基于能量原理的露天矿边坡开挖稳定性突变研究

Energy principle based catastrophe study of slope stability in open-pit excavation

基于边坡系统能量的原理,借助FLAC3D有限差分法内嵌FISH语言进行了三维露天矿边坡模型在开挖过程中能量计算的二次开发。将能量与突变理论相结合,以边坡系统的总耗散能作为状态变量,构建了边坡系统的能量耗散突变判别准则。以大孤山露天矿西北帮边坡为例,通过能量耗散突变分析、塑性区演化分析、安全系数变化分析及关键点位移分析可知,以上分析得到的边坡稳定性演化规律具有一致性,验证了提出的突变判别准则的适用性,研究结果表明:能量突变特征值D<0是露天矿边坡在第ki步开挖后发生失稳的充要力学条件;当进行至第6~8步开挖时,边坡局部岩体系统发生了失稳,且第7、8、9三个台阶受开挖扰动的影响较为严重,与现场的实际开挖情况相符,为预防露天矿边坡在开挖扰动过程中的局部围岩系统失稳提供了一定的理论支持。

Based on the slope system energy principle and FISH language embedded in FLAC3D finite difference method, secondary development of energy calculation in three-dimensional open-pit mine slope excavation model is carried out. Combining energy with catastrophe theory and taking the total dissipative energy of slope system as state variable, the energy dissipation criterion for slope system catastrophe is established. The analysis of sudden change in energy dissipation, plastic zone evolution, safety factor changes and key point displacement is done using the northwest slope of Dagushan open-pit mine as an example. It can be seen that the slope stability evolution obtained by the above analysis is consistent and the applicability of the proposed catastrophe criterion is verified. Results show that energy mutation eigenvalue is a sufficient and necessary mechanical property of slope instability after the ki step excavation. When the excavation is carried out to the 6-8th step, the local rock mass system of the slope is unstable, and the three steps of the 7th, 8th and 9th stage are seriously affected by the excavation disturbance, which is consistent with the actual excavation situation in the field. It provides some theoretical support for preventing the instability of local surrounding rock system during excavation disturbance of open-pit slope.