软土边坡开挖变形特征与临界破坏范围数值模拟

Numerical Simulation of Deformation Characteristics and Critical Failure Range of Soft Soil Slope during Excavation

由于软弱夹层边坡塑性剪切变形是软化参量,在分析边坡临界破坏范围时受到不稳定安全因子影响,无法充分考虑应变软化过程,导致临界破坏范围分析结果不精准。为了解决这个问题,采用了数值模拟方法。通过多点观测方式对巷道断面地质剖面进行观测,统计边坡注浆前后拱顶累计沉降值,分析边坡开挖变形特征。在FLAC^(3D)软件支持下构建应变软化临界破坏数值模型,通过建立Mohr-Coulomb(摩尔-库仑)屈服判据与软化参量之间的关系,反映塑性剪切变形参量的软化特性。计算斜坡安全系数与斜坡滑面间距,以极限均衡理论为基础,结合Geo-slope法获取边坡极限失稳安全系数,以安全系数作为评价指标,对边坡的极限稳定状况进行了研究,并得出了临界失稳范围。以山西省一地质工程为研究对象,由算例分析结果可知,该方法剪应变增量较高,与临界破坏范围三维分析方法一致,且塑性安全系数达到最大值8.0,与实际值一致。

Because the plastic shear deformation of the weak intercalated slope is a softening parameter,it is affected by the unstable safety factor when analyzing the critical failure range of the slope,and the strain softening process cannot be fully considered,resulting in inaccurate analysis results of the critical failure range.To solve this problem,a numerical simulation method was adopted.Through multi-point observation way,the geological section of the roadway section was observed,the accumulated settlement of the arch crown before and after the grouting of the slope was counted,and the deformation characteristics of the slope excavation were analyzed.Under the support of FLAC^(3D)software,a numerical model of strain softening critical failure was built,and the relationship between Mohr-Coulomb yield criterion and softening parameters was established to reflect the softening characteristics of plastic shear deformation parameters.The safety factor of slope and the distance between sliding surfaces of slope were calculated.Based on the limit equilibrium theory and combined with the Geo-slope method,the safety factor of slope ultimate instability was obtained.With the safety factor as the evaluation index,the limit stability of slope was studied and the critical instability range was obtained.Taking a geological engineering in Shanxi Province as the research object,the analysis result of the example showed that the shear strain increment of this method was high,which was consistent with the three-dimensional analysis method of critical failure range,and the plastic safety factor reached the maximum value of 8.0,which was consistent with the actual value.