考虑软弱夹层蠕变特性的某矿山边坡稳定性研究

Study on slope stability of a mine considering creep characteristics of soft and weak interlayer

以往研究含软弱夹层的边坡稳定性时,多将软弱夹层视作弹塑性体,而忽略其蠕变特性。但在实际工况中,软弱夹层的蠕变特性对边坡稳定性存在极大的影响。为研究软弱夹层的存在状态对岩土体强度变形特性的影响,选用PFC3D离散元软件进行不同条件下的复合岩样标准三轴试验模拟,深入分析其强度变化规律、变形破坏特征以及裂缝分布特性;选用FLAC3D软件建立了依托实际工程的三维模型,选用考虑蠕变特性的Burgers模型,对露天矿山边坡的稳定状态进行深入分析,得到如下结论:1)软弱夹层的倾角、厚度、层数等参数均对复合岩样的强度有显著影响;2)不同软弱夹层倾角下的试验均为剪切破坏,而夹层厚度增大使得试样逐渐转变为张拉破坏,随着夹层层数增加,试样出现更明显的张拉破坏;3)考虑露天矿山软弱夹层的蠕变特性所得强度折减系数比不考虑时降低了约10%,为工程提供了更高的强度储备,可供其他工程参考。

In the past,when studying the stability of slopes containing weak inclusions,the weak inclusions were mostly regarded as elastic-plastic bodies,and their creep characteristics were ignored.However,in the actual working condition,the creep characteristics of the weak sandwich layer greatly influence the slope′s stability.To study the influence of the existing state of weak interlayer on the strength-deformation characteristics of the geotechnical body,PFC3D discrete element software was selected to carry out standard triaxial test simulation of composite rock samples under different conditions,and deeply analyze its strength change law,deformation damage characteristics and crack distribution characteristics.FLAC3D software was used to establish a 3D model based on the actual project,and the Burgers model,which takes creep characteristics into account,was selected to conduct an in-depth analysis of the stability state of the slope of the open pit mine.The following conclusions were obtained.1)Parameters such as dip angle,thickness,and the number of layers of the weak interlayer all have significant effects on the strength of composite rock samples.2)The tests with different inclination angles of the weak interlayer are shear damage,while the increase of the interlayer thickness makes the specimens gradually change to tensile damage,and with the increase of the number of interlayer layers,the specimens appear more obvious tensile damage.3)The strength reduction coefficient obtained by considering the creep characteristics of the weak interlayer in the open pit is about 10%lower than when it is not considered,which provides a higher strength reserve for the project and can be used as a reference for other projects.