地下开采作用下“反倾上硬下软”型斜坡崩塌形成机制研究——以贵州开阳磷矿崩塌为例

MECHANISM OF ROCKFALL WITH ANTI-DIP AND TOP HARD-BOTTOM SOFT ROCK BY UNDERGROUND MINING——A CASE STUDY OF ROCKFALL IN KAIYANG PHOSPHORITE,GUIZHOU

以贵州开阳磷矿崩塌为例,通过对地质条件、采矿扰动与变形破坏特点的分析,阐明在地下开采作用下,"反倾上硬下软"型斜坡变形破坏的发展过程,并总结斜坡失稳破坏的3种模式,指出不同类型的破坏变形均以坡顶拉裂为前兆,而斜坡岩体结构特征是产生不同破坏模式的关键控制因素。进一步运用数值模拟与物理模拟方法,分析该类型崩塌的形成机理,认为"反倾上硬下软"型崩塌的形成具有特定的地质背景,动力条件与诱发因素;崩塌最终可能以急剧破坏的形式出现,但其发生并不是一蹴而就的,是经历了从发生、发展直至破坏的长期过程。从地下开采后采空区顶底板的变形,发展到地表裂缝的产生,崩塌的形成是地表裂缝沿着陡倾结构面追踪发展的过程,并受岩体结构特征的控制最终发生倾倒、突破"锁固段"剪出或沿中缓倾结构面滑塌。因此,对此类斜坡地质灾害的监测和防治必须把握前兆现象,加强早期识别与预警。

This paper takes Kaiyang phosphorite rockfall in Guizhou for example.It analyzes the geological conditions,mining exploitation and failure characteristics.It then develops the process of rockfall deformation with anti-dip and top hard-bottom soft rock.The formation mechanism of this type rockfall is studied through numerical simulation and physical simulation.The results show that this rockfall is induced by specific geological background, dynamic conditions and predisposing factors.Especially,there is a long development process from occurrence to destroy.A rapid destruction form is presented finally.They are specifically deformation of the roof and floor rock in the mine area,appearance of cracks on the top of slope and development of cracks along the steep joints in the slope.There are three failure modes：crack-toppling,crack-slide and crack-shear.Therefore,the key about monitoring and prevention of geological disasters to this type rockfall is precursory information for enhancing early identification and warning.