反倾层状岩体斜坡弯曲-拉裂两种失稳破坏之判据探讨

对反倾层状岩体斜坡弯曲-拉裂的失稳破坏判据,已有研究分别基于两种力学模型进行推导,即竖直压杆弹性屈曲稳定和平直梁弯折破坏模型,但对层间错动阻力及挠度产生附加弯矩等因素未加以考虑,不尽合理。在反倾斜坡岩层受力分析基础上,建立考虑了板侧层间错动阻力的下端嵌固、上端自由的斜置等厚弹性悬臂板梁模型,统一地通过瑞利-里兹能量方法,推导了弹性屈曲临界条件和嵌固端弯折破坏临界条件。实例计算及讨论表明,弹性屈曲判据适用于陡立岩层;而中-陡反倾岩层应主要为弯折破坏,但层间的力学性质对弯折临界判据值具有较大影响。

BENDING YIELDING AND TENSILE CRACKING CRITERA FOR FAILURE OF ROCK SLOPE WHOSE DIP DIRECTION OPPOSITE TO THE DIP DIRECTION OF STRATA

There have been two mechanical models for the failure criteria of bending deformation in the rock slope with dip direction opposite to the dip direction of the rock strata.The models are developed using the elastic buckling model of averticam compressive bar and the bending cracking model of a horizontal beam.Whereas,some important factors,such as the additional bending moment induced by the deflection and the slipping resistance on the interface of rock layers are not considered.In this paper,based on the mechanical analyses of the anti-dip rock layers,a model of the slanting elastic cantilever beam with fixed bottom and freeuop boundary and equal thickness is established,in which the slipping resistance on beam’s side face is taken into account.Rayleigh-Ritz energy method was introduced to develope the critical conditions of the elastic buckling of the beam and the bending fracture of the fixed bottom.The application in real case analyses and the discussions afterwards indicate that the elastic buckling model is applicable in very steep rock stratum,and that the bending fracture is the deforming and failure mechanism of median steep to steep anti-dip layered slope.Furthermore,the critical conditions of bending fracture is significantly influenced by the mechanical properties of the interface between layers.