露天矿排土场高边坡动力稳定性研究

A study on Dynamic Stability of Slopes at Dump Sites of Open-Pit Mines

露天矿生产采用爆破手段,除采矿形成边坡外,废矿堆积也常常形成排土场高边坡,现场实测露天矿排土场在生产爆破作用下的振动速度,将实测加速度数据推导得到的水平加速度值,线性插值到每一个土条中,利用等效静力法对边坡在爆破动力作用下的稳定性进行了计算及评价,与传统等效静力法相比,此方法更接近实际振动加速度分布情况。同时,采用模态叠加法,通过有限元动力响应分析的手段,对露天矿排土场高边坡表面不同部位土体位移分布规律进行了分析,最终得到研究边坡在生产爆破动荷载作用下不会产生整体滑移,但在坡面顶部表层或浅层会产生一定深度的拉张裂缝,在重力和爆破动力的作用下裂缝逐渐加深,到一定深度时,表层矿渣会顺坡滑下产生表面滑塌型破坏的结论。

The blasting is a common way adopted in open-pit mines, where higb-angle slopes of waste rock are often formed at dump sites during production. In this study, vibration velocity, which is produced by production blasting, is measured at the dump site in an open-pit mine, and the horizontal acceleration value is derived. Then this acceleration value is interpolated linearly to each soil strip,and the slope stability is calculated and evaluated by the equivalent static force method. Compared with the traditional equivalent static method, the result by this approach can better simulate the actual distribution of vibration accelerations. Besides, using the mode superposition and finite element method, the soil displacements at varied places of the slope surface are analyzed. It is concluded that the slope will not slide down as a whole due to the dynamic loading of production blasting, but some tensile cracks would been produced and developed on the top surface or shallow subsurface. These cracks will become deep under gravity and later blasting,and finally collapse failure will happen when the surface slag slides down along the slope.