程潮铁矿东区地面塌陷机制及扩展机制初探

Study on mechanism of formation and expansion of ground caving-in in the eastern Chengchao Iron Mine

根据程湖东区塌陷历史与现状,借助三维激光扫描技术重建了地面塌陷三维地表模型,结合surfer绘制出了地面累计沉降等值线图和累计沉降值盆地;最初塌陷点大多分布在大理岩及围岩蚀变带中;塌陷区自东向西呈条带状分布,北部塌陷要比南部严重;塌陷区内呈现类似"角峰"、"刃脊"等冰川地貌的特点。根据地质条件、采矿情况以及监测资料分析,认为地下采矿是诱因,地质条件是内因,二者共同作用导致了塌坑大多首先在大理岩及围岩蚀变带区域中出现。在塌坑出现后,较高的水平构造应力得到释放,使得由NE向节理切割成悬臂梁板的岩体被折断。通过建立的力学模型分析得到岩体折断的范围达到了172 m宽。折断的岩体沿着折断面发生倾倒滑移破坏。这种力学扩展机制使得塌坑范围不断扩大,最终形成一个大的塌陷盆地。

According to the history and current situation of ground caving-in in the eastern Chengchao Iron Mine, a 3D surface model of ground caving-in was reconstructed with the help of a 3D laser scanning technology. Furthermore, the ground subsidence contour map and the accumulative subsidence basin were obtained by combing with Surfer program. It showed that the initial ground caving-in points were mostly distributed in the marble area and the wall rock alteration zone. It is found that the ground caving-in area was a zonal distribution from east to west. Moreover, the situation of ground caving-in in the north was more severe than in the south. The terrain and landform of the ground caving-in area show similar glacier landscape features, such as the horn and blade ridge According to geological conditions, underground mining situations and monitoring data of cracks and ground surface deformation by the 3D laser scanning technology, it is considered that underground mining is an internal cause and geological condition is an external cause for ground caving-in. The combined effect of these two factors led ground caving-in to appear mostly in the marble and surrounding rock alteration zone area for the first time. After the emergence of ground caving-in, a high level horizontal tectonic stress was released. As a result, rock mass, which was cut into a cantilever beam-plate by NE-trending joints, was broken. Through the analysis of the mechanical model of a cantilever beam-plate, the scope of fractured rock mass reached up to 172 meters wide. The fractured rock mass produced toppling-sliding failure along the sliding surface. Therefore, this mechanism of mechanical expansion makes the scope of ground caving-in wider, and finally forms a large ground caving-in basin in the eastern Chengchao Iron Mine.