河北唐山某老采煤沉陷区建设场地地基稳定性评价

研究区内历史上存在强烈的以采煤为主的采矿活动，形成了大规模的采空塌陷，为了集约用地和防灾减灾，运用理论分析、定量计算及现场观测相结合的技术路线，根据“三带”理论对采空区波及地表的影响程度和地表移动的范围定性定量评价，应用应力分析法对场区进行稳定性分析。结果表明：该区大部分采空区基本稳定，目前可能处于残余变形阶段，地表处于相对稳定状态，残余变形在建筑物可承受范围之内；浅部采空区存在未完全塌实区，在地表建筑物荷载、地震及地下水等因素的影响下，仍存在二次活化的可能；中南部深部老采空区均超过5a，其“活化”是比较平稳和长期的过程，一般对地表的影响是较小的和缓慢的沉降，其不均衡沉降量是有限的；中南部存在原开滦矾土矿，采矿方式为洞采，赋存深度较浅，在地表建筑物荷载的作用下极易发生塌陷而发生“活化”，危险性大。针对不同的区域和“活化”类型，提出相应的防治措施，对于建设场地地基稳定性评价工作具有一定的参考价值。

Construction Site Foundation Stability Assessment in an Old Gob Subsidence Area in Tangshan,Hebei

There were mining activities mainly coal mining in the study area and formed extensive gob subsidence. For the purpose of intensive use of land and hazard prevention and mitigation, along the technical route of combined theoretical analysis, quantitative com- putation and site observation, Based on the ＂three （caving, fracture and bending） zones＂ theory, qualitatively and quantitatively as- sessed extent of gob area impacts spread to surface and surface displacement range, and using stress analysis method carried out site stability analysis. The result has shown： most gob areas in the area are basically stable and in a residual deformation stage; surface is in a relatively stable condition; residual deformation is within structure acceptable range. Not fully collapsed compaction area is existed in shallow gob area, under the impacts from surface structural load, earthquake and groundwater, still has possibility of secondary activa- tion. The age of old gob area in central south part is more than 5 years, thus the activation process is rather stable and long-range, gen- erally less impact on surface and slow subsiding, its uneven settlement is limited. In central south part had a Kailuan bauxite mine origi- nally, its mining method was tunnel mining, rather shallow occurrence, under the surface structural load, easy to collapse and activated, thus rather hazardous. In allusion to different regions and activation types, put forward corresponding controlling measures, thus has cer- tain reference value in construction site foundation stability assessment.