条带气化开采覆岩移动与地表沉陷实测分析

Measurement analysis of overlying strata movement and surface subsidence by UCG strip mining

为了获得华亭原安口煤矿工广煤柱地下气化极不充分开采条件下地表沉陷规律,在国内首次建立了条带地下气化工作面覆岩移动与地表沉陷观测站。通过地表测点和浅基点岩移钻孔磁环动态下沉过程分析表明,下沉曲线呈"下沉-上升-下沉-上升-下沉"五阶段阶梯式波动下沉规律,条带气化工作面极不充分开采地表移动和变形具有明显的非线性和非连续性。通过不同磁环动态下沉过程分析,确定了岩层离层区位置。通过地下气化炉燃空区物探分析得出燃空区间投影面呈中间宽、两头较窄的似椭圆形。计算了下沉盆地倾向主断面边界角、最大下沉角和地表最大移动变形参数(imax=1.385 mm/m,εmax=0.516 mm/m,Kmax=0.275 mm/m2),得出了下沉盆地并没有达到危险移动边界,条带地下气化开采没有产生明显下沉盆地,在观测期内没有对地表建筑物造成危害的结论。

To obtain the surface sinking regularity in the case of super-subcritical extraction of shaft pillar by underground coal gasification （UCG） at former Ankou Coal Mine in Huating, Gansu Province, the first observation station in China for overlying strata movement and surface subsidence of strip-partial UCG working face is established. After the analysis of dynamic subsidence progress of sur-face measuring point and magnetic rings in surface shallow base point observation drilling, it is found that the subsidence curve shows the fluctuant and stepwise subsidence pattern which has five stages （sinking→rising→sinking→rising→sinking）, and the surface movement and deformation of su-per-subcritical extraction of strip-partial UCG working face are obviously characterized by nonlinearity and discontinuity. The strata separation area is positioned by analyzing the dynamic subsidence progress of different magnetic rings. The geophysical prospecting finds that the projection plane of combustion space area seems like an oval, wide in the middle and narrow at both ends. The greatest subsidence an-gle, boundary angle of incline main section of subsidence basin and the maximum surface movement and deformation parameters （i max = 1.385 mm/m, εmax = 0.516 mm/m, K max = 0.275 mm/m2） are ob-tained, which indicates that the subsidence basin doesn’t reach the critical boundary, and this extraction of strip-partial UCG working face doesn’t form apparent subsidence basin and destroy the surface building in the observation period.