Slope Stability Analysis And Vibration Reduction Study Under Blasting Dynamic Load

Blasting construction technology is more and more widely used in mine engineering,municipal engineering,civil air defense engineering,etc.In the process of slope blasting,the slope is damaged by the impact load.Simultaneously under the action of ground stress,the accumulated damage may eventually lead to slope sliding,resulting in economic losses and casualties.Therefore,the study of slope stability has been valued and developed.In order to effectively control the damage of blasting impact load to slope instability,it is necessary to reduce vibration adopting feasible blasting parameters,which is of vital importance in ensuring the safety of the project.This paper is based on a typical slope project in Northwest China.In order to improve the engineering safety assurance rate and prevent the inaccurate expression of engineering risk degree caused by the common drawbacks or defects of single or similar analysis methods,the limit equilibrium method(Felenius method,Bishop method and Janbu method)and finite element strength reduction factor method(2D,3D)are used to calculate the static load safety factor of the actual slope engineering and determine its potential slip surface.On the basis of the two-dimensional potential sliding surface determined,the three-dimensional model of the same size slope is reconstructed by ANSYS/LS-DYNA for blasting dynamic analysis,in order to minimize the blasting vibration without shear sliding.Firstly,the optimal uncoupled charge structure is determined by the effective stress and Vy time history curve,and then the hole-by-hole millisecond blasting is carried out based on the optimum uncoupled charge structure.Similarly,after analyzing the V time history curve,the optimum delay blasting time is 25 ms to meet the requirement of reducing vibration.Finally,the stress value of the potential sliding surface element of the optimum uncoupled charge structure is extracted and substituted for the limit equilibrium method to obtain the time history curve of dynamic safety factor.The optimum theoretical delay time is obtained as 30 ms by analyzing the curve,which is match to the simulation results.The results show that the charge structure with uncoupling coefficient of 1.43 and the blasting parameters with delay time of 25 ms have the best vibration reduction effect under the engineering geological conditions.Influence factors(geometric parameters,physical parameters and technological parameters)of slope stability are studied by dimensional derivation to analyze the relationship between the factors affecting the stability coefficient under dynamic and static loads.Fuzzy mathematics is used to evaluate the safety of slope stability,and the validity of the evaluation result is analyzed by the principle of maximum validity.