地下采动顺向缓倾构造山坡的滑移机理

SLIDING MECHANISM OF THE GENTLE DIPPING SLOPE ASSOCIATED WITH UNDERGROUND EXCAVATION

采空区地表山体侧向变动,不同于一般天然山坡,也与采空区一般上覆岩层的变形破坏有异;它是二者复合机理的效应。本文在分析考察了毗邻电厂的横山顺倾构造山体、剖析了地下采空情况认为:山体侧向变动中,软弱夹层有决定性作用,变动范围、速率和规模与地下采空有关;并利用地质力学模型试验和数值模拟,探索了采动引起山体应力场及变动规律。结果表明,山体岩层的变形、位移、破坏、由直接顶板向地表发展,采空坍陷诱发了软弱夹层的蠕滑,则产生山体侧向滑移;电厂区地表隆起变形是山体侧向滑移挤压地基土的反映。通过现场实际调研、变形观测资料分析与数值模拟和模型试验的对比研究,提出了“坍落拱梁”的成生效应、挤压蠕滑效应、失稳效应;揭露了顺倾构造山体在采空影响下,具有地表、地下的“复合临空面”的“复合应力场”中“复合变动”的“复合机理”;并提出这种山体侧向变动机理的典型地质模式,借以论证山体稳定性。

The slope activities above mined-out area are different from the deformation and failure of general slope and strata overlying mine area. It is a new problem about compound activities and mechanism. Hengshan slope adjacent to a power plant is an example. Based on analysis of the structural characteristics of low angle dipping strata,this paper deals with the mechanical properties of weak intercalations in the slope. It is considered that weak intercalations have played a leading role in the lateral activities of slope. According to detailed field investigation and analysis of displacements, we found that the deformation of rock mass of the slope is mainly controlled by underground mined-out area, subsidence as well as the creeping of rock mass on the pre-slope toward the landsurface. It is showed that the deformation, displacement and failure of rock formations are through the overlying strata to the landsurface of slope. Weak intercalation creeping induced by mine collapsing beneath slope leads to slope lateral activities. The surface doming of power plant area is caused by pre-slope rock mass pushing a-gainst the bassment soil. By comparing the modelling results to actual deformation and displacement data and geological indications, the effect such as collapsing, creeping, etc. induced by underground coal mining, are analysed in detail. This paper proposes also the ' compound stress field' and ' compound boundary surface'. The typical geological model about the lateral activities of low-angle rock formation on slope jas been put forword.