采空区矿柱流变特性对露天矿边坡稳定性的影响研究

Study on effects of pillars rheological properties on open-pit slope stability

为分析采空区矿柱流变特性对露天矿边坡稳定性的影响,以排山楼金矿边坡井工开采为研究对象,建立采空区矿柱–顶板-边坡系统的流变力学模型。采用FLAC3D分析露天矿边坡的长期稳定性,将矿柱视为符合CVISC模型的黏弹塑性体,获得井工开采完成5 a内各时间段边坡内部的应力场、位移场变化规律。预测采空区顶板的冒落时间,并结合露天矿现场实际情况,进行对比分析,验证预测结果的可靠性。研究表明:井工开采刚刚完成时,采空区顶板出现的拉应力将不超过其抗拉强度,不会导致顶板冒落;随着矿柱流变效应的发展,边坡内拉应力和变形量也随之增加,开采完成4.5 a后,采空区顶板出现局部冒落现象,这时宜对采空区进行充填,以保证边坡的稳定性。

To analyze effects of pillars rheological properties on open-pit slope stability, the slope underground mining of Paishanlou gold mine was taken as an object of study, a rheological model was built for pillar-roof-slope in mining areas. The long-term stability of open pit slope was studied by software FLAC^3D. The pillars were considered as a viscoelastoplastic body conforming to CVISC model. Five year variation scenarios were described for stress field and displacement field of slope. The collapse time was predicted for roof caving . A comparison was made between prediction and actual situation of mine. The results shows that tensile stress on goal roof does not exceed its tensile strength and does not lead to roof caving when the mining is finished, that with development of pillar rheological effect, the tensile stress and deformation increases, that phenomenon of goal roof caving appears after 4.5 years mining, and that it is necessary then to fill the goaf in order to ensure the safety of slope.