【作者】 李伟；

【导师】 王旭春；

【作者基本信息】 青岛理工大学 ， 土木工程， 2018， 硕士

【摘要】 高铁穿越采空区面临诸多问题,对于高速铁路同时穿越软岩与采煤沉陷区的研究案例相对较少,没有形成包括勘察探测、稳定性评价、隐患区治理及路基加固在内的系统化的研究方法。因此,针对该方面展开系统深入的研究具有重要的理论意义和实际工程价值。本文依托贵南高铁南宁市区段穿越软岩采煤沉陷区工程,通过勘察调研、理论计算、数值模拟、室内试验等方法,对采空区稳定性、隐患区探测、地层活化变形、隐患区治理与路基加固等方面展开了系统化的研究。主要研究内容及结论如下:（1）通过历史资料整理分析、现场勘察,初步分析得出原采空区部位已经基本完成塌陷与弯曲变形,且大多已被含水淤泥或者塌陷泥岩充填。综合选线原则、工程概况、社会影响、征拆成本等方面因素,从原规划的3条线路方案中选取线位方案3作为高铁规划通行线路。（2）通过理论计算与FLAC^3D数值模拟相结合的方法对大盘井上九煤层开采引起的地层变形及地表沉降进行分析。计算结果与模拟结果对比分析得出大盘井采空区最大地层沉降可达1319.10mm,最大水平变形为457.19mm,研究区内望胜岭正断层的存在将导致地层变形程度不一。规划高铁线路下伏地层受开采变形影响程度较大。（3）通过终采时间分析、集中移动变形与残余变形计算,对原大盘井采空区稳定性进行分析与评价。大盘井采空区地表移动延续时间约为500天,对比37年的终采时间可知采空区达到初步稳定。通过原始Knothe时间函数进一步推算得出大盘井采空区地表沉陷在闭井后5年内已经完成,达到集中移动变形稳定并进入残余变形期。根据极限下沉曲线推导得出的公式计算得出残余变形期变形参数,结合集中移动期计算结果分析得出大盘井采空区各项指标同时达到场地稳定性要求,在不受外界荷载重新扰动情况下采空区已经达到稳定状态。（4）采用地震映像法与高密度电阻率法结合的物探方法探测得出残余隐患区分布情况,并通过钻探方法对物探结果进行可靠性验证。残余隐患区多已被坍塌泥岩或含水淤泥充填,在上部荷载作用下,残余隐患区的存在可能加剧地层变形。（5）通过FLAC^3D软件分三种工况模拟分析荷载作用下残余隐患区的存在对地层变形的影响。残余隐患区的存在会对地层变形产生不利影响,充填物性质越差,路基工后沉降越大,模拟工况中最大附加沉降变形值为61mm。施加高铁荷载后各工况下的沉降变形基本一致（22²3mm）,没有引起残余隐患区作用下的进一步沉降,分析得出高铁荷载产生的应力几乎不会传递到残余隐患区。由于残余隐患区存在充水情况,在外荷载作用下残余隐患区周边地层可能生成新裂隙,引起水体渗流,加剧地层变形。（6）采用全胶结注浆法对残余隐患区进行治理,在残余隐患区治理完成的基础上采用桩板复合结构对高铁路基进行加固。运用FLAC^3D模拟软件对路基加固效果进行了模拟分析,得出路基表面最大沉降值为8.6mm,其中路基工后沉降为5.2mm,高铁荷载作用下沉降增大3.4mm,能够达到高铁设计规范中“工后沉降不宜超过15mm”的要求。桩板复合结构在软岩路基加固中效果显著。更多还原

