the characteristics of blasting vibration. By comparing the simulation of single-hole blasting and multiple-hole blasting, the influences of characteristics of blasting source, properties of rock mass, delay intervals, distance from blasting source, etc, are analyzed. The relationships of the magnification coefficient after superposition versus the distance from blasting source are presented through numerical simulation.(4) Using experimental formula and LS-DYNA software analyze the damage zone in rockmass. The two calculated results are consistent.(5) The safety criteria for blasting vibration during the excavation of slope are studied. As geological defect of left slope, The safety criteria for blasting vibration is made by stability of high slope. But on right slope, calculating of the dynamic response of high rock slope under blasting vibration with Dynamic Finite Element Method, the safety criteria for rock slope induced by blasting vibration is decided through the statistic relationship between the peak value of tensile stresses and the sidestep according to the failure law of maximum tensile stress.