爆破振动在岩质边坡坡面的放大机制研究

Study on Amplification Mechanism of Blasting Vibration on Rock Slope Surface

岩质边坡坡面的爆破振动放大现象,影响着边坡爆破振动监测及安全评价的准确性。采用数值模拟方法,研究了边坡坡面的振动放大现象,基于结构动力学原理,根据振型分析理论揭示了边坡坡面振动放大机制。数值模拟结果表明:边坡振动放大现象主要发生在台阶坡顶线附近区域,受台阶突出物几何尺寸及岩体物理力学参数的影响,随着平台宽度增大、台阶高度减小、台阶坡比减小以及岩体工程质量等级的降低,台阶坡顶线位置振动速度峰值相对于台阶坡底线位置的振动放大现象逐渐显著,但第一主应力分布与振动速度峰值分布规律相反,因此为了更准确地进行爆破振动安全评价,建议将监测点布置于台阶坡底线位置。振型分析结果表明:台阶突出物的低阶振型中坡底线位置与坡顶线位置的振动速度峰值之比随着台阶几何尺寸及物理力学参数的变化规律与数值模拟计算结果一致。由此可见:边坡坡面的振动放大效应主要由台阶突出物几何尺寸及岩体物理力学参数决定的低阶振型控制。

The amplification of blasting vibration on rock slopes significantly impacts the accuracy of vibration monitoring and slope safety evaluation.This study investigates the phenomenon through numerical simulation and explores the amplification mechanism based on structural dynamics and vibration mode analysis.The simulation results show that the vibration amplification phenomenon primarily occurs in the vicinity of the bench crest.Influenced by the geometric dimensions of the bench crest and the physical and mechanical parameters of the rock mass,higher peak vibration velocities occur at the bench crest than at the bench toe,due to an increase in platform width,a decrease in bench height,a reduction in the slope ratio and a lower rock mass quality.Conversely,the distribution of the first principal stress exhibits an opposite trend to that of the peak vibration velocity.To improve the accuracy of safety assessments,it is recommended that monitoring points be placed at the bottom line of the bench.The vibration mode analysis further confirms that the amplification effect is predominantly governed by the low-order vibration modes,determined by geometric dimensions and mechanical parameters of the rock mass.The agreement between the mode analysis and numerical simulation results highlights the critical role of low-order vibration modes in controlling the slope′s vibration amplification.