【Abstract】 There are many problems in the high-speed railway crossing the goaf,and there are relatively few research cases on the high-speed railway crossing the soft rock and coal mining subsidence area at the same time,and systematic research method including survey detection,stability evaluation,hidden area management and roadbed reinforcement have not been formed.Therefore,systematic and in-depth research on this aspect has important theoretical significance and practical engineering value.This paper relies on the Nanning section of the Guinan High-speed Railway to cross the soft rock mining subsidence area project,systematic research has been carried out on the stability of the goaf,detection of hidden danger areas,stratum activation deformation,control of hidden danger areas and roadbed reinforcement through the methods of investigation and survey,theoretical calculation,numerical simulation and laboratory test.The main research contents and conclusions are as follows:（1）Through historical data analysis and site survey,preliminary analysis shows that the collapse and bending deformation of the original goaf have basically completed,and most areas of original goaf have been filled with water-bearing silt or collapsed mudstone.Based on the factors of comprehensive line selection,project overview,social impact,and cost of demolition,the line plan 3 is selected from the original three planned routes as the high-speed railway planning route.（2）The stratum deformation and surface settlement caused by the mining of Shangjiu Nine Coal Mine in Dapanjing were analyzed through the combination methods of theoretical calculation and FLAC^3D numerical simulation.Comparing the results of calculation and simulation,we can know that the maximum ground settlement in the goaf of Dapanjing can reach 1319.10mm,and the maximum horizontal deformation is 457.19mm.In addition,the existence of the Wangshengling normal fault in research area will lead to different degrees of stratum deformation.The stratum below the high-speed railway planning line is affected by mining deformation.（3）The stability of the original Dapanjing goaf was analyzed and evaluated by the analysis of the mining time,the concentrated movement deformation and the residual deformation calculation.The surface movement of Dapanjing goaf is about 500 days,and it is known that the goaf has reached initial stability compared with the 37-year final mining time.It is further estimated from the original Knothe time function that the surface subsidence of the Dapanjing goaf has been completed within 5 years after the mine closed,reaching the stable period of concentrated moving deformation and entering the residual deformation period.According to the formula derived from the limit sinking curve,the deformation parameters of the residual deformation period are calculated,and combined with the calculation results of the centralized movement period,it is concluded that the various indicators of Dapanjing goaf meet the site stability requirements at the same time,and the goaf has reached a stable state without being disturbed by external loads.（4）The geophysical method combined with seismic mapping method and high-density resistivity method is used to detect the distribution of residual hidden danger zone,and the reliability of geophysical results is verified by drilling.The residual hidden danger zone has been filled with collapsed mudstone or water-bearing silt,the existence of the residual hidden danger zone may aggravate the stratum deformation under the upper load.（5）The influence of the existence of residual hidden danger zone under load on the stratum deformation is simulated by FLAC^3D software with different working conditions.The existence of residual hidden danger zone will adversely affect the stratum deformation,the worse the filling property is,the larger the subgrade post-construction settlement is,and the maximum additional settlement deformation value in the simulated working condition is 61mm.The settlement deformation under all working conditions is basically the same（22²3mm）after applying high-speed railway load,and there is no further settlement under the influence of the residual danger zone,it is analyzed that the stress generated by the high-speed railway load is hardly transmitted to the residual hidden danger zone.Due to the water filling condition in the residual hidden danger zone,new cracks may be formed in the surrounding stratum of the residual hidden danger zone under the external load,causing water body seepage and aggravating the stratum deformation.（6）The residual hidden danger zone is treated by the full cementing grouting method,and the high-speed railway foundation is strengthened by the pile-slab composite structure on the basis of the completion of the residual hidden danger zone.FLAC^3D software was used to simulate the roadbed reinforcement effect,it was found that the pile deformation and side friction resistance played a normal role under load,and the maximum settlement value of the subgrade surface is 8.6mm,in which the subgrade settlement is 5.2mm,and the settlement under the high-speed railway load is increased by 3.4mm,which can meet the requirement of“post-construction settlement should not exceed 15mm”in the high-speed railway design specification.The composite structure of pile-slab is effective in the reinforcement of soft rock roadbed.更多还原