建筑荷载影响下的浅部老采空区覆岩变形破坏相似材料模拟研究

摘要

Surface construction over shallow waste gob may result into instability of overlying strata with small depth-to-thickness rati-o.Applying analogue material test method, residual gap distribution, gap development of overlying strata influenced by buildings’ load and surface sink characteristic was researched.Results showed that:secondary compression of residual gap influenced by load or its in-stability was main factor of occurring new large surface deformation over gob; residual gaps in overlying strata of gob mainly included:long-standing separation without outer disturbance, cracks after long-time compression in caved and fissure zone, and caverns formed by un-fully caved overlying strata at the boundary of mining; there was no whole supporting effect of strata within bending zone in over-lying strata over gob, or thinner overlying strata could not scatter load influence and load was exerted to broken rock in caved and fis-sure zone, which made broken overlying strata secondly to be compressed till instability.Influenced by load, vertical cracks developed upwardly over residual cavern at mining boundary.With load increasing, overlying strata wholly broke along vertical cracks till the cracks developed to surface, which largely influenced structure safety of proposed buildings.%针对在深厚比较小的浅部老采空区地表建设易引发该区覆岩失稳破坏的问题，采用相似材料模拟试验方法，对浅部老采空区残留空隙分布、建筑荷载影响下的覆岩空隙演化及地表沉降特点进行了研究。研究结果表明：受荷载影响的老采空区残留空隙二次压缩或失稳是浅部老采空区地表产生新的较大变形的根本原因；老采空区覆岩残留空隙主要包括：岩层结构已平衡的在无外因扰动下将长期存在的离层、垮落和裂缝带内破损岩层虽经历长时间压实但仍存在的裂隙、开采边界覆岩未完全垮落而形成的空洞；浅部老采空区覆岩内不存在弯曲带岩层的整体性支撑效应或此类覆岩较薄不足以分散荷载的影响，荷载直接作用在垮落和裂缝带破损岩体上，使得破损覆岩再次压密失稳破坏；采空区边界残留空洞受荷载影响，在其上方发育纵向裂缝，随着荷载的增大覆岩沿纵向裂缝整体性断裂，直至切冒到地表，对拟建建（构）筑物的结构安全影响极大。