急倾斜煤层老采空区地基稳定性评价

Evaluation of foundation stability in the old goaf of sharply inclined coal seams

为了保障采空区地表土地高效利用,掌握采空区地基稳定性现状对后期城市规划、确保人民生命财产安全意义重大。以唐山市某煤矿下伏急倾斜煤层老采空区为研究对象,在明确老采空区地质条件、煤层开采情况下,综合采用瞬变电磁法、三维高密度电法探测手段,并在重点区域布设钻探工程加以验证;结合本地实际经验及地质调查成果资料,运用概率积分法计算得出研究区地表残余变形,进而掌握研究区地基整体稳定性。结果表明:①研究区内存在多处残留采空空洞,其分布特征与煤层露头分布走向相关性较好;②研究区未来地表沉降变形将以残余变形为主,地表最大残余下沉量为300.68 mm,地基稳定性为欠稳定—基本稳定。鉴于采空区分布及地表残余变形计算结果,综合分析认定研究区地基稳定性较差,为保证土地后续安全利用,需采取高效治理措施。该研究方法可为急倾斜煤层老采空区探测及地基稳定性评价提供技术参考。

To ensure the efficient use of surface land in the goaf,it is of great significance to grasp the current situation of foundation stability in the goaf for later urban planning and to ensure the safety of people′s lives and properties.This paper takes the old goaf of a coal mine under the sharply inclined coal seam in Tangshan City as the research object,the geological conditions of the old goaf and the mining situation of the coal seam were clarified.Transient electromagnetic method and three-dimensional high-density electrical method detection methods were comprehensively adopted,and drilling projects were deployed in key areas for verification.Combined with local practical experience and geological survey results data,the probability integration method was used to calculate the residual deformation of the surface in the study area,and the overall stability of the foundation in the study area was mastered.The results showed that:①there were many residual mining voids in the study area,and their distribution characteristics correlated well with the distribution of coal seam outcrops;②the future surface subsidence deformation in the study area would be mainly residual deformation,the maximum residual subsidence on the surface was 300.68 mm,and the stability of the foundation was unstable-basically stable.Because of the distribution of the goaf and the calculation results of the surface residual deformation,the comprehensive analysis concludes that the stability of the foundation in the study area is poor,and efficient management measures are needed to ensure the subsequent safe use of the land.The research method can provide technical references for the detection and foundation stability evaluation of old goafs in sharply inclined coal seams.